Plane Talk: Hangar 9 Mustang PTS
FRANK GRANELLI
• Ready to run with everything included with simulator and
buddy cord.
• Upgradable to a sport model with higher performance and
functional flaps.
Pluses and Minuses
+
• Clear canopy is glued in place, making it difficult to install a
scale pilot.
• Landing-gear mounting blocks could have been built stronger.
There was a failure after 43 flights.
With the training gizmos removed, the
Mustang in this trainer starts to shine
through. Inverted flight and Outside Loops
from level are comfortable to do. Costello
photo.
The Mustang PTS is so easy to land that one-wheel crosswind
touchdowns are routine, even in extreme nose-high attitudes.
Make sure to carry some power in the approach. Costello photo.
Clean, the P-51 Mustang is a joy to throw around the sky. It’s better behaved than most
Sport Scale models its size, but “Marie” can perform with the best of them. Frank
Costello photo.
THE DATE IS February 22, 1944. The
skies over Europe are again aflame. It is
Tuesday of “Big Week”: the American air
offensive to destroy the Luftwaffe. American
B-17 and B-24 bombers of the 15th Air Force
are nearing Regensburg to destroy German
aircraft factories.
Suddenly, black dots appear on their
noses. “German fighters, 4 o’clock” echoes
over hundreds of intercoms. Closing speeds
approach 500 mph as the dots become Me
109 fighters starting head-on attacks.
Crew members crouch behind tiny armor
plates, knowing to expect the worst. Then,
high in the Western sky, the sun flashes
brightly off of bare aluminum as silver wings
bank 90° and roll into their dives. At more
than 450 mph, the Mustangs of the yellowtailed
52nd Fighter Group race in front of the
bombers, making the airways ahead safe.
The Mustang Legend continues.
The date is June 4, 2005. It is Saturday
and a 30-something-year-old man appears at
the RC field with his young son. He has been
here before. Even he is not sure why he has
come back.
His imagination has been captured by the
aerobatic airplanes that seem to rotate the
sky itself, while Scale models subtly link the
two aviation worlds. He has always had a
“passing” interest in aviation, but today the
field has given his interest concrete form.
He finally starts to talk to a few pilots—
especially the one with the model of the
North American P-51 Mustang, which was
the hero of so many airplane movies he grew
up with. He has wanted to fly one since he
saw his first “airplane movie.”
However, this man quickly learns that
you can’t learn to fly model aircraft with a
Speed brakes are already attached to the landing gear. Just screw
in place with the nylon straps. Make sure the bottom edge of the
speed brake rests against the front screw as shown to prevent
rotation.
The Mustang PTS is a true RTF airplane with great photo-illustrated instructions and
even a flight simulator.
One wing half has a tab with two holes. The front hole sets the
flaps to zero. Hooking the factory-made linkage to the rear hole
provides 26° of flaps.
Install the flap servo in the factory-prepared mount. Use the small
end of the output arm and set maximum travel to 51% to provide
26° of flap.
Everything on the wing except the wheels, even the servo leads,
are factory installed. Slide the wing halves onto the aluminum
tube and lock in place with two small screws.
Mustang. At least two years of flying one of
those boxy, Cessna-looking typical trainers
and then an advanced trainer is the minimum
experience required before he can even think
about buying the Mustang. He is
disappointed but still not totally lost to us.
Then his son says, “I want to fly the
fighter—not one of those stupid, old things.”
They walk away and we lose two potential
new modelers.
How many times have RC instructors
seen the sad disappointment on potential
model pilots’ faces when they have
discovered the facts about learning to fly?
Many understand it and buy that high-wing
trainer. But that doesn’t mean they are happy
about it! Many others walk away, usually
believing that the difficulties are being
exaggerated or that three airplanes are too
much, or they are let down because they
can’t “have it all” now.
If the date had been September 4, 2005,
the outcome of that visit to the RC field
might have been vastly better. You want to
learn to fly with a Mustang? Great! Not only
can you learn with one, but that same
Mustang can teach you advanced piloting
techniques while becoming one of the bestperforming
Sport Scale aircraft available. It
is three airplanes in one.
Even better, this Mustang is an RTF. No
building skills or special equipment is
required. If you can spare 30 minutes to
assemble the model, you can learn
everything about RC piloting.
The cost is less than $400 for the
airplane, radio, engine, and all airframe
accessories, all factory installed. You save even more money since
you will not need to buy that follow-up “advanced trainer” or
Mustang kit; all three are in the Mustang PTS. There is definitely
potential to grow our sport with this model.
Everything with the Mustang is prebuilt, and even a flight
simulator is included. Unfortunately my computer does not have the
right connection for the simulator cord, and an adaptor has not been
located yet. This part of the review will have to be included on Model
Aviation’s Sport Aviator online magazine (www.masportaviator.com).
Assembly time really is less than 30 minutes. I finished the
aircraft in 21 minutes using just a screwdriver and pliers. Well, I did
use a wrench to make sure the propeller was tight, but that shouldn’t
count since it was.
Complete Assembly: The first job was the wing. As with a modern
airliner, all the real secrets to this aircraft’s performance are located
there. Flaps, speed brakes, ailerons, bolt-on wing-mounting system,
radiator scoop, and LE cuffs are part of the main wing, yet assembly
time is only 10 minutes.
As a photo shows, each wing half slides onto an aluminum tube.
There is an alignment pin to ensure that everything is true and it
works as advertised. The entire wing is held together by a single
nylon strap.
After joining the wing panels, bolt the landing gear in place as
shown and then use the factory-made flap linkage rod to connect the
flaps. The flaps use independent aileron-style torque tubes and are
connected to a fixed wing tab, as shown. The clear-plastic wing
droops are installed at the factory. The wing is finished at this point.
However, I strongly suggest that every potential Mustang pilot
install the flap servo before the first flight. The mount is already
there, and installation takes roughly five minutes.
Completing the fuselage involves bolting on the tail feathers, as
shown. The control surfaces and control horns are already installed.
Use the two lock nuts provided to bolt everything firmly in place.
Everything back there fit well, and it was good to see that the
stabilizer’s bolt holes were reinforced at the factory. Connect the two
control rods to the middle hole on the control horns. The last step is
to bolt the exhaust stacks onto the fuselage so that the 1,450-
horsepower, 12-cylinder Merlin engine can make the ground shake.
Power and Control: No, there isn’t a scaled-down V-1650-7regimes, including downhill and in landing
approaches.
In addition, this propeller’s pitch appears
to be less than 6 inches but is unidentified.
The lower pitch further reduces airspeed at
all throttle settings. Since engine rpm is
reduced under the three-blade’s extra load,
so are maximum airspeeds.
The radio compartment is factory built
with a removable cover to get at the receiver
and battery. The receiver is the popular JR
R700 six-channel FM model.
Onboard power is from JR’s 4N600: a
4.8-volt, 600 mAh Ni-Cd battery pack. The
five factory-installed servos are JR 537 ballbearing
sport units. The cored servo motor
puts out 43 in.-oz. of torque while rotating a
60° arc in just .25 second.
Few RTF aircraft offer ball-bearing
servos. But then, few RTF aircraft are guided
by a computer transmitter.
The Mustang’s transmitter is JR’s fivechannel
XF421, which is a great introductory
computer radio. It features digital travel
adjustments, basic mixing (including
“flaperon”), easy servo reversing, and
memory storage for two aircraft. Few RTFs
feature such an advanced transmitter. The
XF421 is powered by a 600 mAh Ni-Cd
pack and is compatible with most
transmitters for a “buddy” link via the
included trainer cord.
But is this really a trainer? So it was easy to
put together. But come on; it is a Mustang
after all. Even the Army Air Force didn’t put
pilots in Mustangs until they went through
primary and advanced trainers. And they
were sending people out to get shot at!
Look at the heavily tapered wing with the
narrow-chord wingtips. Tell me that won’t
tip-stall into a snap roll at the first
provocation. And that semisymmetricalairfoil
wing is small for a 6.5-pound trainer.
Landing speeds will have to be high. The
airplane is so streamlined that everything
will be happening fast.
So they hung some gizmos all over the
wing, but how much can they help? You
can’t even see that stuff near the wingtips, so
how was this fighter transformed into a
typical trainer? Skull sweat and good design,
that’s how.
Each “gizmo” has a design purpose, and
each one worked as intended. The “speed
brakes” mounted on the landing gear add
drag, reducing the top speed while
preventing the airplane from gaining a great
deal of airspeed when the nose starts to point
earthward. The wing flaps, set at 26°, create
more drag to further slow the airplane while
increasing the wing’s lifting force.
Working together, both devices make it
easy to set up correct landing approaches.
Those invisible—in the air or when trying to
photograph the darn things—clear-plastic LE
cuffs also increase wing lift; first by
increasing the wingtip area and second by
acting as a “flat-bottom” section of the
symmetrical-airfoil wing. The increased
wingtip area reduces tip-stalling to zero.
But the best way to find out whether or not
this is a typical trainer is to fly it. So we did.
In fact, 12 pilots flew it during 57 test flights.
Therefore, some of what follows is
opinion—sometimes educated, sometimes
otherwise.
The net result is that the Mustang PTS
flies identical to a typical trainer. It is slow
and gentle with no bad tendencies. It flies
like a trainer but does not take off or land
like one. This difference is perhaps the
Mustang’s greatest benefit to the new RC
pilot. Let’s go through some flights.
Start the engine. All the Evolution Alpha
engine ever required was to prime the
carburetor and then rotate the spinner cone
backward. It started every time without using
an electric starter.
Taxiing is beyond easy. The landing gear,
with those gigantic tires, is canted so far
forward that it is beyond impossible to tip
the airplane onto its nose. The gear is widely
spaced for excellent ground handling.
Ground steering is positive and not sensitive.
The takeoff roll requires nontrainer
technique. With rudder throw set as
instructed and with the three-blade propeller
providing extra torque, full right rudder is
required for a straight takeoff roll.
Start the airplane rolling slowly and put in
full right rudder while going to full power.
The airplane rolls straight down the runway.
If you are late with the rudder, it may be
impossible to get back to the runway heading.This teaches the student pilot from the
start how to manage rudder during the
takeoff rolls of future, more powerful
aerobatic and Scale models. Rolling any
aircraft down the runway on takeoff will
hold no mystery for the PTS pilot.
As soon as the Mustang PTS breaks
ground, it goes into full training mode. The
climbout is gentle and noncritical.
Mismanage the elevator, even to stalling
the airplane, and the Mustang mushes on up,
climbing slightly with each oscillation.
There is no tip-stalling tendency or nose
drop. Release full up and the airplane goes
back to flying, slowly climbing to altitude
with plenty of time for the new pilot to think
ahead.
Cruise flight requires approximately 60%
throttle. Straight flight is stable. Turns with
banks up to roughly 45° require minimum
up-elevator to hold altitude. Steeper banks
take approximately 30% of the available upelevator
to remain level.
Letting the nose drop in the turn, as most
student pilots would, produces little
noticeable speed increase, and there is never
a tendency to “balloon,” or raising the nose
while losing airspeed, as most trainers do
once the wings are leveled. This is a good
thing since it reduces pilot workload.
Even during tight turns at slow airspeeds
there is never a tendency to tip stall or roll
out of the turn. The Mustang stays put as
directed, remaining tolerant of any abuse—
even full crossed-control stalls, right aileron,
and left rudder.
Spins are difficult and require power to
develop. Rotation stops immediately once
power or elevator input is reduced. Snap
rolls are more like giant barrel rolls, taking
approximately three seconds to complete.
Straight inverted flight is barely possible,
but level inverted turns are not; the airplane
runs out of down-elevator. The rudder is
notably ineffective, making knife-edge flight
impossible. So far the Mustang PTS flies
like every other typical trainer.
Power-off stalls are amazing. The wings
stay level, aileron control remains, and the
model just floats through the sky, defying
gravity and common sense. True, it comes
down, but slowly—maybe 200 feet per
minute or maybe less.
Starting from roughly 400 feet up, with
the engine at high idle—2,800 rpm—and
holding full up-elevator, the Mustang PTS
floats the entire available flight length of the
field, which was approximately 1/4 mile, and
is still roughly 100 feet from the ground.
This is not a recommended landing
technique because there could not be a
“flare,” breaking the descent before
touchdown, and the airplane would be
damaged. But add a bit of power to the
approach and reduce the elevator input, and
it could almost be. And that brings me to
landing the Mustang PTS.
Landing is different from that of a typical
trainer, which is usually executed by cutting
the engine to idle while approximately 75
feet high and 100 feet away from the runway
and then gliding in. However, the Mustang
PTS’s speed brakes, flaps, and LE droops
provide a good amount of drag.
Therefore, this airplane is landed as most
high-performance sport and Scale aircraft
are, using engine power. The approach and
touchdown are flown slowly at trainerlike
airspeeds, but approximately 30% engine
power is needed to “glide” to the runway.
The Mustang PTS teaches the new pilot
now—not later—how to land all those highperformance
sport and Scale airplanes
waiting in his or her future. Mastering the
power landing, with its intricate dance of
power for altitude and elevator for airspeedcontrol, can be difficult to learn once the
power-off typical trainer landing becomes
habit. This will not happen to the Mustang
PTS pilot.
The Mustang’s extra drag is why I
suggest installing operating flaps from the
start. There isn’t a great deal of glide with
everything hanging out in the slipstream. If
the engine runs out of fuel or quits, the
runway is unreachable unless it happens to
be close when the propeller goes rigid.
Raising the flaps dramatically extends
gliding distance, allowing the airplane to
“make the field” in such situations.
Using the transmitter’s travel-adjust
feature, set maximum flap movement—
channel 5—to 51%. This provides the same
26° of flap deployment as the fixed
mounting point would.
Three student pilots who had not yet
soloed flew the Mustang PTS in the air only,
using the “buddy box” system. Two flew
without the instructor’s having to take
control, and the third, having flown only a
small electric-powered trainer, needed
instructor help only three times in the eightminute
flight. All pronounced the Mustang
PTS to be a great trainer and felt they could
easily learn to fly with one.
Five newly soloed pilots flew the airplane
and felt the same way. Four club instructors
gave the model a fair workout, and all
thought they could easily teach new pilots
how to fly with it.
Is it a typical trainer? Yes, but with a
twist.
Learning to fly with the Mustang PTS is
as easy as learning on a typical trainer, but
the process will require two or three hours of
extra airtime to learn the advanced takeoff
and landing skills. But after soloing the
Mustang PTS pilot will have those additional
advanced skills and graduate flight school a
better flier, enjoying more complete piloting
skills for the experience.
Beyond Training: The idea behind the
Progressive Training System (the “PTS” in
Mustang PTS) is that the airplane can
quickly be reconfigured for more advanced
performance as the pilot’s skills advance.
Once the new pilot solos and has mastered
basic skills, the Mustang PTS is ready to take
him or her to the next step.
According to Hangar 9, the first step is to
remove the landing-gear speed brakes. I
believe the first step is increasing the amount
of elevator travel to 105% up and 120%
down. Rudder movement should be set to
150%. The ailerons are factory set at 75%
travel, so move those limits to 100%.
With all that done, the airplane becomes
more critical of improper elevator inputs and
will actually drop the nose in the stall.
Ground handling becomes more sensitive
and less than full right rudder is required for
takeoff.
The roll rate quickens, but not that much.
It becomes possible to spin the airplane
without using engine power to aid rotation
entry. Inverted flight, straight and turns,
becomes possible, but no Outside Loops yet!
After mastering this setup, remove the
speed brakes which are held in place with
two plastic tie wraps. Cut them with a hobby
knife (be careful) or use wire clippers.
Removing the speed brakes increases the
Mustang’s airspeed by roughly 15%. Loop
diameter increases from 50 feet to
somewhere near 75 feet. The airplane’s
airspeed become more pitch related as well.
Since cruise airspeed is higher, all the
controls become that much more sensitive.
Everything else remains basically the same;
there are still no bad habits.
These two small changes move the
Mustang approximately one-third of the way
toward offering Sport Scale piloting
challenges. It remains docile in every way,
but things happen faster and the airplane is a
bit more responsive. This is a great
intermediate stage that usually requires
purchasing an advanced trainer.
The next step is to raise those flaps.
Either hit the transmitter switch or reset the
mechanical flaps to the “zero” hole on the
wing tab. Now things change a little more.
Airspeed increases to roughly 50% more
than the original speed. The airplane will
pick up speed if the nose points below level.
Roll rate increases, and all the controls
become more sensitive. There are no trim
changes when flaps are deployed.
Without flaps and speed brakes, throttle
control during landing approaches becomes
more critical. Takeoffs require longer ground
runs, so rudder-control difficulties increase.100 feet, and good stall turns are now
possible. For the first time knife-edge flight
and Slow Rolls are manageable. However,
the airplane remains docile and has no
unwelcome surprises awaiting the unwary
pilot.
The LE droops are held in place with
clear tape. Peel the tape away, and the
droops are history. Before removing these
lift devices, the pilot should be comfortable
with the airplane’s handling and be able to
easily manage the increased performance up
to this point. Without the droops, the
Mustang loses the PTS label and matures
into a P-51 Mustang fighter.
True, the Mustang remains an excellentflying
Sport Scale aircraft—maybe one of
the best for its size—but when all the
training aids are gone, so is the safety net. If
you pull a turn too tightly, with too much upelevator,
the P-51 will drop the bottom wing,
rotating into the turn. There is no snap roll,
but the wing drop is quick.
Single stalls remain controllable with
a straight-ahead nose drop, but holding
the aircraft into multiple deep stalls, with
no flaps, will eventually lead to a snap
roll. Spin rotation is fast, but recovery
still happens as soon as the controls are
centered. Keep the nose level, or below,
during final approach, or unfortunate
surprises may await the pilot if the
airspeed is permitted to drop too far.
