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Old 09-16-2008, 03:37 PM   #1
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Smile Need Help with Futaba GY401 gyro+9254 servo

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I just installed a GY401 gyro on my Century Hawk Pro and not sure if it works like it should .

When I switch it on HH or AVCS the light comes on solid red and when I input right rudder without the engine running the servo does not return to the center position same thing when I give it left. However it works well with HH off when i am hovering it seems to work properly. I am afraid to switch te Heading Hold on for fear that it will go Haywire

Any help would be welcome

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Old 09-16-2008, 04:08 PM   #2
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Re: Need Help with Futaba GY401 gyro+9254 servo

In HH the 401 isnt supposed to center!.So it sounds like its working *o)
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Old 09-16-2008, 09:28 PM   #3
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Re: Need Help with Futaba GY401 gyro+9254 servo

yes your servo is working correctly ..
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Old 10-03-2008, 01:08 PM   #4
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Re: Need Help with Futaba GY401 gyro+9254 servo

From what I understand , if you move your stick side to side 3 times then let it go, it will center.
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Old 10-03-2008, 03:01 PM   #5
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Re: Need Help with Futaba GY401 gyro+9254 servo

Yes, everything is working properly.

In HH mode, the gyro controlls the tail position, not the servo. Centering works in a different way.

Make sure you follow the setup instructions carefully regarding physical centering of the servo between HH and regular mode. After that just fly adn enjoy.
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Old 10-09-2008, 02:48 PM   #6
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Re: Need Help with Futaba GY401 gyro+9254 servo

This is normal HH operation. The reason is that you have called for a heading change and the gyro has not seen it yet, so will continue to try and get you there. In RATE mode you are not so much calling for a heading change as an angular RATE change. Once you release the stick the gyro loses that command, so recenters the servo.

A couple of pointers about HH gyros, not just the 401: Use the ATV pot to set the ultimate servo travel limit, NOT the adjustments in the transmitter. You want the travel limits in the Tx set to 100% for rudder Channel #4. Otherwise, If you tried to limit the servo travel in RATE with the Tx, in HH mode the gyro will overide those settings and continue to run the servo, possibly beyond mechanical limits. This can damage the mechanics and/or the servo.

Another procedural point to make is that you want your first flight tests to be in RATE mode, (even though you need the 401 in HH mode for power up to init properly). This will tell you if the servo is positioned correctly on the boom to cancel out heading changes.

You will probably have to do a few "Hops and Stops" to adjust the servo along the boom till all drift is gone. Only then can you use HH mode with the confidence it has equal authority in both directions and does not have to bias the rudder to keep the nose straight. Once you have it positioned correctly, go back and recheck the ATV setting to ensure it will not bind in either direction.

There is also the matter about warm up time. Most of the HH gyros need to be powered up in whatever environment you will fly for an average of 5 minutes to temp normalize and center. Once that's done you need to power the gyro down and back up again for the settings to engage. This will help prevent the dreaded "Gyro Drift" tendency.

Finally, a little trick to help cancel drift. If you absolutely cannot wait the 5 minutes, you can force the issue by quickly flipping the gyro switch from HH to RATE mode and back again for a few seconds, then end with the switch in HH mode. This will force the gyro to recenter, but the further into the 5 minute warmup the better it will work. The heli MUST also be sitting still just as in initial power up for it to initiate again.
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