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Design Forum >> Flight Dynamics >> Nose Down Attitude
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Message started by PutPut on 22nd Oct, 2011 at 11:46pm

Title: Nose Down Attitude
Post by PutPut on 22nd Oct, 2011 at 11:46pm
I am currently modeling the Piper PA-12 Super Cruiser.  The FDE is based on the default Piper J-3.   This gives it a decided nose down attitude when trimmed for level flight.  The real PA-12's that I have seen don't do this.  What parameters in the .cfg and or .air file control this?  I have fooled with wing and horizontal stab incidence with no success.

Thanks,  Paul 

Title: Re: Nose Down Attitude
Post by jimslost on 23rd Oct, 2011 at 1:25am
I had an answer to this question on my old computer, which, unfortunately, fried itself in June.  I'll take a look at my paper notes tomorrow and see what I can find there.

In the meantime, I would recommend using a different airplane's .cfg and .air files for your starting point.  The J-3 flew with a fairly pronounced nose down attitude at cruising speed, especially if you found one that would go faster than 75 mph indicated (which was somewhat rare; the fastest J-3 I ever flew only cruised at 82 indicated). The Super Cruiser was noticeably faster than the J-3, and you are probably seeing exactly what would happen if you pushed the J-3 that fast.

It would be a lot of work changing all the other parameters, but you have my blessing to use the files from my Curtiss Robin as a starting point.  It's freeware, and if you can't find it at Avsim or Sim-Outhouse, I can send you the files if you're interested.

jim

Title: Re: Nose Down Attitude
Post by PutPut on 23rd Oct, 2011 at 2:24pm
Thanks for the kind offer.  However, I was able to achieve the desired results by substituting the Cessna 172 .air file with a few changes to keep the engine running at idle.  I had really forgotten how nose down the J-3 was, and I had several hours in one years ago.

Paul

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