Plane Talk: E-flite Stearman PT-17 15e ARF - 2011/02

52 MODEL AVIATION
Plane Talk: E-flite Stearman PT-17 15e ARF
JAY SMITH
Access to the flight battery, receiver, and
rudde r and eleva tor se rv o s is un d er th e
large magnetic hatch. Motor mounting bolts
p r o t r u d e s lig ht ly f r om the bac k o f t h e
firewall, so foam was used as a barrier.
An easy-to-fly replica of the
1930s US Army Air Corps
primary trainer
Photos by the author
THERE ARE MANY reasons to pick a
certain model. It could be looks, flight
performance, or a personal bond with an
aircraft. For me this airplane fits into all three
of those categories.
I have a true appreciation for biplanes, but
the Stearman stands out. Maybe it’s because it
is powered by a radial engine that is
uncovered and easy to admire. Or it could be
the attractive US Army trim scheme that
appeals to me as an Army veteran.
The biggest reason might be the fact that I
have flown in a full-scale PT-17 and
experienced the freedom of open-cockpit
flying with the same thrill of the brave men
and women who learned to fly war machines
with the help of that aircraft.
I have owned a couple of RC models of
this prolific biplane; one was made from foam
and the other was a conversion from a rubberpowered
aircraft. Although both flew well,
they left me wanting something larger and
electric powered. So when I saw the E-flite
version, I felt like Ralphie Parker from the
movie A Christmas Story, with his desire for
a Red Ryder BB Gun.
Fortunately for me, my enthusiasm for
the project allowed me to get a Stearman
without relying on my parents or Santa
Claus.
I have always had good luck with E-flite
airplanes and appreciate the work that goes
into them to help ensure success, such as
preapplied decals and detailed, photoillustrated
manuals. The PT-17 is the sixth Eflite
model I have owned and the first one
since my review PT-19 that was featured in
the Fall 2009 Park Pilot magazine.
The beautiful Stearman needs only a pilot figure to get the
full effect. A small amount of down-elevator trim is required
for level flight.
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February 2011 53
Small black stripes at the right and
left center-section of the upper wing
is electric al ta pe used to mark t he
CG. The two holes provide access to
upper wing bolts.
Far left: The PT-17 has only ailerons on
the lower wing and uses a hatch for a
clean-looking installation. Included
pushrods are prebent and threaded to
allow for clevis adjustment.
The cowl is easy to mount using the tab method and blue painter’s
tape. Servo extension packaging was used as the tabs that located
the mounting screw locations.
Near left: Two sets of spacers are
provided to allow different power
options. The E-flite Power 15 motor
provides more than enough horsepower.
Additional downthrust was added using
one #4 washer behind the top two #6
mounting bolts.
The dummy engine is well detailed
out of the box, and the wooden Vess
propeller complements the package.
A heavy hub allows the model to
balance with no additional weight.
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54 MODEL AVIATION
Specifications
Pluses and Minuses
Test-Model Details
Model type: Semiscale RC ARF
Skill level: Intermediate builder;
intermediate pilot
Wingspan: 44 inches
Wing area: 608 square inches
Length: 35 inches
Weight: 3.5-3.8 pounds
Wing loading: 13.26-14.4 ounces/
square foot
Power System: 320- to 420-watt system
Radio: Four channels with four servos
Construction: Balsa, plywood,
fiberglass and plastic details
Covering/finish: UltraCote, painted
plastic, and fiberglass
Price: $179.99
Power: E-flite Power 15 brushless
outrunner motor, 40-amp ESC
Battery: E-flite three-cell, 3200 mAh
Li-Poly
Propeller: Vess 12 x 6 wood
Radio system: JR 11X transmitter,
AR6200 DSM2 receiver, two JR Sport
MN48 servos, two JR Sport MN35
servos, two 9-inch servo extensions
Ready-to-fly weight: 3 pounds, 11.5
ounces
Flight duration: 12-15 minutes
Pluses
• Built-up and sheeted wood
construction with fiberglass and plastic
details.
• Realistic, factory-painted nine-cylinder
dummy radial engine.
• All decals are preapplied.
• Accurate details with high-visibility
Army Air Corps trim scheme.
• Included wing fixture allows for easy
removal, transport, and storage of
detachable wing panels.
• Large magnetic hatch provides easy
access to battery and electronics.
Minuses
• Tail wheel shaft is too long to mount
flush with the fuselage.
• Pilot figure not included.
• Additional downthrust added to limit
the amount of down-trim required for
level flight.
Assembly: The Stearman arrived well
packaged, and a quick inspection showed that
everything was accounted for and
undamaged. I like to completely unpack an
airplane and let it sit overnight, to allow it to
adjust to climate changes, before I touch up
the covering.
I use that spare time to read the manual, to
gain an understanding of what is required to
build and equip the model. The only thing
worse than having to stop everything and run
to the hobby shop is realizing that you need
something when it’s closed. The necessary
materials were listed on page 3.
