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#11
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"Trentus" wrote in
: "Mr.Twistair" wrote in message ... Joss, this heli is slightly described at http://twistairclub.narod.ru including photos of it's step-by-step unfolding. It wasn't ever flown. The main reason why is mostly explained as "no suitable engine which would fit this design that time". I've heard that it was designed to be powered by small rotary engine but the engine wasn't actually built (never run good enough - to be exact). Pardon me while I drop my guard and flash my ignorance to all and sundry. No tail rotor? I assume the twin sets of rotors turned in opposite directions to counter the resultant forces that would cause it to spin otherwise. How would you then turn one? I believe you turn a helicopter by altering the amount the tail rotor counters the tendency of the craft to spin? How would you turn a helicopter that has no tail rotor. Sorry about coming into this so late... The coaxial rotor helicopters have fully-articulated rotors on both heads. Yawing is acheived by increasing the pitch on one (and probably decreasing the pitch on the other simultaneously, so no increase in overall lift). This produces more drag from one head, less from the other, so the anti-torque effect is minimized and the aircraft rotates against the increased pitch rotor. I, personally, would like to see a closeup of the swash plate and links assembly, to see how they manage to get past the lower head to articulate the upper. Everything I've thought of so far leaves out some aspect of either collective, cyclic, or precession. - Al. -- To reply, insert dash in address to separate G and I in the domain |
#12
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Al Denelsbeck wrote:
I, personally, would like to see a closeup of the swash plate and links assembly, to see how they manage to get past the lower head to articulate the upper. Everything I've thought of so far leaves out some aspect of either collective, cyclic, or precession. This makes it all so clear... http://www.b-domke.de/AviationImages...head/1363.html |
#13
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terra wrote in
: Al Denelsbeck wrote: I, personally, would like to see a closeup of the swash plate and links assembly, to see how they manage to get past the lower head to articulate the upper. Everything I've thought of so far leaves out some aspect of either collective, cyclic, or precession. This makes it all so clear... http://www.b-domke.de/AviationImages...head/1363.html Umm, yeah, kinda... ;-) It's a good detail pic, thanks! Still hashing it out, but looks roughly like my first suspicions. But something puzzles me, not being involved in rotor design or maintenance: I was told, a long time back, that because of precession, the cyclic input for forward flight, for instance. occurred slightly ahead of the point where pitch was intended to be greatest. In other words, a little advanced in the rotation from full rear position on the rotor disk (much like ignition timing on a car, just for different reasons). Easy enough to do on a standard rotor assembly, but requires displacement to both sides on a coax. This doesn't seem to show such a design, unless I'm missing it (entirely possible). Was I misinformed long ago? Anyone? - Al. -- To reply, insert dash in address to separate G and I in the domain |
#14
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"Al Denelsbeck" wrote in message . 8... terra wrote in : Al Denelsbeck wrote: I, personally, would like to see a closeup of the swash plate and links assembly, to see how they manage to get past the lower head to articulate the upper. Everything I've thought of so far leaves out some aspect of either collective, cyclic, or precession. This makes it all so clear... http://www.b-domke.de/AviationImages...head/1363.html Umm, yeah, kinda... ;-) It's a good detail pic, thanks! Still hashing it out, but looks roughly like my first suspicions. But something puzzles me, not being involved in rotor design or maintenance: I was told, a long time back, that because of precession, the cyclic input for forward flight, for instance. occurred slightly ahead of the point where pitch was intended to be greatest. In other words, a little advanced in the rotation from full rear position on the rotor disk (much like ignition timing on a car, just for different reasons). Easy enough to do on a standard rotor assembly, but requires displacement to both sides on a coax. This doesn't seem to show such a design, unless I'm missing it (entirely possible). Was I misinformed long ago? Anyone? - Al. -- To reply, insert dash in address to separate G and I in the domain Precession and dyssemetry of lift are cancled in coaxials as far as I know. |
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