However, performance also increases.
Full-speed “strafing runs” are exciting as
they originally were. Loops approach 125
feet in diameter. Slow rolls are great, but it is
still nearly impossible to hold knife-edge
flight. So move the rudder control rod to the
innermost hole in the control horn, and
welcome to Four Point Rolls.
Outside Loops are easy but do require
small rudder input at the top to remain on
heading. Inverted flight, multiple inverted to
inverted rolls, and outside snap rolls (downelevator
used from inverted flight) are pretty,
but not so fast that they are difficult to
manage. Inverted spins rotate more slowly
than upright; recovery is just as easy.
The last step is to replace the three-blade
propeller with a two-blade performance
propeller such as the APC 10 x 6 or 11 x 5 or
an equivalent. At these maximum power
levels, the Evolution Alpha rockets the P-51
along at a respectable top speed.
Loops top 150 feet in diameter and rolls
become fast. Flying Inside and Outside
Avalanches—Loops with snap rolls at the
top—are fun, and knife-edge flight is better
but remains rudder-limited. Field-length
Slow Rolls are eye-catching.
The 10 x 6 propeller increases approach
speeds, requiring an idle of less than 2,200
rpm. I recommend the 11 x 5 as the best
choice.
However, there is a price for this
increased performance. A truly reliable idle
near 2,300 rpm is required for manageable
landing approaches, or just use the flaps.
Airspeeds at all throttle settings are faster.
The aircraft accelerates much faster when
taking off, so the whole maneuver happens
quickly. The P-51 gains speed in any descent
mode. All these characteristics are common
to most Sport Scale models, but this aircraft
handles the increased performance a little
better than most others do.
Most P-51s do not fly around with big
wheels hanging out the bottom, so
mechanical retracts might be in this
airplane’s future. That upgrade will take
some engineering on my part. I wonder
how far this PTS concept can be pushed.
To find out what else happened with this
model, check the Sport Aviator Web site.
Since most MA readers are pilots who have
some experience, this review focused more
on the PTS upgrades. MA Associate Editor
Michael Ramsey has written an excellent
Mustang PTS review for Sport Aviator that
focuses on the airplane as a typical trainer,
and it includes all the performance
numbers for the various PTS
configurations. MA
Frank Granelli
[email protected]
Distributor:
Horizon Hobby, Inc.
4105 Fieldstone Rd.
Champaign IL 61822
(877) 504-0233
www.hangar-9.com
Edition: Model Aviation - 2006/02
Page Numbers: 55,56,57,58,61,62,64
Edition: Model Aviation - 2006/02
Page Numbers: 55,56,57,58,61,62,64
Plane Talk: Hangar 9 Mustang PTS
FRANK GRANELLI
• Ready to run with everything included with simulator and
buddy cord.
• Upgradable to a sport model with higher performance and
functional flaps.
Pluses and Minuses
+
• Clear canopy is glued in place, making it difficult to install a
scale pilot.
• Landing-gear mounting blocks could have been built stronger.
There was a failure after 43 flights.
With the training gizmos removed, the
Mustang in this trainer starts to shine
through. Inverted flight and Outside Loops
from level are comfortable to do. Costello
photo.
The Mustang PTS is so easy to land that one-wheel crosswind
touchdowns are routine, even in extreme nose-high attitudes.
Make sure to carry some power in the approach. Costello photo.
Clean, the P-51 Mustang is a joy to throw around the sky. It’s better behaved than most
Sport Scale models its size, but “Marie” can perform with the best of them. Frank
Costello photo.
THE DATE IS February 22, 1944. The
skies over Europe are again aflame. It is
Tuesday of “Big Week”: the American air
offensive to destroy the Luftwaffe. American
B-17 and B-24 bombers of the 15th Air Force
are nearing Regensburg to destroy German
aircraft factories.
Suddenly, black dots appear on their
noses. “German fighters, 4 o’clock” echoes
over hundreds of intercoms. Closing speeds
approach 500 mph as the dots become Me
109 fighters starting head-on attacks.
Crew members crouch behind tiny armor
plates, knowing to expect the worst. Then,
high in the Western sky, the sun flashes
brightly off of bare aluminum as silver wings
bank 90° and roll into their dives. At more
than 450 mph, the Mustangs of the yellowtailed
52nd Fighter Group race in front of the
bombers, making the airways ahead safe.
The Mustang Legend continues.
The date is June 4, 2005. It is Saturday
and a 30-something-year-old man appears at
the RC field with his young son. He has been
here before. Even he is not sure why he has
come back.
His imagination has been captured by the
aerobatic airplanes that seem to rotate the
sky itself, while Scale models subtly link the
two aviation worlds. He has always had a
“passing” interest in aviation, but today the
field has given his interest concrete form.
He finally starts to talk to a few pilots—
especially the one with the model of the
North American P-51 Mustang, which was
the hero of so many airplane movies he grew
up with. He has wanted to fly one since he
saw his first “airplane movie.”
However, this man quickly learns that
you can’t learn to fly model aircraft with a
Speed brakes are already attached to the landing gear. Just screw
in place with the nylon straps. Make sure the bottom edge of the
speed brake rests against the front screw as shown to prevent
rotation.
The Mustang PTS is a true RTF airplane with great photo-illustrated instructions and
even a flight simulator.
One wing half has a tab with two holes. The front hole sets the
flaps to zero. Hooking the factory-made linkage to the rear hole
provides 26° of flaps.
Install the flap servo in the factory-prepared mount. Use the small
end of the output arm and set maximum travel to 51% to provide
26° of flap.
Everything on the wing except the wheels, even the servo leads,
are factory installed. Slide the wing halves onto the aluminum
tube and lock in place with two small screws.
Mustang. At least two years of flying one of
those boxy, Cessna-looking typical trainers
and then an advanced trainer is the minimum
experience required before he can even think
about buying the Mustang. He is
disappointed but still not totally lost to us.
Then his son says, “I want to fly the
fighter—not one of those stupid, old things.”
They walk away and we lose two potential
new modelers.
How many times have RC instructors
seen the sad disappointment on potential
model pilots’ faces when they have
discovered the facts about learning to fly?
Many understand it and buy that high-wing
trainer. But that doesn’t mean they are happy
about it! Many others walk away, usually
believing that the difficulties are being
exaggerated or that three airplanes are too
much, or they are let down because they
can’t “have it all” now.
If the date had been September 4, 2005,
the outcome of that visit to the RC field
might have been vastly better. You want to
learn to fly with a Mustang? Great! Not only
can you learn with one, but that same
Mustang can teach you advanced piloting
techniques while becoming one of the bestperforming
Sport Scale aircraft available. It
is three airplanes in one.
Even better, this Mustang is an RTF. No
building skills or special equipment is
required. If you can spare 30 minutes to
assemble the model, you can learn
everything about RC piloting.
The cost is less than $400 for the
airplane, radio, engine, and all airframe
accessories, all factory installed. You save even more money since
you will not need to buy that follow-up “advanced trainer” or
Mustang kit; all three are in the Mustang PTS. There is definitely
potential to grow our sport with this model.
Everything with the Mustang is prebuilt, and even a flight
simulator is included. Unfortunately my computer does not have the
right connection for the simulator cord, and an adaptor has not been
located yet. This part of the review will have to be included on Model
Aviation’s Sport Aviator online magazine (www.masportaviator.com).
Assembly time really is less than 30 minutes. I finished the
aircraft in 21 minutes using just a screwdriver and pliers. Well, I did
use a wrench to make sure the propeller was tight, but that shouldn’t
count since it was.
Complete Assembly: The first job was the wing. As with a modern
airliner, all the real secrets to this aircraft’s performance are located
there. Flaps, speed brakes, ailerons, bolt-on wing-mounting system,
radiator scoop, and LE cuffs are part of the main wing, yet assembly
time is only 10 minutes.
As a photo shows, each wing half slides onto an aluminum tube.
There is an alignment pin to ensure that everything is true and it
works as advertised. The entire wing is held together by a single
nylon strap.
After joining the wing panels, bolt the landing gear in place as
shown and then use the factory-made flap linkage rod to connect the
flaps. The flaps use independent aileron-style torque tubes and are
connected to a fixed wing tab, as shown. The clear-plastic wing
droops are installed at the factory. The wing is finished at this point.
However, I strongly suggest that every potential Mustang pilot
install the flap servo before the first flight. The mount is already
there, and installation takes roughly five minutes.
Completing the fuselage involves bolting on the tail feathers, as
shown. The control surfaces and control horns are already installed.
Use the two lock nuts provided to bolt everything firmly in place.
Everything back there fit well, and it was good to see that the
stabilizer’s bolt holes were reinforced at the factory. Connect the two
control rods to the middle hole on the control horns. The last step is
to bolt the exhaust stacks onto the fuselage so that the 1,450-
horsepower, 12-cylinder Merlin engine can make the ground shake.
Power and Control: No, there isn’t a scaled-down V-1650-7regimes, including downhill and in landing
approaches.
In addition, this propeller’s pitch appears
to be less than 6 inches but is unidentified.
The lower pitch further reduces airspeed at
all throttle settings. Since engine rpm is
reduced under the three-blade’s extra load,
so are maximum airspeeds.
The radio compartment is factory built
with a removable cover to get at the receiver
and battery. The receiver is the popular JR
R700 six-channel FM model.
Onboard power is from JR’s 4N600: a
4.8-volt, 600 mAh Ni-Cd battery pack. The
five factory-installed servos are JR 537 ballbearing
sport units. The cored servo motor
puts out 43 in.-oz. of torque while rotating a
60° arc in just .25 second.
Few RTF aircraft offer ball-bearing
servos. But then, few RTF aircraft are guided
by a computer transmitter.
The Mustang’s transmitter is JR’s fivechannel
XF421, which is a great introductory
computer radio. It features digital travel
adjustments, basic mixing (including
“flaperon”), easy servo reversing, and
memory storage for two aircraft. Few RTFs
feature such an advanced transmitter. The
XF421 is powered by a 600 mAh Ni-Cd
pack and is compatible with most
transmitters for a “buddy” link via the
included trainer cord.
But is this really a trainer? So it was easy to
put together. But come on; it is a Mustang
after all. Even the Army Air Force didn’t put
pilots in Mustangs until they went through
primary and advanced trainers. And they
were sending people out to get shot at!
Look at the heavily tapered wing with the
narrow-chord wingtips. Tell me that won’t
tip-stall into a snap roll at the first
provocation. And that semisymmetricalairfoil
wing is small for a 6.5-pound trainer.
Landing speeds will have to be high. The
airplane is so streamlined that everything
will be happening fast.
So they hung some gizmos all over the
wing, but how much can they help? You
can’t even see that stuff near the wingtips, so
how was this fighter transformed into a
typical trainer? Skull sweat and good design,
that’s how.
Each “gizmo” has a design purpose, and
each one worked as intended. The “speed
brakes” mounted on the landing gear add
drag, reducing the top speed while
preventing the airplane from gaining a great
deal of airspeed when the nose starts to point
earthward. The wing flaps, set at 26°, create
more drag to further slow the airplane while
increasing the wing’s lifting force.
Working together, both devices make it
easy to set up correct landing approaches.
Those invisible—in the air or when trying to
photograph the darn things—clear-plastic LE
cuffs also increase wing lift; first by
increasing the wingtip area and second by
acting as a “flat-bottom” section of the
symmetrical-airfoil wing. The increased
wingtip area reduces tip-stalling to zero.
But the best way to find out whether or not
this is a typical trainer is to fly it. So we did.
In fact, 12 pilots flew it during 57 test flights.
Therefore, some of what follows is
opinion—sometimes educated, sometimes
otherwise.
The net result is that the Mustang PTS
flies identical to a typical trainer. It is slow
and gentle with no bad tendencies. It flies
like a trainer but does not take off or land
like one. This difference is perhaps the
Mustang’s greatest benefit to the new RC
pilot. Let’s go through some flights.
Start the engine. All the Evolution Alpha
engine ever required was to prime the
carburetor and then rotate the spinner cone
backward. It started every time without using
an electric starter.
Taxiing is beyond easy. The landing gear,
with those gigantic tires, is canted so far
forward that it is beyond impossible to tip
the airplane onto its nose. The gear is widely
spaced for excellent ground handling.
Ground steering is positive and not sensitive.
The takeoff roll requires nontrainer
technique. With rudder throw set as
instructed and with the three-blade propeller
providing extra torque, full right rudder is
required for a straight takeoff roll.
Start the airplane rolling slowly and put in
full right rudder while going to full power.
The airplane rolls straight down the runway.
If you are late with the rudder, it may be
impossible to get back to the runway heading.This teaches the student pilot from the
start how to manage rudder during the
takeoff rolls of future, more powerful
aerobatic and Scale models. Rolling any
aircraft down the runway on takeoff will
hold no mystery for the PTS pilot.
As soon as the Mustang PTS breaks
ground, it goes into full training mode. The
climbout is gentle and noncritical.
Mismanage the elevator, even to stalling
the airplane, and the Mustang mushes on up,
climbing slightly with each oscillation.
There is no tip-stalling tendency or nose
drop. Release full up and the airplane goes
back to flying, slowly climbing to altitude
with plenty of time for the new pilot to think
ahead.
Cruise flight requires approximately 60%
throttle. Straight flight is stable. Turns with
banks up to roughly 45° require minimum
up-elevator to hold altitude. Steeper banks
take approximately 30% of the available upelevator
to remain level.
Letting the nose drop in the turn, as most
student pilots would, produces little
noticeable speed increase, and there is never
a tendency to “balloon,” or raising the nose
while losing airspeed, as most trainers do
once the wings are leveled. This is a good
thing since it reduces pilot workload.
Even during tight turns at slow airspeeds
there is never a tendency to tip stall or roll
out of the turn. The Mustang stays put as
directed, remaining tolerant of any abuse—
even full crossed-control stalls, right aileron,
and left rudder.
Spins are difficult and require power to
develop. Rotation stops immediately once
power or elevator input is reduced. Snap
rolls are more like giant barrel rolls, taking
approximately three seconds to complete.
Straight inverted flight is barely possible,
but level inverted turns are not; the airplane
runs out of down-elevator. The rudder is
notably ineffective, making knife-edge flight
impossible. So far the Mustang PTS flies
like every other typical trainer.
Power-off stalls are amazing. The wings
stay level, aileron control remains, and the
model just floats through the sky, defying
gravity and common sense. True, it comes
down, but slowly—maybe 200 feet per
minute or maybe less.
Starting from roughly 400 feet up, with
the engine at high idle—2,800 rpm—and
holding full up-elevator, the Mustang PTS
floats the entire available flight length of the
field, which was approximately 1/4 mile, and
is still roughly 100 feet from the ground.
This is not a recommended landing
technique because there could not be a
“flare,” breaking the descent before
touchdown, and the airplane would be
damaged. But add a bit of power to the
approach and reduce the elevator input, and
it could almost be. And that brings me to
landing the Mustang PTS.
Landing is different from that of a typical
trainer, which is usually executed by cutting
the engine to idle while approximately 75
feet high and 100 feet away from the runway
and then gliding in. However, the Mustang
PTS’s speed brakes, flaps, and LE droops
provide a good amount of drag.
Therefore, this airplane is landed as most
high-performance sport and Scale aircraft
are, using engine power. The approach and
touchdown are flown slowly at trainerlike
airspeeds, but approximately 30% engine
power is needed to “glide” to the runway.
The Mustang PTS teaches the new pilot
now—not later—how to land all those highperformance
sport and Scale airplanes
waiting in his or her future. Mastering the
power landing, with its intricate dance of
power for altitude and elevator for airspeedcontrol, can be difficult to learn once the
power-off typical trainer landing becomes
habit. This will not happen to the Mustang
PTS pilot.
The Mustang’s extra drag is why I
suggest installing operating flaps from the
start. There isn’t a great deal of glide with
everything hanging out in the slipstream. If
the engine runs out of fuel or quits, the
runway is unreachable unless it happens to
be close when the propeller goes rigid.
Raising the flaps dramatically extends
gliding distance, allowing the airplane to
“make the field” in such situations.
Using the transmitter’s travel-adjust
feature, set maximum flap movement—
channel 5—to 51%. This provides the same
26° of flap deployment as the fixed
mounting point would.
Three student pilots who had not yet
soloed flew the Mustang PTS in the air only,
using the “buddy box” system. Two flew
without the instructor’s having to take
control, and the third, having flown only a
small electric-powered trainer, needed
instructor help only three times in the eightminute
flight. All pronounced the Mustang
PTS to be a great trainer and felt they could
easily learn to fly with one.
Five newly soloed pilots flew the airplane
and felt the same way. Four club instructors
gave the model a fair workout, and all
thought they could easily teach new pilots
how to fly with it.
Is it a typical trainer? Yes, but with a
twist.
Learning to fly with the Mustang PTS is
as easy as learning on a typical trainer, but
the process will require two or three hours of
extra airtime to learn the advanced takeoff
and landing skills. But after soloing the
Mustang PTS pilot will have those additional
advanced skills and graduate flight school a
better flier, enjoying more complete piloting
skills for the experience.
Beyond Training: The idea behind the
Progressive Training System (the “PTS” in
Mustang PTS) is that the airplane can
quickly be reconfigured for more advanced
performance as the pilot’s skills advance.
Once the new pilot solos and has mastered
basic skills, the Mustang PTS is ready to take
him or her to the next step.
According to Hangar 9, the first step is to
remove the landing-gear speed brakes. I
believe the first step is increasing the amount
of elevator travel to 105% up and 120%
down. Rudder movement should be set to
150%. The ailerons are factory set at 75%
travel, so move those limits to 100%.