The PT-17 needed little work on the
covering; I removed a few wrinkles with a
trim iron. The tape used to hold the ailerons
and the foam blocks over the mounting lugs
on the lower wing left a sticky residue, which
I removed using CA debonder.
One of the first assembly steps requires
you to remove the cockpit hatch, which is
tabbed in the front and held down in the rear
by some strong magnets. I was unable to take
off the hatch without the help of a broken
propeller under the rear edge. Removing the
hatch roughly a half-dozen times while
assembling and setting up the model was
good practice.
Using the recommended servos ensured
that they were simple to fit without
modification. The instructions even describe
the proper way to install the bushing in the
grommet—from the bottom—which is
commonly done incorrectly.
The only deviation I made was to open the
holes on the servo arms for the pushrods. I
find that easier to do before mounting the
servos.
Moving on to the tail, the builder gets a
head start; the vertical stabilizer is already
attached. Covering does need to be removed
from the bottom of the horizontal stabilizer,
which I did with the help of a soldering iron.
The elevator must be inserted into the
fuselage and then the horizontal stabilizer.
After test-fitting the CA hinges, I glued them
to the elevator before installing it in the
fuselage.
Once both the elevator and horizontal
stabilizer are slid into the fuselage, it’s a bit
challenging to insert the hinges into the
stabilizer. Angling the elevator and installing
the hinges in the order recommended in the
manual helped. The other tip was to
temporarily install the hinges in the stabilizer;
they helped guide the actual hinge.
The steerable tail wheel is well thought out
and easy to install. The tail wheel shaft enters
a predrilled hole in the fuselage. Then the
shaft is glued into the rudder when it is
attached to the stabilizer. The tail wheel
assembly slides over the shaft and is held in
place with a socket screw.
Earlier versions of the Stearman have a
slightly longer tail wheel shaft, which can be
shortened to allow the tail wheel assembly to
mount flush with the bottom of the fuselage.
The preassembled landing gear slides into
slots on the side of the fuselage and is held in
place with 6/32-inch Allen screws and washers.
The aluminum-core gear struts fit nicely and
provide a scale appearance.
Although solidly attached, the gear will
bend slightly on a less than perfect landing.
Thread locker is used for the landing gear and
all metal-to-metal fasteners.
The Stearman has ailerons only on the
lower wings and uses a hatch on both the left
and right wing for a cleaner-looking servo
installation. Servo mounting blocks are
included but not glued in place, allowing for
different-size servos to be used. The JR Sport
MC35 Micro units fit with room to spare.
As do the rudder and elevator, the
ailerons must be hinged and the control
horns must be mounted. There are no pilot
holes for the control horns, but they are easy
to line up using the linkage. You can use a
felt-tip pen to mark the hole locations, which
are drilled using a 1/16-inch bit in a pin vise.
Thin CA was used to strengthen holes
drilled into the control surface before the
control horn installation. The pushrods are
threaded, allowing the nylon clevis to be
screwed on until the proper length is reached.
To mount the wings on the Stearman, the
cabane struts must be installed first. This is
easy to accomplish using 4-40 Allen bolts and
washers that are attached from inside the
fuselage. Then the center-section of the upper
wing can be attached using Allen bolts and
washers.
Carbon-fiber wing tubes are used to
support both the upper and lower wings. Each
wing utilizes a mounting tab with a blind nut
to attach the wing. These tabs are accessed
from the bottom of the wings, making them
easy to access using a ball driver.
With the wings in place, it’s time to install
the interplane struts. The key to mounting
these correctly is to remember that when
viewing at the airplane from the right
(starboard) side, the struts should look like an
“N.”
The Stearman includes a transport fixture
that allows the wings to be removed, moved,
and stored with each side’s top and bottom
wing together. This requires only the removal
of four bolts. I can transport and store the
model with the wings installed, but anyone
who can’t will appreciate this nice addition.
The recommended power system for the
PT-17 is an E-flite Power 15 motor and 40-
amp ESC. The ARF includes two sizes of
spacers, to allow for a Power 25 or similarsize
motor to be used. Although the airplane
requires no more power than what is
recommended, you could use a larger motor
since the model requires nose weight to
balance properly.
The manual included a notice stating that
E-flite does not recommend using the ESC’s
BEC because of possible receiver/servo
overload if used with digital or miniservos
and extreme flight control input in hot
conditions. A separate BEC or receiver pack
was recommended.
I have done all flight-testing in
temperatures cooler than 80°, using the ESC’s
BEC without issue.
When installing the Power 15, I added a
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small amount of downthrust, with the use of a
#4 washer, behind the motor mount on both
the top right and left. I made that minor
modification to help compensate for issues
with the PT-17’s pitching up on takeoff and
climbing under power, which other pilots had
reported.
The ESC is mounted to the bottom of the
motor box using Velcro. The cowl clears the
ESC and wires with no problems and was
easy to install using alignment templates I
made from the servo extension packaging.
