Plane Talk: E-flite BAe Hawk 15 DF ARF - 2010/03

DUCTED FANS HAVE always been
interesting to me, but I’ve resisted because I
decided it would have to be in a turbinepowered
jet or an electric that had the power
to get out of its own way. For a long time,
the second criteria didn’t exist on the mass
market, but E-flite has corrected that in a big
way.
Not only did the company come up with a
complete plug-and-play system that works,
but it did so with a beautiful sport-scale ARF
version of the British Aerospace Hawk. This
model is finished in the Central Flying
School (of the Royal Air Force) air show
team’s color scheme.
The BAe Hawk, so designated in an
employee naming contest, is an advanced jet
trainer that is in use around the world, with
more than 900 in service. The actual contestwinning
name was “Tercel,” which is a male
hawk, but “Hawk” proved to be more
popular and won in the end.
The tandem-seat jet was perfect for air-toair
and air-to-ground combat training. In a
pinch, it can be fitted with two AIM-9L
Sidewinder air-to-air missiles, and its
centerline gun pod carries a 30mm ADEN
cannon. Thirty-three years after the Hawk’s
entry to service, it still serves a role in both
combat and training.
Construction: The E-flite model comes with
an incredibly detailed and fully illustrated
instruction manual. The whole assembly
process should require only a few nights of
spare time.
All of the materials you’ll need for radio
gear, building, etc. are listed in the front of
the booklet. The photos for each step are clear
and answer any questions you may have.
The components shake out of the box
bagged and protected from shipping damage.
Mine arrived in perfect condition, and
assemblies were grouped to make things
easier yet.
Decide on your power package before you
begin assembly, because the fan/motor unit is
the first step. Since E-flite designed a plugand-
play power package for this aircraft, I
chose that.
The Delta-V 15 (69mm) fan unit is ready
for the 15 Ducted Fan brushless motor.
Construction is easy, and the fuselage already
has the fan intake installed.
A word of caution for you gorillas out
there: don’t break the fan blades when you
tighten the nut on the prop shaft adapter. Be
sure to hold the hub, and don’t stick your big
ol’ fingers in the blades to hold it.
Fortunately, my local hobby shop (Toy
Town Hobbies in Fuquay-Varina, North
Carolina) was quickly able to get me the
replacement fan.
Before you drill holes to secure the fan
unit to the plywood mounts that are already in
the fuselage, dry-fit the assembly. It should
slide forward squarely into the intake. In my
case, it didn’t.
To get it straight into the intake, I had to
put the fan unit’s upper flange behind the
plywood mount and the lower flange on top
of the mount. This meant slightly rotating the
fan unit, which was no problem, but it also
meant that merely drilling and screwing to
the mount wasn’t going to work for me.
I did that on the bottom flange and then
drilled a pilot hole on the top mount, through
to the flange. I pulled the fan out and used a
tap to thread the holes on the flange, drilled
the hole on the mount slightly bigger, and
then reinstalled the unit.
By doing this, I could use a machine
screw and thread lock to secure the upper
flange to the back of the mount. It’s no
+•
Incredible quality and assembly.
• Great illustrated instructions.
• Packaged matched power system
available.
• Paint and color scheme.
• Quality linkages and hardware.
-•
Cheater holes in fuselage instead of
inlet ducting.
Pluses and Minuses
Model type: Sport-scale, electricducted-
fan ARF
Skill level: Intermediate builder,
advanced pilot
Wingspan: 33.5 inches
Wing area: 206 square inches
Length: 35.5 inches
Weight (with battery): 44 ounces
Wing loading: 30.7 ounces/square
foot
Power (recommended): 15-size
ducted-fan brushless motor/fan, 3S
or 4S Li-Poly battery, 60-amp ESC
Radio: Four channels
Construction: Molded fiberglass
fuselage, built-up wings
Covering/finish: Precovered with
UltraCote, pretrimmed, painted
fuselage
Price: $159.99
Specifications
Motor: E-flite BL15 Ducted Fan
Brushless Motor, 3600 Kv
Battery: E-flite 3200 mAh 3S 11.1-
volt 20C Li-Poly
Fan unit: E-flite Delta-V 15 (69mm)
ESC: E-flite 60-amp Pro Switch-
Mode ESC
Motor output: 380 watts measured
on bench with 3S pack
Radio system: Spektrum DX7
transmitter, Spektrum AR6200
receiver, four E-flite S75 servos
Ready-to-fly weight: 44 ounces
Flight duration: Five to six minutes
with throttle management
Test-Model Details
Above: The wings butt-glue to the
f iberglass fuselage, al igned with
composite pins. There’s opportunity for
the builder to finish the cockpit with
Hangar 9 accessories.
