World models: P-82 Twin Mustang

World models: P-82 Twin Mustang

Onorato, Jim

Twice the power-twice the fun

World Models Mfg. Co., Ltd.makes a number of high-quality, almost–ready–to–fly airplanes. Perhaps the most unique is the P-82 Mustang, better known as the “Twin Mustang.” A 90-percent complete, precision-built kit, the World Models’ P-82 blends innovation with quality craftsmanship in an easily assembled ARF that is a must-have in any modeler’s collection. It doubles the excitement of an American aviation classic and promises to thrill you with its performance just as it does in its conception. World Models kits are exclusively distributed in the U.S. by AirBorne Models.

WHAT’S IN THE BOX It is apparent when you open the that this a well–made “kit.” Each of the major pieces is enclosed in a separate plastic bag. The fuselages are constructed of balsa and lite-ply and come fully sheeted, the wing and elevator are built up and the tail feathers, except for the elevator, are solid sheet balsa. The entire plane is nicely covered with colored aluminum Oracover.

This kit includes everything you need except the engines, props and radio. It comes with installed retracts, hinged control surfaces and a functional split flap. It also includes painted fiberglass cowls, fiberglass radiator scoops, adjustable engine mounts, fuel tanks, spinners, tailwheels, painted pilot figures, a decal sheet and a complete hardware package. A transparent dummy cowl makes it easier to trim the fiberglass cowls around the engines.

The P-82 is designed to be powered by two .32 to .40ci 2-strokes or two .40ci 4strokes. I’ve seen this plane fly with two .40 2-strokes, and I would not recommend anything larger. I used two MDS .38s, and they provided more than enough power.

The plane requires a 6-channel radio, nine servos and a whole bunch of extensions and Y-harnesses. It is clear from the 11-page instruction booklet that this plane is not intended for inexperienced builders. The booklet consists of just 23 drawings and symbols with almost no written instructions. As with most ARK a plan is not necessary and is not included.

ASSEMBLY

You begin with the wing-the most complex part of the plane. It has retracts, ailerons and a split flap, and it requires four servos and a mess of wires and connectors. The wing comes in three sections. Each outer section contains an aileron and an aileron servo, and the center section contains the retracts, retract servo, split flap and flap servo. Because the ailerons and retracts are installed, I simply removed the covering material from the servo bays and glued the hinges for the split flap. I regret that I did not remove the retracts to check their mounts because they later ripped out on what I thought was a smooth landing. The mounting plates are 1/4-inch lite-ply and are partially cut away to make room for the coil on the landing gear strut. They are susceptible to breakage whenever rearward force is applied to the gear-such as in landing. After mine ripped out, I replaced the mounts with wider ones that extended back to the spar, and I added a reinforcing block where the mounts were glued to the ribs. I strongly recommend that you remove the landing gear and reinforce the mounts before the first flight. At the very least, add a couple of pieces of spruce triangle stock between the mounting plates and the ribs. Trust me; this is a lot easier than rebuilding the mounts later.

Once you have mounted the aileron and flap servos on their sides and attached them to the two mounting blocks, epoxy the blocks to the servo-bay covers. I discarded the balsa mounting blocks and replaced them with hardwood blocks. I attached the servo-bay covers to the wing with four sheet-metal screws then installed the retract servo. A coloredaluminum plastic plate covers the retract servo, which you also secure with four sheet-metal screws. The retract servo bay is not very deep, so it requires a low-profile retract servo.

The P-82 kit comes with unique control horns. They consist of a 3mm machine bolt molded into a triangular plastic base. The pushrod clevis is attached to a plastic fitting which is then threaded onto the bolt, so the length of the control horn can be adjusted. You attach the control horns to the control surfaces with three self-tapping bolts that thread into matching triangular backing plates. There are three short ones for the ailerons and flap and three longer ones for the rudders and elevator.

Before you join the wing panels, decide which radio components will go into which fuselage so that the necessary Y-harnesses and extensions can be routed through the wing. I placed a rudder servo and a throttle servo in the left fuse and rudder, and throttle and elevator servos in the right fuse along with the receiver and the battery pack. The instructions show the receiver and battery pack in the left fuse, but that arrangement requires an extra servo extension for the elevator servo.

After I joined the outer panels to the center section with an aluminum-tube wing joiner and installed locater pins, I secured everything together with two bolts and epoxy.

When I completed the wing, I began work on the fuselages. I installed the fins, rudders and tailwheels on the two fuselages, then assembled and installed the fuel tanks. Next, I bolted the adjustable engine mounts onto the firewalls and installed the engines in the upright position. The blind nuts for the mounting bolts were already installed in the firewalls. Then, I used the transparent dummy cowl to trim the fiberglass cowls around the engines and attached the finished cowls with four sheet-metal screws.

Installing the solid wire rudder and elevator pushrods into the installed, plastic outer tubes was easy. Each of the fuselages includes two installed outer tubes, but I did not use the elevator tube in the right fuse. You need to install the left throttle pushrod tubes, however, because their locations depend on the engine you decide to use. The fuselages also come with pilot figures and canopies.

The next step is to fit the stabilizer between the two fins and secure it with four bolts that thread into installed fittings in the stab. Do not install the stab until you have firmly attached the fuselages to the wing. To make final assembly (and field assembly) easier, I made a Styrofoam cradle to hold parallel and ages the proper and at the proper distance from one another. I then placed the fuselages upside-down in the cradle and attached the wing, air scoops, the stab and the elevator pushrod.

The plane’s configuration requires three Y-harnesses for the rudder, throttle and aileron servos. In addition, the connections between the fuselages require several extensions. To simplify things and make sure everything gets hooked up properly, I labeled all of the connectors.

The World Models Mfg. P-82 Mustang is a well-made ARF that is easy to assemble and looks great when complete. If you are looking for a rather unusual “twin” but don’t want to spend a lot of time building one from a kit, this plane may be just what you’re looking for. I guarantee that fellow pilots will notice it at the flying field!

AirBorne Models, 2127-H S. Vasco Rd., Livermore, CA 94550; (925) 371-0922; fax (925) 371-0923.

Copyright Air Age Publishing Jul 2001

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