Testing a gyro for tail holding ability...

[fiveoboy01]

What's the best way to test a gyro to see if the tail is holding well?

Preferably a maneuver that won't put me in a real screwed-up position if the tail blows out

[MarkWebber]

You could fly fast sideways in front of yourself. If it doesn't hold, you'll be in ff. Or be going backwards and be ready for it to weathervane.

[TMoore]

There are a number of tests that I do, initially. Flying sideways at speed is always good. Testing for max allowable gain is something that I do especially with the 601/611 gyros and the CSM's. Each gyro is a little different. If you run the gain up on the 601/611's too much you can overheat the tail servo, while on the CSM 630/720 you can run the gain up to 80-90% with the appropriate digital servo and still get extremely good holding power without heating up the servo. You can dial up the gain, do a full tail rotor command and let the TX stick snap back to center and watch for bounce. If the tail bounces reduce the overall gain. You will have to run the tail rotor channel EPA up high enough to get a decent piro rate to use this technique. Once you get the tail to quit bouncing, dial up the tail rotor chanel EPA to give you the tail piro rate you want.

If you can fly the machine backwards either upright or inverted do that for around 3-5 minutes solid and then take an IR thermometer and check the tail servo temps. The more aggressive the flying the better. The tail servo should be less than 140 degrees F. If the tail servo temps are too high reduce the overall gain and the tail rotor endpoint accordingly until the tail servo temps stabilize. With the 601/611 I usually see gains in the 45-50% range on the brain box with the piro rate on the tail fairly crisp running either VTR on the tail channel or 20% expo. Vertical tail slides while rolling the heli is a good test of holding power as well as doing a spiral dive with the heli in its side watching for any piro of the heli body.

Backwards hurricaines really test the gyro as well and you can usually hear the tail servo really working to keep the tail in alignment with the direction of flight. Generally speaking you want to run enough gain to do the job but no more than is absolutely necessary. Excess gain results in low tail servo life, especially frying the motor and wearing out the pot.

Depending on what gyro and tail servo you use, everyone's gain value will vary according to their flying taste and heli config. If the tail tends to wander a little during flight you may be giving tail rotor and not even know it, so having a little expo on the tail channel is a good thing for that.

TM

[nadavbarak]

Best Regards,
Nadav Barak.