autopilot switchology

I am installing the GRT auto pilot. The instructions call for two mandatory switches and at least one optional switch.

The first mandatory switch for the panel is the autopilot on/off switch which sends power to the servos.

The second mandatory switch is an engage/disengage switch to activate the auto pilot. The instructions say to put this switch on tha panel but GRT advised me in an email that I could put this switch wherever I wanted it.

The optional switch is a disengage/CWS switch for the stick.

I am not sure why I would want both the engage/disengage switch and the disengage/CWS switch.

I am leaning toward two switches. The on/off switch on the panel and the engage/disengage switch on the stick. Does anyone know of a disadvantage in doing that? The optional disengage/CW switch just seems to be half of the mandatory engage/disengage switch and therefore redundant.

Am I missing something?

I think the switch on the stick would be a momentary disengage.

You have it right.

2 switches are required. One that supplies power to the servos and one that is a momentary contact switch to tell the EFIS to engage/disengage. You can mount these where you see fit.

The options are for a separate momentary switch on the stick or somewhere handy are available but I didn't use any. You can also use a separate switch for each axis, that is just configured on the EFIS.

Sounds to me like the you are correct - both momentary switches seem to do the same thing (are they wired in series or to 2 different pins?). I would have one momentary switch on the stick or close to the throttle to the CWS thing easy.

Pete

thanks for the input

penguin said:

Sounds to me like the you are correct - both momentary switches seem to do the same thing (are they wired in series or to 2 different pins?). I would have one momentary switch on the stick or close to the throttle to the CWS thing easy.

Pete

Click to expand...

Good point penguin, they are wired to separate pins.

I appreciate the input from all of you.

Here is the answer, and its for SAFETY and ergonomics.

To justify it let me tell a quick story of a Lancair IV I flew last weekend. It had the engage AP on the stick, on the Ray Allen grip, the little buttons that poke out, and the disengage was on the other.

We experienced sever control issues going through 700 feet and at no time was it apparent the AP was engaged.... one of us had bumped the switch

So here are my thoughts.......and exactly how we did ours and it works really well.

1. Circuit breaker swith for AP servo's
2. Panel mounted ENGAGE/DISENGAGE, you have to want to hit it to get it.
3. AP disengage either on the stick or on the panel near the throttle.

You really need all three. Do not skimp on this, if you do not agree with me, or understand why, you will one day