pitch oscillation problem

[George7]

I recently downloaded file l-17 -c and cannot get the Navion to trim. I have even applied full DOWN trim without success. I suspect the problem has to do with pitch MOI; but am not sure of the change necessary.

[Staiduk]

I'll get it myself and take a look at it.

[Romflyer]

Auto-pilot??

[Staiduk]

George, I couldn't find the aircraft you're speaking about. Can you provide more specific information please?

[George7]

Thanks for your interest!

The file is for a North American Navion - military version l-17a-b.

There is no autopilot involved.

[Staiduk]

Thanks for your interest!

The file is for a North American Navion - military version l-17a-b.

There is no autopilot involved.

The one on Avsim? I'll D/L that one and take a look.

[Staiduk]

Wups - probably not that one. That's a Ryan Navion and when I tried it it flies steady as a rock. I'll try again.

[dave3cu]

Staiduk,

I think he may be referring to Tim Conrad's, 'L-17B-C.zip', at Sim-Outhouse.

http://www.fswarbirds.com/index.php?page=downloadsbak&FileUploadName=Piglet

George,

I tried this one out and found it trimmed out nicely.

Dave

[commoner]

...mmm....I also downloaded this file and couldn't get the nose down even with full down trim and the stick fully forward :-?

I tried just moving the CofG forward with some success but not sure if that was the problem or not..........give it a whirl...at least it is now flyable without any apparent problems.........commoner

Just change this section of the aircraft.cfg to look like this....or any other number you find works.

reference_datum_position = 0, 0, 0
empty_weight_CG_position

[dave3cu]

Hmmmm, I had no problem trimming Tim's L-17, although the trim indicator had to be slightly 'nose down'.

One thing I did note: Although there is no Autopilot, the autopilot is available in the aircraft.cfg file (autopilot_available = 1). You might try cycling the ap on/off key (Z) 'till you hear the 'ap off' signal, in case the ap is on due to errant Z or carry-over setting. Or edit to; autopilot_available = 0

Dave

[Hagar]

Hmmmm, I had no problem trimming Tim's L-17, although the trim indicator had to be slightly 'nose down'.

Just for the record I had no problems either.

[Staiduk]

Staiduk,

I think he may be referring to Tim Conrad's, 'L-17B-C.zip', at Sim-Outhouse.

http://www.fswarbirds.com/index.php?page=downloadsbak&FileUploadName=Piglet

George,

I tried this one out and found it trimmed out nicely.

Dave

Thanks for the link, Dave.

Well; I checked it out pretty thoroughly. I couldn't find any oscillations at all in a variety of flight conditions; from low-level cruise to screaming powerdive.

Whatever the question, you've gotta check it in a screaming powerdive.  ;D

It's a nice airplane, innit? The graphics are a bit blocky and the .cfg definitely needs work, but it's way better than I could ever do - and it's a nice looking little thing too.

Judging from my tests; I think Dave is bang-on in his assessment. I think it's the latent autopilot that's causing you problems, George. As he said; just go into the CFG and change the autopilot value to 0, and you'll be fine. (I think. Sometimes the autopilot works even with that number at zero. Dunno why - it just does.)

Also as Dave suggests, when you're flying, George; as soon as you feel the nose-up issue you've described, hit the 'Z' key. If the model's latent autopilot is engaged, that will turn it off. You'll hear a high-pitched alarm tone confirming this.

Hope this helps.