説明
The Spin-TOL was an attempt at a VTOL tail sitter design where the rotor blades become wings. The concept has merit, but is complex to implement. I tried to simplify it by using quad-copter style control instead of collective and cyclic pitch but failed. The control authority offered by the quad was insufficient, plus there is a natural instability associated with the fixed pitch rotor. It hovered OK and was weakly controllable, but as soon as it started moving sideways the control authority was beyond what the quad could deliver and it entered a spiral oscillation. After 2 such crashes we decided to try it in forward flight, but it failed there as well. The complication there is that the fuselage comes in 3 sections that have to spin relative to one another. This requires proper low friction bearings, but the nylon bushings used were both not stiff enough, and had too much friction. As a result, the nose section, which was not supposed to spin, rolled over and up elevator became down elevator causing a crash. I always knew that the design was marginal, and only pursued it because there was interest in its ability to fly as a Triebflugel, which is a spinning wing aircraft contemplated by German aircraft designers in WW2. The full scale Treibflugel was never built or flown, but has remained a subject of fascination in terms of whether it could have worked. The consensus is that it could have, but the complexity of such a thing makes it highly impractical. As if to prove the point, the Spin-TOL failed because it didn’t fully embrace the complexity required. I tried to “cheap out” or “simple out” and it didn’t work. A successful Treibflugel will have to wait until someone commits to doing it correctly, which is a lot of work.
R.D.