I've just got going a 23cc Petrol Kalt Helicopter and I am using flat bottom blades (non-Symmetrical).
When ever the collective is in the negitive pitch range it seems that with increasing head speed, the pitch becomes even greater negitive as if it is feeding back.
So much so that if I idle up in slightly negitive pitch, the collective pitch servo does not have enough grunt to bring it positive??
If I start with slightly positive pitch, then it is fine and i have complete control over the collective??

Any ideas welcome!!!!

check the mixing arms for loose connections. Flat bottoms don't do that normally. I fly them more than not on my gassers.

Got enough servo?

thats exactly what I was wondering, what kind of servo is it? I'm sure it would have to be pretty powerful to run the collective on a gaser.

There is little or no slop on the mixing arms anywhere. The servo is a futaba 3003, nothing flash but they have done the job on similar size helis before?
I've now noticed that with increasing head speed even in positive pitch, it will return to negative untill the power is off again???

Those servos don't have enough to handle gasser size stuff, minimum 9202.

yea, that servo shouldn't be used on the collective of a 30 size helicopter. You should try a servo with more torque.

It was the blades in the end.
I changed for some good solid glass semi-semetrical blades and it's flys beautifully... even with the futaba 3003 servo on collective??
I have used these servos with similar sized heli's in the past and had no problems. Is there anything I need to beware of using such a standard servo??

servo failure. A good servo costs $50, how much is your investment in your heli?

I'm assuming that the heli in question is a Kalk Alpha XII (called the Alpha 60), I've got the Kalt Baron XII (called the Baron 60) which is the same as the Alpha but it's a glow engine design not gasser... the collective linkage system has leverage built in to the design for use with a standard servo, they didn't have all these high torque versions to choose from many yrs ago when these helis were common place. mine is 10+ yrs old and has many thousands of hours on it and has always used a standard servo on all controls but the tail (high speed upgrade about 5 yrs ago, but still uses a JR NEJ 120 ball bearing gyro) and it's never had any problems with under torqued servo restrictions. granted this heli is for precision flight not aggressive 3D but it does fly better then even my X-Cell Pro Graphite.

kc

Helijack Date 4/11/2006 1:18:25 PM
"Servo failure. A good servo costs $50, how much is your investment in your heli?

The investment in my heli was $200 NZ Dollars for 2 helis, this one "Kalt Baron" and another "Kalt Cyclone"
Not a great deal but still don't want them in pieces I guess!


Thanks "KC36330", I didn't think it was nessasary to have a high torque servo there. You are right my one is a 10-15 year old machine with a 23cc Petrol engine.

Maybe i'll invest in some slightly better servos, I don't know. Seems to be working ok at the mo and i've never had a Futaba 3003 fail on me yet.[quote]ORIGINAL: KC36330