The included fixture helps cradle and set a correct anhedral angle
in the horizontal stabilizer halves. A waxed paper barrier is smart
to use here.
Outer winglets are a functional part of the
Hawk. They help manage airflow over the
wing and prevent a premature departure
stall.
Aileron servos are hard-mounted inside
the wing to offer as much control-surface
support as possible. A plastic cover
aerodynamically hides these parts.
Rudder control operates only the nose wheel. The E-flite 3S 3200 20C battery sits up
front. There’s room for the heavier 4S pack to sit farther aft.
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March 2010 37
Once installed, the fan unit is accessible from a hatch in the jet’s
side. The E-flite power system with ESC and battery is plug-andplay.
The fuselage bottom is full of cheater holes and necessary for
airflow to the fan unit, since the scale-sized inlet isn’t ducted.
Photos by the author
The trick to landing a jet is to never let it stall; fly it to the runway. The E-flite Hawk is
designed so it’s stable at slow speed and comfortable to land.
The hook is attached to the radio deck, and the canopy is held securely in place. The
canopy also has locating pins to keep it aligned—a well-thought-out system.
biggie, but make sure that it fits squarely in
the intake before securing it to the mounts.
The aileron servos are installed in wells
on each wing panel, using ingeniously
designed mounts that fit the E-flite S75s
perfectly. Once installed, they are hidden
with a white plastic cover.
Strings inside the panels help you guide
the servo leads to the root exit holes. The
included hardware worked perfectly for easy
aileron setup.
The wings slide onto carbon rods that go
through the fuselage and into the other wing
panel.
Be sure that you’ve installed the servos
in both panels before gluing either one to
the rods and fuselage. I used 15-minute
epoxy and painter’s tape to hold the servos
in place while everything set up.
The stabilizer is presanded at the root to
the proper angle and glued together using
the fixture that is included in the kit. The
fixture is a simple plywood assembly that
you glue together, and I put a piece of
waxed paper over it before gluing the
stabilizer halves together. This ensured that
I didn’t end up with a fixture glued to the
stabilizer.
Pay attention to the instructions and
insert the stabilizer through the fuselage
before installing the elevator halves. If you
don’t, you won’t get them through the slots
in the fuselage. Square the stabilizer with
the wings and glue it in place.
At this point, the elevators will slide in
and fit perfectly. The control rods are
already in the fuselage, so it’s a simple
matter of connecting them to the control
horn and securing them with the keepers.
Installing the landing gear is optional—
it depends on your flying field—but it is
included in the kit. I installed the gear
although I fly from a grass field.
Everything is prebent and fits into
existing channels and holes. The steering
mechanism for the nose gear works nicely
and, because there is no rudder, requires its
own servo. The nose gear height is
adjustable, and there is a long flat already
filed on the strut to help things stay in
place.
Don’t set it too nose-low or you’ll have
difficultly rotating for takeoff. Set it up for
a nice, level attitude at rest.
The canopy is held on by an ingenious
system made from a rubber band, two
eyehooks, and a leftover piece of control
rod. Make the hook as shown in the book
and connect the canopy deck to the radio
tray. It’s simple and effective. The canopy
has positioning dowels installed for you.
Radio installation is simple. I used the
S75 servos, a Spektrum AR6200 receiver,
and the E-flite 60-amp Pro Switch-Mode
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BEC brushless ESC. With the cheater
holes in the bottom of the fuselage, you
can drop the wires from the motor and
controller through and connect them.
If you find that your fan turns the
wrong direction, it’s an easy matter of
pulling them back through the holes and
changing any two wires. The controller is
fastened to the bottom of the fuselage with
Velcro and a zip tie for peace of mind.
