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Old Sep 04, 2005, 02:17 PM
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Differences bt electronic (piezo) & mechanical gyro?

anyone know the true differences between the electrical (piezo) and mechanical gyro? Some have dual rate and reverse functions, wat that? i'm guessing reverse func is for 3d when inverted, but not so sure...thoughts?
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Old Sep 04, 2005, 02:45 PM
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Piezo has no moving parts, mechanical has a spinning wheel. Don't know if you can actually still get mechanical ones, and don't know why you would...

You reverse the gyro if it compensates in the wrong direction, doesn't matter if it's upside down (the gyro doesn't know it's upside down, it only knows about rotation in a single plane, yaw).

Dunno what you mean by dual rate. Some gyros have a Heading Hold mode, some don't, and the HH ones can usually switch to Rate mode (where the gyro compensates for all movement, even commanded by you). This might be what you mean...
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Old Sep 04, 2005, 03:22 PM
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Piezo gyros weigh less, use less power and can be made to function at larger yaw rates than mechanical ones.
As far as I know none of the mechanical ones offer heading hold.
I still have mechanical gyros in some of my older helicopters and they work fine, but the newer piezo ones are a definite improvement.
If I flew the old ones much, they would probably get new piezo gyros.
Pat MacKenzie
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Old Sep 04, 2005, 03:31 PM
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I missed two of your questions.
The reverse switch on any gyro is there so that when mounted right side up the feedback can be applied in the correct direction.
This depends on the servo and tail rotor arrangement so there has to be a switch, or you have to flip the gyro upside down.

Dual rates on older gyros were a way to allow high gain when the head speed was low for hovering and lower gain when the head speed was higher or in fast forward flight.
Higher end mechanical gyros had variable gain controlled from the transmitter, just like some piezo gyros (GY401 for example)
Pat MacKenzie
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Old Sep 04, 2005, 05:25 PM
NO NO come back...spLAT!!
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well said, thank you all, i have a GY401 gyro on a gas heli i recently acquired, was planning on strip the heli aprt and sell the parts to generate fund for a trex, now i dont think i'll sell that gyro, lol.

gas heli is such a @#$%, the fuel mess everywhere! i might say that everytime youfly, it's like the heli went thru a period of diahrea. so i'm goin all electric.
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Old Sep 05, 2005, 03:22 AM
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piezo gyros do have moving parts...the crystal sensor vibrates and the coriolis forces caused by the yaw are measured.

State of the art gyro's now use arrays of micro machined parts and basicly are mechanical gyros again. Albeit being very very very small.


The futuba line of gyros is the only type of gyro that uses a round sensor (instead of just one string of crystal material) that is more accurate than most other gyros. They are less prone to vibration as the round shape helps it to be inneffected by vibration.

That's why futuba gyros don't need damping with foam while others can benifit greatly from physical damping.

If you've ever seen a futuba gyro from the inside you'll notice that about 60 procent of it's weight comes from the sensor alone. (very big metal case inside)

This makes am so heavy compared to others but it's als the reason that for the micro's they are the best hands down.
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Old Sep 05, 2005, 04:55 AM
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we need more peopl like you (matt), answer with actual knowledge and not just personal like or dislike. thnx
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Old Sep 05, 2005, 07:02 AM
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Quote:
Originally Posted by kryptoniteRxn
we need more peopl like you (matt), answer with actual knowledge and not just personal like or dislike. thnx
nice to hear

I might be biased too as i've only tried GY's and csm gyros.

The sensor on futuba's being very good quality is fact though.

They have less temperature drift and are less prone to vibration.


The fact that csm recommends you to warm up the gyro for 2 minutes for "competition usage" says alot to me !



BTW some very good threads about the workings of gyros have been posted here but i can't be bothered tp look them up as i've got alot on my mind lately. I'm applying for a secondary master education and i have an entrance exam tomorrow
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