Jim Wilson wrote:
> But I'm still hitting top at just over FL300. When I switch to the
> old weathercm to see if I can get the FL360 yasim won't initialize the
> 747 (tried dc3 and c172 and they both come up).
Sorry, I wasn't clear. Not the weathercm stuff -- YASim used to use
its own Atmosphere class before the environment was exported through
properties. The changes are back about 1-2 revisions in YASim.cxx.
But as David points out, setting the sea level pressure to 29.92 in
the preferences.xml file will work just as well.
> Any chance we're looking at another 2.95.2 math issue here...for both
> this bug and the differences in what we are seeing for flight
> performance?
> [...]
> The evidence for my "time" question is that after I hit a stall and
> drop down several thousand to recover full speed, that attainable
> altitude ceiling decreases by 5-10% or so.
I'm pretty sure we're seeing the same behavior here, actually. I'll
take a look at the reduction in climb performance, but I'm pretty sure
you're just being fooled by the slower speed (once you drop below 260
knots or so, it takes a *long* time to get back to 300, even if you
dive).
Here's my plan for testing 747 climb:
1.) Set autopilot to runway heading before takeoff, then disengage
with ^H. Verify that all trim controls are zero.
2.) Throttle up.
3.) Rotate at 190 knots. Gear up. Engage autopilot heading mode.
4.) Hold the nose at 15� until the aircraft reaches 250 kias.
5.) Hand fly the aircraft at 250 knots until 10k feet.
6.) Reduce back pressure on the yoke as the aircraft accelerates to
300-310 knots. Trim up very (!) slightly to hold this speed.
Use very small movements of the stick to damp the phugoid.
If the pressure fix is in, you should see 1000 fpm up through FL300,
and a service ceiling of about FL350-360. Fly it back down to sea
level and repeat, making sure the speeds are correct. It worked for
me a few times in succession.
There's still a bug in there; you can see it by the difference between
the solution target and actual performance at 36000 ft.
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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