p.h.

When flying fast backwards the csm 420 seems to have a job holding, it works
great flying normally, but when you need it going in reverse it lets me
down, should I have gone for the 560 so I could tinker with the parameters?

Any suggestions to correct it?

Regards
P.H.

beav

parameters?


I doubt it. The 560 AND the 420 work well for holding the tail in fast
backwards AND sideways flight, so it's more than likely NOT the gyro that's
at fault.

Check your tail rotor linkage front to back for ANY sign of friction or
slop, then, when you're sure there isn't any of either, check the setup of
the gyro and follow the manual to the letter, including suggested servo arm
lengths.


--
Beav


Please note my E-mail address is "beavis dot original at ntlworld dot com"
(with the obvious changes)

Beavisland now lives at
http://www.beavisoriginal.co.uk

douglas kaip

Can you tell us what the failure mode is?

Does is work in slower backwards flight then all of a sudden swing around as
you increase the speed? If so, then perhaps your tail blades are stalling.

Douglas

p.h.

The problem is a gradual one, once in the manoeuvre (fast backwards) the
tail will gradually swing round if not corrected, in slow or slowish
backwards then everything is fine, the model is only a few months old, so
wear in the tail mechanism is unlikely.

What is tail stalling?

Regards
P.H.

rhodesst

The tail rotor blades are airfoils (wings), just like the main rotor blades or
the wings of an airplane. It's possible to stall them, just like any other
airfoil.

Admittedly, on model model helicopters, it's a rare thing, but it can happen.
When it does, it's like there's no tail rotor there at all. I'm sure you can
visualize the outcome! ;-)

Fly Safe,
Steve R.

douglas kaip

Does it happen both directions, i.e. with torque and against torque, or in
just one direction, i.e. against torque?

If it is just happening in just the direction against torque I would chance
a guess that you just don't have enough yaw power to hold the tail in those
conditions. I suspect corrections to this would be higher head speed and /
or better tail blades ( this might mean longer, stiffer, wider, etc. I
will let the more experienced chime in here). ...

I guess I should actually read and understand what you say before I answer,
sorry. I assume when you say corrected that you mean with yaw input from
you it will again return to tail first flight. If that is the case, the
only WAGs that I currently have are 1) that you are changing the temperature
of the gyro a lot in FBF and inducing drift or 2) that your pushrod is
flexing under the strain.

Good Luck,

Douglas