With all that done, the airplane becomes
more critical of improper elevator inputs and
will actually drop the nose in the stall.
Ground handling becomes more sensitive
and less than full right rudder is required for
takeoff.
The roll rate quickens, but not that much.
It becomes possible to spin the airplane
without using engine power to aid rotation
entry. Inverted flight, straight and turns,
becomes possible, but no Outside Loops yet!
After mastering this setup, remove the
speed brakes which are held in place with
two plastic tie wraps. Cut them with a hobby
knife (be careful) or use wire clippers.
Removing the speed brakes increases the
Mustang’s airspeed by roughly 15%. Loop
diameter increases from 50 feet to
somewhere near 75 feet. The airplane’s
airspeed become more pitch related as well.
Since cruise airspeed is higher, all the
controls become that much more sensitive.
Everything else remains basically the same;
there are still no bad habits.
These two small changes move the
Mustang approximately one-third of the way
toward offering Sport Scale piloting
challenges. It remains docile in every way,
but things happen faster and the airplane is a
bit more responsive. This is a great
intermediate stage that usually requires
purchasing an advanced trainer.
The next step is to raise those flaps.
Either hit the transmitter switch or reset the
mechanical flaps to the “zero” hole on the
wing tab. Now things change a little more.
Airspeed increases to roughly 50% more
than the original speed. The airplane will
pick up speed if the nose points below level.
Roll rate increases, and all the controls
become more sensitive. There are no trim
changes when flaps are deployed.
Without flaps and speed brakes, throttle
control during landing approaches becomes
more critical. Takeoffs require longer ground
runs, so rudder-control difficulties increase.100 feet, and good stall turns are now
possible. For the first time knife-edge flight
and Slow Rolls are manageable. However,
the airplane remains docile and has no
unwelcome surprises awaiting the unwary
pilot.
The LE droops are held in place with
clear tape. Peel the tape away, and the
droops are history. Before removing these
lift devices, the pilot should be comfortable
with the airplane’s handling and be able to
easily manage the increased performance up
to this point. Without the droops, the
Mustang loses the PTS label and matures
into a P-51 Mustang fighter.
True, the Mustang remains an excellentflying
Sport Scale aircraft—maybe one of
the best for its size—but when all the
training aids are gone, so is the safety net. If
you pull a turn too tightly, with too much upelevator,
the P-51 will drop the bottom wing,
rotating into the turn. There is no snap roll,
but the wing drop is quick.
Single stalls remain controllable with
a straight-ahead nose drop, but holding
the aircraft into multiple deep stalls, with
no flaps, will eventually lead to a snap
roll. Spin rotation is fast, but recovery
still happens as soon as the controls are
centered. Keep the nose level, or below,
during final approach, or unfortunate
surprises may await the pilot if the
airspeed is permitted to drop too far.
However, performance also increases.
Full-speed “strafing runs” are exciting as
they originally were. Loops approach 125
feet in diameter. Slow rolls are great, but it is
still nearly impossible to hold knife-edge
flight. So move the rudder control rod to the
innermost hole in the control horn, and
welcome to Four Point Rolls.
Outside Loops are easy but do require
small rudder input at the top to remain on
heading. Inverted flight, multiple inverted to
inverted rolls, and outside snap rolls (downelevator
used from inverted flight) are pretty,
but not so fast that they are difficult to
manage. Inverted spins rotate more slowly
than upright; recovery is just as easy.
The last step is to replace the three-blade
propeller with a two-blade performance
propeller such as the APC 10 x 6 or 11 x 5 or
an equivalent. At these maximum power
levels, the Evolution Alpha rockets the P-51
along at a respectable top speed.
Loops top 150 feet in diameter and rolls
become fast. Flying Inside and Outside
Avalanches—Loops with snap rolls at the
top—are fun, and knife-edge flight is better
but remains rudder-limited. Field-length
Slow Rolls are eye-catching.
The 10 x 6 propeller increases approach
speeds, requiring an idle of less than 2,200
rpm. I recommend the 11 x 5 as the best
choice.
However, there is a price for this
increased performance. A truly reliable idle
near 2,300 rpm is required for manageable
landing approaches, or just use the flaps.
Airspeeds at all throttle settings are faster.
The aircraft accelerates much faster when
taking off, so the whole maneuver happens
quickly. The P-51 gains speed in any descent
mode. All these characteristics are common
to most Sport Scale models, but this aircraft
handles the increased performance a little
better than most others do.
Most P-51s do not fly around with big
wheels hanging out the bottom, so
mechanical retracts might be in this
airplane’s future. That upgrade will take
some engineering on my part. I wonder
how far this PTS concept can be pushed.
To find out what else happened with this
model, check the Sport Aviator Web site.
Since most MA readers are pilots who have
some experience, this review focused more
on the PTS upgrades. MA Associate Editor
Michael Ramsey has written an excellent
Mustang PTS review for Sport Aviator that
focuses on the airplane as a typical trainer,
and it includes all the performance
numbers for the various PTS
configurations. MA
Frank Granelli
[email protected]
Distributor:
Horizon Hobby, Inc.
4105 Fieldstone Rd.
Champaign IL 61822
(877) 504-0233
www.hangar-9.com
Edition: Model Aviation - 2006/02
Page Numbers: 55,56,57,58,61,62,64
Plane Talk: Hangar 9 Mustang PTS
FRANK GRANELLI
• Ready to run with everything included with simulator and
buddy cord.
• Upgradable to a sport model with higher performance and
functional flaps.
Pluses and Minuses
+
• Clear canopy is glued in place, making it difficult to install a
scale pilot.
• Landing-gear mounting blocks could have been built stronger.
There was a failure after 43 flights.
With the training gizmos removed, the
Mustang in this trainer starts to shine
through. Inverted flight and Outside Loops
from level are comfortable to do. Costello
photo.
The Mustang PTS is so easy to land that one-wheel crosswind
touchdowns are routine, even in extreme nose-high attitudes.
Make sure to carry some power in the approach. Costello photo.
Clean, the P-51 Mustang is a joy to throw around the sky. It’s better behaved than most
Sport Scale models its size, but “Marie” can perform with the best of them. Frank
Costello photo.
THE DATE IS February 22, 1944. The
skies over Europe are again aflame. It is
Tuesday of “Big Week”: the American air
offensive to destroy the Luftwaffe. American
B-17 and B-24 bombers of the 15th Air Force
are nearing Regensburg to destroy German
aircraft factories.
Suddenly, black dots appear on their
noses. “German fighters, 4 o’clock” echoes
over hundreds of intercoms. Closing speeds
approach 500 mph as the dots become Me
109 fighters starting head-on attacks.
Crew members crouch behind tiny armor
plates, knowing to expect the worst. Then,
high in the Western sky, the sun flashes
brightly off of bare aluminum as silver wings
bank 90° and roll into their dives. At more
than 450 mph, the Mustangs of the yellowtailed
52nd Fighter Group race in front of the
bombers, making the airways ahead safe.
The Mustang Legend continues.
The date is June 4, 2005. It is Saturday
and a 30-something-year-old man appears at
the RC field with his young son. He has been
here before. Even he is not sure why he has
come back.
His imagination has been captured by the
aerobatic airplanes that seem to rotate the
sky itself, while Scale models subtly link the
two aviation worlds. He has always had a
“passing” interest in aviation, but today the
field has given his interest concrete form.
He finally starts to talk to a few pilots—
especially the one with the model of the
North American P-51 Mustang, which was
the hero of so many airplane movies he grew
up with. He has wanted to fly one since he
saw his first “airplane movie.”
However, this man quickly learns that
you can’t learn to fly model aircraft with a
Speed brakes are already attached to the landing gear. Just screw
in place with the nylon straps. Make sure the bottom edge of the
speed brake rests against the front screw as shown to prevent
rotation.
The Mustang PTS is a true RTF airplane with great photo-illustrated instructions and
even a flight simulator.
One wing half has a tab with two holes. The front hole sets the
flaps to zero. Hooking the factory-made linkage to the rear hole
provides 26° of flaps.
Install the flap servo in the factory-prepared mount. Use the small
end of the output arm and set maximum travel to 51% to provide
26° of flap.
Everything on the wing except the wheels, even the servo leads,
are factory installed. Slide the wing halves onto the aluminum
tube and lock in place with two small screws.
Mustang. At least two years of flying one of
those boxy, Cessna-looking typical trainers
and then an advanced trainer is the minimum
experience required before he can even think
about buying the Mustang. He is
disappointed but still not totally lost to us.
Then his son says, “I want to fly the
fighter—not one of those stupid, old things.”
They walk away and we lose two potential
new modelers.
How many times have RC instructors
seen the sad disappointment on potential
model pilots’ faces when they have
discovered the facts about learning to fly?
Many understand it and buy that high-wing
trainer. But that doesn’t mean they are happy
about it! Many others walk away, usually
believing that the difficulties are being
exaggerated or that three airplanes are too
much, or they are let down because they
can’t “have it all” now.
If the date had been September 4, 2005,
the outcome of that visit to the RC field
might have been vastly better. You want to
learn to fly with a Mustang? Great! Not only
can you learn with one, but that same
Mustang can teach you advanced piloting
techniques while becoming one of the bestperforming
Sport Scale aircraft available. It
is three airplanes in one.
Even better, this Mustang is an RTF. No
building skills or special equipment is
required. If you can spare 30 minutes to
assemble the model, you can learn
everything about RC piloting.
The cost is less than $400 for the
airplane, radio, engine, and all airframe
accessories, all factory installed. You save even more money since
you will not need to buy that follow-up “advanced trainer” or
Mustang kit; all three are in the Mustang PTS. There is definitely
potential to grow our sport with this model.
Everything with the Mustang is prebuilt, and even a flight
simulator is included. Unfortunately my computer does not have the
right connection for the simulator cord, and an adaptor has not been
located yet. This part of the review will have to be included on Model
Aviation’s Sport Aviator online magazine (www.masportaviator.com).
Assembly time really is less than 30 minutes. I finished the
aircraft in 21 minutes using just a screwdriver and pliers. Well, I did
use a wrench to make sure the propeller was tight, but that shouldn’t
count since it was.
Complete Assembly: The first job was the wing. As with a modern
airliner, all the real secrets to this aircraft’s performance are located
there. Flaps, speed brakes, ailerons, bolt-on wing-mounting system,
radiator scoop, and LE cuffs are part of the main wing, yet assembly
time is only 10 minutes.
As a photo shows, each wing half slides onto an aluminum tube.
There is an alignment pin to ensure that everything is true and it
works as advertised. The entire wing is held together by a single
nylon strap.
After joining the wing panels, bolt the landing gear in place as
shown and then use the factory-made flap linkage rod to connect the
flaps. The flaps use independent aileron-style torque tubes and are
connected to a fixed wing tab, as shown. The clear-plastic wing
droops are installed at the factory. The wing is finished at this point.
However, I strongly suggest that every potential Mustang pilot
install the flap servo before the first flight. The mount is already
there, and installation takes roughly five minutes.
Completing the fuselage involves bolting on the tail feathers, as
shown. The control surfaces and control horns are already installed.
Use the two lock nuts provided to bolt everything firmly in place.
Everything back there fit well, and it was good to see that the
stabilizer’s bolt holes were reinforced at the factory. Connect the two
control rods to the middle hole on the control horns. The last step is
to bolt the exhaust stacks onto the fuselage so that the 1,450-
horsepower, 12-cylinder Merlin engine can make the ground shake.
Power and Control: No, there isn’t a scaled-down V-1650-7regimes, including downhill and in landing
approaches.
In addition, this propeller’s pitch appears
to be less than 6 inches but is unidentified.
The lower pitch further reduces airspeed at
all throttle settings. Since engine rpm is
reduced under the three-blade’s extra load,
so are maximum airspeeds.
The radio compartment is factory built
with a removable cover to get at the receiver
and battery. The receiver is the popular JR
R700 six-channel FM model.
Onboard power is from JR’s 4N600: a
4.8-volt, 600 mAh Ni-Cd battery pack. The
five factory-installed servos are JR 537 ballbearing
sport units. The cored servo motor
puts out 43 in.-oz. of torque while rotating a
60° arc in just .25 second.
Few RTF aircraft offer ball-bearing
servos. But then, few RTF aircraft are guided
by a computer transmitter.
The Mustang’s transmitter is JR’s fivechannel
XF421, which is a great introductory
computer radio. It features digital travel
adjustments, basic mixing (including
“flaperon”), easy servo reversing, and
memory storage for two aircraft. Few RTFs
feature such an advanced transmitter. The
XF421 is powered by a 600 mAh Ni-Cd
pack and is compatible with most
transmitters for a “buddy” link via the
included trainer cord.
But is this really a trainer? So it was easy to
put together. But come on; it is a Mustang
after all. Even the Army Air Force didn’t put
pilots in Mustangs until they went through
primary and advanced trainers. And they
were sending people out to get shot at!
Look at the heavily tapered wing with the
narrow-chord wingtips. Tell me that won’t
tip-stall into a snap roll at the first
provocation. And that semisymmetricalairfoil
wing is small for a 6.5-pound trainer.
Landing speeds will have to be high. The
airplane is so streamlined that everything
will be happening fast.
So they hung some gizmos all over the
wing, but how much can they help? You
can’t even see that stuff near the wingtips, so
how was this fighter transformed into a
typical trainer? Skull sweat and good design,
that’s how.
Each “gizmo” has a design purpose, and
each one worked as intended. The “speed
brakes” mounted on the landing gear add
drag, reducing the top speed while
preventing the airplane from gaining a great
deal of airspeed when the nose starts to point
earthward. The wing flaps, set at 26°, create
more drag to further slow the airplane while
increasing the wing’s lifting force.
Working together, both devices make it
easy to set up correct landing approaches.
Those invisible—in the air or when trying to
photograph the darn things—clear-plastic LE
cuffs also increase wing lift; first by
increasing the wingtip area and second by
acting as a “flat-bottom” section of the
symmetrical-airfoil wing. The increased
wingtip area reduces tip-stalling to zero.
But the best way to find out whether or not
this is a typical trainer is to fly it. So we did.
In fact, 12 pilots flew it during 57 test flights.
Therefore, some of what follows is
opinion—sometimes educated, sometimes
otherwise.
The net result is that the Mustang PTS
flies identical to a typical trainer. It is slow
and gentle with no bad tendencies. It flies
like a trainer but does not take off or land
like one. This difference is perhaps the
Mustang’s greatest benefit to the new RC
pilot. Let’s go through some flights.
Start the engine. All the Evolution Alpha
engine ever required was to prime the
carburetor and then rotate the spinner cone
backward. It started every time without using
an electric starter.
Taxiing is beyond easy. The landing gear,
with those gigantic tires, is canted so far
forward that it is beyond impossible to tip
the airplane onto its nose. The gear is widely
spaced for excellent ground handling.
Ground steering is positive and not sensitive.
The takeoff roll requires nontrainer
technique. With rudder throw set as
instructed and with the three-blade propeller
providing extra torque, full right rudder is
required for a straight takeoff roll.
Start the airplane rolling slowly and put in
full right rudder while going to full power.
The airplane rolls straight down the runway.
If you are late with the rudder, it may be
impossible to get back to the runway heading.This teaches the student pilot from the
start how to manage rudder during the
takeoff rolls of future, more powerful
aerobatic and Scale models. Rolling any
aircraft down the runway on takeoff will
hold no mystery for the PTS pilot.
As soon as the Mustang PTS breaks
ground, it goes into full training mode. The
climbout is gentle and noncritical.
Mismanage the elevator, even to stalling
the airplane, and the Mustang mushes on up,
climbing slightly with each oscillation.
There is no tip-stalling tendency or nose
drop. Release full up and the airplane goes
back to flying, slowly climbing to altitude
with plenty of time for the new pilot to think
ahead.
Cruise flight requires approximately 60%
throttle. Straight flight is stable. Turns with
banks up to roughly 45° require minimum
up-elevator to hold altitude. Steeper banks
take approximately 30% of the available upelevator
to remain level.
Letting the nose drop in the turn, as most
student pilots would, produces little
noticeable speed increase, and there is never
a tendency to “balloon,” or raising the nose
while losing airspeed, as most trainers do
once the wings are leveled. This is a good
thing since it reduces pilot workload.
Even during tight turns at slow airspeeds
there is never a tendency to tip stall or roll
out of the turn. The Mustang stays put as
directed, remaining tolerant of any abuse—
even full crossed-control stalls, right aileron,
and left rudder.
Spins are difficult and require power to
develop. Rotation stops immediately once
power or elevator input is reduced. Snap
rolls are more like giant barrel rolls, taking
approximately three seconds to complete.
Straight inverted flight is barely possible,
but level inverted turns are not; the airplane
runs out of down-elevator. The rudder is
notably ineffective, making knife-edge flight
impossible. So far the Mustang PTS flies
like every other typical trainer.
Power-off stalls are amazing. The wings
stay level, aileron control remains, and the
model just floats through the sky, defying
gravity and common sense. True, it comes
down, but slowly—maybe 200 feet per
minute or maybe less.
Starting from roughly 400 feet up, with
the engine at high idle—2,800 rpm—and
holding full up-elevator, the Mustang PTS
floats the entire available flight length of the
field, which was approximately 1/4 mile, and
is still roughly 100 feet from the ground.
This is not a recommended landing
technique because there could not be a
“flare,” breaking the descent before
touchdown, and the airplane would be
damaged. But add a bit of power to the
approach and reduce the elevator input, and
it could almost be. And that brings me to
landing the Mustang PTS.
Landing is different from that of a typical
trainer, which is usually executed by cutting
the engine to idle while approximately 75
feet high and 100 feet away from the runway
and then gliding in. However, the Mustang
PTS’s speed brakes, flaps, and LE droops
provide a good amount of drag.
