Guys,
I had a strange experience today. I flew my Raptor in the morning for an entire tank, doing loops, rollls, and hovering and it was perfectly fine.

Then when I flew it after about 2 hours again, and attempted a loop, the tail sort of "kicked" on the back part - something i never experienced before.
Well the roll went OK , but on the stall turn, it again did - Was very nasty, and for a moment i thought that i was going to crash.

After that i did more hovering, and it was absolutely OK. I feel it was happening only on the stall turn  and roll.

Any ideas why it could happen ? I did check the belt tension and it wasnt too loose.

Gaurav

have u grounded the tail boom?

if not do so, every belt driven tail need to be grounded, if not sooner or later crash

Well this happened on a Raptor 50 Nitro Heli.  Not sure if we need to ground on this ?

ok i thought it was a helicopter?

Oops. my bad. Yes it was a heli.

  ok then u need to ground, some people have no problem but it is always there and a change of belt tension, new electronics , re routing a wire, a bit dryer day etc and if unlucky esd and restart of receiver or gyro freakout aso

best is always to ground even if u not having problem even tail case to boom if possible

Looks like its linked to RX battery (A123) issue. Will be posting a new thread for the same.

did u not feel that the tail had bad holding power and weak cyclic before the brown out, if it is the battery?

gaurav, do check the belt tension and missing teeth on the belt. its always better to troubleshoot a few areas before zeroing in.

I checked the belt tension immediately after landing , and it was OK. I did not feel any loss of holding power before the event.
Notably, when i got back, i charged the A123 battery and it took 360mah to get it to full charged Which is OK for a 1-1/2 tanks of sport flying.
BUT, when i cycled the battery, by discharging it, i got ONLY 500mah. So it leaves me to conclude that only 150 mah remained, and the voltage dropped at the time of peak load - pulling out of the loop and at the stall turn ?

I have a new A123 pack in it now, that cycles to full capacity, and will take it to the field in a couple of days.

150mah remaining!! phew....you should thank your stars for not attempting another flight with that. The tail would have more then kicked then.

It could also be an issue with the Gyro, as you mentioned it only happens when you are doing a roll or a loop.

Hellyflyer