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#2
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"Gil G." wrote in message
... I think the tank would be too heavy to take along... However, I am thinking that a scuba tank could be used with a regulator and quick disconnect system to prerotate the rotor, then disconnect the air hose and immediately start the take-off. How about a catapult? Rich "Cum catapultae proscriptae erunt tum soli proscripti catapultas habebunt " S. |
#3
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this one http://celag.free.fr/museum/tresor/us_so1220_1.htm
even hoovered with 'cool' gas exiting at the wingtips -loef (www.loeff.de) "Rich S." wrote in message ... "Gil G." wrote in message ... I think the tank would be too heavy to take along... However, I am thinking that a scuba tank could be used with a regulator and quick disconnect system to prerotate the rotor, then disconnect the air hose and immediately start the take-off. How about a catapult? Rich "Cum catapultae proscriptae erunt tum soli proscripti catapultas habebunt " S. |
#4
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I believe that in order to have the capability for a jump take-off, the rotor blades would have to be depitched to zero, and then when a lot of rotor rpm is built up, the pitch has to be added in rather rapidly to achieve the jump. Ken J. - Sandy A. Gowe Ken, I've heard that they actually overspeed the rotor system relative to it's normal autorotative rpm. The added inertia is what gets them airborne but it's then critical to get some forward speed going so it can establish an autorotative state when the rotor system slows back down to normal rpms. I've also heard that they actually over pitch the rotor blades to make the jump and that has to be let back down to a setting that will allow the rotor blades to establish an autorotative state as the aircraft accelerates forward. This part really makes me wonder. It sounds like it would be pretty critical to get it right. Can confirm whether this is true or not? Wondering! Fly Safe, Steve R. |
#5
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I've heard that they actually overspeed the rotor system relative to it's
normal autorotative rpm. The added inertia is what gets them airborne but it's then critical to get some forward speed going so it can establish an autorotative state when the rotor system slows back down to normal rpms. I've got some time in the Air & Space 18A and it uses this method for a jump takeoff. I'd have to dig out the books, but it seems that the rotor is oversped about 100 RPM. When the jump is commenced rotor RPM decays immediately though. I've also heard that they actually over pitch the rotor blades to make the jump and that has to be let back down to a setting that will allow the rotor blades to establish an autorotative state as the aircraft accelerates forward. This part really makes me wonder. It sounds like it would be pretty critical to get it right. Can confirm whether this is true or not? As far as the 18A goes, this is not the case. When the jump is began in the 18A the hydraulic pressure holding the blades at flat pitch is released allowing them to pitch. Once pitch is introduced the rotors remain at that pitch until the flight is ended. There is no mechanism for varying the pitch in flight. Other aircraft may vary. Stephen Austin Austin Ag Aviation Charleston, Missouri |
#6
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I like the idea of compressed gas for the pre-rotar! That might be do very
able... "sanman" wrote in message om... Hi, I'd done some reading about pre-rotators for gyroplanes which can be used to give them a jump takeoff. I was wondering if any of them have tried using compressed gas to power the pre-rotator? I got the idea after reading these links: http://www.howstuffworks.com/question133.htm http://news.bbc.co.uk/1/hi/world/africa/988265.stm http://auto.howstuffworks.com/air-car.htm http://www.evworld.com/databases/sho...=news190503-04 Gee, now that I think about it, why couldn't compressed air even be used to power the gyroplane pusher prop during regular flight? An onboard compressor could even be used to compress air into the cylinder in the first place. Liquified nitrogen gas can store a lot of energy, pressure-wise -- more so than what a battery could store. That compressor could be reversible as a motor. |
#7
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"Red" wrote in message ...
I like the idea of compressed gas for the pre-rotar! That might be do very able... Where is the gas going to exit...at the tips of the blades, I'm presuming? Now you have plumbing running through the blades plus a lot of plumbing and complexity where the gas enters the roots of the blades. Gyro blades are hard enough to balance as is, with a gram added here and there via powdered lead or a tiny washer or 2. I got a long ride in an Air & Space and the blades are depitched to zero until about 300+ rpm, I believe. Then the blades are quickly released to their normal pitch for the jump. I doubt you'll get anywhere leaving them pitched and spinning them up, even to a high number. Otherwise A & E would have skipped the complexity of being able to depitch and repitch the blades rapidly if all it took was some rpm. Then you'd have a "helicopter" spinning wildly out of control as soon as it left the ground because it doesn't have any means to counteract the torque. To those that think it's doable...do it and then show us how you did it. We'll all be anxiously awaiting. Ken J. - SDCAUSA "sanman" wrote in message om... Hi, I'd done some reading about pre-rotators for gyroplanes which can be used to give them a jump takeoff. I was wondering if any of them have tried using compressed gas to power the pre-rotator? I got the idea after reading these links: http://www.howstuffworks.com/question133.htm http://news.bbc.co.uk/1/hi/world/africa/988265.stm http://auto.howstuffworks.com/air-car.htm http://www.evworld.com/databases/sho...=news190503-04 Gee, now that I think about it, why couldn't compressed air even be used to power the gyroplane pusher prop during regular flight? An onboard compressor could even be used to compress air into the cylinder in the first place. Liquified nitrogen gas can store a lot of energy, pressure-wise -- more so than what a battery could store. That compressor could be reversible as a motor. |
#8
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Hmm, well what's happening with these newer elastomeric bearings,
these days? How are they coming along, and where are they falling short? I've heard that they are at the cutting edge of rotor hub technology, and could be used to change the rotor pitch on a gyroplane, for jump purposes. |
#9
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#10
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At last someone who stands up and tell the whole story
Thanks "Ken Sandyeggo" a écrit dans le message news: ... (sanman) wrote in message . com... Hmm, well what's happening with these newer elastomeric bearings, these days? How are they coming along, and where are they falling short? I've heard that they are at the cutting edge of rotor hub technology, and could be used to change the rotor pitch on a gyroplane, for jump purposes. Uh....O.K. The gyroplane market is so miniscule, one would have to be an idiot to develop anything over a cost of a couple thou and 2 to 3 weeks in your basement or garage. Hardly any 2 gyros are alike. Gyroheads are the "Kings of Modification." To make something that was adaptable to the whole gyro market would be an exercise in futility. Too many variations and little standardization. You lost me on the elastomeric bearings. They are far from new and in about 6 years on a very active gyro forum, I don't recall the subject ever coming up. No one there is interested in jump take-offs. If they were, they'd be on the heli forum. Gyros are meant for the simpler end of rotary flight. Jump take-off adds a complexity that actual, flying gyroheads are disinterested in. It's good for mental masturbation on NGs, but that's about it. Ken J. - Sandy, eh?.......GO!!! |
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