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Zoom › Futaba 401 and HS 50.......Subtrim?
10-22-2004 08:22 PM  13 years agoPost 1
greg

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Yorkville, IL

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A friend of mine is running a Futaba 401 gyro with the HS50 tail servo in his Shogun. To stop the servo from creeping he has added about 87% subtrim. Is this normal?

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10-22-2004 09:12 PM  13 years agoPost 2
rob_jones

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Perry, GA

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No. Subtrim should be "0" with a 401. If it's not, it will make it drift.

Blade 550X, T-Rex 450 Pro FBL

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10-22-2004 09:38 PM  13 years agoPost 3
craneyum

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warwickshire uk

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Tell your friend to take out the subtrim and adjust the tail pitch mechanically.
Nigel

Learn By Other Peoples Mistakes It Costs Less

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10-22-2004 09:40 PM  13 years agoPost 4
8AxleEd

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San Jose, CA

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You set the subtrim usually by looking to see that the servo arm, when the normal trim is at '0', to be at a 90 degree angle to the tail boom. A subtrim of 87 to do that is okay I guess.

At that point, put the gyro into "rate gyro" mode and lift off. Set the normal trim in this mode to make sure the model doesn't rotate left or right. When that is done, then switch the gyro to heading hold mode.

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10-22-2004 09:48 PM  13 years agoPost 5
8AxleEd

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San Jose, CA

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There is not a proper way to mechanically adjust the tail linkage correctly with an HS50 servo.

The best way to do it mechanically is to have a wheel that you can drill the holes into such that when the trims are '0', the line from the servo head screw to the control link hole is 90 degrees from the tail boom.

If you do it mechanically such that the servo head screw to control link hole is *not* 90 degrees, then the rate will go faster at one end than the other because of the sinusoidal properties of the servo head. It rotates in a circle, calculate the sin(x) and cos(x) through the circle and you will see it will pull faster in one direction than the other if the control link isn't 90 degrees from the tail boom.

There are no wheel heads for the HS50 servo. It is better to use the "sub trim" than to do it mechanically.

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10-22-2004 09:57 PM  13 years agoPost 6
greg

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Yorkville, IL

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I guess I am not being clear. When the heli is on the bench and the gyro is switched to HH the servo takes off in one direction (with no input from the transmitter). To stop this creeping (or movement by the servo) 87% subtrim has to be added to the rudder channel. Mechanically the gyro/servo is set up correctly. Would like some comments from people currently using the 401/HS50 combo in their shoguns. Thanks

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10-22-2004 10:32 PM  13 years agoPost 7
neTWork

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UK

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This behaviour with the 401 is normal from you description. It would be the same regardless of the servo type. The instructions for the 401 are not very clear, The info is in there but needs clarification.
I have sent you a PM regards proper setup.

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10-22-2004 10:40 PM  13 years agoPost 8
greg

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Yorkville, IL

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Thanks neTWork

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10-22-2004 10:48 PM  13 years agoPost 9
8AxleEd

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San Jose, CA

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When your friend setup his gyro, did he set the trim when in "rate gyro" mode *before* he switched to heading hold mode? Does he have revolution mixing turned off?

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10-22-2004 11:16 PM  13 years agoPost 10
Hunter69

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California

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Greg,

I know the problem you are having with the tail creeping. How is your layout of the gyro and speedcontrol? After I put together 5 or 6 shogun, I found out that if the speedcontrol is too close to the gyro, it cause the tail to driff to one side. First, try to move the speedcontrol far away from the gyro when you plug in the power. if it does no driff then rearange the setup. The second thing you should check is that Revo mixing is off, that will cause the gyro not to center the servo. Hope this helps.

Hung

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