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HomeAircraftHelicopterMain Discussion › Installing GY401
12-15-2003 02:00 PM  14 years agoPost 1
Knud Pedersen

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Denmark - Europe

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I have just got my new Futaba Gyro GY401 + digital servo

I have installed whit my “old analogue servo”, later I will install it whit the digital servo. Then I hope I can see/feel the difference….

May tail isn’t holding in heading hold….
I have the flightsmode:
- Norm.mode = Starting the heli, light/fun hover (Gyro Norm-mode)
- Idleup1 = hover (Gyro HH-mode)
- Idleup2 =acrobatic (Gyro Norm-mode
(In time I think I change all flightsmode to Gyro HH-mode)

This I how I have make the installation:
1. I have turned off all revomix, trim, subtrim ect.
2. I have 100% ATV on the tailservo, the servo in center, servohorn 90° to the pushrod
3. I have installed the tail-pushrod so that there are now bindings.
4. I then turn on the transmitter, then shift to Idelup1 (gyro HH-mode)
5. Then I turn on the heli, wait for aproxx. 3 sec. then the red light, on the gyro is red = HH-mode
6. On the Transmitter, I return to norm.flightmode (gyro Norm-mode)
7. Started the engine
8. Hover the heli, in Norm.flight mode
9. I then adjust the tail-pushrod + transmitter Trim, so that the heli is heading (not turning) in hover
10. Land the heli, copy the Trim % to the other Flightmode
11. then I go flying….BUT the tail isent holding, wenn I Hover I Idelup1?????

Questions A:
Must I trim the transmitter Trim, in ALL flightsmode, whit the gyro I Norm-mode??????
(Note: I have differenced engine-RPM ,,,,)
Questions B:
What about weather condition??? more wind,, less wind ?????
Questions C:
When the servo is in center, the servohorn must be 90° to the pushrod, and the heli must heading (not turning). Then there is more movement left to the one side, but nothing left to the other side….That means: I do not use all tail-movement (tailpitch)….Is that okay???

Knud Pedersen

12-15-2003 02:10 PM  14 years agoPost 2


New England

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you're making this very complicated.

you cannot have any trim when in HH
mode. make any adjustment by
changing the length of the pushrod.

12-15-2003 02:10 PM  14 years agoPost 3
garry keogh


Wicklow, Ireland

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Trim may be your problem
Hi Knud,
I am guessing that you have it mostly right. I have a 401 in my 30V2 raptor and don't use standard mode at the moment. Until I have enough time to setup the revo mix and trim offsets properly I won't even try.
If you use normal mode and find that you need any trim at all, then once you switch to HH (AVCS) mode the helicopter will yaw. When you power up in HH mode like you describe, the gyro samples the stick center position and the heli in a stationary (no yaw) position and this is what it will replicate for HH mode in flight. Should you add any trim while you are flying in normal mode, then switch back to HH, the gyro will interpret this trim as a yaw request and it WILL YAW!

Have you tried switching on as you describe and flying in HH mode without ever switching into normal mode and trimming. I am guessing that the heli will hold well?

Stupid question I know but, did you set the gyro to normal servo mode? I think mine came in digital servo mode as it came with the 9253.

Hope you get sorted, I am very happy with my 401 so far!

12-15-2003 03:15 PM  14 years agoPost 4


Bonnie Scotland

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There is a bit in the manual about flicking from normal to HH a few times in quick succession to tell HH the new neutral position. Next time you've got the trim right in normal mode, land the model, carry out the above procedure and then see how it goes. Alternatively shut the whole thing down. When you next switch on (in HH mode) the new in trim centre point will be memorised.