Therefore, this airplane is landed as most
high-performance sport and Scale aircraft
are, using engine power. The approach and
touchdown are flown slowly at trainerlike
airspeeds, but approximately 30% engine
power is needed to “glide” to the runway.
The Mustang PTS teaches the new pilot
now—not later—how to land all those highperformance
sport and Scale airplanes
waiting in his or her future. Mastering the
power landing, with its intricate dance of
power for altitude and elevator for airspeedcontrol, can be difficult to learn once the
power-off typical trainer landing becomes
habit. This will not happen to the Mustang
PTS pilot.
The Mustang’s extra drag is why I
suggest installing operating flaps from the
start. There isn’t a great deal of glide with
everything hanging out in the slipstream. If
the engine runs out of fuel or quits, the
runway is unreachable unless it happens to
be close when the propeller goes rigid.
Raising the flaps dramatically extends
gliding distance, allowing the airplane to
“make the field” in such situations.
Using the transmitter’s travel-adjust
feature, set maximum flap movement—
channel 5—to 51%. This provides the same
26° of flap deployment as the fixed
mounting point would.
Three student pilots who had not yet
soloed flew the Mustang PTS in the air only,
using the “buddy box” system. Two flew
without the instructor’s having to take
control, and the third, having flown only a
small electric-powered trainer, needed
instructor help only three times in the eightminute
flight. All pronounced the Mustang
PTS to be a great trainer and felt they could
easily learn to fly with one.
Five newly soloed pilots flew the airplane
and felt the same way. Four club instructors
gave the model a fair workout, and all
thought they could easily teach new pilots
how to fly with it.
Is it a typical trainer? Yes, but with a
twist.
Learning to fly with the Mustang PTS is
as easy as learning on a typical trainer, but
the process will require two or three hours of
extra airtime to learn the advanced takeoff
and landing skills. But after soloing the
Mustang PTS pilot will have those additional
advanced skills and graduate flight school a
better flier, enjoying more complete piloting
skills for the experience.
Beyond Training: The idea behind the
Progressive Training System (the “PTS” in
Mustang PTS) is that the airplane can
quickly be reconfigured for more advanced
performance as the pilot’s skills advance.
Once the new pilot solos and has mastered
basic skills, the Mustang PTS is ready to take
him or her to the next step.
According to Hangar 9, the first step is to
remove the landing-gear speed brakes. I
believe the first step is increasing the amount
of elevator travel to 105% up and 120%
down. Rudder movement should be set to
150%. The ailerons are factory set at 75%
travel, so move those limits to 100%.
With all that done, the airplane becomes
more critical of improper elevator inputs and
will actually drop the nose in the stall.
Ground handling becomes more sensitive
and less than full right rudder is required for
takeoff.
The roll rate quickens, but not that much.
It becomes possible to spin the airplane
without using engine power to aid rotation
entry. Inverted flight, straight and turns,
becomes possible, but no Outside Loops yet!
After mastering this setup, remove the
speed brakes which are held in place with
two plastic tie wraps. Cut them with a hobby
knife (be careful) or use wire clippers.
Removing the speed brakes increases the
Mustang’s airspeed by roughly 15%. Loop
diameter increases from 50 feet to
somewhere near 75 feet. The airplane’s
airspeed become more pitch related as well.
Since cruise airspeed is higher, all the
controls become that much more sensitive.
Everything else remains basically the same;
there are still no bad habits.
These two small changes move the
Mustang approximately one-third of the way
toward offering Sport Scale piloting
challenges. It remains docile in every way,
but things happen faster and the airplane is a
bit more responsive. This is a great
intermediate stage that usually requires
purchasing an advanced trainer.
The next step is to raise those flaps.
Either hit the transmitter switch or reset the
mechanical flaps to the “zero” hole on the
wing tab. Now things change a little more.
Airspeed increases to roughly 50% more
than the original speed. The airplane will
pick up speed if the nose points below level.
Roll rate increases, and all the controls
become more sensitive. There are no trim
changes when flaps are deployed.
Without flaps and speed brakes, throttle
control during landing approaches becomes
more critical. Takeoffs require longer ground
runs, so rudder-control difficulties increase.100 feet, and good stall turns are now
possible. For the first time knife-edge flight
and Slow Rolls are manageable. However,
the airplane remains docile and has no
unwelcome surprises awaiting the unwary
pilot.
The LE droops are held in place with
clear tape. Peel the tape away, and the
droops are history. Before removing these
lift devices, the pilot should be comfortable
with the airplane’s handling and be able to
easily manage the increased performance up
to this point. Without the droops, the
Mustang loses the PTS label and matures
into a P-51 Mustang fighter.
True, the Mustang remains an excellentflying
Sport Scale aircraft—maybe one of
the best for its size—but when all the
training aids are gone, so is the safety net. If
you pull a turn too tightly, with too much upelevator,
the P-51 will drop the bottom wing,
rotating into the turn. There is no snap roll,
but the wing drop is quick.
Single stalls remain controllable with
a straight-ahead nose drop, but holding
the aircraft into multiple deep stalls, with
no flaps, will eventually lead to a snap
roll. Spin rotation is fast, but recovery
still happens as soon as the controls are
centered. Keep the nose level, or below,
during final approach, or unfortunate
surprises may await the pilot if the
airspeed is permitted to drop too far.
However, performance also increases.
Full-speed “strafing runs” are exciting as
they originally were. Loops approach 125
feet in diameter. Slow rolls are great, but it is
still nearly impossible to hold knife-edge
flight. So move the rudder control rod to the
innermost hole in the control horn, and
welcome to Four Point Rolls.
Outside Loops are easy but do require
small rudder input at the top to remain on
heading. Inverted flight, multiple inverted to
inverted rolls, and outside snap rolls (downelevator
used from inverted flight) are pretty,
but not so fast that they are difficult to
manage. Inverted spins rotate more slowly
than upright; recovery is just as easy.
The last step is to replace the three-blade
propeller with a two-blade performance
propeller such as the APC 10 x 6 or 11 x 5 or
an equivalent. At these maximum power
levels, the Evolution Alpha rockets the P-51
along at a respectable top speed.
Loops top 150 feet in diameter and rolls
become fast. Flying Inside and Outside
Avalanches—Loops with snap rolls at the
top—are fun, and knife-edge flight is better
but remains rudder-limited. Field-length
Slow Rolls are eye-catching.
The 10 x 6 propeller increases approach
speeds, requiring an idle of less than 2,200
rpm. I recommend the 11 x 5 as the best
choice.
However, there is a price for this
increased performance. A truly reliable idle
near 2,300 rpm is required for manageable
landing approaches, or just use the flaps.
Airspeeds at all throttle settings are faster.
The aircraft accelerates much faster when
taking off, so the whole maneuver happens
quickly. The P-51 gains speed in any descent
mode. All these characteristics are common
to most Sport Scale models, but this aircraft
handles the increased performance a little
better than most others do.
Most P-51s do not fly around with big
wheels hanging out the bottom, so
mechanical retracts might be in this
airplane’s future. That upgrade will take
some engineering on my part. I wonder
how far this PTS concept can be pushed.
To find out what else happened with this
model, check the Sport Aviator Web site.
Since most MA readers are pilots who have
some experience, this review focused more
on the PTS upgrades. MA Associate Editor
Michael Ramsey has written an excellent
Mustang PTS review for Sport Aviator that
focuses on the airplane as a typical trainer,
and it includes all the performance
numbers for the various PTS
configurations. MA
Frank Granelli
[email protected]
Distributor:
Horizon Hobby, Inc.
4105 Fieldstone Rd.
Champaign IL 61822
(877) 504-0233
www.hangar-9.com
Edition: Model Aviation - 2006/02
Page Numbers: 55,56,57,58,61,62,64
Plane Talk: Hangar 9 Mustang PTS
FRANK GRANELLI
• Ready to run with everything included with simulator and
buddy cord.
• Upgradable to a sport model with higher performance and
functional flaps.
Pluses and Minuses
+
• Clear canopy is glued in place, making it difficult to install a
scale pilot.
• Landing-gear mounting blocks could have been built stronger.
There was a failure after 43 flights.
With the training gizmos removed, the
Mustang in this trainer starts to shine
through. Inverted flight and Outside Loops
from level are comfortable to do. Costello
photo.
The Mustang PTS is so easy to land that one-wheel crosswind
touchdowns are routine, even in extreme nose-high attitudes.
Make sure to carry some power in the approach. Costello photo.
Clean, the P-51 Mustang is a joy to throw around the sky. It’s better behaved than most
Sport Scale models its size, but “Marie” can perform with the best of them. Frank
Costello photo.
THE DATE IS February 22, 1944. The
skies over Europe are again aflame. It is
Tuesday of “Big Week”: the American air
offensive to destroy the Luftwaffe. American
B-17 and B-24 bombers of the 15th Air Force
are nearing Regensburg to destroy German
aircraft factories.
Suddenly, black dots appear on their
noses. “German fighters, 4 o’clock” echoes
over hundreds of intercoms. Closing speeds
approach 500 mph as the dots become Me
109 fighters starting head-on attacks.
Crew members crouch behind tiny armor
plates, knowing to expect the worst. Then,
high in the Western sky, the sun flashes
brightly off of bare aluminum as silver wings
bank 90° and roll into their dives. At more
than 450 mph, the Mustangs of the yellowtailed
52nd Fighter Group race in front of the
bombers, making the airways ahead safe.
The Mustang Legend continues.
The date is June 4, 2005. It is Saturday
and a 30-something-year-old man appears at
the RC field with his young son. He has been
here before. Even he is not sure why he has
come back.
His imagination has been captured by the
aerobatic airplanes that seem to rotate the
sky itself, while Scale models subtly link the
two aviation worlds. He has always had a
“passing” interest in aviation, but today the
field has given his interest concrete form.
He finally starts to talk to a few pilots—
especially the one with the model of the
North American P-51 Mustang, which was
the hero of so many airplane movies he grew
up with. He has wanted to fly one since he
saw his first “airplane movie.”
However, this man quickly learns that
you can’t learn to fly model aircraft with a
Speed brakes are already attached to the landing gear. Just screw
in place with the nylon straps. Make sure the bottom edge of the
speed brake rests against the front screw as shown to prevent
rotation.
The Mustang PTS is a true RTF airplane with great photo-illustrated instructions and
even a flight simulator.
One wing half has a tab with two holes. The front hole sets the
flaps to zero. Hooking the factory-made linkage to the rear hole
provides 26° of flaps.
Install the flap servo in the factory-prepared mount. Use the small
end of the output arm and set maximum travel to 51% to provide
26° of flap.
Everything on the wing except the wheels, even the servo leads,
are factory installed. Slide the wing halves onto the aluminum
tube and lock in place with two small screws.
Mustang. At least two years of flying one of
those boxy, Cessna-looking typical trainers
and then an advanced trainer is the minimum
experience required before he can even think
about buying the Mustang. He is
disappointed but still not totally lost to us.
Then his son says, “I want to fly the
fighter—not one of those stupid, old things.”
They walk away and we lose two potential
new modelers.
How many times have RC instructors
seen the sad disappointment on potential
model pilots’ faces when they have
discovered the facts about learning to fly?
Many understand it and buy that high-wing
trainer. But that doesn’t mean they are happy
about it! Many others walk away, usually
believing that the difficulties are being
exaggerated or that three airplanes are too
much, or they are let down because they
can’t “have it all” now.
If the date had been September 4, 2005,
the outcome of that visit to the RC field
might have been vastly better. You want to
learn to fly with a Mustang? Great! Not only
can you learn with one, but that same
Mustang can teach you advanced piloting
techniques while becoming one of the bestperforming
Sport Scale aircraft available. It
is three airplanes in one.
Even better, this Mustang is an RTF. No
building skills or special equipment is
required. If you can spare 30 minutes to
assemble the model, you can learn
everything about RC piloting.
The cost is less than $400 for the
airplane, radio, engine, and all airframe
accessories, all factory installed. You save even more money since
you will not need to buy that follow-up “advanced trainer” or
Mustang kit; all three are in the Mustang PTS. There is definitely
potential to grow our sport with this model.
Everything with the Mustang is prebuilt, and even a flight
simulator is included. Unfortunately my computer does not have the
right connection for the simulator cord, and an adaptor has not been
located yet. This part of the review will have to be included on Model
Aviation’s Sport Aviator online magazine (www.masportaviator.com).
Assembly time really is less than 30 minutes. I finished the
aircraft in 21 minutes using just a screwdriver and pliers. Well, I did
use a wrench to make sure the propeller was tight, but that shouldn’t
count since it was.
Complete Assembly: The first job was the wing. As with a modern
airliner, all the real secrets to this aircraft’s performance are located
there. Flaps, speed brakes, ailerons, bolt-on wing-mounting system,
radiator scoop, and LE cuffs are part of the main wing, yet assembly
time is only 10 minutes.
As a photo shows, each wing half slides onto an aluminum tube.
There is an alignment pin to ensure that everything is true and it
works as advertised. The entire wing is held together by a single
nylon strap.
After joining the wing panels, bolt the landing gear in place as
shown and then use the factory-made flap linkage rod to connect the
flaps. The flaps use independent aileron-style torque tubes and are
connected to a fixed wing tab, as shown. The clear-plastic wing
droops are installed at the factory. The wing is finished at this point.
However, I strongly suggest that every potential Mustang pilot
install the flap servo before the first flight. The mount is already
there, and installation takes roughly five minutes.
Completing the fuselage involves bolting on the tail feathers, as
shown. The control surfaces and control horns are already installed.
Use the two lock nuts provided to bolt everything firmly in place.
Everything back there fit well, and it was good to see that the
stabilizer’s bolt holes were reinforced at the factory. Connect the two
control rods to the middle hole on the control horns. The last step is
to bolt the exhaust stacks onto the fuselage so that the 1,450-
horsepower, 12-cylinder Merlin engine can make the ground shake.
Power and Control: No, there isn’t a scaled-down V-1650-7regimes, including downhill and in landing
approaches.
In addition, this propeller’s pitch appears
to be less than 6 inches but is unidentified.
The lower pitch further reduces airspeed at
all throttle settings. Since engine rpm is
reduced under the three-blade’s extra load,
so are maximum airspeeds.
The radio compartment is factory built
with a removable cover to get at the receiver
and battery. The receiver is the popular JR
R700 six-channel FM model.
Onboard power is from JR’s 4N600: a
4.8-volt, 600 mAh Ni-Cd battery pack. The
five factory-installed servos are JR 537 ballbearing
sport units. The cored servo motor
puts out 43 in.-oz. of torque while rotating a
60° arc in just .25 second.
Few RTF aircraft offer ball-bearing
servos. But then, few RTF aircraft are guided
by a computer transmitter.
The Mustang’s transmitter is JR’s fivechannel
XF421, which is a great introductory
computer radio. It features digital travel
adjustments, basic mixing (including
“flaperon”), easy servo reversing, and
memory storage for two aircraft. Few RTFs
feature such an advanced transmitter. The
XF421 is powered by a 600 mAh Ni-Cd
pack and is compatible with most
transmitters for a “buddy” link via the
included trainer cord.
But is this really a trainer? So it was easy to
put together. But come on; it is a Mustang
after all. Even the Army Air Force didn’t put
pilots in Mustangs until they went through
primary and advanced trainers. And they
were sending people out to get shot at!
Look at the heavily tapered wing with the
narrow-chord wingtips. Tell me that won’t
tip-stall into a snap roll at the first
provocation. And that semisymmetricalairfoil
wing is small for a 6.5-pound trainer.
Landing speeds will have to be high. The
airplane is so streamlined that everything
will be happening fast.
So they hung some gizmos all over the
wing, but how much can they help? You
can’t even see that stuff near the wingtips, so
how was this fighter transformed into a
typical trainer? Skull sweat and good design,
that’s how.
Each “gizmo” has a design purpose, and
each one worked as intended. The “speed
brakes” mounted on the landing gear add
drag, reducing the top speed while
preventing the airplane from gaining a great
deal of airspeed when the nose starts to point
earthward. The wing flaps, set at 26°, create
more drag to further slow the airplane while
increasing the wing’s lifting force.
Working together, both devices make it
easy to set up correct landing approaches.
Those invisible—in the air or when trying to
photograph the darn things—clear-plastic LE
cuffs also increase wing lift; first by
increasing the wingtip area and second by
acting as a “flat-bottom” section of the
symmetrical-airfoil wing. The increased
wingtip area reduces tip-stalling to zero.
But the best way to find out whether or not
this is a typical trainer is to fly it. So we did.
In fact, 12 pilots flew it during 57 test flights.
Therefore, some of what follows is
opinion—sometimes educated, sometimes
otherwise.
The net result is that the Mustang PTS
flies identical to a typical trainer. It is slow
and gentle with no bad tendencies. It flies
like a trainer but does not take off or land
like one. This difference is perhaps the
Mustang’s greatest benefit to the new RC
pilot. Let’s go through some flights.
Start the engine. All the Evolution Alpha
engine ever required was to prime the
carburetor and then rotate the spinner cone
backward. It started every time without using
an electric starter.
Taxiing is beyond easy. The landing gear,
with those gigantic tires, is canted so far
forward that it is beyond impossible to tip
the airplane onto its nose. The gear is widely
spaced for excellent ground handling.
Ground steering is positive and not sensitive.
The takeoff roll requires nontrainer
technique. With rudder throw set as
instructed and with the three-blade propeller
providing extra torque, full right rudder is
required for a straight takeoff roll.
Start the airplane rolling slowly and put in
full right rudder while going to full power.
The airplane rolls straight down the runway.
