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Some Gyro Myths

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Some Gyro Myths

Old 06-26-2013, 10:13 AM
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Chris Smith
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Default Some Gyro Myths

There's some mis-information in some threads regarding gyros. There is a lot of good info too if you are willing to search and read.

It would be untrue that gyros are mysterious voodoo that seeks out and destroys jets. Quite the contrary.
It would be true that we don't want to use cheap foamy type gyros in a jet or any high performance airplane. This is no different than cheap servos or receivers.

That said:
1. It is a MYTH that a helicopter gyro can't be used in a fixed wing aircraft. Therefore:
2. It is a MYTH that a jet must use a gyro intended only for airplanes.

If the user sets up the gyro properly, and the gyro is RATE capable, then most any quality gyro is usable. Jets will use the gyro in RATE mode 99.5% of the time. The gyro has no idea whether it is in a helicopter or airplane. It simply responds to movement in the axis it is aligned to.

Keep in mind that helicopter flyers use much higher gains than is necessary or desired in a jet. Helicopters also use Heading Lock/hold for most flight profiles for good reason. Airplanes/jets don't need heading lock for most flying we do, but a jet using heading lock is perfectly do-able if desired. Thus:

3. It is a MYTH that mearly using heading hold (Heading lock, AVCS, all the same thing) will crash a fixed wing model including a jet.

If the gains are way high, or the gyro is set up improperly, and the pilot does not know what is going on, or how to fly all 4 primary stick axis' (Elevator, Aileron, Throttle, AND rudder), then it is possible the jet can exhibit behavior in Heading hold that could confuse the pilot. However, this could also be true in RATE mode. At the lower gains used on jets, even in heading hold, the airplane can fly quite safely since the controls are still moved by the pilot and gyro response is easily overridden or "reset". However the problem comes in if the gains are dialed way up. Some jets can have undesired coupling that may result in confusing behavior that could lead to a crash, but don't decide that it is a heading hold issue alone. It's a setup issue. Just as, if you set RATE mode backwards or too high gain, we could say that would also lead to a crash. Would that mean RATE mode is also unusable?

4. It is a MYTH that gyros fly the airplane.

Most of us are not using gyros to "fly" the airplane for us. We don't need an autopilot (which a gyro is not). We use gyros to help dampen unwanted axis movements or oscillations due to winds, turbulence, or perhaps difficult runway behavior. In some cases we use them to help with an unwanted coupling or a design characteristic inherant to that model, for example Dutch roll. Therefore we use only enough gains to accomplish that task.

In short, a gyro can make some jets feel bigger than they are, and look and feel more realistic in flight. One must still pilot the jet for best results. Any quality gyro is usable in a jet, and the user must know how to set it up or get the proper assistance.
Old 06-26-2013, 10:20 AM
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binsonc
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Default RE: Some Gyro Myths

Good point.
Old 06-26-2013, 10:22 AM
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erbroens
 
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Default RE: Some Gyro Myths

Problem is that in the JR gyro printed manual says that the heli gyro isn´t intended to use in airplanes.. (anyway I used two of this gyros in a F-18 with very good results).. maybe this is why the myth persists.

http://www.jrradios.com/ProdInfo/Fil...structions.pdf

Anyway, the Igyro from powerbox has a significant feature that outclasses any gyro like this. . This is why I have one in hands right now!



best regards, Enrique.

p.s. forgot to mention you are 100% right.
Old 06-26-2013, 10:59 AM
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essyou35
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Default RE: Some Gyro Myths

Hmm, I had a GY420 gyro on my jet. It didnt do much until I put the gain at over 50%. Not sure what a high gain is, but since you said Helis use a high gain, any heli I have had has been under 10% gain.



Sooo...
Old 06-26-2013, 03:56 PM
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rcand
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Default RE: Some Gyro Myths


ORIGINAL: erbroens

Problem is that in the JR gyro printed manual says that the heli gyro isn´t intended to use in airplanes.. (anyway I used two of this gyros in a F-18 with very good results).. maybe this is why the myth persists.

http://www.jrradios.com/ProdInfo/Fil...structions.pdf

Anyway, the Igyro from powerbox has a significant feature that outclasses any gyro like this. . This is why I have one in hands right now!



best regards, Enrique.

p.s. forgot to mention you are 100% right.
I tried the 770 years ago and set it with low gain and sensitivity and it would go into heading lock, therefore never flew with it. you just hav to pick the right gyro.

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