Flat spins

[mad max]

Reminds me of the parachuting days. We were jumping old rotten korean war parachutes and instructed to spit if the chute opened full of holes. If the spit went down you were OK. If it went up throw the reseve out the side.

[birdy]

[i]BTW, is the word "cyclic" actually used in the manual??

[gyroo]

[i]BTW, is the word "cyclic" actually used in the manual??

[MadMuz]

Oh, ok...... sort of makes sense......I will engage the grey cells..... I have just not thought of gyros having any sort of cyclic system. Are there any threads for further info? This is off topic for this thread

[birdy]

Muz, next time your Standn next to your gyro, tie the stick to any position other than centered forward, grab a blade end and walk with it one revolution, watchn the end change pitch as you hold it the same hight off the ground as you go.Wot you see is cyclic action, in action.If you have access to a choppy, do the same, and zactly the same thing will happen at the blade end.That"s why the stick between your legs ina choppy and a gyro are called cyclics, they both apply cyclic pitching to the blades, just by different means.

[MadMuz]

I agree, but it is not a cyclic change of a pitch angle (created by a pilot to achieve a predicted result) of each rotor in a particular part of the cycle of the rotor as we know

[gyroo]

Dear oh dear oh dear oh dear.Mad Muz .........With respect, we are going to have to pack you off to 21st Century rotary wing ground school. Please buy or access any of the standard rotary wing textbooks or even academic texts such as Gessow and Meyers, etc, in relation to how 2-bladed semi-rigid rotors work with tilting hubs.Once again, Birdy is absolutely right in what he says and you, my friend, unfortunately, are dead wrong.A gyro pilot sitting on his machine deflects the stick to tilt the spindle shaft (or put more simply, tilts the hub) As the spindle tilts, and particularly 12 to 14 times per second as the hub bar aligns 90 degrees from the direction of the spindle tilt twice per rotor rev, the 2 opposing blades receive a tiny cyclic input via the teeter bolt that puts one blade a tiny bit nose down and the opposite number a tiny bit nose up. The slight incremental cyclic pitch changes at an amplitude of 2 per rev quickly and smoothly add up to result in a definitive noticeable tilt of the rotor disk in the direction the spindle has been tilted. The tilt occurs because each blade sweeps in a slightly different arc causing what we see as a tilting of the rotor disk. The tilting of the rotor disk will stop automatically once the 2 opposing blades achieve what aerodynamicists call "aerodynamic equivalence", which in layman"s terms is when the flapping moments of each blade are precisely cancelled out by the opposite blade and the disk then remains tilted in the new tip path plane that the pilot wanted.If the pilot moves the stick in another direction, tilting the spindle, the rotor will extremely quickly follow the spindle tilt until "aerodynamic equivalence" is again achieved and the disk tilt stops.Mad Muz, if you are going to start talking about weight-shift, then think again. That forlorn belief has been well and truly discredited more than a decade ago, and the very few isolated remaining adherents of it betray their profound ignorance about the principles of rotary wing aviation by retaining such silly ideas.Yours truly,Mark RMelbourne

[birdy]

Muz, before you post again, do wot I said to your rotor.If the blade changes pitch twice per rev,( cyclically) wot would you call it?

[MadMuz]

I don"t go along with the weight shift idea, although Robs Gyke has to make one think

[MadMuz]

Muz, before you post again, do wot I said to your rotor.If the blade changes pitch twice per rev,( cyclically) wot would you call it?Thanks Birdy, I am aware of the path of a rotor blade in the disk itself, given the blade stationary on the right side, the joystick definitely does appear to change pitch to the positive, but when the same rotor is straight ahead the rotor merely rocks forward in its entirity with no change in pitch...... our disk when rotating at flying speed is an animal unto its self..... our airframe is merely suspended below it and we control it thru our understanding of the principles of gyroscopes, centrifugal forces and kinetic energy.That is why the airframe section of our gyros can basically take any shape, tractor, pusher, pod/no pod, square tube, round tube, long and skinny (parsons/euro clone) wide and blunt (side by side 2 seat open).... with floats, with floating pod and outriggers..... the list goes on.... the disk is one thing, whatever is under it is another... I have even seen pictures of both an actual Florida airboat with a mast and rotors that actually flies (350 chev and all ) all be it in ground effect.... and I remember seeing a hovercraft with mast and rotors actually flying

[aussie_paul]

Muz, there will be quite a bit of stuff you/we were taught back then that is WRONG. Those were the days of the "half blind leading the blind". Nothing to be ashamed of, just the way the gyro world was back then.First thing to do is understand is "gyroscopic precession".Aussie Paul.

[MadMuz]

Thanks Paul, I have a fairly good understanding of gyroscopic precession, one gets a whole shootload of it all at once if the rotors hit anything hard.....On helicopters, GP is the reason the cyclic swashplate is 90 degrees early, so in effect the lifted rotor passing the tail boom for example, results in the disk lifting on the right, to tilt the disk to the left.... same as the rotor pitching up at the right, results in the nose raising and so on....Not all that is old is wrong Paul, I don"t believe there is much wrong about the principles I have mentioned here.....

[MadMuz]

Well, this thread has been well and truly hijacked and off topic