Trying to get to grips with the ATT autopilot mode
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Hi there,
I've purchased both Dukes and am loving them! One thing I'm struggling with is trim in general and the ATT AP mode specifically. Regarding trim, I've noticed that the plane will climb like a rocket even with the trim in a fairly nose-down attitude. I'm getting better at managing it, but I'm wondering if I'm missing something.
Regarding the ATT mode, I have bound AP Set Pitch (which I'm taking to be the equivalent of CWS) to one of my yoke buttons and am getting the hang of it, but one thing I'm really struggling with is the transition from ALT to ATT modes, particularly when descending. I'll be sitting in ALT nice and level, then change my altitude preselector to the desired altitude, change to ATT mode and the aircraft will shoot off to the moon. This is with trim previously having been in the green. I then have to fight the yoke to bring the pitch down to a reasonable VS then I can re-engage ATT mode and have a nice descent, the problem is that this really doesn't feel very controlled, and I'm sure my virtual passengers run out of sick bags in the back.
Does anyone have any tips for how to transition from level flying in ALT mode, to a nice gentle descent in ATT mode? The manual mentions something about uncommanded pitch changes while in GS mode, but nothing about the aircraft attempting to break the surly bonds of Earth.
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I think in ATT mode it's the "other" trim being used - the one with a green band is the normal elevator trim. As soon as you go to ATT then it's the AP pitch trim down on the back of the pedestal. If you climb in ATT then the trim will be set nose up to give you 120kts or whatever. You get to target and the AP levels off and goes to ALT hold. The AP pitch is not zero'd so as soon as you re-enter ATT to descend there is a hard pitch up commanded. For the moment I try to remember when I hit ALT mode to look down and zero the pitch - I'm going to cheat with a script in Spad to do it whenever I hit the ATT button.
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what I tend to do with it is hit att and then slowly move the pitch trim the little one on the autopilots, not the big one and it tends to descend nicely and smoothly.
Oh, I forgot when climbing AP off set the climb rate set hit att then AP should hold the pitch
what I do is takeoff and then get my climb rate sorted then hit ap att is on already and it holds the pitch give or take adust the little pitch trim to what I want then let the autopilot capture the attitude I have set Then if i want to say step up i hit att again it will not do anything till you move the little pitch trim up or down and then the plane will pitch up or down. the little pitch trim is the same as VS in any other autopilot just its very fine to control and no numbers but it works more or less the same. -
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@eker said in Trying to get to grips with the ATT autopilot mode:
(Or maybe the Alt sel panel r/h side?)
Yes, right side of altitude selector.
As per manual: "NOTE: A hidden clickspot on the right of the altitude selector can be used to adjust the
attitude holding pitch in lieu of using the pitch knob on the autopilot control panel." -
@ExcessionOCP These are my configs - first is the pitch rocker on the yoke which moves either trim wheel or AP pitch depending is AP is engaged or not. The second config is what happens when I hit the ATT mode - it sends the event to toggle mode and depending whether it's going on or off I zero the AP pitch wheel either before or after the send. I just tested that on a hop to Shannon and it was much better. It seemed to command an initial 500fpm down but that's preferable to a lurch up :-)
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I cant seem to get the plane to descend with AP on at all. Climb works fine and as described in the manual, but when I go to descend, lower the altitude selector, and press ATT, the only thing that happens is that it resets the altitude selector to my current altitude? I've also tried turning AP off, starting the descent, then pressing ATT and turning it back on, but it seems to do the same thing, resetting the preselector to the altitude I was already at. In the C414, I have to deactivate ALT mode manually before starting a descent, and I was hoping the same thing would work here, but clicking on ALT does not turn it off.
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