Curtis L. Olson wrote:
> Andy, I think YASim has a bug. :-)
>
> YASim:   0.000000 AGL
>          4.946215 ASL
>          YASim is saying that the CG is exactly on the ground level
>          which is physically impossible.  It compensates by saying the
>          ground level is 4.9' above the real ground level.  I think
>          this is a bug, but it probably looks ok visually.

Believe it or not, this was actually intended as a feature. :)

The MSL value that YASim supplies is the position of the nose of the
aircraft, and agrees with the other FDMs and with reality.  But the
AGL is computed as the distance from the nearest gear tip to the
ground.  This was done for things like radar altimeters and jetliner
annunciators -- the altitude of the 747 on the runway is something
like 100ft, which isn't right if what you're trying to drive is a
touchdown annunciation.

I wasn't aware that anything was interpreting this as a "hard"
position anywhere.  An AGL value seemed like a "soft", computed number
that I could fudge at will.

Fixing this is trivial (it involves removing a few lines of code, and
adding none).  But what is the desired behavior?  To me, it would seem
nice to have a number like the AGL value YASim reports -- something
that instruments can interpreted as a height of the wheels above the
runway.

Andy

-- 
Andrew J. Ross                NextBus Information Systems
Senior Software Engineer      Emeryville, CA
[EMAIL PROTECTED]              http://www.nextbus.com
"Men go crazy in conflagrations.  They only get better one by one."
 - Sting (misquoted)


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