Autopilot install

[jakej]

Just a few pointers to installing any autopilot system, this is what I do  -

1. level the aircraft, on ground, and check that skid ball is in centre - 'adjust' if necessary.

2. Go fly & check that skid ball is centred at normal cruise power settings - if not centred then use a rudder trim/tab of some sort to acheive this.

3.  IF aircraft is then one wing heavy (wants to turn) do what ever is needed, ie fit a trim tab (or crimp trailing edge of RV aileron) or other device, to get it to fly level.

4. Your plane should now fly "hands off", or almost   

Now the airframe is now 'rigged' to fly properly - then you should tune the autopilot to suit your plane - there can be differences between different builds of the same model due to friction & binding etc but the above will allow the a/pilot to work better/easier.

Sorry if this sounds like preaching, but I thought it may be good to state the basics as it doesn't appear to have been done recently & the above may be helpful to someone.

Jake J 

 

[mmarien]

Good advise Jake.

One thing I found about my Glasair II is that the AP pitch is rarely happy. The worst case is when the CG is about the middle - pilot and half fuel. Unless it's perfectly smooth air, the AP does a lot of complaining about trimming up or down, and the aircraft does a lot of oscillating about the altitude bug. The solution for me is to disengage the AP ALT and then re engage it. It saves a lot of trimming. When I disengage the AP I know right away if the pitch trim is out. In most cases it isn't. Re engaging the AP makes the TRIM warning disappear. It's much quicker then trying to trim out the TRIM warning. I believe Glasair II's probably have negative stability in pitch which causes the oscillations.

The exception is when the CG is aft heavy. Pitch is pretty steady then as the trim is against the spring and in extreme cases I'm flying on both wings. In my plane it's never the other way. I think I need a heavier engine.