Giant-Scale Tiger Moth

Model Airplane News, Jul 2004 by Allen, Gary, Davisson, Budd

The fin/rudder assembly is built in much the same manner. The rudder horn and the rudder bellcrank are made of two laminations of 1/32-inch ply covered with a top and bottom lamination of 0.014-inch carbon fiber. The tailwheel assembly is made with music wire, various sizes of brass tubes, sheet brass, wheel colors and hardware-store springs. The finished assembly looks quite convincing and is very functional.

The control cables are commercially available and work quite well. It is important to make sure that the cables are securely attached to the rudder and elevator control horns. Make them easily detachable if you plan to remove the tail assemblies for model transportation.

WING PANELS

The top and bottom wings are constructed similarly. They feature �� 5/8-inch spruce or basswood front and rear spars, 3/32-inch ribs and false ribs and capstrips. The bottom wings use large barn-door ailerons that are driven by high-torque servos. The top wing has leading-edge slats. The mechanism shown on the plans is similar to that used on full-size aircraft and isn't too difficult to fabricate. Forego this option unless you enjoy fiddling.

* Rigging. The process for rigging the finished model is quite simple and is described fully in the detailed construction instructions. The flying and landing wires as well as the interplane brace wires are all functional. I fabricated them out of 4-40 threaded rods, threaded couplers and Du-Bro threaded and solder attachment fittings. The interplane struts are basswood. Make the attachment fittings from 1/16-inch brass stock and attach them to each wing panel at the front and rear spars with 4-40 bolts. The landing- and flyingwire anchors are part of the wing-root structures, so the entire rigged wing-panel assemblies (with interplane struts in place) can be handled as a unit during assembly and disassembly. Only five bolts per wing assembly hold everything together.

COVERING AND FINISHING

I used Solartex fabric covering throughout. I simulated the rib stitching by using glue dabs and medical-paper adhesive tape for the rib tapes. I painted the model with paint-store-mixed polyurethane enamel, and then I added the various other surface details such as the venturi and Pitot tubes, windscreen, fuel lines (containing the leading-edge-slat servo wires), cabane bracing wires, flying hood-attachment points, anti-spin strakes, etc.

FLYING

Takeoffs are very easy, even in slight crosswinds, and require very little rudder correction. Scale takeoffs are best achieved by slowly advancing the throttle and holding a bit of up-elevator as the model starts to roll. Even with only a lOmph headwind, the model will lift off within a few feet when you apply full power. Turns require a bit of coordinated rudder, especially during the climbout. As with the full-size Tiger Moth, which featured a significant positive decalage, you must advance the throttle to climb and retard the throttle to descend.

The model is capable of amazingly slow flight. Though not dramatic, deployment of the leading-edge slats enhances slowspeed control. The Tiger Moth could never be mistaken for a jungmeister, but it is nevertheless quite capable of many aerobatic maneuvers. Really nice loops, stall turns and wingovers are all easily within its capability, though its roll performance leaves something to be desired. Even with differential aileron and the judicious use of the rudder, an alarmingly slow barrel roll is the best that I can achieve.