Mark's aircraft

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page updated: 2005.11.20

aircraft - early - multi task

early electric power gliders helicopter indoor technology future

tyro major multi task combat wing

selection

This was 1 of my later attempts at aircraft design. I wanted something fast, aerobatic. I also wanted to drop things from the wings.

construction

Limited by what was available ie. the Skyleader 3 channel 27M radio, OS25 engine. I designed the wings around standard 3' length balsa with a 1/16" sheet D box and balsa spars, with an otherwise open structure. The depth of the wing was just deep enough to fit the standard servo flush, so that the wing could knock off cleanly in impacts (usual dowel and rubber band arrangement). Used the 1 "white spot" servo that works in the opposite sense to normal, in order to get the ailerons to work correctly using plastic bellcranks and piano wire push rods. This made it a bit too deep for speed really. Also flat bottomed section to make it easy to build which is not very good aerodynamically. Recently getting into electronics, I made a simple oscillator with some high power transistors to go in the wing, driving bulbs alternately in transparent, silver foil lined areas in each wing tip. This was meant to improve visibilty in dusk conditions. Never actually got used, as it would be too risky to drive these from the radio supply. I put slots in the underside of each wing which could take a loop of wire, retained by spring loaded pins, held in place by further loops in the centre section. These in turn were held in place by a pin sticking up into the wing from the fuselage. When triggered this would be withdrawn and release whatever the wings were carrying. Lacking any spare channels/servos this was to be triggered by activation of extreme control of either elevator or throttle (I can't remember which - I suppose I could go and have a look). Again, never actually used. Finished in the usual red solarfilm, with an orange/yellow orientation stripe on 1 wing.

The fuselage was just a square box big enough (just !) to carry the engine, tank and radio. The tailplane had a rather large elevator with a thread hinge. My idea was that this would be half way to a fully flying tail surface. Unfortunately it tended to be a bit floppy and vague. I fitted a 3.5mm jack socket to the fuselage side, wired to the glow plug, so that the glow could be applied/removed really easily. This actually worked well, and I used the same setup on a stock car. Engine has the (by then) standard pressure feed from the silencer to the clunk tank. Didn't think of any clever way of retaining the tank hatch, so it was held down with a rubber band.

flight

I don't really remember much about flying this when I built it. I'm pretty sure it did fly, as I remember the engine starting nicely. I think the rather large amount of play in the aileron linkages and the floppy tail/elevator made trimming it impossible, so rather hard work to fly.

When I got back into flying this was 1 of the few intact aircraft available, so I put the new Futaba radio into it and went to fly it at Warwick. Did all the usual pre flight checks, including waggling all the control surfaces and launched it. A slight drop of 1 wing required a small correction, but it got much worse, and quickly smacked into the ground at full power, upside down. Analysis revealed my error. All new radio comes with channel reversing switches now, so all servos are standard sense operation. I had forgotten that the original radio fitted had a reversed servo in the wing. Now I check for correct sense of control before launch. The front of the wing got a bit squashed back in the crash and 1 of the wing bellcranks broke away. I repaired this, but haven't tried to fly it since.