View Full Version : Autopilot newbie: Altitude hold

07-25-2007, 03:31 AM

I've just read Stein's article on autopilots in Kitplanes. As a complete novice in this area I'm wondering about the following:

Does 'Altitude Hold' also mean 'Wing Leveler'.

I can see that for some a basic 'straight and level' autopilot without the more advanced and expensive features like GPS Nav, GPSS etc would be a useful aid.

Just wondering...

Bob Axsom
07-25-2007, 05:14 AM
Altitude hold involves elevator control only. Tru Trak's Altrak altitude hold is what I eventually installed in our RV-6A after flying for approximately 1 year both IFR and VFR. The value of this change cannot be overstated. At the same time I added a Tru Trak Pictorial pilot (which requires a GPS serial input) which involves aileron control only. The value of this change cannot be overstated either.

Bob Axsom

07-25-2007, 07:31 AM
Would I be correct in assuming that you must have electric elevator trim to install an altitude hold AP? Likewise for a wing leveler?



07-25-2007, 07:34 AM
Neither are required. The upper scale servos will give a warning when it is requiring too much power to maintain level flight (you need to adjust trim). For trutrak, this is elevator only.

wing leveler is a function of the roll servo.

Sam Buchanan
07-25-2007, 11:26 AM
Lots of good info on the various autopilot vendor websites.

The Trio Avionics site even lets you download the installation and user manuals:


Some time browsing the manuals will answer most of the questions about what is needed and how it all works.

Bob Axsom
07-25-2007, 12:42 PM
My pitch trim is manual and the roll trim is the Van's spring tensioner lever for balancing fuel load. The latter I installed but never use since I keep the fuel load fairly well balanced - it does work fine however.

Bob Axsom

07-26-2007, 11:53 AM

Does 'Altitude Hold' also mean 'Wing Leveler'.

No, a wing leveler is a roll autopilot. You can buy them with or without altitude hold. The wing leveler controls an aileron servo, and the altitude hold controls an elevator servo.

07-26-2007, 12:09 PM
How much extra weight to you suffer when fitting a typical one or two-axis device?