I found that installing the wind screens
was omitted from the manual. The only things
required to accomplish that were a small
amount of canopy glue and blue painter’s tape
to hold the screens in place overnight.
I also used canopy glue to adhere a
military pilot, not included with the kit
(available from Horizon Hobby), in place.
While I was at it, I made a scarf for the figure
using a small piece of silk from the craft store.
To complete the Stearman I chose a Vess
wood propeller and a 2.5-ounce Great Planes
Brass Heavy Spinner Nut, to provide
additional nose weight. According to the
manual, 2-4 ounces is required to attain the
recommended CG of 3.25-3.75 inches behind
the upper wing LE.
I marked both locations with a sliver of
electrical tape so that I could feel them when
balancing the model. I was happy to find that
it fell precisely in the middle with the battery
mounted all the way forward.
Throws were set per the manual. I was
surprised to see only one set listed, as
opposed to the high and low settings
I am accustomed
to getting. I also decided to use 20%
exponential on all control throws, to
slightly soften my inputs.
The completed model is stunning. I don’t
know who was smiling more when I set the
Stearman down on the runway: the dummy
pilot in the cockpit or the one holding the
transmitter.
Flying: As does its full-scale counterpart, the
E-flite Stearman gets airborne quickly. I have
found that rapidly advancing the throttle to
three-quarters provides ample power for
takeoff, and only minor rudder correction is
needed.
I have also learned that no up-elevator is
required to get the model airborne, even with
the small amount of down-trim that was added
on the first flight. By allowing the aircraft to
take to the air on its own, you also help
eliminate the chance of its pitching up
aggressively on takeoff.
The Stearman is more than happy to cruise
around with the throttle set to just above half.
And it’s not finicky about whether turns are
made with rudder, aileron, or both.
Basic aerobatics are no issue, and the
Stearman performs them in a scale manner. It
can do nice, round loops, barrel rolls, and
hammerhead turns all day long. Inverted flight
is manageable with a touch of down pressure.
The PT-17 feels solid in the air. It has
enough weight to handle the wind, yet its
ample wing area allows it to fly slowly and it
has a bit of a floaty feel. It will stall, signified
by a slow drop of the wing when only upelevator
is applied, but it is easy to recover as
long as you have a bit of altitude.
This model can land on the mains or as a
three-pointer. The latter is recommended on
either pavement or grass, because the lower
airspeed won’t encourage bouncing or the
dreaded ground loop.
The key to either landing is good
airflow over the controls during the
approach. Use the throttle and maintain
power, so that the controls stay effective
until the wheels touch.
The E-flite PT-17 delivers on all levels. It
provides a scale representation of full scale
that anyone can enjoy directly out of the box.
The flight characteristics are also in line with
those of the full-scale aircraft and are nothing
for an intermediate or better pilot to fear.
Construction of this model is well thought
out, from easy access to the electronics and
battery to provisions for simple removal of
the wings for transport and storage. This
biplane is hassle free. MA
Jay Smith
[email protected]
Manufacturer/Distributor:
E-flite/Horizon Hobby
4105 Fieldstone Rd.
Champaign IL 61822
(800) 338-4639
www.e-fliterc.com
Sources:
JR Radio
(877) 504-0233
www.jrradios.com
56 MODEL AVIATION
Requirements for this position are simple:
• Must possess a love of all aspects of model aviation
• Must own an RV suitable for 30-day stays
• Must have outstanding people skills and a willingness
to represent AMA in a positive manner to fellow
members and guests
• Must be willing to live on-site for one month during
the season—April-September
• Must follow all flying-site rules and guidelines
• Must have a familiarity with model-aviation flying sites
(norms and customs a plus)
• Individuals who provide a service (such as a vendor)
will not be allowed to participate in the program
• Only couples may apply
AMA will provide these volunteers with the following:
• A camping site with full hookups
• Transportation for use on-site
• Caps and golf shirts with an “AMA host” designation
Duties will include:
• Helping members and guests visiting the flying site
• Helping ensure that the AMA Safety Code is
observed on the flightlines
• Helping check in members and visitors at the
camping sites
• Communicating with AMA staff concerning
conditions of the flying site
Volunteer Host/
Hostess Program
We are seeking couples for each month of the flying season. If you would like to apply to become an AMA host and hostess,
contact Wendy Cummins at [email protected] or (765) 287-1256, extension 210.
www.modelaircraf t .org/news / seekinghos t .aspx
Keeping watch over the 1,100-acre National Flying Site in Muncie,
Indiana, is a formidable task. Borrowing a page from the National Park
Service and many successful state park programs, the Academy is
seeking retired volunteers to become flying-site hosts.
C o m e J o i n U s
at the Inte r n a t io nal
Ae romode ling Ce n te r !
Spektrum RC
(217) 352-1913
www.spektrumrc.com
Vess Propellers
(919) 872-5611
www.vessaero.com
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