If you are late with the rudder, it may be
impossible to get back to the runway heading.This teaches the student pilot from the
start how to manage rudder during the
takeoff rolls of future, more powerful
aerobatic and Scale models. Rolling any
aircraft down the runway on takeoff will
hold no mystery for the PTS pilot.
As soon as the Mustang PTS breaks
ground, it goes into full training mode. The
climbout is gentle and noncritical.
Mismanage the elevator, even to stalling
the airplane, and the Mustang mushes on up,
climbing slightly with each oscillation.
There is no tip-stalling tendency or nose
drop. Release full up and the airplane goes
back to flying, slowly climbing to altitude
with plenty of time for the new pilot to think
ahead.
Cruise flight requires approximately 60%
throttle. Straight flight is stable. Turns with
banks up to roughly 45° require minimum
up-elevator to hold altitude. Steeper banks
take approximately 30% of the available upelevator
to remain level.
Letting the nose drop in the turn, as most
student pilots would, produces little
noticeable speed increase, and there is never
a tendency to “balloon,” or raising the nose
while losing airspeed, as most trainers do
once the wings are leveled. This is a good
thing since it reduces pilot workload.
Even during tight turns at slow airspeeds
there is never a tendency to tip stall or roll
out of the turn. The Mustang stays put as
directed, remaining tolerant of any abuse—
even full crossed-control stalls, right aileron,
and left rudder.
Spins are difficult and require power to
develop. Rotation stops immediately once
power or elevator input is reduced. Snap
rolls are more like giant barrel rolls, taking
approximately three seconds to complete.
Straight inverted flight is barely possible,
but level inverted turns are not; the airplane
runs out of down-elevator. The rudder is
notably ineffective, making knife-edge flight
impossible. So far the Mustang PTS flies
like every other typical trainer.
Power-off stalls are amazing. The wings
stay level, aileron control remains, and the
model just floats through the sky, defying
gravity and common sense. True, it comes
down, but slowly—maybe 200 feet per
minute or maybe less.
Starting from roughly 400 feet up, with
the engine at high idle—2,800 rpm—and
holding full up-elevator, the Mustang PTS
floats the entire available flight length of the
field, which was approximately 1/4 mile, and
is still roughly 100 feet from the ground.
This is not a recommended landing
technique because there could not be a
“flare,” breaking the descent before
touchdown, and the airplane would be
damaged. But add a bit of power to the
approach and reduce the elevator input, and
it could almost be. And that brings me to
landing the Mustang PTS.
Landing is different from that of a typical
trainer, which is usually executed by cutting
the engine to idle while approximately 75
feet high and 100 feet away from the runway
and then gliding in. However, the Mustang
PTS’s speed brakes, flaps, and LE droops
provide a good amount of drag.
Therefore, this airplane is landed as most
high-performance sport and Scale aircraft
are, using engine power. The approach and
touchdown are flown slowly at trainerlike
airspeeds, but approximately 30% engine
power is needed to “glide” to the runway.
The Mustang PTS teaches the new pilot
now—not later—how to land all those highperformance
sport and Scale airplanes
waiting in his or her future. Mastering the
power landing, with its intricate dance of
power for altitude and elevator for airspeedcontrol, can be difficult to learn once the
power-off typical trainer landing becomes
habit. This will not happen to the Mustang
PTS pilot.
The Mustang’s extra drag is why I
suggest installing operating flaps from the
start. There isn’t a great deal of glide with
everything hanging out in the slipstream. If
the engine runs out of fuel or quits, the
runway is unreachable unless it happens to
be close when the propeller goes rigid.
Raising the flaps dramatically extends
gliding distance, allowing the airplane to
“make the field” in such situations.
Using the transmitter’s travel-adjust
feature, set maximum flap movement—
channel 5—to 51%. This provides the same
26° of flap deployment as the fixed
mounting point would.
Three student pilots who had not yet
soloed flew the Mustang PTS in the air only,
using the “buddy box” system. Two flew
without the instructor’s having to take
control, and the third, having flown only a
small electric-powered trainer, needed
instructor help only three times in the eightminute
flight. All pronounced the Mustang
PTS to be a great trainer and felt they could
easily learn to fly with one.
Five newly soloed pilots flew the airplane
and felt the same way. Four club instructors
gave the model a fair workout, and all
thought they could easily teach new pilots
how to fly with it.
Is it a typical trainer? Yes, but with a
twist.
Learning to fly with the Mustang PTS is
as easy as learning on a typical trainer, but
the process will require two or three hours of
extra airtime to learn the advanced takeoff
and landing skills. But after soloing the
Mustang PTS pilot will have those additional
advanced skills and graduate flight school a
better flier, enjoying more complete piloting
skills for the experience.
Beyond Training: The idea behind the
Progressive Training System (the “PTS” in
Mustang PTS) is that the airplane can
quickly be reconfigured for more advanced
performance as the pilot’s skills advance.
Once the new pilot solos and has mastered
basic skills, the Mustang PTS is ready to take
him or her to the next step.
According to Hangar 9, the first step is to
remove the landing-gear speed brakes. I
believe the first step is increasing the amount
of elevator travel to 105% up and 120%
down. Rudder movement should be set to
150%. The ailerons are factory set at 75%
travel, so move those limits to 100%.
With all that done, the airplane becomes
more critical of improper elevator inputs and
will actually drop the nose in the stall.
Ground handling becomes more sensitive
and less than full right rudder is required for
takeoff.
The roll rate quickens, but not that much.
It becomes possible to spin the airplane
without using engine power to aid rotation
entry. Inverted flight, straight and turns,
becomes possible, but no Outside Loops yet!
After mastering this setup, remove the
speed brakes which are held in place with
two plastic tie wraps. Cut them with a hobby
knife (be careful) or use wire clippers.
Removing the speed brakes increases the
Mustang’s airspeed by roughly 15%. Loop
diameter increases from 50 feet to
somewhere near 75 feet. The airplane’s
airspeed become more pitch related as well.
Since cruise airspeed is higher, all the
controls become that much more sensitive.
Everything else remains basically the same;
there are still no bad habits.
These two small changes move the
Mustang approximately one-third of the way
toward offering Sport Scale piloting
challenges. It remains docile in every way,
but things happen faster and the airplane is a
bit more responsive. This is a great
intermediate stage that usually requires
purchasing an advanced trainer.
The next step is to raise those flaps.
Either hit the transmitter switch or reset the
mechanical flaps to the “zero” hole on the
wing tab. Now things change a little more.
Airspeed increases to roughly 50% more
than the original speed. The airplane will
pick up speed if the nose points below level.
Roll rate increases, and all the controls
become more sensitive. There are no trim
changes when flaps are deployed.
Without flaps and speed brakes, throttle
control during landing approaches becomes
more critical. Takeoffs require longer ground
runs, so rudder-control difficulties increase.100 feet, and good stall turns are now
possible. For the first time knife-edge flight
and Slow Rolls are manageable. However,
the airplane remains docile and has no
unwelcome surprises awaiting the unwary
pilot.
The LE droops are held in place with
clear tape. Peel the tape away, and the
droops are history. Before removing these
lift devices, the pilot should be comfortable
with the airplane’s handling and be able to
easily manage the increased performance up
to this point. Without the droops, the
Mustang loses the PTS label and matures
into a P-51 Mustang fighter.
True, the Mustang remains an excellentflying
Sport Scale aircraft—maybe one of
the best for its size—but when all the
training aids are gone, so is the safety net. If
you pull a turn too tightly, with too much upelevator,
the P-51 will drop the bottom wing,
rotating into the turn. There is no snap roll,
but the wing drop is quick.
Single stalls remain controllable with
a straight-ahead nose drop, but holding
the aircraft into multiple deep stalls, with
no flaps, will eventually lead to a snap
roll. Spin rotation is fast, but recovery
still happens as soon as the controls are
centered. Keep the nose level, or below,
during final approach, or unfortunate
surprises may await the pilot if the
airspeed is permitted to drop too far.
However, performance also increases.
Full-speed “strafing runs” are exciting as
they originally were. Loops approach 125
feet in diameter. Slow rolls are great, but it is
still nearly impossible to hold knife-edge
flight. So move the rudder control rod to the
innermost hole in the control horn, and
welcome to Four Point Rolls.
Outside Loops are easy but do require
small rudder input at the top to remain on
heading. Inverted flight, multiple inverted to
inverted rolls, and outside snap rolls (downelevator
used from inverted flight) are pretty,
but not so fast that they are difficult to
manage. Inverted spins rotate more slowly
than upright; recovery is just as easy.
The last step is to replace the three-blade
propeller with a two-blade performance
propeller such as the APC 10 x 6 or 11 x 5 or
an equivalent. At these maximum power
levels, the Evolution Alpha rockets the P-51
along at a respectable top speed.
Loops top 150 feet in diameter and rolls
become fast. Flying Inside and Outside
Avalanches—Loops with snap rolls at the
top—are fun, and knife-edge flight is better
but remains rudder-limited. Field-length
Slow Rolls are eye-catching.
The 10 x 6 propeller increases approach
speeds, requiring an idle of less than 2,200
rpm. I recommend the 11 x 5 as the best
choice.
However, there is a price for this
increased performance. A truly reliable idle
near 2,300 rpm is required for manageable
landing approaches, or just use the flaps.
Airspeeds at all throttle settings are faster.
The aircraft accelerates much faster when
taking off, so the whole maneuver happens
quickly. The P-51 gains speed in any descent
mode. All these characteristics are common
to most Sport Scale models, but this aircraft
handles the increased performance a little
better than most others do.
Most P-51s do not fly around with big
wheels hanging out the bottom, so
mechanical retracts might be in this
airplane’s future. That upgrade will take
some engineering on my part. I wonder
how far this PTS concept can be pushed.
To find out what else happened with this
model, check the Sport Aviator Web site.
Since most MA readers are pilots who have
some experience, this review focused more
on the PTS upgrades. MA Associate Editor
Michael Ramsey has written an excellent
Mustang PTS review for Sport Aviator that
focuses on the airplane as a typical trainer,
and it includes all the performance
numbers for the various PTS
configurations. MA
Frank Granelli
[email protected]
Distributor:
Horizon Hobby, Inc.
4105 Fieldstone Rd.
Champaign IL 61822
(877) 504-0233
www.hangar-9.com
Edition: Model Aviation - 2006/02
Page Numbers: 55,56,57,58,61,62,64
Plane Talk: Hangar 9 Mustang PTS
FRANK GRANELLI
• Ready to run with everything included with simulator and
buddy cord.
• Upgradable to a sport model with higher performance and
functional flaps.
Pluses and Minuses
+
• Clear canopy is glued in place, making it difficult to install a
scale pilot.
• Landing-gear mounting blocks could have been built stronger.
There was a failure after 43 flights.
With the training gizmos removed, the
Mustang in this trainer starts to shine
through. Inverted flight and Outside Loops
from level are comfortable to do. Costello
photo.
The Mustang PTS is so easy to land that one-wheel crosswind
touchdowns are routine, even in extreme nose-high attitudes.
Make sure to carry some power in the approach. Costello photo.
Clean, the P-51 Mustang is a joy to throw around the sky. It’s better behaved than most
Sport Scale models its size, but “Marie” can perform with the best of them. Frank
Costello photo.
THE DATE IS February 22, 1944. The
skies over Europe are again aflame. It is
Tuesday of “Big Week”: the American air
offensive to destroy the Luftwaffe. American
B-17 and B-24 bombers of the 15th Air Force
are nearing Regensburg to destroy German
aircraft factories.
Suddenly, black dots appear on their
noses. “German fighters, 4 o’clock” echoes
over hundreds of intercoms. Closing speeds
approach 500 mph as the dots become Me
109 fighters starting head-on attacks.
Crew members crouch behind tiny armor
plates, knowing to expect the worst. Then,
high in the Western sky, the sun flashes
brightly off of bare aluminum as silver wings
bank 90° and roll into their dives. At more
than 450 mph, the Mustangs of the yellowtailed
52nd Fighter Group race in front of the
bombers, making the airways ahead safe.
The Mustang Legend continues.
The date is June 4, 2005. It is Saturday
and a 30-something-year-old man appears at
the RC field with his young son. He has been
here before. Even he is not sure why he has
come back.
His imagination has been captured by the
aerobatic airplanes that seem to rotate the
sky itself, while Scale models subtly link the
two aviation worlds. He has always had a
“passing” interest in aviation, but today the
field has given his interest concrete form.
He finally starts to talk to a few pilots—
especially the one with the model of the
North American P-51 Mustang, which was
the hero of so many airplane movies he grew
up with. He has wanted to fly one since he
saw his first “airplane movie.”
However, this man quickly learns that
you can’t learn to fly model aircraft with a
Speed brakes are already attached to the landing gear. Just screw
in place with the nylon straps. Make sure the bottom edge of the
speed brake rests against the front screw as shown to prevent
rotation.
The Mustang PTS is a true RTF airplane with great photo-illustrated instructions and
even a flight simulator.
One wing half has a tab with two holes. The front hole sets the
flaps to zero. Hooking the factory-made linkage to the rear hole
provides 26° of flaps.
Install the flap servo in the factory-prepared mount. Use the small
end of the output arm and set maximum travel to 51% to provide
26° of flap.
Everything on the wing except the wheels, even the servo leads,
are factory installed. Slide the wing halves onto the aluminum
tube and lock in place with two small screws.
Mustang. At least two years of flying one of
those boxy, Cessna-looking typical trainers
and then an advanced trainer is the minimum
experience required before he can even think
about buying the Mustang. He is
disappointed but still not totally lost to us.
Then his son says, “I want to fly the
fighter—not one of those stupid, old things.”
They walk away and we lose two potential
new modelers.
How many times have RC instructors
seen the sad disappointment on potential
model pilots’ faces when they have
discovered the facts about learning to fly?
Many understand it and buy that high-wing
trainer. But that doesn’t mean they are happy
about it! Many others walk away, usually
believing that the difficulties are being
exaggerated or that three airplanes are too
much, or they are let down because they
can’t “have it all” now.
If the date had been September 4, 2005,
the outcome of that visit to the RC field
might have been vastly better. You want to
learn to fly with a Mustang? Great! Not only
can you learn with one, but that same
Mustang can teach you advanced piloting
techniques while becoming one of the bestperforming
Sport Scale aircraft available. It
is three airplanes in one.
Even better, this Mustang is an RTF. No
building skills or special equipment is
required. If you can spare 30 minutes to
assemble the model, you can learn
everything about RC piloting.
The cost is less than $400 for the
airplane, radio, engine, and all airframe
accessories, all factory installed. You save even more money since
you will not need to buy that follow-up “advanced trainer” or
Mustang kit; all three are in the Mustang PTS. There is definitely
potential to grow our sport with this model.
Everything with the Mustang is prebuilt, and even a flight
simulator is included. Unfortunately my computer does not have the
right connection for the simulator cord, and an adaptor has not been
located yet. This part of the review will have to be included on Model
Aviation’s Sport Aviator online magazine (www.masportaviator.com).
Assembly time really is less than 30 minutes. I finished the
aircraft in 21 minutes using just a screwdriver and pliers. Well, I did
use a wrench to make sure the propeller was tight, but that shouldn’t
count since it was.
Complete Assembly: The first job was the wing. As with a modern
airliner, all the real secrets to this aircraft’s performance are located
there. Flaps, speed brakes, ailerons, bolt-on wing-mounting system,
radiator scoop, and LE cuffs are part of the main wing, yet assembly
time is only 10 minutes.
As a photo shows, each wing half slides onto an aluminum tube.
There is an alignment pin to ensure that everything is true and it
works as advertised. The entire wing is held together by a single
nylon strap.
After joining the wing panels, bolt the landing gear in place as
shown and then use the factory-made flap linkage rod to connect the
flaps. The flaps use independent aileron-style torque tubes and are
connected to a fixed wing tab, as shown. The clear-plastic wing
droops are installed at the factory. The wing is finished at this point.
However, I strongly suggest that every potential Mustang pilot
install the flap servo before the first flight. The mount is already
there, and installation takes roughly five minutes.
Completing the fuselage involves bolting on the tail feathers, as
shown. The control surfaces and control horns are already installed.
Use the two lock nuts provided to bolt everything firmly in place.
Everything back there fit well, and it was good to see that the
stabilizer’s bolt holes were reinforced at the factory. Connect the two
control rods to the middle hole on the control horns. The last step is
to bolt the exhaust stacks onto the fuselage so that the 1,450-
horsepower, 12-cylinder Merlin engine can make the ground shake.
Power and Control: No, there isn’t a scaled-down V-1650-7regimes, including downhill and in landing
approaches.
In addition, this propeller’s pitch appears
to be less than 6 inches but is unidentified.
The lower pitch further reduces airspeed at
all throttle settings. Since engine rpm is
reduced under the three-blade’s extra load,
so are maximum airspeeds.
The radio compartment is factory built
with a removable cover to get at the receiver
and battery. The receiver is the popular JR
R700 six-channel FM model.
Onboard power is from JR’s 4N600: a
4.8-volt, 600 mAh Ni-Cd battery pack. The
five factory-installed servos are JR 537 ballbearing
sport units. The cored servo motor
puts out 43 in.-oz. of torque while rotating a
60° arc in just .25 second.
Few RTF aircraft offer ball-bearing
servos. But then, few RTF aircraft are guided
by a computer transmitter.
The Mustang’s transmitter is JR’s fivechannel
XF421, which is a great introductory
computer radio. It features digital travel
adjustments, basic mixing (including
“flaperon”), easy servo reversing, and
memory storage for two aircraft. Few RTFs
feature such an advanced transmitter. The
XF421 is powered by a 600 mAh Ni-Cd
pack and is compatible with most
transmitters for a “buddy” link via the
included trainer cord.
