Roll Axis Heading Hold Gyro
 

Does anyone have experience of using a gyro (Cortex Pro) in bank angle heading hold for regular flying (scale jets)?

My current scratch build (Blackburn Buccaneer) exhibits a very strong tendency to roll to wings level with the full-span flaperons drooped for landing. So much so, that it makes flying the landing pattern very untidy, as you are constantly fighting the plane during base and final turns. If I reduce and eliminate the flaperon droop this tendency to roll wings level goes away.

The thought had occurred to me to try switching the gyro roll axis to heading hold mode when the flaps are drooped, but wanted to see if there was any issues with it before trying it.


Thanks

Paul

Hi Paul,
I’ve tried just about every setting when flying in hold mode and didn’t like it. In your case I think it would be worse. Best/safest way to try it is to set up a bank and set the radio so you can switch banks easily.

How torsionally stiff are the wing panels now?

Dave,

The wings are extremely stiff - wing twist is not the issue. It files at high speed very smoothly and predictably.

This roll to level tendency only happens when the full-span flaperons are drooped at slow speed for landing. I've tried with the droop amount on a knob and with minimal droop it will sit in a turn, but with 10-15deg droop it will roll positively back to wings level and then remain wings level. It is not out of trim as it happens in both directions and it will maintain wings level with no stick input.

My only explanation so far is an aerodynamic roll moment due to sideslip - I have not yet tried holding in proverse rudder to see if that helps it stay in the bank.

I'd like to find a setting that avoids having to constantly fight it.

Paul

How much droop can you get maximum on the Flaperon? I guess it’s to do with the wing sweep back and inside wing catching the airflow.

My T-7 XXL is the same with gear down. I wants to level itself and constantly needs aileron input to keep it in the bank. Really annoying..

Danny,

Can you describe what you didn't like about heading hold, particularly in regard to roll/ bank angle hold? I can see pitch/ yaw heading hold resulting in some very different characteristics, but bank angle hold would appear to be relatively normal.


Paul

My primary complaint is the model does not respond “naturally” when any axis is in hold mode.
I’ve had similar issues with roll control when drooping the ailerons for additional camber on certain airplanes. Any additional downward aileron travel adds a lot of adverse yaw. In airplanes with highly swept wings this tends to cause it to want to roll out of the turn. The solution is to limit the “aileron” travel to only up and/or using a bit of rudder to counter the adverse yaw.

Do ensure that your heading hold function is not assigned to rudder in any flight mode.
My own experience with attitude hold on aileron using the Powerbox I gyro sat has been very positive, no problems at all, in fact very enjoyable, it hols the bank angle with extreme accuracy, a bit like Boeing,s CWS !

The iGyro and Cortex differ fundamentally in the way they handle hold mode. With the iGyro the gyro reverts to rate mode as soon as you move the stick away from center.

About the only thing hold mode on a Cortex is really good for his hovering and torque rolling, which it does fantastically but it's not for flying around.