Beechcraft T-34C Turbo-Mentor (oz14814)

About this Plan

Beechcraft T-34C Turbo-Mentor. Radio control scale model for electric power. Wingspan 33-1/2 in, wing area 192 sq in. For Speed 400 motor. Scale is 1/12.

Quote: "Beech T-34C Turbo Mentor, by Steve Griffiths and Mike Briggs.

Introduction: The T-34C Turbo Mentor aircraft was first flown in 1973. This airplane evolved out of the A and B Mentor models. T-34Cs are unpressurized two-place, tandem-cockpit, low-wing, single-engine monoplane airplanes that are manufactured by Raytheon Aircraft Company (formally Beech Aircraft of Wichita, Kansas). A model PT6A-25 turbo-propeller engine, which is manufactured by Pratt and Whitney Aircraft of Canada, powers the aircraft.

T-34Cs are used to provide primary flight training for student pilots, but the aircraft supports other missions as well. This aircraft has been in service with forces in Algeria, Peru, the Philippines, Spain, Taiwan, Turkey, the United States, Uruguay, and Venezuela, so it has flown in many colors.

Model Airplane: As a model, the T-34 is built in 1/12 scale, with only minor deviations from true scale. The model, as designed, is intended for power scale soaring (PSS) or for Speed-400 electric power. As such, the T-34 model easily converts between PSS and e-power (flying at a weight of around 16 oz as a glider, and 21 oz as electric). Flight controls are ailerons and elevator.

Building: I recommend that you use cyanoacrylate adhesive for all of the wood-to-wood joints, except where stated otherwise. Also, it is best to equip this model with a reasonably small receiver and servos, as well as a lightweight speed controller if it is electric powered. Note that this model flies satisfactorily on a direct drive 6-volt Speed-400 motor that turns a Graupner 6x4 propeller. Power comes from a 7/8-cell, 500-mAh AR battery. If the model is built as a glider however, it is wise to move the servos forward in the aircraft to reduce the need for nose weight.

I find that the best approach to building models is to make up a 'kit' of parts beforehand. First, make the wing skins, joining the sheets. While the glue on the skin sheets dries, cut the tail joiner for the longerons, all of the formers, the wing spar, the spar brace, the ribs, the battery plate, the horizontal stabilizer, the elevator, and the fin. The full-span main spar sets the dihedral angle automatically, and is cut from medium-hard 1/8-in, balsa sheet and notched for the ribs. Two sets of ribs W3-W7 can be made by the sandwich method. The W1 and W2 ribs are cut individually.

Wings: Start the wing by gluing the 1/16 plywood brace to the main spar. Mark the rib positions on the lower skin, and score it lightly chordwise on the centerline. The bottom skin is one piece, with each wing being built one side at a time, so the following procedures are performed for one side and then repeated for the other.

With the bottom skin mounted flat on the building board, glue the main spar and false trailing edge (aileron spar) to it. Place the front brace loosely in position (it will be held by the W3 ribs). Gluing only from the spar backward, attach the ribs to the spars and skin. Now, press the spar down onto the unfinished side of the lower skin, which should crease neatly along the center where it was scored. Repeat the gluing operations on the one side, without forgetting the off-center extras for the servo box and the triangular fillets.

Lift the leading edge of the skin with a straightedge, and glue the ribs to the skin ahead of the spar, checking to ensure that the lower skin is in contact with both W1 ribs ahead of the spar. Glue any joints remaining, and then add the false leading edge.

Next, apply the top wing skins. These are glued in place as two halves, one panel at a time, before you trim off any overhanging skins. Then, attach and shape the wing's leading edge..."

Beech Turbo Mentor from Quiet Flyer, February 2004.

Direct submission to Outerzone.

Supplementary file notes

Article pages, thanks to RFJ.

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