Re: [Flightgear-devel] Negative-drag-bug in 20 aircraft models

[<And...@gm...>]

>>I'm currently maintaining the 737-300, and it has this issue as well but 
I 
>> wonder if a fix might make the model worse. 
>> Though it comes much closer to the Vr, it needs plenty of force on the 
elevator 
>> to rotate and lift off. And with that bug fixed I fear it will getting 
worse 
>> than now. 

I haven't tried what happens to each aircraft when the bug is fixed, 
but my guess is that the bug only is relevant to the propulsion of the 
model, 
because the property "aero/coefficient/CDde" doesn't rotate the aircraft, 
it only 
slows it down.
All the bug does is, instead of slowing the model down, it reacts like a 
little
boost rocket which magically accelerates the plane as soon as you pull back 
the yoke.
During takeoff-roll the elevator deflection is almost zero, so the bug 
doesn't
contribute to reaching Vr anyway.
When the bug really is needed to rotate the aircraft, then perhaps 
increasing the
elevator's area or angle, or increasing engine power, or checking the 
center of gravity is what's really needed here.

But I'm only guessing! I haven't verified this, I'm sure you know how to do 
your 
maintenance job! 

Andreas