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E-Sky › Regarding pirouette stops and bounce or wag:
08-14-2010 05:47 AM  7 years agoPost 1
BOB WHO?

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Downey, Ca.

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KV, I'll start here where we left off on the Quark thread. I had tested the Quark for pirouette stops both left and right. Remember that this gyro was set-up at the radio, no software. As I was about to test the Futaba 520 for it's behavior on the same kind of stops, I discovered something that makes the first test invalid. Like a brainless dummy I reported that all stops, left and right, on the Quark had a small bounce or wag. I was releasing rudder gimbal from full L or R by letting it go. Duh....... It's spring loaded and the stick vibrates back and forth until it stops. Guess what the tail does while the stick is vibrating to a stop? That right! It bounces and wags. What a surprise! On my new tests I stopped the piro by stopping and holding the rudder as still as I could. So I have now retested the Quark and have slightly different results: Now there is only one minor bounce or a barely detectable bounce on both L and or R. The gyro is even better than I thought. Now for the results for piro stops with the Futaba 520: This gyro (on an identical Trex 450 as the Quark is on) stops the tail dead cold. When you center and hold the stick while pirouetting, that tail just quietly stops right where it is. I had to stop many times with this gyro to get even the slightest bounce or movement. I think it is a better gyro from the results of my crude testing.

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08-14-2010 10:37 PM  7 years agoPost 2
Gregor99

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Western Wa

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So the Quark's stops are not as dead cold as the Futaba?

Revolectrix Beta Team

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08-15-2010 12:29 AM  7 years agoPost 3
BOB WHO?

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Downey, Ca.

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Not on my identical 450s. The left stop with the 520 is a dead stop. The right stop has just the slightest bounce or correction about half of the time, not more and probably less than the Quark. The other half of the time the tail stops cold. Remember both of these gyros are set-up with the radio not any software. They are both great gyros, but if I had to pick one it would be the Futaba 520.

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08-15-2010 02:14 AM  7 years agoPost 4
Heli_KV

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Ottawa, Canada

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Bob, I am glad that your stops are fine. Mine are fine as well now. Well, almost. Depends on how I stop. Softer or more abrupt. In any case stopping is pretty complicated process from the point of view of gyro work and it depends on a number of reasons each of which is individual to heli. Just to make brief and incomplete illustration, imagine heli piroed and then suddenly stick was moved to neutral position very fast. Tail should stop also the same fast, but it has mass, so it requires some time, otherwise acceleration will be infinite. So it is kind of pushing break on a moving car. About the same dynamics. Back to tail. So tail stops decelerating and it can go beyond new direction, then it should go back - here we are wag. That's why there is deceleration profile, stop gain, etc, which allows to fine tune all stuff.

The best work of gyro of what I read is explained by Capi (HFG) on another site in 101 gyro or something like this. Not sure how it will look if I give reference to that site, but it can be found there. Also On Spartan site, there is explanation about that gyro behaviour. Just a sec. No, I cannot find with my slow Internet.

As for Quark and 520, seems to me that 520's default parameters are just better suit your particular situation. All in all manufacturers try to supply default parameters as close as possible to most common helis.

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08-16-2010 05:19 AM  7 years agoPost 5
BOB WHO?

rrKey Veteran

Downey, Ca.

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I flew the 450s today and the Futaba 520 continues to impress me. Both the Quark and Futaba 520 will hold the tail in full collective punch-outs, as will most HH gyros. On fast backward flight though the Quark just couldn't hang on to the tail; it just let the heli spin around when the g-force got high. The 520 was a different story. Both Trex 450s are identical and the one with the 520 would hold in fast backwards flight. The tail never spun out once. I kept increasing the gain on the Quark to get the tail to hold. Finally I had to stop adding gain when the wag was present in hovering.

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