World Models Manufacturing Company has re-created a scale
version of the P-82 Twin Mustang meant for two .40-size glow
quick build ARF has the following features:
hand iron-on covering film
proof decals and factory painted pilot figures
split flap and pre-installed retracts
with all hardware and accessories
conversion project will use two AXI
4120/14 outrunner motors with the radial mount set.
Note that the less expensive AXI 2826/10 or /12 motor would
also work well in converting this classic warbird to clean
and quiet electric power. In either case, I choose the Jeti
JESAP40P Advance PLUS 40 Amp Opto Brushless Controller.
of the sections and parts are exact duplicates to provide
the needed "twin" items. The model is highly pre-fabricated
and the construction quality is excellent. The glow engine
mounting holes and tee-nuts were pre-installed. The low-temperature
Ultracote (Oracover) needed some touch-ups with the heat
gun but the overall covering job was well done.
wing comes in three sections that are ready to be attached
together with only a few screws. There is no need to epoxy
the wing sections together as the manual suggests.
locking bars and tee-nuts are pre-installed. Athough the
manual has instructions for mounting the ailerons and retracts,
everything is already pre-installed. The retracts use a
single 90-100oz/in. retract servo.
canopy, cowl, rudder, pilot, and spinner are all duplicated
HS-422 Pro servos for all the control surfaces. The
HS-422 is one of the most durable and reliable servos Hitec
has ever offered. With its dual iron-oilite bushings, high
impact resin gear train and high performance circuitry,
the HS-422 features excellent centering and resolution.
They are a great value!
the motor, which is often my favorite task, proved to be
very simple and inexpensive. I needed a 1.5" motor
offset to make a 4" total length between my firewall
and the spinner backplate.
trip to my local home improvement store (Home Depot) revealed
that a common PVC part is a (NIBCO C437-168) 1-1/4"
x 1" coupler that has an octagonal end on one side
and round on the other. The $0.79 cent part can be used
unmodified. I simply sanded the ends on a flat surface to
remove the slippery wax-based finish.
PVC stands for PolyVinylChloride, and it is a plastic used
to make drain pipe for household plumbing.
then used #8-32 x 2" round head machine screws and
#8-32 x 1/4" tee-nuts to mount the 4120 motor with
the radial mount set that includes the prop adapter.
of the four mounting holes uses an existing hole and the
other three were marked with a felt tip pen by holding the
motor up to the firewall.
drilled a large hole for the three motor wires to pass back
into the fuselage and extra airholes for cooling the ESC
the standard American hardware available at Lowe's, Home
Depot, or any local hardware store. Of course, metric equivalents
will work here just as well. The supplied stock tee-nuts
are M4 so you just need 2" (50mm) long M4 machine screws
to mount the motor. The mounted motor looked great and followed
the right thrust offset built into the firewall.
cowl, prop, and spinner mounted nicely. I needed to trim
the bottom corners of the fuselage for a snug cowl fit and
slightly deepen the slots in the spinner cone for my APC
motor was mounted a bit low but it followed the thrust angle
of the firewall. Ideally, it needs to be about 1/4"
higher but I'll just follow the same scheme on the other
side to match this one since it doesn't look too bad.
P-82 wing was built in three sections. The center section
had clear fishing line running from each of the outer holes
to the flap bay for pulling servo leads. A third line was
run from the retract servo bay to the flap bay. After some
decision making, I decided to follow the manual servo setup
and replace only the throttle servos with ESC control line
extensions. Most of the servo leads needed 24" extensions.
P-82 has no center pod like a P-38 so the receiver must
reside in one side. The manual uses the right pod to house
the receiver and Rx. battery and so did I. I will replace
the Rx. battery with a UBEC that feeds both Opto-isolated
ESCs via the control line. Each pod will have its own motor
I mixed up the left and right aileron labels, the wire layout
can be seen on the wing above as it is being viewed from
the front top side.
HS-75BB retract servo worked nicely with the stock wheel.
I used an Astro Flight servo tester and a heavy-duty receiver
battery to test the up and down swing. The right photo above
shows gear down position of the servo wheel. The rods stop
just short of touching and do not cause to servo "hum"
or draw current in either position stop.
retracts are shown in both up and down locked positions.
It is important to test that the retracts lock in both directions
and that there is no stress (or force) on the servo at either
end point. Always favor the locked down position when setting
the linkage. The retract servo bay is covered with a painted
plastic piece that I used my own black screws to secure.
I added one of the kit's decals over the cover plate but
it is not likely a "true to scale" place for the
finished routing my last two cables from the left side to
the right for rudder and speed control.
my retracts were finished, I installed the flap linkage.