But is this really a trainer? So it was easy to
put together. But come on; it is a Mustang
after all. Even the Army Air Force didn’t put
pilots in Mustangs until they went through
primary and advanced trainers. And they
were sending people out to get shot at!
Look at the heavily tapered wing with the
narrow-chord wingtips. Tell me that won’t
tip-stall into a snap roll at the first
provocation. And that semisymmetricalairfoil
wing is small for a 6.5-pound trainer.
Landing speeds will have to be high. The
airplane is so streamlined that everything
will be happening fast.
So they hung some gizmos all over the
wing, but how much can they help? You
can’t even see that stuff near the wingtips, so
how was this fighter transformed into a
typical trainer? Skull sweat and good design,
that’s how.
Each “gizmo” has a design purpose, and
each one worked as intended. The “speed
brakes” mounted on the landing gear add
drag, reducing the top speed while
preventing the airplane from gaining a great
deal of airspeed when the nose starts to point
earthward. The wing flaps, set at 26°, create
more drag to further slow the airplane while
increasing the wing’s lifting force.
Working together, both devices make it
easy to set up correct landing approaches.
Those invisible—in the air or when trying to
photograph the darn things—clear-plastic LE
cuffs also increase wing lift; first by
increasing the wingtip area and second by
acting as a “flat-bottom” section of the
symmetrical-airfoil wing. The increased
wingtip area reduces tip-stalling to zero.
But the best way to find out whether or not
this is a typical trainer is to fly it. So we did.
In fact, 12 pilots flew it during 57 test flights.
Therefore, some of what follows is
opinion—sometimes educated, sometimes
otherwise.
The net result is that the Mustang PTS
flies identical to a typical trainer. It is slow
and gentle with no bad tendencies. It flies
like a trainer but does not take off or land
like one. This difference is perhaps the
Mustang’s greatest benefit to the new RC
pilot. Let’s go through some flights.
Start the engine. All the Evolution Alpha
engine ever required was to prime the
carburetor and then rotate the spinner cone
backward. It started every time without using
an electric starter.
Taxiing is beyond easy. The landing gear,
with those gigantic tires, is canted so far
forward that it is beyond impossible to tip
the airplane onto its nose. The gear is widely
spaced for excellent ground handling.
Ground steering is positive and not sensitive.
The takeoff roll requires nontrainer
technique. With rudder throw set as
instructed and with the three-blade propeller
providing extra torque, full right rudder is
required for a straight takeoff roll.
Start the airplane rolling slowly and put in
full right rudder while going to full power.
The airplane rolls straight down the runway.
If you are late with the rudder, it may be
impossible to get back to the runway heading.This teaches the student pilot from the
start how to manage rudder during the
takeoff rolls of future, more powerful
aerobatic and Scale models. Rolling any
aircraft down the runway on takeoff will
hold no mystery for the PTS pilot.
As soon as the Mustang PTS breaks
ground, it goes into full training mode. The
climbout is gentle and noncritical.
Mismanage the elevator, even to stalling
the airplane, and the Mustang mushes on up,
climbing slightly with each oscillation.
There is no tip-stalling tendency or nose
drop. Release full up and the airplane goes
back to flying, slowly climbing to altitude
with plenty of time for the new pilot to think
ahead.
Cruise flight requires approximately 60%
throttle. Straight flight is stable. Turns with
banks up to roughly 45° require minimum
up-elevator to hold altitude. Steeper banks
take approximately 30% of the available upelevator
to remain level.
Letting the nose drop in the turn, as most
student pilots would, produces little
noticeable speed increase, and there is never
a tendency to “balloon,” or raising the nose
while losing airspeed, as most trainers do
once the wings are leveled. This is a good
thing since it reduces pilot workload.
Even during tight turns at slow airspeeds
there is never a tendency to tip stall or roll
out of the turn. The Mustang stays put as
directed, remaining tolerant of any abuse—
even full crossed-control stalls, right aileron,
and left rudder.
Spins are difficult and require power to
develop. Rotation stops immediately once
power or elevator input is reduced. Snap
rolls are more like giant barrel rolls, taking
approximately three seconds to complete.
Straight inverted flight is barely possible,
but level inverted turns are not; the airplane
runs out of down-elevator. The rudder is
notably ineffective, making knife-edge flight
impossible. So far the Mustang PTS flies
like every other typical trainer.
Power-off stalls are amazing. The wings
stay level, aileron control remains, and the
model just floats through the sky, defying
gravity and common sense. True, it comes
down, but slowly—maybe 200 feet per
minute or maybe less.
Starting from roughly 400 feet up, with
the engine at high idle—2,800 rpm—and
holding full up-elevator, the Mustang PTS
floats the entire available flight length of the
field, which was approximately 1/4 mile, and
is still roughly 100 feet from the ground.
This is not a recommended landing
technique because there could not be a
“flare,” breaking the descent before
touchdown, and the airplane would be
damaged. But add a bit of power to the
approach and reduce the elevator input, and
it could almost be. And that brings me to
landing the Mustang PTS.
Landing is different from that of a typical
trainer, which is usually executed by cutting
the engine to idle while approximately 75
feet high and 100 feet away from the runway
and then gliding in. However, the Mustang
PTS’s speed brakes, flaps, and LE droops
provide a good amount of drag.
Therefore, this airplane is landed as most
high-performance sport and Scale aircraft
are, using engine power. The approach and
touchdown are flown slowly at trainerlike
airspeeds, but approximately 30% engine
power is needed to “glide” to the runway.
The Mustang PTS teaches the new pilot
now—not later—how to land all those highperformance
sport and Scale airplanes
waiting in his or her future. Mastering the
power landing, with its intricate dance of
power for altitude and elevator for airspeedcontrol, can be difficult to learn once the
power-off typical trainer landing becomes
habit. This will not happen to the Mustang
PTS pilot.
The Mustang’s extra drag is why I
suggest installing operating flaps from the
start. There isn’t a great deal of glide with
everything hanging out in the slipstream. If
the engine runs out of fuel or quits, the
runway is unreachable unless it happens to
be close when the propeller goes rigid.
Raising the flaps dramatically extends
gliding distance, allowing the airplane to
“make the field” in such situations.
Using the transmitter’s travel-adjust
feature, set maximum flap movement—
channel 5—to 51%. This provides the same
26° of flap deployment as the fixed
mounting point would.
Three student pilots who had not yet
soloed flew the Mustang PTS in the air only,
using the “buddy box” system. Two flew
without the instructor’s having to take
control, and the third, having flown only a
small electric-powered trainer, needed
instructor help only three times in the eightminute
flight. All pronounced the Mustang
PTS to be a great trainer and felt they could
easily learn to fly with one.
Five newly soloed pilots flew the airplane
and felt the same way. Four club instructors
gave the model a fair workout, and all
thought they could easily teach new pilots
how to fly with it.
Is it a typical trainer? Yes, but with a
twist.
Learning to fly with the Mustang PTS is
as easy as learning on a typical trainer, but
the process will require two or three hours of
extra airtime to learn the advanced takeoff
and landing skills. But after soloing the
Mustang PTS pilot will have those additional
advanced skills and graduate flight school a
better flier, enjoying more complete piloting
skills for the experience.
Beyond Training: The idea behind the
Progressive Training System (the “PTS” in
Mustang PTS) is that the airplane can
quickly be reconfigured for more advanced
performance as the pilot’s skills advance.
Once the new pilot solos and has mastered
basic skills, the Mustang PTS is ready to take
him or her to the next step.
According to Hangar 9, the first step is to
remove the landing-gear speed brakes. I
believe the first step is increasing the amount
of elevator travel to 105% up and 120%
down. Rudder movement should be set to
150%. The ailerons are factory set at 75%
travel, so move those limits to 100%.
With all that done, the airplane becomes
more critical of improper elevator inputs and
will actually drop the nose in the stall.
Ground handling becomes more sensitive
and less than full right rudder is required for
takeoff.
The roll rate quickens, but not that much.
It becomes possible to spin the airplane
without using engine power to aid rotation
entry. Inverted flight, straight and turns,
becomes possible, but no Outside Loops yet!
After mastering this setup, remove the
speed brakes which are held in place with
two plastic tie wraps. Cut them with a hobby
knife (be careful) or use wire clippers.
Removing the speed brakes increases the
Mustang’s airspeed by roughly 15%. Loop
diameter increases from 50 feet to
somewhere near 75 feet. The airplane’s
airspeed become more pitch related as well.
Since cruise airspeed is higher, all the
controls become that much more sensitive.
Everything else remains basically the same;
there are still no bad habits.
These two small changes move the
Mustang approximately one-third of the way
toward offering Sport Scale piloting
challenges. It remains docile in every way,
but things happen faster and the airplane is a
bit more responsive. This is a great
intermediate stage that usually requires
purchasing an advanced trainer.
The next step is to raise those flaps.
Either hit the transmitter switch or reset the
mechanical flaps to the “zero” hole on the
wing tab. Now things change a little more.
Airspeed increases to roughly 50% more
than the original speed. The airplane will
pick up speed if the nose points below level.
Roll rate increases, and all the controls
become more sensitive. There are no trim
changes when flaps are deployed.
Without flaps and speed brakes, throttle
control during landing approaches becomes
more critical. Takeoffs require longer ground
runs, so rudder-control difficulties increase.100 feet, and good stall turns are now
possible. For the first time knife-edge flight
and Slow Rolls are manageable. However,
the airplane remains docile and has no
unwelcome surprises awaiting the unwary
pilot.
The LE droops are held in place with
clear tape. Peel the tape away, and the
droops are history. Before removing these
lift devices, the pilot should be comfortable
with the airplane’s handling and be able to
easily manage the increased performance up
to this point. Without the droops, the
Mustang loses the PTS label and matures
into a P-51 Mustang fighter.
True, the Mustang remains an excellentflying
Sport Scale aircraft—maybe one of
the best for its size—but when all the
training aids are gone, so is the safety net. If
you pull a turn too tightly, with too much upelevator,
the P-51 will drop the bottom wing,
rotating into the turn. There is no snap roll,
but the wing drop is quick.
Single stalls remain controllable with
a straight-ahead nose drop, but holding
the aircraft into multiple deep stalls, with
no flaps, will eventually lead to a snap
roll. Spin rotation is fast, but recovery
still happens as soon as the controls are
centered. Keep the nose level, or below,
during final approach, or unfortunate
surprises may await the pilot if the
airspeed is permitted to drop too far.
However, performance also increases.
Full-speed “strafing runs” are exciting as
they originally were. Loops approach 125
feet in diameter. Slow rolls are great, but it is
still nearly impossible to hold knife-edge
flight. So move the rudder control rod to the
innermost hole in the control horn, and
welcome to Four Point Rolls.
Outside Loops are easy but do require
small rudder input at the top to remain on
heading. Inverted flight, multiple inverted to
inverted rolls, and outside snap rolls (downelevator
used from inverted flight) are pretty,
but not so fast that they are difficult to
manage. Inverted spins rotate more slowly
than upright; recovery is just as easy.
The last step is to replace the three-blade
propeller with a two-blade performance
propeller such as the APC 10 x 6 or 11 x 5 or
an equivalent. At these maximum power
levels, the Evolution Alpha rockets the P-51
along at a respectable top speed.
Loops top 150 feet in diameter and rolls
become fast. Flying Inside and Outside
Avalanches—Loops with snap rolls at the
top—are fun, and knife-edge flight is better
but remains rudder-limited. Field-length
Slow Rolls are eye-catching.
The 10 x 6 propeller increases approach
speeds, requiring an idle of less than 2,200
rpm. I recommend the 11 x 5 as the best
choice.
However, there is a price for this
increased performance. A truly reliable idle
near 2,300 rpm is required for manageable
landing approaches, or just use the flaps.
Airspeeds at all throttle settings are faster.
The aircraft accelerates much faster when
taking off, so the whole maneuver happens
quickly. The P-51 gains speed in any descent
mode. All these characteristics are common
to most Sport Scale models, but this aircraft
handles the increased performance a little
better than most others do.
Most P-51s do not fly around with big
wheels hanging out the bottom, so
mechanical retracts might be in this
airplane’s future. That upgrade will take
some engineering on my part. I wonder
how far this PTS concept can be pushed.
To find out what else happened with this
model, check the Sport Aviator Web site.
Since most MA readers are pilots who have
some experience, this review focused more
on the PTS upgrades. MA Associate Editor
Michael Ramsey has written an excellent
Mustang PTS review for Sport Aviator that
focuses on the airplane as a typical trainer,
and it includes all the performance
numbers for the various PTS
configurations. MA
Frank Granelli
[email protected]
Distributor:
Horizon Hobby, Inc.
4105 Fieldstone Rd.
Champaign IL 61822
(877) 504-0233
www.hangar-9.com
Edition: Model Aviation - 2006/02
Page Numbers: 55,56,57,58,61,62,64
Plane Talk: Hangar 9 Mustang PTS
FRANK GRANELLI
• Ready to run with everything included with simulator and
buddy cord.
• Upgradable to a sport model with higher performance and
functional flaps.
Pluses and Minuses
+
• Clear canopy is glued in place, making it difficult to install a
scale pilot.
• Landing-gear mounting blocks could have been built stronger.
There was a failure after 43 flights.
With the training gizmos removed, the
Mustang in this trainer starts to shine
through. Inverted flight and Outside Loops
from level are comfortable to do. Costello
photo.
The Mustang PTS is so easy to land that one-wheel crosswind
touchdowns are routine, even in extreme nose-high attitudes.
Make sure to carry some power in the approach. Costello photo.
Clean, the P-51 Mustang is a joy to throw around the sky. It’s better behaved than most
Sport Scale models its size, but “Marie” can perform with the best of them. Frank
Costello photo.
THE DATE IS February 22, 1944. The
skies over Europe are again aflame. It is
Tuesday of “Big Week”: the American air
offensive to destroy the Luftwaffe. American
B-17 and B-24 bombers of the 15th Air Force
are nearing Regensburg to destroy German
aircraft factories.
Suddenly, black dots appear on their
noses. “German fighters, 4 o’clock” echoes
over hundreds of intercoms. Closing speeds
approach 500 mph as the dots become Me
109 fighters starting head-on attacks.
Crew members crouch behind tiny armor
plates, knowing to expect the worst. Then,
high in the Western sky, the sun flashes
brightly off of bare aluminum as silver wings
bank 90° and roll into their dives. At more
than 450 mph, the Mustangs of the yellowtailed
52nd Fighter Group race in front of the
bombers, making the airways ahead safe.
The Mustang Legend continues.
The date is June 4, 2005. It is Saturday
and a 30-something-year-old man appears at
the RC field with his young son. He has been
here before. Even he is not sure why he has
come back.
His imagination has been captured by the
aerobatic airplanes that seem to rotate the
sky itself, while Scale models subtly link the
two aviation worlds. He has always had a
“passing” interest in aviation, but today the
field has given his interest concrete form.
He finally starts to talk to a few pilots—
especially the one with the model of the
North American P-51 Mustang, which was
the hero of so many airplane movies he grew
up with. He has wanted to fly one since he
saw his first “airplane movie.”
However, this man quickly learns that
you can’t learn to fly model aircraft with a
Speed brakes are already attached to the landing gear. Just screw
in place with the nylon straps. Make sure the bottom edge of the
speed brake rests against the front screw as shown to prevent
rotation.
The Mustang PTS is a true RTF airplane with great photo-illustrated instructions and
even a flight simulator.
One wing half has a tab with two holes. The front hole sets the
flaps to zero. Hooking the factory-made linkage to the rear hole
provides 26° of flaps.
Install the flap servo in the factory-prepared mount. Use the small
end of the output arm and set maximum travel to 51% to provide
26° of flap.
Everything on the wing except the wheels, even the servo leads,
are factory installed. Slide the wing halves onto the aluminum
tube and lock in place with two small screws.
Mustang. At least two years of flying one of
those boxy, Cessna-looking typical trainers
and then an advanced trainer is the minimum
experience required before he can even think
about buying the Mustang. He is
disappointed but still not totally lost to us.
Then his son says, “I want to fly the
fighter—not one of those stupid, old things.”
They walk away and we lose two potential
new modelers.
How many times have RC instructors
seen the sad disappointment on potential
model pilots’ faces when they have
discovered the facts about learning to fly?
Many understand it and buy that high-wing
trainer. But that doesn’t mean they are happy
about it! Many others walk away, usually
believing that the difficulties are being
exaggerated or that three airplanes are too
much, or they are let down because they
can’t “have it all” now.
If the date had been September 4, 2005,
the outcome of that visit to the RC field
might have been vastly better. You want to
learn to fly with a Mustang? Great! Not only
can you learn with one, but that same
Mustang can teach you advanced piloting
techniques while becoming one of the bestperforming
Sport Scale aircraft available. It
is three airplanes in one.
Even better, this Mustang is an RTF. No
building skills or special equipment is
required. If you can spare 30 minutes to
assemble the model, you can learn
everything about RC piloting.
The cost is less than $400 for the
airplane, radio, engine, and all airframe
accessories, all factory installed. You save even more money since
you will not need to buy that follow-up “advanced trainer” or
Mustang kit; all three are in the Mustang PTS. There is definitely
potential to grow our sport with this model.
Everything with the Mustang is prebuilt, and even a flight
simulator is included. Unfortunately my computer does not have the
right connection for the simulator cord, and an adaptor has not been
located yet. This part of the review will have to be included on Model
Aviation’s Sport Aviator online magazine (www.masportaviator.com).
Assembly time really is less than 30 minutes. I finished the
aircraft in 21 minutes using just a screwdriver and pliers. Well, I did
use a wrench to make sure the propeller was tight, but that shouldn’t
count since it was.
