Rainier Lamers
Well Known Member
Stein I'm quite confused on this. In my simple way of thinking both an autopilot and an AH have to know which way is down. And to do this they must rely on gyros (in the case of the Dynon EFIS and the TruTrak autopilot they're presumably solid state gyros). But all gyros, whether mechanical or solid state, accumulate error. So if the Trutrak does not have aiding how does it deal with this error.
Let me answer that as nobody is comming to the rescue.
In principle few autopilots know which way is up. They operate in the "relative" domain and do not need complex AHRS systems.
A typical horizontal autopilot may need only a single gyro aligned in the yaw axis. It does not need a good gyro and something as basic as a gyro used in a model helicopter (to stabilise the yaw) is quite good enough.
It's only purpose is to monitor left/right yaw and use airlerons or rudder (depending on what the servo controls) to counteract the yaw. If coupled to a GPS you can use this to allow a turn at a defined rate of turn to intercept and lock onto a heading.
A vertical autopilot does not need any servo at all - it just needs to know your current vertical rate of climb or sink, altitude and target altitude. Simpler systems don't even use the vertical rate.
Of course, autopilots like this cannot take over your aircraft and be commanded to fly some impressive aerobatics. Your aircraft needs to be in a stabilized attitude and if you ever get out of that you need to take control from the autopilot because if you don't, you'll need to buy a new plane soon.
Does this help ?
Rainier
CEO MGL Avionics