Electrical P-51 Mustang

Model Airplane News, Sep 2002 by Rittinger, Mark

Reno Racer or WWII fighter. Have it your way

I have been modeling for more than 20 years, and for the past four years, I've been into electric planes. Their convenience, cleanliness and fun quotient can't be beat. I also like designing electric scale airplanes that are light, tough and easy to build and, most Important, fly well. Many times, that's a tall order for one airframe to accomplish, but I think it has been done with this Mustang.

With a Master Airscrew gearbox geared 3.5:1, a 10-cell 1250 SCR battery pack and a 12x10 prop, this 42-inch-span model flies wonderfully well! It's very smooth and has fantastic vertical performance. With throttle management, I can get 6-minute flights. With the throttle wide open, a flight lasts about 41/12 minutes. If you're looking for a scale P-51 and have been thinking of trying electrics, this is the plane for you! The plan has details to build an A, B, C, or D version of the Mustang, plus a Reno Racer for you race fans.

LET'S GET STARTED

For the wings, you'll need 2-inch-thick pink foam; I bought a 4x8-foot sheet from a home-supply store for about $20. To keep the weight down, use only high-quality balsa, and limit your use of epoxy. Remember to "think light" while building, and don't omit anything from the airframe. It's designed so that many pieces do more than one job. You'll also need various thicknesses of balsa for the wing skins, hatch, fuselage and doublers and fin and stab, plus miscellaneous triangles and blocks. For equipment, you'll need at least a 3-channel radio, a 10-cell battery pack (1250 SCRs are a good starting point), a Master Airscrew 3.5:1 gearbox, a Magnetic Mayhem Reverse motor from Kyosho and a 30A ESC with BEC.

FUSELAGE CONSTRUCTION

The fuselage is simple to build. Begin by cutting out the fuselage parts to make a "kit." Make the fuselage sides oversize on the top rear to allow it to curve over the rear deck. Now glue the doubters to the sides and add the 1/8-inch plywood firewall (no right thrust), former F2 and the 1/4-inch triangle stock to the right fuselage side.

Depending on which version you build, install the appropriate F3B (bottom) and RM (middle) formers. Glue the correct F3T to the top of F3M, and add the 1/2-inch triangle stock behind it along the bottom of both fuselage sides, as shown on the plan. Line up and glue the left fuselage side to the formers and the motor mount. Now install the 1/8-inch-ply nose ring and 1/4-inch sheet in the nose. Install F4 and add the top stringer, and then wet the fuselage sides and roll them over to form the top deck and glue them to the stringer. Now sheet the bottom of the fuselage with 1/16-inch balsa used cross-grain.

Make the front blocks and tack them into place with a few drops of CA. Carve them to shape, then remove and hollow them out to a wall thickness of 18 inch. I make the bottom front a little thicker; it takes a beating during landings. When finished, permanently glue the blocks to the fuselage. Add the 1/4-inch square in the cockpit area, and the basic fuselage is complete.

THE HATCH

The hatch is built on the fuselage and is simple to construct. Pin the hatch floor to the fuselage and attach the hatch front; don't forget the gussets. Make the rear bulkhead by placing a piece of paper on F3T and tracing around it. Mark off 1/16 inch inside of that, and it becomes the pattern for the rear bulkhead hatch. Make the rear bulkhead from balsa and glue it into place, and then sheet the assembly with lhs-inch balsa.

THE WING

Because of the wing's shape, it's made in four sections and is cut from 2-inch pink insulation foam. Do not use white foam; the compression strength is different. Cut the templates from 32-inch ply, and make the inner section of the wing first; use the root and center templates for these. Now use the center and tip templates to make the outer panels with 1/8-inch washout in each tip. Save the beds from the cores; you will need them later to sheet the wing.

Join the inner and outer sections of the wing-cores with white glue or epoxy; make sure they're straight. Now cut out the servo pockets and handhold areas, and make a 3/8-inch-deep cut with a sharp knife from the root to the pockets. Carefully push the Y-harness for the aileron servos into the cores so the servos are just below the surface of the foam.

To sheet the cores, I use Southern Sorghum wing-core glue. Because I find it difficult to edge-glue 1/32-inch skins, I tape them together and lay them on the core bed. I then coat the bottom of the wingcore and the sheeting with the wing-core glue. When the glue has set, I carefully put the wing-core on the sheeting, being careful not to induce warping. Repeat the process to sheet the top of the wing. Once both panels have been sheeted, check them for warps (other than the required washout).

After you've sheeted both panels, block up the tips 1 5/8 inch and sand the dihedral angle into the roots. Glue the panels together, making sure that each panel has the proper dihedral. For strength, wrap the center joint with nylon tape and apply a light coat of epoxy. Sand the leading edge of the wing flat and glue on the 1/8-inch leading edge. Add the wingtips and sand the leading edge to shape. Do not make it too sharp; a rounded leading edge performs much better! Mark the aileron locations and then cut them out of the wing; be sure to allow for the thickness of the facings. Glue the facings onto the wing and the ailerons, and the wing is complete.