Complete Assembly: The first job was the wing. As with a modern
airliner, all the real secrets to this aircraft’s performance are located
there. Flaps, speed brakes, ailerons, bolt-on wing-mounting system,
radiator scoop, and LE cuffs are part of the main wing, yet assembly
time is only 10 minutes.
As a photo shows, each wing half slides onto an aluminum tube.
There is an alignment pin to ensure that everything is true and it
works as advertised. The entire wing is held together by a single
nylon strap.
After joining the wing panels, bolt the landing gear in place as
shown and then use the factory-made flap linkage rod to connect the
flaps. The flaps use independent aileron-style torque tubes and are
connected to a fixed wing tab, as shown. The clear-plastic wing
droops are installed at the factory. The wing is finished at this point.
However, I strongly suggest that every potential Mustang pilot
install the flap servo before the first flight. The mount is already
there, and installation takes roughly five minutes.
Completing the fuselage involves bolting on the tail feathers, as
shown. The control surfaces and control horns are already installed.
Use the two lock nuts provided to bolt everything firmly in place.
Everything back there fit well, and it was good to see that the
stabilizer’s bolt holes were reinforced at the factory. Connect the two
control rods to the middle hole on the control horns. The last step is
to bolt the exhaust stacks onto the fuselage so that the 1,450-
horsepower, 12-cylinder Merlin engine can make the ground shake.
Power and Control: No, there isn’t a scaled-down V-1650-7regimes, including downhill and in landing
approaches.
In addition, this propeller’s pitch appears
to be less than 6 inches but is unidentified.
The lower pitch further reduces airspeed at
all throttle settings. Since engine rpm is
reduced under the three-blade’s extra load,
so are maximum airspeeds.
The radio compartment is factory built
with a removable cover to get at the receiver
and battery. The receiver is the popular JR
R700 six-channel FM model.
Onboard power is from JR’s 4N600: a
4.8-volt, 600 mAh Ni-Cd battery pack. The
five factory-installed servos are JR 537 ballbearing
sport units. The cored servo motor
puts out 43 in.-oz. of torque while rotating a
60° arc in just .25 second.
Few RTF aircraft offer ball-bearing
servos. But then, few RTF aircraft are guided
by a computer transmitter.
The Mustang’s transmitter is JR’s fivechannel
XF421, which is a great introductory
computer radio. It features digital travel
adjustments, basic mixing (including
“flaperon”), easy servo reversing, and
memory storage for two aircraft. Few RTFs
feature such an advanced transmitter. The
XF421 is powered by a 600 mAh Ni-Cd
pack and is compatible with most
transmitters for a “buddy” link via the
included trainer cord.
But is this really a trainer? So it was easy to
put together. But come on; it is a Mustang
after all. Even the Army Air Force didn’t put
pilots in Mustangs until they went through
primary and advanced trainers. And they
were sending people out to get shot at!
Look at the heavily tapered wing with the
narrow-chord wingtips. Tell me that won’t
tip-stall into a snap roll at the first
provocation. And that semisymmetricalairfoil
wing is small for a 6.5-pound trainer.
Landing speeds will have to be high. The
airplane is so streamlined that everything
will be happening fast.
So they hung some gizmos all over the
wing, but how much can they help? You
can’t even see that stuff near the wingtips, so
how was this fighter transformed into a
typical trainer? Skull sweat and good design,
that’s how.
Each “gizmo” has a design purpose, and
each one worked as intended. The “speed
brakes” mounted on the landing gear add
drag, reducing the top speed while
preventing the airplane from gaining a great
deal of airspeed when the nose starts to point
earthward. The wing flaps, set at 26°, create
more drag to further slow the airplane while
increasing the wing’s lifting force.
Working together, both devices make it
easy to set up correct landing approaches.
Those invisible—in the air or when trying to
photograph the darn things—clear-plastic LE
cuffs also increase wing lift; first by
increasing the wingtip area and second by
acting as a “flat-bottom” section of the
symmetrical-airfoil wing. The increased
wingtip area reduces tip-stalling to zero.
But the best way to find out whether or not
this is a typical trainer is to fly it. So we did.
In fact, 12 pilots flew it during 57 test flights.
Therefore, some of what follows is
opinion—sometimes educated, sometimes
otherwise.
The net result is that the Mustang PTS
flies identical to a typical trainer. It is slow
and gentle with no bad tendencies. It flies
like a trainer but does not take off or land
like one. This difference is perhaps the
Mustang’s greatest benefit to the new RC
pilot. Let’s go through some flights.
Start the engine. All the Evolution Alpha
engine ever required was to prime the
carburetor and then rotate the spinner cone
backward. It started every time without using
an electric starter.
Taxiing is beyond easy. The landing gear,
with those gigantic tires, is canted so far
forward that it is beyond impossible to tip
the airplane onto its nose. The gear is widely
spaced for excellent ground handling.
Ground steering is positive and not sensitive.
The takeoff roll requires nontrainer
technique. With rudder throw set as
instructed and with the three-blade propeller
providing extra torque, full right rudder is
required for a straight takeoff roll.
Start the airplane rolling slowly and put in
full right rudder while going to full power.
The airplane rolls straight down the runway.
If you are late with the rudder, it may be
impossible to get back to the runway heading.This teaches the student pilot from the
start how to manage rudder during the
takeoff rolls of future, more powerful
aerobatic and Scale models. Rolling any
aircraft down the runway on takeoff will
hold no mystery for the PTS pilot.
As soon as the Mustang PTS breaks
ground, it goes into full training mode. The
climbout is gentle and noncritical.
Mismanage the elevator, even to stalling
the airplane, and the Mustang mushes on up,
climbing slightly with each oscillation.
There is no tip-stalling tendency or nose
drop. Release full up and the airplane goes
back to flying, slowly climbing to altitude
with plenty of time for the new pilot to think
ahead.
Cruise flight requires approximately 60%
throttle. Straight flight is stable. Turns with
banks up to roughly 45° require minimum
up-elevator to hold altitude. Steeper banks
take approximately 30% of the available upelevator
to remain level.
Letting the nose drop in the turn, as most
student pilots would, produces little
noticeable speed increase, and there is never
a tendency to “balloon,” or raising the nose
while losing airspeed, as most trainers do
once the wings are leveled. This is a good
thing since it reduces pilot workload.
Even during tight turns at slow airspeeds
there is never a tendency to tip stall or roll
out of the turn. The Mustang stays put as
directed, remaining tolerant of any abuse—
even full crossed-control stalls, right aileron,
and left rudder.
Spins are difficult and require power to
develop. Rotation stops immediately once
power or elevator input is reduced. Snap
rolls are more like giant barrel rolls, taking
approximately three seconds to complete.
Straight inverted flight is barely possible,
but level inverted turns are not; the airplane
runs out of down-elevator. The rudder is
notably ineffective, making knife-edge flight
impossible. So far the Mustang PTS flies
like every other typical trainer.
Power-off stalls are amazing. The wings
stay level, aileron control remains, and the
model just floats through the sky, defying
gravity and common sense. True, it comes
down, but slowly—maybe 200 feet per
minute or maybe less.
Starting from roughly 400 feet up, with
the engine at high idle—2,800 rpm—and
holding full up-elevator, the Mustang PTS
floats the entire available flight length of the
field, which was approximately 1/4 mile, and
is still roughly 100 feet from the ground.
This is not a recommended landing
technique because there could not be a
“flare,” breaking the descent before
touchdown, and the airplane would be
damaged. But add a bit of power to the
approach and reduce the elevator input, and
it could almost be. And that brings me to
landing the Mustang PTS.
Landing is different from that of a typical
trainer, which is usually executed by cutting
the engine to idle while approximately 75
feet high and 100 feet away from the runway
and then gliding in. However, the Mustang
PTS’s speed brakes, flaps, and LE droops
provide a good amount of drag.
Therefore, this airplane is landed as most
high-performance sport and Scale aircraft
are, using engine power. The approach and
touchdown are flown slowly at trainerlike
airspeeds, but approximately 30% engine
power is needed to “glide” to the runway.
The Mustang PTS teaches the new pilot
now—not later—how to land all those highperformance
sport and Scale airplanes
waiting in his or her future. Mastering the
power landing, with its intricate dance of
power for altitude and elevator for airspeedcontrol, can be difficult to learn once the
power-off typical trainer landing becomes
habit. This will not happen to the Mustang
PTS pilot.
The Mustang’s extra drag is why I
suggest installing operating flaps from the
start. There isn’t a great deal of glide with
everything hanging out in the slipstream. If
the engine runs out of fuel or quits, the
runway is unreachable unless it happens to
be close when the propeller goes rigid.
Raising the flaps dramatically extends
gliding distance, allowing the airplane to
“make the field” in such situations.
Using the transmitter’s travel-adjust
feature, set maximum flap movement—
channel 5—to 51%. This provides the same
26° of flap deployment as the fixed
mounting point would.
Three student pilots who had not yet
soloed flew the Mustang PTS in the air only,
using the “buddy box” system. Two flew
without the instructor’s having to take
control, and the third, having flown only a
small electric-powered trainer, needed
instructor help only three times in the eightminute
flight. All pronounced the Mustang
PTS to be a great trainer and felt they could
easily learn to fly with one.
Five newly soloed pilots flew the airplane
and felt the same way. Four club instructors
gave the model a fair workout, and all
thought they could easily teach new pilots
how to fly with it.
Is it a typical trainer? Yes, but with a
twist.
Learning to fly with the Mustang PTS is
as easy as learning on a typical trainer, but
the process will require two or three hours of
extra airtime to learn the advanced takeoff
and landing skills. But after soloing the
Mustang PTS pilot will have those additional
advanced skills and graduate flight school a
better flier, enjoying more complete piloting
skills for the experience.
Beyond Training: The idea behind the
Progressive Training System (the “PTS” in
Mustang PTS) is that the airplane can
quickly be reconfigured for more advanced
performance as the pilot’s skills advance.
Once the new pilot solos and has mastered
basic skills, the Mustang PTS is ready to take
him or her to the next step.
According to Hangar 9, the first step is to
remove the landing-gear speed brakes. I
believe the first step is increasing the amount
of elevator travel to 105% up and 120%
down. Rudder movement should be set to
150%. The ailerons are factory set at 75%
travel, so move those limits to 100%.
With all that done, the airplane becomes
more critical of improper elevator inputs and
will actually drop the nose in the stall.
Ground handling becomes more sensitive
and less than full right rudder is required for
takeoff.
The roll rate quickens, but not that much.
It becomes possible to spin the airplane
without using engine power to aid rotation
entry. Inverted flight, straight and turns,
becomes possible, but no Outside Loops yet!
After mastering this setup, remove the
speed brakes which are held in place with
two plastic tie wraps. Cut them with a hobby
knife (be careful) or use wire clippers.
Removing the speed brakes increases the
Mustang’s airspeed by roughly 15%. Loop
diameter increases from 50 feet to
somewhere near 75 feet. The airplane’s
airspeed become more pitch related as well.
Since cruise airspeed is higher, all the
controls become that much more sensitive.
Everything else remains basically the same;
there are still no bad habits.
These two small changes move the
Mustang approximately one-third of the way
toward offering Sport Scale piloting
challenges. It remains docile in every way,
but things happen faster and the airplane is a
bit more responsive. This is a great
intermediate stage that usually requires
purchasing an advanced trainer.
The next step is to raise those flaps.
Either hit the transmitter switch or reset the
mechanical flaps to the “zero” hole on the
wing tab. Now things change a little more.
Airspeed increases to roughly 50% more
than the original speed. The airplane will
pick up speed if the nose points below level.
Roll rate increases, and all the controls
become more sensitive. There are no trim
changes when flaps are deployed.
Without flaps and speed brakes, throttle
control during landing approaches becomes
more critical. Takeoffs require longer ground
runs, so rudder-control difficulties increase.100 feet, and good stall turns are now
possible. For the first time knife-edge flight
and Slow Rolls are manageable. However,
the airplane remains docile and has no
unwelcome surprises awaiting the unwary
pilot.
The LE droops are held in place with
clear tape. Peel the tape away, and the
droops are history. Before removing these
lift devices, the pilot should be comfortable
with the airplane’s handling and be able to
easily manage the increased performance up
to this point. Without the droops, the
Mustang loses the PTS label and matures
into a P-51 Mustang fighter.
True, the Mustang remains an excellentflying
Sport Scale aircraft—maybe one of
the best for its size—but when all the
training aids are gone, so is the safety net. If
you pull a turn too tightly, with too much upelevator,
the P-51 will drop the bottom wing,
rotating into the turn. There is no snap roll,
but the wing drop is quick.
Single stalls remain controllable with
a straight-ahead nose drop, but holding
the aircraft into multiple deep stalls, with
no flaps, will eventually lead to a snap
roll. Spin rotation is fast, but recovery
still happens as soon as the controls are
centered. Keep the nose level, or below,
during final approach, or unfortunate
surprises may await the pilot if the
airspeed is permitted to drop too far.
However, performance also increases.
Full-speed “strafing runs” are exciting as
they originally were. Loops approach 125
feet in diameter. Slow rolls are great, but it is
still nearly impossible to hold knife-edge
flight. So move the rudder control rod to the
innermost hole in the control horn, and
welcome to Four Point Rolls.
Outside Loops are easy but do require
small rudder input at the top to remain on
heading. Inverted flight, multiple inverted to
inverted rolls, and outside snap rolls (downelevator
used from inverted flight) are pretty,
but not so fast that they are difficult to
manage. Inverted spins rotate more slowly
than upright; recovery is just as easy.
The last step is to replace the three-blade
propeller with a two-blade performance
propeller such as the APC 10 x 6 or 11 x 5 or
an equivalent. At these maximum power
levels, the Evolution Alpha rockets the P-51
along at a respectable top speed.
Loops top 150 feet in diameter and rolls
become fast. Flying Inside and Outside
Avalanches—Loops with snap rolls at the
top—are fun, and knife-edge flight is better
but remains rudder-limited. Field-length
Slow Rolls are eye-catching.
The 10 x 6 propeller increases approach
speeds, requiring an idle of less than 2,200
rpm. I recommend the 11 x 5 as the best
choice.
However, there is a price for this
increased performance. A truly reliable idle
near 2,300 rpm is required for manageable
landing approaches, or just use the flaps.
Airspeeds at all throttle settings are faster.
The aircraft accelerates much faster when
taking off, so the whole maneuver happens
quickly. The P-51 gains speed in any descent
mode. All these characteristics are common
to most Sport Scale models, but this aircraft
handles the increased performance a little
better than most others do.
Most P-51s do not fly around with big
wheels hanging out the bottom, so
mechanical retracts might be in this
airplane’s future. That upgrade will take
some engineering on my part. I wonder
how far this PTS concept can be pushed.
To find out what else happened with this
model, check the Sport Aviator Web site.
Since most MA readers are pilots who have
some experience, this review focused more
on the PTS upgrades. MA Associate Editor
Michael Ramsey has written an excellent
Mustang PTS review for Sport Aviator that
focuses on the airplane as a typical trainer,
and it includes all the performance
numbers for the various PTS
configurations. MA
Frank Granelli
[email protected]
Distributor:
Horizon Hobby, Inc.
4105 Fieldstone Rd.
Champaign IL 61822
(877) 504-0233
www.hangar-9.com
Edition: Model Aviation - 2006/02
Page Numbers: 55,56,57,58,61,62,64
Plane Talk: Hangar 9 Mustang PTS
FRANK GRANELLI
• Ready to run with everything included with simulator and
buddy cord.
• Upgradable to a sport model with higher performance and
functional flaps.
Pluses and Minuses
+
• Clear canopy is glued in place, making it difficult to install a
scale pilot.
• Landing-gear mounting blocks could have been built stronger.
There was a failure after 43 flights.
With the training gizmos removed, the
Mustang in this trainer starts to shine
through. Inverted flight and Outside Loops
from level are comfortable to do. Costello
photo.
The Mustang PTS is so easy to land that one-wheel crosswind
touchdowns are routine, even in extreme nose-high attitudes.
Make sure to carry some power in the approach. Costello photo.
Clean, the P-51 Mustang is a joy to throw around the sky. It’s better behaved than most
Sport Scale models its size, but “Marie” can perform with the best of them. Frank
Costello photo.
THE DATE IS February 22, 1944. The
skies over Europe are again aflame. It is
Tuesday of “Big Week”: the American air
offensive to destroy the Luftwaffe. American
B-17 and B-24 bombers of the 15th Air Force
are nearing Regensburg to destroy German
aircraft factories.
Suddenly, black dots appear on their
noses. “German fighters, 4 o’clock” echoes
over hundreds of intercoms. Closing speeds
approach 500 mph as the dots become Me
109 fighters starting head-on attacks.
Crew members crouch behind tiny armor
plates, knowing to expect the worst. Then,
high in the Western sky, the sun flashes
brightly off of bare aluminum as silver wings
bank 90° and roll into their dives. At more
than 450 mph, the Mustangs of the yellowtailed
52nd Fighter Group race in front of the
bombers, making the airways ahead safe.
The Mustang Legend continues.
The date is June 4, 2005. It is Saturday
and a 30-something-year-old man appears at
the RC field with his young son. He has been
here before. Even he is not sure why he has
come back.
His imagination has been captured by the
aerobatic airplanes that seem to rotate the
sky itself, while Scale models subtly link the
two aviation worlds. He has always had a
“passing” interest in aviation, but today the
field has given his interest concrete form.
He finally starts to talk to a few pilots—
especially the one with the model of the
North American P-51 Mustang, which was
the hero of so many airplane movies he grew
up with. He has wanted to fly one since he
saw his first “airplane movie.”
However, this man quickly learns that
you can’t learn to fly model aircraft with a
Speed brakes are already attached to the landing gear. Just screw
in place with the nylon straps. Make sure the bottom edge of the
speed brake rests against the front screw as shown to prevent
rotation.
