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Was talking with fellow gyronaut the other day, he had an incident in flite that gave him one hell of a fright.....At 1500ft he pulls off power to do a vertical drop out, next thing in the blink of an eye, he goes into a very fast flat spin, that rudder etc will not control. In desparation he drops nose, full power, managed to get out of it......kakin himselfI have never experienced that myself, all spins have been totally controlled, and good to do, good to others watching etc, but this was so quick to engage, extremely fast rotations......luckily the guy had some height to sort it.Any feedback out there.......Russ....A1014 NT....gods country
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Russ,Head bearings or, if it has a pre-rotator, something has become momentarily engaged.Does it have a rotor brake that could have dragged?Fish.
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This has happened many times, some have even spun to the ground but all have walked away. It would seem that the shorter the gyro and the bigger the prop the more chance of it entering a spin during a vertical descent. With a very large slow turning prop, the airflow up from the bottom effectively increases the pitch on one side and decreases it on the other giving an uneven thrust tending to turn the gyro (the same way that a rotor without a teeter hinge will roll a gyro). Reports suggest that increasing the power frightens most pilots because it makes the spin rate faster. However Jacko suggests that you have to go to full power with opposite rudder and although the spin initially speeds up, the spin circle gets bigger until the gyro flys out of it. It was never a problem with the old basic Bensen which would quite happily spin in either direction and recover straight away with opposite rudder (in this case the shorter less efficient high speed prop running less pitch had considerably less pitch variation from one side to the other). To enter an uncommanded spin the gyro usually has to commence a "vertical" with a fairly nose high attitude. It is a lot harder to do with a big stabilizer because as the gyro starts to sink, the nose drops and the gyro maintains some forward speed.Tim McClure
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Tim.......for an oldie, you're bloody good[
]this machine is SHORT....76" prop....small tail.....soobyI sugested to him if it happened again......turn the spin into a spiral......go with the flow, so to speak[?]nose down, power,left stick. Must admit, never heard of this before, the spin I meanjust my view.....Russ....A1014 NT....gods country
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Wal Flaks had a theory about this too, if your stab is flat, and is maybe tilted one way, that might induce a spin. I like Tim's idea and the rotor friction may help as well.One of our club members did this with a hirth engine, from 2000', short machine, big prop, small tail. Had to fly out of it as well, but what happens when your motor doesn't want to play any more - ride it down I think is the answer and walk away less one machine.Tim might be able to ilucidate on this one..I hypothesise that the tail should have some dihederal on it, say 10 to 15 degrees, so it vees into the updraught and nuetralises the spin. The alternate as you may have seen with the old kellet and pitcairn gyros is for a triple fin on the tail, significant vertical area.Your comments Tim?Cheers,Nick.
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Russ - easy on this "oldie" business. I recall Gary Percy at one stage testing out a new tall tail. He commenced a spin at 5000ft and after a couple of turns he decided that it was enough. The gyro had other ideas and he finally recovered at 1500ft. Over 3500ft of spinning descent he tried many ways to recover including switching the engine off but nothing seemed to work. He finally grit his teeth and held on full power until the spiral got bigger and it flew out of it. He used to do spins regularly with his "conventional" tail (which was further back) and had no trouble recovering. I dont think doing spins tickled his fancy much after that. "what happens when your motor doesn't want to play any more"Good question. Maybe if you were game enough to put the nose down steeply enough to turn the spin into a spiral dive you may be able to recover. I don't really know though because all the ones that I am aware of still had the noise generator.Tim McClure
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Tim, If a rotor brake has grabbed ( or grabbing) the loss of rotor rpm's would nearly be terminal wouldn't it?Ted
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A rotor break wouldn't have the bite to stop the rotors in flight Ted.Plenty o times I'v flown the RAF and forgottn to release the break, with no noticable change when I released it.And RAF breakes are pretty strong.Ignorance is bliss............but only till you realise you were.You can always get the answer you want, if you ask enough experts.
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It would want to be a hell of a good rotor brake to slow your blades enough it to do that , a seizing rotor bearing is more likely to bring you undone.
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Hmm,This sort of buggers the idea of dropping out of a cloud some, doesn't it? Thanks for the input Tim.So the problem is more to do with the coupling on the control surfaces over the size of them, though a bigger one does help if the coupling is short.Any comments on 'V'ing the tail?Nick.
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I was taught flat spins and recovery during my training 13 years ago and have never remotely considered one since. I may be a scaredy cat but it was a sensation I did not like one bit.Also, am not completely sure how or why but there is a combination of flat attitude, rudder and back stick that is deadly at zero and low airspeeds.
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Regarding a " Vee" tail, although never having flown one, I asked the question of my instructor some time ago. He suggested that in the "olden days" when everyone flew a VW and no one went very far, a few Vee tails appeared and with this advance in technology, came more flat spins. I guess thats why you only see them on old Bonanza's? dont know.Mark.
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Mr Horribulus Maximus..My idea was dihederal on the tail, not a V tail per se'.You retain the tail fin and rudder, but have a stabiliser that has a vee shape on end view, so that the stabs were 10 to 15 off the flat, pointing up ... if they pointed down it would be anhederal, not a good arrangement for a gyro.Let me postulate for a bit..In a vertical descent the flow of air and moment about the centre of gravity is not affected by the operation of the rudder because its movements are parallel to the air flow..If you raked the axis of the rudder hinge pin forward at the top, say 30 to 45 degrees, then the rudder would have an affect on the vertical air flow and thus induce a moment about the centre of gravity. The problem is that in doing this the air flow is also deflected down when you execute a normal turn, would this be overcome with the stick though, ie, you could compensate for it? It would push the nose down in a turn if it was so arranged.It would be interesting to know the rate of revs per second that were encountered in this vertical spin - any info there Tim?Cheers,Nick.
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Don't know - never really timed them. It seems very fast but is probably something like 3 turns every 2 seconds. When you are sitting in it, it certainly feels fast. Some gyros turn much more slowely and some will not really spin at all.Tim McClure
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ah, yes, it would be scarey.Do we have a method of measuring how much resistance to spin a gyro has, ie, hang it by the teeter bolt, put a spring scale on it and pull it around to determine the resistance to spin? Is it a measurement criteria for a gyro for registration?Nick.
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