Static pitch? or Contact point? or COG?

[Fnerg]

I found something curious about my Firefly model. I sent it to a friend to beta test and he is reporting back that the tail sinks into the pavement only after landing. But it doesn't do this on my computer. I was wondering what to tell him because I don't know if it's my model or his computer. How can one of these settings be fine on on computer and not on another? This only happens after the plane has been airborne and lands. Any ideas?

Thanks
Doug

 

[Milton Shupe]

I will take a look at this in the morning but I suspect it is teh contact point 0.

point.0= 1, -18.367, 0.000, -3.040, 1575, 0, 0.577, 20.000, 0.100, 0.030, 0.800, 6.000, 6.000, 0

You only show 1.2" of static compression (way too stiff) and the max to static ratio is only .03 (maybe .1" more available-essentially already fully compressed) where it is normally 2.0 to 2.5.

Typically nose and tail gear carry around 20% of the weight so static compression may only be 1-2". But, you should have at least 2-3 times that in max compression.

Not sure what you have animated but I would change it to be less stiff (so it will not break) and give it lots of extra possible compression on a hard landing.

Try this:

point.0= 1, -18.367, 0.000, -3.040, 1575, 0, 0.577, 20.000, 0.200, 2.00, 0.800, 6.000, 6.000, 0

Also, the main gear contact points are unequal in suspension setup. This will not work well. You need identical animations and contact point specs for them.

point.0= 1, -18.367, 0.000, -3.040, 1575, 0, 0.577, 20.000, 0.100, 0.030, 0.800, 6.000, 6.000, 0
point.1= 1, 1.023, -6.257, -7.979, 1575, 1, 1.370, 0.000, 0.390, 1.251, 0.800, 8.000, 7.000, 2
point.2= 1, 1.007, 6.180, -7.931, 1575, 2, 1.370, 0.000, 0.348, 1.250, 0.800, 7.000, 9.000, 3

I will do some testing now.

EDIT2: I made the following changes and tested without issues. More static compression for the tail wheel and a larger max to static ration so the gear is not so stiff.
Also changed the mains so that the gear coords are the same.
You really need to add some animated suspension (about 6") to the tail wheel (frames 100-200).

point.0= 1, -18.367, 0.000, -3.40, 1575, 0, 0.577, 20.000, 0.300, 2.030, 0.800, 6.000, 6.000, 0
point.1= 1, 1.023, -6.257, -7.979, 1575, 1, 1.370, 0.000, 0.390, 1.251, 0.800, 8.000, 7.000, 2
point.2= 1, 1.023, 6.257, -7.979, 1575, 2, 1.370, 0.000, 0.390, 1.251, 0.800, 7.000, 9.000, 3