Tail Hunting during first take-off, then OK on next take-offs - why? - RC Groups
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Aug 30, 2004, 11:27 PM
Oz Micro Antenna Maker

Tail Hunting during first take-off, then OK on next take-offs - why?

After several weeks in this exciting and expensive hobby, I've learned to hover without hitting anything. But I have not quite figured out why my Dragonfly's tail over-reacts when I first take-off after plugging in the battery. It's like the gyro only knows full-power or no power. But after I leave it in the air for a couple of seconds and land (not easy when the tail is madly going left-right ), it's perfect. Subsequent take-offs hold the tail beautifully. Is it my Novatech ESC (el cheapo) with Auto Program Mode (APM), or is it the JR 410 Gyro (in HH mode) that's "learning"? Is this normal, or is there a way to get around this? I've tried teaching the helicopter full left and full right tail before I take-off, but this doesn't help. Oh yeah, I've got a DD tail.
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Aug 31, 2004, 12:53 AM
"Simplify, then add lightness"
What battery are you using? Have you tried reducing the gyro gain? It may just be that with a fully charged battery, the DD tail is too powerful for your gain setting, and settles down after the battery voltage drops a little.
Aug 31, 2004, 01:34 AM
Oz Micro Antenna Maker
I'm using 2S1P etec 1200. No, it's not the battery -- if I unplug and plug the battery, it'll tail wag on the first takeoff again. I have adjusted the gain from 0 to 100% -- no luck there either.
Sep 02, 2004, 07:39 AM
loving turbos
turbolover's Avatar
I have a similar problem. With my brushed Johnson 250 I arm the tail and it stays. Now with the brushless HiMaxx the tail start accelearting without the heli moving or the TX sending anything. Weird.
Sep 02, 2004, 11:58 PM
Oz Micro Antenna Maker
I just figured out why the tail wags on the first takeoff. The Auto Program Mode of the ESC learns the top end of its setting -- the range is really compressed after power-up, causing very quick changes in tail rpm. The only way to fully expand the range is if the Gyro gives a full-throttle command. The easiest way to do this is to pick up the heli after power-up and quickly swing the tail counter-clockwise.

The same applies for the main rotor ESC. I now plug in the battery with the throttle on full, then arm by going to zero throttle. The moral of the story is -- don't buy an ESC with fixed APM, it sucks!
Jan 16, 2008, 04:14 PM
Registered User
Ok, I know am in the wrong group but I believe I am dealing with the same issue. So what I am to understand upon power up you should excercise the remote the full length of the the throw to teach the esc. its range.


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