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Tail and gyro problems, advice needed

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Tail and gyro problems, advice needed

Old 06-29-2006, 02:27 PM
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HR Titan
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Default Tail and gyro problems, advice needed

Hello all,
I've been doing the linkage adjustments on my Century hawk pro in the middle of no man's land in the middle east...no experts closer than 10,000miles away... so far i've been successful in setting up collective, throttle, elevator and aileron linkages.
As a note, i'm using an airtronics RD6000 along with its stock servos, the rudder however has a hitek 525b hi-speed servo. the gyro i'm using is a JR 412T heading-hold gyro (set at heading hold "off" for the sake of adjustments.
the tail servo ball that connects to the linkage is set a 90degrees and is pretty well centered, it allows full servo movement left and right, moving the tail rotor angle accordingly. at the center position the tail rotor angle is centered as well.
The tail servo is connected to the gyro, and the gyro is connected to the "rudder" spot on the receiver.
When all systems are on, if the helicopter is manually rotated in either direction, i can see the tail servo moving the tail rotor angle to "counter" the rotation.
So far so good.
When i try to test the helicopter, turn the engine on, install the training kit and all:
When the heli is about to lift off from the groud, if i move the rudder input slightly to the left, and then quickly move the rudder stick back to center position, the heli keeps spinning to the left. I have a feeling the gyro is not doing its job correctly. The gain is set correctly as specified in the gyro manual.
This test has been realized when throttle is minimal, only enough to get the heli about to lift-off, maybe an inch off the ground or so.
Any ideas on what might be causing this endless spin?
Thanks a lot for your help people!
Old 06-29-2006, 04:21 PM
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syclic
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Default RE: Tail and gyro problems, advice needed

Sounds like the gyro and/or rudder is reversed.
Old 06-29-2006, 06:50 PM
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HR Titan
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Default RE: Tail and gyro problems, advice needed

Looks like the servo is alright as well as the gyro, when i spin the heli manually while holding it from the upper main rotor the gyro reacts well and moves the rudder servo in the right direction... it keepts the tail servo at its endpoint until the heli stops spinning and then centers again, so i think the channels are fine.... maybe lowering the throttle while in mid air causes the tail to loose power and fail to do its job? not sure...
Old 06-30-2006, 03:59 PM
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grouper1
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Default RE: Tail and gyro problems, advice needed

SOUNDS LIKE YOU NEED TO SWITCH THE GYRO "REVERSE", NOT THE SERVO. IF IT SPINS OUT OF CONTROL WITH ANY RUDDER CAMMAND, THE GYRO IS INCORRECT. IT SHOULD HAVE A REVERSE SWITCH. SWITCH THE DIRECTION AND ATTEMPT TO HOVER A COUPLE INCHES OFF THE GROUND. YOU'LL KNOW IF IT'S RIGHT OR NOT.

GOOD LUCK WITH YOU PRO HAWK. I WAS VERY UNHAPPY WITH THE QUALITY AND DESIGN. PLUS, YOU NEED TO DISASEMBLE HALF THE BIRD JUST TO REMOVE THE ENGINE.

NEXT BIRD, TRY THE JR "VENTURE CP". WHAT A GREAT MACHINE!
Old 07-01-2006, 08:54 AM
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lawnhawk
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Default RE: Tail and gyro problems, advice needed

The problem here is nothing to do with design or quality of the copter. As long as the tail rotor is able to move, the gyro should be able to do its job.

HR, if the spin is real fast, then yes I would agree the gyro needs to be reversed.

Also, you mentioned the tail rotor is centered when the servo is at 90 degrees. What exactly is 'centered?' The tail blades should not be at zero pitch. At 90 degree servo, the blades should be at the proper pitch to counter the torque.

The Hawk is a GREAT copter. I have lost count of the gallons of fuel I put through mine with only minimal maintenance.
Old 07-03-2006, 12:22 AM
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rf_reggie
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Default RE: Tail and gyro problems, advice needed

I will try to help:

1. You must insure there is no binding in the linkage, it must be smooth as silk. remove the servo horn with the control rod attached and check full travel. Your problem may be that your ball links from the slider to the grips are too tight.
2. Adjust control rod length so when the servo is centered, the tail blades have about 10° pitch nose right (with about 1600 head speed). This is a ballpark setting.
3. Turn revo-mix OFF, rudder trim centered, Gyro in normal, gain very low (<10)
4. run it up very slowly and adjust the control rod length as required to keep the nose some what straight when heli begins to lift.

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