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HomeAircraftHelicopterMain Discussion › Tail Rudd Servo
10-19-2009 05:00 PM  8 years agoPost 1
Madden

rrNovice

Windsor, Ct - US

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Hello ruff ryders. I have the hardest time trying to keep my heli from spending around. i have a t-rex 450xl. Sprektrum DX6i trans. GY401. HS-65HB Tail servo. When i thro up my heli i see that my tail starts moving to the right. It will sets center at first but the more i thro it moves. Any tips on what should i do? Thank You.

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10-19-2009 05:03 PM  8 years agoPost 2
krashtagain

rrKey Veteran

ohio

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Try running the gain up . But your best bet would be to rid of the 65 and put a JR 3400 or a Footaba 9650 or 9257 on the tail . Problem solved .

If you're not living on the edge you're just taking up space !

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10-19-2009 05:17 PM  8 years agoPost 3
Madden

rrNovice

Windsor, Ct - US

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Thank you. i had the JR3400 on here before and it work fine. i'm going to go get another one. Thanks agian for the tip.

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10-19-2009 05:54 PM  8 years agoPost 4
jschenck

rrProfessor

La Vista, NE.

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also take a look at headspeed. The Trex tail works much better with a higher head/tail speed.

BUT the number one issue I've seen with this size heli's is the little wire that pushes the tail control. I've solved 90% of 400 size tail problems by replacing that control rod with a CF tail rod , getting rid of the guides. That wire just bends too easily and too flexible.

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10-19-2009 06:46 PM  8 years agoPost 5
MartyH

rrProfessor

USA

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I think they have you covered on this one. Consider changing the tail servo and confirm your headspeed.

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10-19-2009 10:52 PM  8 years agoPost 6
zbird

rrNovice

newtonfalls ohio trumbull

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Tail Rudd Servo
I have a T-REX 450 SA with HS65HB servos,including tail. 401 gyro, I have no problems with it spinning out of control. In fact it locks in pretty good.

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10-20-2009 05:17 AM  8 years agoPost 7
dkshema

rrMaster

Cedar Rapids, IA

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Let's check the basics first. Trex 450 XL, HS65 HB for tail control. Not the sexiest servo on the block for a rudder, but it should at least hold the tail in place.

Sit the heli down with its nose to your right, tail to your left, tail rotor shaft sticking out towards you. The tail rotor should be turning COUNTER CLOCKWISE. If it isn't, your belt is twisted the wrong way. Fix it, and make sure you only have 1/4 twist in the belt.

If the TR is turning CCW, the blade on the right side of the TR shaft is moving UP, its leading edge is moving UP, and the control ball is on TOP. The blade on the left side of the TR shaft is going down. Leading edge DOWN, control ball DOWN. Fix anything that is not right.

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Right Rudder stick must tell the TR servo to PULL the TR control rod FORWARD. If it doesn't, REVERSE the RUDDER CHANNEL in your TX.

Pick the heli up, turn its nose to the LEFT while watching the TR servo output arm. When you turn the heli's nose to the LEFT, the gyro must tell the servo to PULL the TR control rod FORWARD. If it goes the other direction, flip the NOR/REV switch on the GYRO body.

Both the RUDDER stick AND the GYRO have to be set up correctly with regard to which way they move to control the tail.

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Initialize the GY401 in Heading Hold mode EVERY TIME you apply power. The red LED on the gyro body will be ON solid if you initialized properly. If it's blinking slowly, you didn't initialize in HH mode at power up and all bets are off on how well the gyro will work.

As an aside, make sure your transmitter is set up to select HH mode, set your throttle stick to low and low trim, and re-bind the receiver. This will insure that the gyro initializes in HH mode, and it will set your throttle fail-safe setting to kill the motor if the RX goes into fail-safe.

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Since you are using an HS65HB servo with the 401, make absolutely certain that the DS switch on your gyro is set to OFF unless you want to watch your servo go up in a cloud of smoke. If you have the DS switch ON with that HS65, there is a good chance you are in the process of killing the servo, or may have already killed it.

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This basic setup ought to at least get the darn thing to stay put when you throttle up.

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A few finer points once you get the gross setup correct. Initialize the gyro in HH mode, then switch over to normal/rate mode. The servo will follow the stick in this mode. Pick the distance between the center of the servo shaft and the center of the ball link so that with the gyro LIMIT pot set to 100%, rudder end-point/travel set to 100%, the servo moves AT LEAST +/- 45 degrees from neutral WITHOUT binding or stalling the servo at full left/right. The idea here is to get at least +/-45 degrees servo travel with the travel limit set to 100%, without coming up to a mechanical stop at full left or right. If the ball is too far out, you lose resolution of the servo, as it only has to move a small amount to move the pitch slider stop to stop. If the ball is too far out, you end up running low gains and a very small movement of the servo translates to very large movements at the tail. Move the ball inwards, you can run higher gains, and you get a lot more resolution out of the servo movement. The gyro is able to respond to yaw changes faster, and small servo movements don't translate to large tail excursions.

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If your DELAY setting on the gyro isn't set to ZERO, set it to ZERO.

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Make sure that any form of REVolution MIXing in your transmitter is disabled, or dialed to zero.

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Make sure that your gain control lead of the gyro is plugged into CHANNEL 5 of the RX, and that your transmitter is really controlling the gyro gain as you think it should.

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Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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