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I have recently bought the twin otter and I cannot figure out the autopilot.

 

I have read all the relevant form posts.

 

My problem:  climb is fine in IAS mode, capturing the altitude via the alerter.  Alt comes on and I cruise fine.  But when time to descend, I get extreme pitch up if I turn odd the ALt or if I atttempt to use the pitch down on the center of yoke.  Of course I enter the lower altitude in the selector and press the alerter.  No matter how I try to descend with autopilot, I get violent pitch up.

 

Suggestions?

 

--Randall Griffin

 

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First, if you're cruising on ALT Hold, using the thumbwheel (centre console) to initiate a descent should cancel ALT Hold and begin descending. I think you do get an initial pitch up before the AP settles down, but I don't think it should be violent or extreme. (That said, I don't use the VC control as I have button programmed and I usually find myself holding down the button to get it to repeat, so you may want to try that. I will try it in the VC when I get FSX going tonight.)

 

Next thing is, if you turn off ALT Hold and descend, you select a lower altitude on the ALT Alerter knob and press the ALT ALERT button. If you press the ALT button instead, this tries to re-attain the altitude it was holding before, which will cause a major pitch up.

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12 hours ago, MarkHurst said:

I will try it in the VC when I get FSX going tonight.

 

I don't see any great departures using the VC control to make the adjustments. There is a noticeable kick up when using the thumbwheel to come off ALT Hold even in the downward direction, but it's not violent or extreme, which is how you described yours.

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Thanks for your replies. 

 

The most troubling thing is that when ready to descend from cruise, I press the ALT button to do a manual autopilot descent, I get a violent pitch up.  This is with the autopilot engaged, nav or heading hold on.  I should be able to enter lower altitude in the selecter, press the alerter on, disengage ALT, and engage thumbwheel to pitch down a few degrees.  When turning ALT off, I get major pitch up.  If I leave the ALT on and use thumbwheel to pitch down, Iagain I get what seems to me excessive pitch up.

 

I have my elevator and aileron axes directly mapped through FSUIPC, as well as the elevator trim through FSUIPC.  Would this make a difference?

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I think I found the problem.  It appears to be a tail-heavy loadout with the fuel planner.

 

I now load fuel and payload through fsx and avoid putting much if any weight in the rear of the plane.

 

--Randall Griffin

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I avoid the pitch up by (a) throttling back somewhat (b) waiting several seconds to let the AC slow 20 knots or so (c) engaging IAS mode, (d) adjusting throttle to maintain desired VS.

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