The servos fit in precut holes that
position them perfectly to stay out of
everything else’s way. The receiver is
mounted to the top of the turtledeck,
behind the cockpit. The battery for the
motor has plenty of room to be mounted to
the equipment tray.
Flying: This is not a trainer. Be sure that
you are up to the task of flying a fast, agile
jet and double-check everything.
Since my field is grass and dormant
because of winter, I was confident that the
Hawk had enough power for a running
takeoff. So that’s what we did.
It took a long way to get the model off
38 MODEL AVIATION
of the ground because of the drag on those
small wheels from the grass, but it did and
climbed out with authority. I had the
ailerons on high rate, and it was soon
evident that that needed to be changed in
spite of my 30% exponential selection.
I hit the low rates and the aircraft
settled down and headed for the
distance—which arrives quickly with an
airplane this clean and small. After once
around the pattern to let my knees settle
down, it was already clear that the Hawk
was going to track nicely and have plenty
of power.
A check of the stall characteristics
showed that it mushes nicely before
dropping the nose and falling slightly to
one side. With a bit of power it was flying
again, so there was nothing scary there.
I did that several times, though, to get a
feel for the model’s actual speed and to
judge the distance of something so small. I
didn’t want any surprises when I brought
it in for the first landing.
I go over everything thoroughly after a
test flight, and my flying buddy, Wayne
Parrish, double-checks my work. We
decided to move the CG back a bit, charge
up, and go again.
That time Wayne did the honors while
I shot some photos and video. He’s an
experienced jet pilot, and I always use his
input to confirm what I think about a new
airplane.
This time it got off the ground slightly
quicker. Knowing that the ailerons were
touchy, Wayne used low rates to make it
much nicer. He did tons of low passes and
tried some high-alpha attitudes, which
worked out well. But with all those
cheater holes in the bottom, the Hawk
becomes extremely draggy.
I’ll move the CG back a bit more.
Fortunately, there is a great deal of room
in which to adjust the 3S Li-Poly pack
position and set the CG to please.
On subsequent flights with the CG in the
sweet spot, which proved to be at the aft
position that the instructions suggested, the
jet had even more life. I’m still flying it on
3S, but E-flite claims that it’s fine to go for
4S if you want more zip.
I will remove the gear if I continue to fly
from my grass field, because it takes too
much power from the battery to get the
Hawk off of the ground. I have not tried to
hand launch it yet, and probably won’t, but I
will use a bungee. If I had a paved runway, I
don’t think it would take 100 feet to get this
model into the air; there is plenty of power.
Rolls are tight and axial, especially on
high rate. Loops can be as big as you like
and as round as you’re able to make them,
with proper throttle control. The vertical
climb is more than adequate.
Our experience with landing the airplane
was better when we flew it all the way to the
ground rather than idling back and letting it
glide in. I kept having it drop from a couple
of feet when I tried that technique, although
nothing was damaged from the drop. I
preferred the higher speed and deliberate
angle to the ground. Your model’s mileage
might vary depending on technique.
I am impressed, not only with the quality
of the kit and assembly, but also with the
total package. The recommended power
system flies the airplane beautifully, and
there’s no doubt that a 4S pack would liven
it up.
The color scheme makes this jet easy to
see, and that’s a plus when you’re flying
something this size and fast. E-flite “gets it”
and has provided what many of us asked for
years ago: a system that can be dropped into
an aircraft and work from the start, without
our having to tinker and experiment.
The Hawk is not a record-setter in speed,
but it’s more than adequate and won’t
disappoint. I expect that I’ll see even more
performance with the gear removed and a
bungee launch. This fed my “need for
speed” and has me thinking about getting
another jet for the arsenal. MA
Greg Gimlick
[email protected]
Manufacturer/Distributor:
E-flite/Horizon Hobby
4105 Fieldstone Rd.
Champaign IL 61822
(217) 355-9511
www.e-fliterc.com
Sources:
Spektrum RC
(800) 338-4639
www.spektrumrc.com
Other Printed Reviews:
Backyard Flyer: September 2009
Model Airplane News: July 2009
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