The Mustang PTS is a true RTF airplane with great photo-illustrated instructions and
even a flight simulator.
One wing half has a tab with two holes. The front hole sets the
flaps to zero. Hooking the factory-made linkage to the rear hole
provides 26° of flaps.
Install the flap servo in the factory-prepared mount. Use the small
end of the output arm and set maximum travel to 51% to provide
26° of flap.
Everything on the wing except the wheels, even the servo leads,
are factory installed. Slide the wing halves onto the aluminum
tube and lock in place with two small screws.
Mustang. At least two years of flying one of
those boxy, Cessna-looking typical trainers
and then an advanced trainer is the minimum
experience required before he can even think
about buying the Mustang. He is
disappointed but still not totally lost to us.
Then his son says, “I want to fly the
fighter—not one of those stupid, old things.”
They walk away and we lose two potential
new modelers.
How many times have RC instructors
seen the sad disappointment on potential
model pilots’ faces when they have
discovered the facts about learning to fly?
Many understand it and buy that high-wing
trainer. But that doesn’t mean they are happy
about it! Many others walk away, usually
believing that the difficulties are being
exaggerated or that three airplanes are too
much, or they are let down because they
can’t “have it all” now.
If the date had been September 4, 2005,
the outcome of that visit to the RC field
might have been vastly better. You want to
learn to fly with a Mustang? Great! Not only
can you learn with one, but that same
Mustang can teach you advanced piloting
techniques while becoming one of the bestperforming
Sport Scale aircraft available. It
is three airplanes in one.
Even better, this Mustang is an RTF. No
building skills or special equipment is
required. If you can spare 30 minutes to
assemble the model, you can learn
everything about RC piloting.
The cost is less than $400 for the
airplane, radio, engine, and all airframe
accessories, all factory installed. You save even more money since
you will not need to buy that follow-up “advanced trainer” or
Mustang kit; all three are in the Mustang PTS. There is definitely
potential to grow our sport with this model.
Everything with the Mustang is prebuilt, and even a flight
simulator is included. Unfortunately my computer does not have the
right connection for the simulator cord, and an adaptor has not been
located yet. This part of the review will have to be included on Model
Aviation’s Sport Aviator online magazine (www.masportaviator.com).
Assembly time really is less than 30 minutes. I finished the
aircraft in 21 minutes using just a screwdriver and pliers. Well, I did
use a wrench to make sure the propeller was tight, but that shouldn’t
count since it was.
Complete Assembly: The first job was the wing. As with a modern
airliner, all the real secrets to this aircraft’s performance are located
there. Flaps, speed brakes, ailerons, bolt-on wing-mounting system,
radiator scoop, and LE cuffs are part of the main wing, yet assembly
time is only 10 minutes.
As a photo shows, each wing half slides onto an aluminum tube.
There is an alignment pin to ensure that everything is true and it
works as advertised. The entire wing is held together by a single
nylon strap.
After joining the wing panels, bolt the landing gear in place as
shown and then use the factory-made flap linkage rod to connect the
flaps. The flaps use independent aileron-style torque tubes and are
connected to a fixed wing tab, as shown. The clear-plastic wing
droops are installed at the factory. The wing is finished at this point.
However, I strongly suggest that every potential Mustang pilot
install the flap servo before the first flight. The mount is already
there, and installation takes roughly five minutes.
Completing the fuselage involves bolting on the tail feathers, as
shown. The control surfaces and control horns are already installed.
Use the two lock nuts provided to bolt everything firmly in place.
Everything back there fit well, and it was good to see that the
stabilizer’s bolt holes were reinforced at the factory. Connect the two
control rods to the middle hole on the control horns. The last step is
to bolt the exhaust stacks onto the fuselage so that the 1,450-
horsepower, 12-cylinder Merlin engine can make the ground shake.
Power and Control: No, there isn’t a scaled-down V-1650-7regimes, including downhill and in landing
approaches.
In addition, this propeller’s pitch appears
to be less than 6 inches but is unidentified.
The lower pitch further reduces airspeed at
all throttle settings. Since engine rpm is
reduced under the three-blade’s extra load,
so are maximum airspeeds.
The radio compartment is factory built
with a removable cover to get at the receiver
and battery. The receiver is the popular JR
R700 six-channel FM model.
Onboard power is from JR’s 4N600: a
4.8-volt, 600 mAh Ni-Cd battery pack. The
five factory-installed servos are JR 537 ballbearing
sport units. The cored servo motor
puts out 43 in.-oz. of torque while rotating a
60° arc in just .25 second.
Few RTF aircraft offer ball-bearing
servos. But then, few RTF aircraft are guided
by a computer transmitter.
The Mustang’s transmitter is JR’s fivechannel
XF421, which is a great introductory
computer radio. It features digital travel
adjustments, basic mixing (including
“flaperon”), easy servo reversing, and
memory storage for two aircraft. Few RTFs
feature such an advanced transmitter. The
XF421 is powered by a 600 mAh Ni-Cd
pack and is compatible with most
transmitters for a “buddy” link via the
included trainer cord.
But is this really a trainer? So it was easy to
put together. But come on; it is a Mustang
after all. Even the Army Air Force didn’t put
pilots in Mustangs until they went through
primary and advanced trainers. And they
were sending people out to get shot at!
Look at the heavily tapered wing with the
narrow-chord wingtips. Tell me that won’t
tip-stall into a snap roll at the first
provocation. And that semisymmetricalairfoil
wing is small for a 6.5-pound trainer.
Landing speeds will have to be high. The
airplane is so streamlined that everything
will be happening fast.
So they hung some gizmos all over the
wing, but how much can they help? You
can’t even see that stuff near the wingtips, so
how was this fighter transformed into a
typical trainer? Skull sweat and good design,
that’s how.
Each “gizmo” has a design purpose, and
each one worked as intended. The “speed
brakes” mounted on the landing gear add
drag, reducing the top speed while
preventing the airplane from gaining a great
deal of airspeed when the nose starts to point
earthward. The wing flaps, set at 26°, create
more drag to further slow the airplane while
increasing the wing’s lifting force.
Working together, both devices make it
easy to set up correct landing approaches.
Those invisible—in the air or when trying to
photograph the darn things—clear-plastic LE
cuffs also increase wing lift; first by
increasing the wingtip area and second by
acting as a “flat-bottom” section of the
symmetrical-airfoil wing. The increased
wingtip area reduces tip-stalling to zero.
But the best way to find out whether or not
this is a typical trainer is to fly it. So we did.
In fact, 12 pilots flew it during 57 test flights.
Therefore, some of what follows is
opinion—sometimes educated, sometimes
otherwise.
The net result is that the Mustang PTS
flies identical to a typical trainer. It is slow
and gentle with no bad tendencies. It flies
like a trainer but does not take off or land
like one. This difference is perhaps the
Mustang’s greatest benefit to the new RC
pilot. Let’s go through some flights.
Start the engine. All the Evolution Alpha
engine ever required was to prime the
carburetor and then rotate the spinner cone
backward. It started every time without using
an electric starter.
Taxiing is beyond easy. The landing gear,
with those gigantic tires, is canted so far
forward that it is beyond impossible to tip
the airplane onto its nose. The gear is widely
spaced for excellent ground handling.
Ground steering is positive and not sensitive.
The takeoff roll requires nontrainer
technique. With rudder throw set as
instructed and with the three-blade propeller
providing extra torque, full right rudder is
required for a straight takeoff roll.
Start the airplane rolling slowly and put in
full right rudder while going to full power.
The airplane rolls straight down the runway.
If you are late with the rudder, it may be
impossible to get back to the runway heading.This teaches the student pilot from the
start how to manage rudder during the
takeoff rolls of future, more powerful
aerobatic and Scale models. Rolling any
aircraft down the runway on takeoff will
hold no mystery for the PTS pilot.
As soon as the Mustang PTS breaks
ground, it goes into full training mode. The
climbout is gentle and noncritical.
Mismanage the elevator, even to stalling
the airplane, and the Mustang mushes on up,
climbing slightly with each oscillation.
There is no tip-stalling tendency or nose
drop. Release full up and the airplane goes
back to flying, slowly climbing to altitude
with plenty of time for the new pilot to think
ahead.
Cruise flight requires approximately 60%
throttle. Straight flight is stable. Turns with
banks up to roughly 45° require minimum
up-elevator to hold altitude. Steeper banks
take approximately 30% of the available upelevator
to remain level.
Letting the nose drop in the turn, as most
student pilots would, produces little
noticeable speed increase, and there is never
a tendency to “balloon,” or raising the nose
while losing airspeed, as most trainers do
once the wings are leveled. This is a good
thing since it reduces pilot workload.
Even during tight turns at slow airspeeds
there is never a tendency to tip stall or roll
out of the turn. The Mustang stays put as
directed, remaining tolerant of any abuse—
even full crossed-control stalls, right aileron,
and left rudder.
Spins are difficult and require power to
develop. Rotation stops immediately once
power or elevator input is reduced. Snap
rolls are more like giant barrel rolls, taking
approximately three seconds to complete.
Straight inverted flight is barely possible,
but level inverted turns are not; the airplane
runs out of down-elevator. The rudder is
notably ineffective, making knife-edge flight
impossible. So far the Mustang PTS flies
like every other typical trainer.
Power-off stalls are amazing. The wings
stay level, aileron control remains, and the
model just floats through the sky, defying
gravity and common sense. True, it comes
down, but slowly—maybe 200 feet per
minute or maybe less.
Starting from roughly 400 feet up, with
the engine at high idle—2,800 rpm—and
holding full up-elevator, the Mustang PTS
floats the entire available flight length of the
field, which was approximately 1/4 mile, and
is still roughly 100 feet from the ground.
This is not a recommended landing
technique because there could not be a
“flare,” breaking the descent before
touchdown, and the airplane would be
damaged. But add a bit of power to the
approach and reduce the elevator input, and
it could almost be. And that brings me to
landing the Mustang PTS.
Landing is different from that of a typical
trainer, which is usually executed by cutting
the engine to idle while approximately 75
feet high and 100 feet away from the runway
and then gliding in. However, the Mustang
PTS’s speed brakes, flaps, and LE droops
provide a good amount of drag.
Therefore, this airplane is landed as most
high-performance sport and Scale aircraft
are, using engine power. The approach and
touchdown are flown slowly at trainerlike
airspeeds, but approximately 30% engine
power is needed to “glide” to the runway.
The Mustang PTS teaches the new pilot
now—not later—how to land all those highperformance
sport and Scale airplanes
waiting in his or her future. Mastering the
power landing, with its intricate dance of
power for altitude and elevator for airspeedcontrol, can be difficult to learn once the
power-off typical trainer landing becomes
habit. This will not happen to the Mustang
PTS pilot.
The Mustang’s extra drag is why I
suggest installing operating flaps from the
start. There isn’t a great deal of glide with
everything hanging out in the slipstream. If
the engine runs out of fuel or quits, the
runway is unreachable unless it happens to
be close when the propeller goes rigid.
Raising the flaps dramatically extends
gliding distance, allowing the airplane to
“make the field” in such situations.
Using the transmitter’s travel-adjust
feature, set maximum flap movement—
channel 5—to 51%. This provides the same
26° of flap deployment as the fixed
mounting point would.
Three student pilots who had not yet
soloed flew the Mustang PTS in the air only,
using the “buddy box” system. Two flew
without the instructor’s having to take
control, and the third, having flown only a
small electric-powered trainer, needed
instructor help only three times in the eightminute
flight. All pronounced the Mustang
PTS to be a great trainer and felt they could
easily learn to fly with one.
Five newly soloed pilots flew the airplane
and felt the same way. Four club instructors
gave the model a fair workout, and all
thought they could easily teach new pilots
how to fly with it.
Is it a typical trainer? Yes, but with a
twist.
Learning to fly with the Mustang PTS is
as easy as learning on a typical trainer, but
the process will require two or three hours of
extra airtime to learn the advanced takeoff
and landing skills. But after soloing the
Mustang PTS pilot will have those additional
advanced skills and graduate flight school a
better flier, enjoying more complete piloting
skills for the experience.
Beyond Training: The idea behind the
Progressive Training System (the “PTS” in
Mustang PTS) is that the airplane can
quickly be reconfigured for more advanced
performance as the pilot’s skills advance.
Once the new pilot solos and has mastered
basic skills, the Mustang PTS is ready to take
him or her to the next step.
According to Hangar 9, the first step is to
remove the landing-gear speed brakes. I
believe the first step is increasing the amount
of elevator travel to 105% up and 120%
down. Rudder movement should be set to
150%. The ailerons are factory set at 75%
travel, so move those limits to 100%.
With all that done, the airplane becomes
more critical of improper elevator inputs and
will actually drop the nose in the stall.
Ground handling becomes more sensitive
and less than full right rudder is required for
takeoff.
The roll rate quickens, but not that much.
It becomes possible to spin the airplane
without using engine power to aid rotation
entry. Inverted flight, straight and turns,
becomes possible, but no Outside Loops yet!
After mastering this setup, remove the
speed brakes which are held in place with
two plastic tie wraps. Cut them with a hobby
knife (be careful) or use wire clippers.
Removing the speed brakes increases the
Mustang’s airspeed by roughly 15%. Loop
diameter increases from 50 feet to
somewhere near 75 feet. The airplane’s
airspeed become more pitch related as well.
Since cruise airspeed is higher, all the
controls become that much more sensitive.
Everything else remains basically the same;
there are still no bad habits.
These two small changes move the
Mustang approximately one-third of the way
toward offering Sport Scale piloting
challenges. It remains docile in every way,
but things happen faster and the airplane is a
bit more responsive. This is a great
intermediate stage that usually requires
purchasing an advanced trainer.
The next step is to raise those flaps.
Either hit the transmitter switch or reset the
mechanical flaps to the “zero” hole on the
wing tab. Now things change a little more.
Airspeed increases to roughly 50% more
than the original speed. The airplane will
pick up speed if the nose points below level.
Roll rate increases, and all the controls
become more sensitive. There are no trim
changes when flaps are deployed.
Without flaps and speed brakes, throttle
control during landing approaches becomes
more critical. Takeoffs require longer ground
runs, so rudder-control difficulties increase.100 feet, and good stall turns are now
possible. For the first time knife-edge flight
and Slow Rolls are manageable. However,
the airplane remains docile and has no
unwelcome surprises awaiting the unwary
pilot.
The LE droops are held in place with
clear tape. Peel the tape away, and the
droops are history. Before removing these
lift devices, the pilot should be comfortable
with the airplane’s handling and be able to
easily manage the increased performance up
to this point. Without the droops, the
Mustang loses the PTS label and matures
into a P-51 Mustang fighter.
True, the Mustang remains an excellentflying
Sport Scale aircraft—maybe one of
the best for its size—but when all the
training aids are gone, so is the safety net. If
you pull a turn too tightly, with too much upelevator,
the P-51 will drop the bottom wing,
rotating into the turn. There is no snap roll,
but the wing drop is quick.
Single stalls remain controllable with
a straight-ahead nose drop, but holding
the aircraft into multiple deep stalls, with
no flaps, will eventually lead to a snap
roll. Spin rotation is fast, but recovery
still happens as soon as the controls are
centered. Keep the nose level, or below,
during final approach, or unfortunate
surprises may await the pilot if the
airspeed is permitted to drop too far.
However, performance also increases.
Full-speed “strafing runs” are exciting as
they originally were. Loops approach 125
feet in diameter. Slow rolls are great, but it is
still nearly impossible to hold knife-edge
flight. So move the rudder control rod to the
innermost hole in the control horn, and
welcome to Four Point Rolls.
Outside Loops are easy but do require
small rudder input at the top to remain on
heading. Inverted flight, multiple inverted to
inverted rolls, and outside snap rolls (downelevator
used from inverted flight) are pretty,
but not so fast that they are difficult to
manage. Inverted spins rotate more slowly
than upright; recovery is just as easy.
The last step is to replace the three-blade
propeller with a two-blade performance
propeller such as the APC 10 x 6 or 11 x 5 or
an equivalent. At these maximum power
levels, the Evolution Alpha rockets the P-51
along at a respectable top speed.
Loops top 150 feet in diameter and rolls
become fast. Flying Inside and Outside
Avalanches—Loops with snap rolls at the
top—are fun, and knife-edge flight is better
but remains rudder-limited. Field-length
Slow Rolls are eye-catching.
The 10 x 6 propeller increases approach
speeds, requiring an idle of less than 2,200
rpm. I recommend the 11 x 5 as the best
choice.
However, there is a price for this
increased performance. A truly reliable idle
near 2,300 rpm is required for manageable
landing approaches, or just use the flaps.
Airspeeds at all throttle settings are faster.
The aircraft accelerates much faster when
taking off, so the whole maneuver happens
quickly. The P-51 gains speed in any descent
mode. All these characteristics are common
to most Sport Scale models, but this aircraft
handles the increased performance a little
better than most others do.
Most P-51s do not fly around with big
wheels hanging out the bottom, so
mechanical retracts might be in this
airplane’s future. That upgrade will take
some engineering on my part. I wonder
how far this PTS concept can be pushed.
To find out what else happened with this
model, check the Sport Aviator Web site.
Since most MA readers are pilots who have
some experience, this review focused more
on the PTS upgrades. MA Associate Editor
Michael Ramsey has written an excellent
Mustang PTS review for Sport Aviator that
focuses on the airplane as a typical trainer,
and it includes all the performance
numbers for the various PTS
configurations. MA
Frank Granelli
[email protected]
Distributor:
Horizon Hobby, Inc.
4105 Fieldstone Rd.
Champaign IL 61822
(877) 504-0233
www.hangar-9.com