Autopilot IAS mode (pitch control)

[winsth]

Hi,

I'm currently programming a "standalone" addon for FS9. This time it's a SAAB340. The SAAB does not have an autothrottle so I need to find a way to make the autopilot pitch for airspeed in IAS-mode.

Does anyone have any leads for me? :)

I guess one alternative is to control the elevator trim from the addon, but I'm not that good at physics. I can't figure out the correct formulas to maintain a selected IAS and at the same time prevent a phugoid. I guess I have to take things like trim position, angular acceleration, vertical acceleration, delta-IAS etc. into consideration?

Please help! This is one of the last things to complete on my SAAB...

Fly safe!!

[winsth]

...cont'd...

Of course I'm also interested in comments/questions on this topic - not only a solution. Am I the only one finding the lack of "IAS by pitch" in MSFS annoying - or am I not looking hard enough?

There are a lot of aircraft "out there" (IRL) with the IAS-mode connected to the elevator - not to the throttles.

I can't belive I'm the only one interested in this mode so grab your pen... ehrr.. keyboard.. and share with this forum/topic what you know. :)

Have a great day!

And Peter... I truly admire your work!