Autothrottle on Turboprops

[fruitnnut]

Someone help please!
When flying a prop such as Embraer EMB120, when IAS
is activated the throttle closes and speed decreases.
Anybody else had this problem?

[beefhole]

Hmm... I didn't think they had A/T on turboprops...

[WebbPA]

I concur with beefhole.

[Nexus]

"IAS activated" is probably the IAS hold.
fruitnnut, I don't know if you are aware that the IAS hold is not the same as an Autothrottle.
Yes, the aircraft can be set-up to hold a selected airspeed, but only during climbs and descents, when the aircraft controls the airspeed with elevator commands.

For example, your descending through 21.000 for 10.000. You have selected 210kts as the target airspeed. If you pull back on the power lever(s), the aircraft's nose will pitch down, aircraft is descending more rapidly to make up for the loss of thrust when you reduced the power

[WebbPA]

I learn something new every day.  Since it's almost midnight I will consider this my new fact for Tuesday.  Thanks.

(Edit - Oops - it's only 11:56 pm)

[Nexus]

Well, it's still by definition not an autothrottle, but yet a very handy feature

[JerryH]

fruitnnut,

Whether it's called autothrottle or speed hold, sometimes the turboprop .air file has an error.  Section 329 of the .air file should read "Speed hold=true" and "Mach hold=true".  You'll need the program AirEd to read the .air file and revise it if necessary.

Also, in the past year I've read two recommendations about the value of "autothrottle_max_rpm" in the (Autopilot) section of the aircraft.cfg file.  One said the value should be 2800; the other said 99999. I suggest you search the forum files at several sites to see if you can find the logic behind this. I don't remember.

The earlier explanation of speed hold by Nexus was very interesting, and I have no reason to disagree. However, I think the turboprops in FS are using the same autothrottle logic as the turbojets.

I don't often fly any of the turboprops. But, whenever I've tried to use speed hold on a turboprop, it either failed or didn't work very well.

I hope some of these suggestions help. I'm sure you can improve your current problem, but don't be surprised if you never get it the way you want it.

Regards,
JerryH