Simviation Forums

I have a hawk that really fly awesome and is very stable. I also have a M339 display jet. however the problem is that the M339 nose keep on going up and down all the time when I fly with it. Somewhere there is a setting in Aircraft.cfg, that can be set to make it more stable. Can anybody help me.

I have changed this setting on another aircraft and it was then really nice and stable. I just cannot remember which one it was.

Anybody that can help me.

Thanks
JB

Just a stab...it sounds like it might be related to the moi entries in the aircraft.cfg:

[WEIGHT_AND_BALANCE]
reference_datum_position     =  0.0000, 0.0000, 0.0000       // (feet) distance from FlightSim Reference position: (1/4 chord, centerline, waterline)
empty_weight_CG_position=0.000000,0.000000,0.000000
max_number_of_stations=50
station_load.0=0.000000,0.000000,0.000000,0.000000
empty_weight=19840.000000
empty_weight_roll_MOI=325000.000000
empty_weight_pitch_MOI=400000.000000
empty_weight_yaw_MOI=350000.000000
empty_weight_coupled_MOI=0.000000
max_gross_weight=44090.000000

Try increasing the moi figures to get things more stable. You may want to check the numbers for the M339 against the Hawk to see what the differences are before forging ahead.

I have a hawk that really fly awesome and is very stable. I also have a M339 display jet. however the problem is that the M339 nose keep on going up and down all the time when I fly with it. Somewhere there is a setting in Aircraft.cfg, that can be set to make it more stable. Can anybody help me.

I have changed this setting on another aircraft and it was then really nice and stable. I just cannot remember which one it was.

Anybody that can help me.

Thanks
JB

This sounds like a weight and balance problem with the airplane selected choose the change fuel /payload icon then look to see where the center of gravity is at. From what you describe it sounds tail heavy you can try to inrease the weight in the forward most station. I think that would be ststion 0 but not 100% sure. If the aircraft has a center tank you can try moving this forward as well but this is tricky to say the least but what ever you decide BACK up before you touch anything 8-)

I have tried the following  change in the aircraft cfg.

wing_pos-apex_lon = 1.000
It worked on several aircraft.  Use trial and error settings to get the setting to work.
I also tried the reduction of elevator effectiveness from 1.0.  The older vintage aircraft have sloppy and slow controls.

Another way if your not too good at making the adjustment, try downloading another model of the same type and copying the weight sections from that and try it, or try copying the weight sections from a very similar aircraft.
Sometimes it works, I've done it and hit on it straight away, but not always, just a quick tip.