On Tuesday 08 June 2004 21:31, Ampere K. Hardraade wrote:
> On June 8, 2004 02:20 pm, Durk Talsma wrote:
> > Blast, do we have a few millions to buy us another one? :-)
> >
> >
> > Seriously though, does this always happen at KLGB? I did a quick test
> > there yesterday, but couldn't see anything unusual.
> Yes, it does.  Sometimes, it stars to sink in less than a minute, while
> other times, you need to wait for about ten minutes.
> From my observation, this is due to the location of the aft landing gears
> and the position of center of gravity.  Then again, it may be related to
> trimming issues.  Anyway, to fix the former, all one have to do is move the
> landing gear toward the rear in the XML file.  As for the latter, I don't
> think the center of gravity is this much toward the back when the plane is
> on the ground.  If I recall correctly, MD-11's FMS moves the center of
> gravity toward the rear of the plane during liftoff by pumping fuel to the
> horizontal stabilizer.  Check out:
> http://www.geocities.com/Eureka/Concourse/7349/gestation.html for more
> details.
> > One thing I found though, is
> > that the MD11 doesn't do ground handling very well yet. ONe day, I need
> > to sit down and add a few contact points, because right now you can fly
> > it straight trough the earth's crust, without anything happening. Just
> > for a bit of fun: Try running the MD11 with idle throttle and zero speed.
> > Now raise the gears, and be prepared for a journey to the center of the
> > earth.
> I've tried that... it is crazy.
> On a serious note, I think FlightGear needs to have a more advance
> collision detection system.
> Regards,
> Ampere

I'm not so sure that simply moving the main gear backwards towards the rear of 
the a/c is a good solution to the problem of it tipping up backwards.  This 
really indicates that the mass distribution is wrong and will almost 
certainly have adverse consequences with regard to the flight behaviour.


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