12-15-2003 06:26 PM  14 years agoPost 5
Knud Pedersen

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Denmark - Europe

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Hallo agian,,,

My "old analogservo" is a Graupner C4835,,,5 month old,,,,
My Transmitter is a Futaba FC28 ver.3
My heli is a standard X-cell 60 (it is great)

Perhaps I school try to explain the TRIM again:

In the Gy401 manual under ”Flight adjustment, Rudder neutral positionadjustment” there is standing:
* Turn on Transmitter, set Gyro in HH-mode, turn on helicopter, wait for approx. 3 sec.
* Switch Tx to Gyro normal mode
* Lift off the helicopter and hover, adjust the rudder neutral position with the transmitter TRIM
lever (Larger rudder neutral position deviation may require readjustment of the fuselage linkage)

Under “AVCS side adjustment”:
* Set rudder trimposition for all flight conditions which use the AVAC mode to the trim position
flight-adjusted in the normale mode.

That means I have (in the first test-flight):
* started the HELI with the TX in GYRO-HH-mode
* then switch the TX to Gyro-norm-mode
* lift of the helicopter, adjust the linkage
* BUT the minimum turn I can make on the linkage is ½ turn, and thereby the heli isn’t heading.
Therefore I give it a little trim on the Tx trim lever.
* Then I land the heli, copy the Tx-trim to all the other flight conditions (I got I Futaba FC28,here
you have a trim Memo,, where you can copy the Trim into other flight conditions, and/or
memorized the Trim, and then afterwards move back the trim-lever to center).
* Then I switch the TX to HH-mode, turn the heli off and on.
* Then should the Gyro memorized the “new” rudder center position.

I cant remember ob I did center the rudderhorn/linkage without the gyro connected…. I may tried the setup ones more

Wingtip, you wrote:
when its test flown first hover in normal and adjust the ROD length to achieve proper rudder trim... once this is done then flip to hh and you can trim with the radio trims...

Now I am totally confused ,,,the above, ,,,is that the same as in the manual????

New questions:
It was my attention to start with gyro-norm-mode for Idelup2 (acrobatic, NOT 3d,,,,I have only just learned loop, roll,,,J rookieJ,,,I think I like the weathervane effect) But my dreams is full blown 3D,,,so perhaps I should go for the HH-mode,,,,??? I do on the realflightJ
BUT if I use gyro-norm-mode,,,,then does I also need REVO mix,,,right????

12-15-2003 06:54 PM  14 years agoPost 6


Morgan Hill, CA (near San Jose)

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You wrote that the manual says to " * Turn on Transmitter, set Gyro in HH-mode, turn on helicopter, wait for approx. 3 sec.
* Switch Tx to Gyro normal mode"

I thought the 401 needed to be powered up with the transmitter set to NORMAL or RATE mode. Mine wouldn't work if I powered it up in HH mode. The light would blink, instead of being solid.

So I ALWAYS set the Xmitter switch to RATE mode, then just when I was about to increase throttle to take off, I would switch to HH.

Does you LED become a SOLID color on powerup? If it keeps blinking after powerup, something is wrong.


12-15-2003 07:12 PM  14 years agoPost 7
Knud Pedersen

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Denmark - Europe

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yes, the LED become a SOLID color on powerup (in HH-mode)


12-15-2003 07:13 PM  14 years agoPost 8


New England

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you would be wrong.

the 401 requires HH mode during startup.

12-17-2003 08:29 PM  14 years agoPost 9
Knud Pedersen

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Denmark - Europe

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Haven’t try your setup’s yet,,,,bad weather in Denmark, and dark at four o’clock,,,so I must wait until the weekend/holidays……

Wingtip you wrote:
When its test flow first hover in normal and adjust the ROD-length to achieve proper rudder trim,,,,once this is done then flip to HH-mode and then you can trim the radio trims…..

Do you mean test hover in normal gyromode or normal flightmode???
Flip to HH-mode??? Do you mean flip to HH-mode in the same flightmode, or flip to a flightmode with Gyro H-mode???

How much gain????

My Gyrogains in the flightsmode are:
Flight mode Normal = 60% Gyro norn.mode
Idelup1 = 50 % Gyro HH-mode
Idel up = 50 % Gyro norn.mode

I have bin told that the gyrogain schold be as low as possible, so that the servo isn’t damaged, and save batteripower…..the GY601 as low as 38%….

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