Gyro vs. elevator to flap mix?
 

If an airframe usually needs some elevator compensation to counteract flaps (i.e Habu 32 or Ultraflash), am I correct in assuming that you do not set this up when using a 3 axis gyro? In other words, no elevator mix with half or full flaps with a gyro? I am setting up a JR AXIS gyro, but I doubt gyro brand matters.

Thanks - Jeremy

From my (limited) experience with helis - No.

A gyro damps unwanted MOVEMENT, no movement, no compensating effect.

Sure, if your model rears up or down when you operate flaps a gyro would detect this movement &
fight it but once the model settled down & you would be left with an un-trimmed model.

Surely someone knows more about this than me? :confused:

Normally on a forum you would have 10 different opinions, all of them different! :rolleyes:

John.

you still need to trim the aircraft in all the configuration.

The AXIS setup instructions say to set all flight modes to a common trim. So if you mixed in elevator with flap, wouldn't the gyro see this effectively as stick input? And in which case it would not counteract any additional unwanted movement (same with Helis)?

I have got Gyros in all my jets now and they are all set up to fly with out a gyro, if the plane needs elevator compensation dial it in .
Mav

The gyros that we use for our models are in fact mostly setup with accelerometers.
They detect accelerations in all rotation axis and are able to compensate for this at given rate/ gain.
So consider that your gyro is excellent at compensating for sudden flight path deviations but not so good in compensating trends or very slow movements ( out of trim conditions, engine failures on a twin ).

Thanks for the help guys. Makes sense now.

Hi spike,

nobody has really explained why then the instructions say to have trims zeroed in each flight mode. Perhaps it relates to the gyro functioning in heading hold mode, if you are going to use that. With a heli gyro, if you are in HH mode and have trim dialled in, the gyro will interpret that as a desired constant rate tail deflection and it will rotate the tail constantly one way or another, depending on the direction of trim.

I have been trying to answer this question for some time.....

Use elevator compensation. You don't fly a plane around in heading hold mode.

The exception is the IGyro where it has hold mode that releases when you move the stick.

So the JR AXIS instructions also say it has heading hold and damping modes. Like some other posters, my experience is with heli gyros (both tail only and FBL). with the IGyro, how does it handle the elevator compensation when in heading mode? If the gyro interprets the elevator compensation as "move the stick", will it then not be stabilizing anymore, or just to a reduced effect?

Using a mix in the IGyro would make the gyro interpret it as a stick input and revert to rate mode

Perhaps the "common trim" the instructions speak of really means "straight and level" in all modes.

Heading hold gyros measure the signal width at boot up of the channels they control, that is the neutral (they don't assume 1520us because not every radio centers the same).

Anything after that measurement is presumed to be stick input. Change the trim and reboot the gyro or change the sub trim and reboot the gyro, then that becomes the new center measurement.

Problems arose when guys had different trims for different flight modes, boot the gyro in normal mode, take off and flip to idle 1, Idle 1 rudder trim is different and the gyro took it as a command to turn, the result was it looked to the pilot like the tail was "drifting" when in fact it was doing exactly what it was asked to do.

you don't have to trim when you use a gyro, I tend to turn off the gyro and trim the plane in all flight modes so that in the event the gyro fails and I have to shut it off I can and not have to deal with trimming at an awkward time

That not true at all but if it works for you keep at it.