I needed to open the bay slot a bit to allow room for the
snap keeper and control rod bend. A longer servo arm here
would help. All the hardware shown is included in the kit.
I programmed my Futaba Super-8 transmitter for a 15 degree
and 30 degree flap offset on a 3-position switch. I prefer
this fixed offset instead of using a knob since it eliminates
any guesswork during a flight and I can do it with just
a glance at the switch.
aileron linkage was identical to my flap linkage. Again,
the servo arm was a bit short which required me to cut away
a portion of the bay hatch. The aileron servos are mounted
in a reverse position so I only needed to connect them together
with a "Y" adapter and then to a single channel.
The wing is now complete with working ailerons, flap, and
retracts. I'll finish up my second motor mount and start
the final assembly.
rudder comes pre-hinged on the vertical stabilizer so it
was an easy task to glue it in place. The custom fit provided
perfect alignment. I used thick white glue to attach the
vertical stabilizer. The custom tailwheel assembly also
installed easily. You need to drill a hole in the rudder
bottom first so that the swivel is aligned with the hinge
area to prevent binding. I glued the metal bar into the
rudder with epoxy and also secured the two screws in place
rudder linkage is duplicated on both fuselage sections.
The manual position for the rudder servo is incorrect so
you need to reverse the positions shown since the tubing
crosses sides inside the fuselage. The metal rods installed
easily since the tubing is pre-mounted. My technique was
to push the threaded end of the rod through the tubing and
poke it out through the covering. I used the supplied control
horns and quick links.
elevator linkage only connects on the right fuselage. My
third control horn was broken so I used a large white plastic
horn that screws to a plate on the other side of the elevator.
I expect little movement is needed from either the elevator
or the dual rudders so I used low throw setting on both
sides of the linkage.
4-cell Kokam 3.2AH (20C) pack above weighs 12.8oz. It is
shown with a 3.0AH NiMH pack for size comparison. Note that
the new cell width is the same as a sub-C cell length. The
4-cell Lithium pack has a voltage equal to about 14 cells
NiMH which weighs about 26oz or twice the weight of the
Kokam pack. This is a pre-production test pack without the
taps to monitor each cell. The production version from FMA
Direct will be called Skyvolts. I'll be using one of these
Kokam packs in each fuselage of my P-82 Twin Mustang to
power the 4120 motor.
mount my 4-cell Kokam 3.2AH packs, I used the stock glow
fuel tanks. After drilling holes in one end and cutting
off the other end, I surrounded the Lithium packs with shock
absorbing IMPAD foam pads from FMA Direct. This held the
pack perfectly inside the plastic fuel tank and will help
protect them in a crash.
doubt that much air will flow through but I don't expect
the packs to get hot in this application due to the excessive
power level and type of scale warbird flying. The fuel tanks
slide into pre-mounted stock plywood formers. In the photo
shown, the pack position resulted in the CG being 1"
forward from the recommended spot so I had to slide them
back about 1".
final assembly went very well although, at the last minute,
I realize that I had forgotten to mount an On/Off switch to
arm the motors. Fortunately, I keep a spare Tower Hobbies
System 3000 On/Off switch assembly on hand.
laid the two fuselages on top of the wing to start. The left
fuselage needed the rudder servo and ESC connections made
to the wing that route over to the right fuselage. Note that
my Hitec Electron 6 receiver is mounted in between the unused
servo bays with servo tape and a tywrap. The antenna wire
is routed under the fuselage belly and will later be partially
covered by the final mock air duct.
right fuselage has many connections to the receiver. The
ailerons, retract servo, flap servo, rudders, ESCs, and
elevator. I used a "Y" adapter in channel six
to connect both the flap servo and the UBEC output that
runs through my On/Off switch. The rudder servos were connected
to channel 4 with a "Y" adapter cable. The ESCs
and aileron servos were also connected to the reciever with
a "Y" adapter cable.
horizontal stabilizer is mounting using the supplied screws
and washers through the vertical fin into pre-installed hidden
wing can then be screwed in place using the supplied screws
and washers into pre-installed T-nuts. The front of the
wing is held by dual wooden dowels on each fuselage.
the wing is secure, the mock air scoops easily mount using
a single screw into a pre-installed nut. Again, the front
of the scoop is held by dual wooden dowel rods. Other than
applying the decals, my assembly was compete.
checked the balance of my P-82 using the Great Planes CG Machine
and discovered that I was about 1" forward of my 3.5"
target. I moved both the packs back about 1" and the
CG was now just right.