RunRyder - Tail Hunting Issue

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Compass Knight 50 > Tail Hunting Issue

larren
Senior Heliman
Location: Malaysia

Hi again,

I got my Knight in the air again after the crash but unfortunately the tail hunting issue arise. It is hunting up to almost 90 degree tail right during the normal tail in hover. Adjust the gyro gain on my 502 but all attempts fails.

I did change the tail rotor shaft, tail plastic blade grip and the tail rotor center hub on the spot but all turn out to be negative. hunt.....hunt and hunt. I do noticed that the tail servo (9254) gets real HOT even 3 minutes of hunt hovering

Can someone advise? I can see that it is a common problem after crashes for a Knight 50 in my team.

Thanks,

Larr

01-18-2007 Over year old.

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JONW
Heliman
Location: Fontana, Ca

Make sure the push rod is really free, no bends and the guides are stright.

01-18-2007 Over year old.

Rodney
Veteran
Location: Tavares,Florida

There has to be an issue with binding or bad servo if the servo heats up that fast.

01-19-2007 Over year old.

larren
Senior Heliman
Location: Malaysia

Thanks guys. I have checked. The slider and push rod were moving freely.

Just an update. I might have finally found the tail haunting issue. The clutch bell is unround/not round after the crash. The impact may have deformed it. I am going to test fly my Knight 50 today to confirm.

Thanks,

Larr

The good condition clutch bell is on the right.

01-20-2007 Over year old.

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GScott
Key Veteran
Location: Lewis Center, OH

Is this a common issue with the Knight? I've crashed a number of helis but never bent/damaged a clutch bell. If this is normal then I will have to rethink the new 50 3D as this gives me pause about the quality of the rest of the heli.

01-21-2007 Over year old.

larren
Senior Heliman
Location: Malaysia

GScott,

I would not say it is a common issue as only 2 of us out 10 Knight 50s in my team has got this problem.

I am not commenting about Knight 3D but I would say Knight 50 is one of the best 50 size I ever try. It can perform what most 90 can.

Larr.

01-21-2007 Over year old.

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Vander
Senior Heliman
Location: St.Cloud,FL USA

I dont think that your going to find the clutch bell deformation as a common problem.Some crashes just have some really strange effects on certain parts of the heli...for instance if when the heli was crashed if the motor went to high throttle the excess heat could have caused the deformation.On another note i wouldnt worry too much about the quality of the Knight,they hold up very well to abuse.One friend of mine"Rodney" has a Knight that has been crashed 4 times and still hasnt replaced the mainshaft yet...very durable heli.

Vance

01-22-2007 Over year old.

kirk
Veteran
Location: Thornton, Colorado

larren

When you replace the tail parts did you make sure that you got the thrust bearing in the right way? If they are not in the right way it could cause binding in the tail at flying RPM. Just a thought... I have had tails act strange when the thrust bearing were in wrong

Kirk

01-22-2007 Over year old.

larren
Senior Heliman
Location: Malaysia

Vander,
I agree with you especially on the main shaft. I have had 6 crashes with out any bend on main shaft but I have just changed the main shaft. Just in case if there is a cracks which is not visible to our naked eye.

kirk,
Good info there. I think I must have posibly installed it the wrong way. Will check it out.

Thanks to all,

Larr

01-22-2007 Over year old.

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eric_b
Key Veteran
Location: Denver, CO, USA

If your 9254 is still running hot then I would worry about that. Tail servos can be erratic when near the end of their lifespan. Try swapping in another tail servo and see if the hunting disappears.

01-22-2007 Over year old.

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larren
Senior Heliman
Location: Malaysia

Thank you Eric.

I have tested hover this morning. It is still bad. Tails still haunts. It swings to and fro (not wag) at almost 90 degree.

Thing which I have done so far:-
- check if rudder push rod binds,
- check if tail slider binds,
- check if servo or gyro is reverse,
- check if tail blade too tight,
- check if drive belt is over turn,
- check if clutch bell is touching the clutch,
- check trust bearings at tail blade grip position
- check all cables connections if loose or poor contact(GY502)
- check battery nicad 4.8v 2400mah is 90% full with Hitec battery checker,
- check Rev Max is in digital mode with 9254 on the throttle

Parts which I have changed after the crash:-
- tail boom
- tail rotor hub
- tail plastic blade grip
- clutch
- clutch bell
- carbon main blade
- flybar rod
- tail vertical and horizontal fins
- rudder push rod

Need advise,

Thanks,

Larr

01-23-2007 Over year old.

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Roger Hamilton
Senior Heliman
Location: Surrey, England

I had a similar issue on a different model using a 502 gyro. Turned out it was the gyro sensor or amp that had a fault. Substitute the gyro if you can to eliminate this.

01-23-2007 Over year old.

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eric_b
Key Veteran
Location: Denver, CO, USA

If I were you, I would try a different gyro and tail servo. Perhaps you have a spare to try, or maybe a buddy can lend you one to test? If the tail is wagging (large angular deviations like you've described) and not necessarily "hunting" (which would be small deviations, like 5-15 degrees, usually at 2-3Hz) then I would bet that the gyro or tail servo is to blame.

Also, what is your headspeed when this is ocurring?

01-24-2007 Over year old.

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larren
Senior Heliman
Location: Malaysia

Finally the nightmare is over. Found the culprits which causes all this. The trust bearings on the tail blade grip. Replaced and all ok now.

The has been no report on this issue for the metal tail blade grip but already 3 cases reported in our team for those who uses plastic tail blade grip.

Larr.

01-29-2007 Over year old.

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Compass Knight 50 > Tail Hunting Issue

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