Pushback problems

[Noble.]

I'm currently having an issue pushing back the PMDG MD-11. The main issue is that when the push is complete and I'm asked to set the parking brake, I get flung backwards quite violently (and sometimes 50 feet up into the air). Also, during the push the aircraft rolls to the left and right very slightly and the default FSX head movements go quite crazy. I'm sure it must be a configuration error with contact points, but the first couple of times it worked perfectly (and I hadn't changed anything). I have also tried doing a complete reinstall, which hasn't fixed the issue. I've tried this at both a default FSX scenery and an addon scenery - it happens at both. With the NGX, I don't get "flung" but when I'm asked to set the parking brake, the aircraft does drop a good 2-3 feet.

Thanks.

[virtuali]

I'm sure it must be a configuration error with contact points, but the first couple of times it worked perfectly (and I hadn't changed anything).

It's possible the PMDG MD-11 has a peculiar/unusual contact points configuration because, some users reported also problems with it when landing, such as crashing into invisible objects, as if the contact points weren't exactly were they are supposed to be.

It's not really something we can fix from GSX, the Pushback routine is the same for any airplane, and doesn't cause any problems with all the other airplanes out there.

It's possible the scenery used has something to do with this too, I've just tried a Pushback with the PMDG MD-11 from A42 at Zurich, and it went very smoothly, with no bumps or head shake.

[Noble.]

I'm sure it must be a configuration error with contact points, but the first couple of times it worked perfectly (and I hadn't changed anything).

It's possible the PMDG MD-11 has a peculiar/unusual contact points configuration because, some users reported also problems with it when landing, such as crashing into invisible objects, as if the contact points weren't exactly were they are supposed to be.

It's not really something we can fix from GSX, the Pushback routine is the same for any airplane, and doesn't cause any problems with all the other airplanes out there.

It's possible the scenery used has something to do with this too, I've just tried a Pushback with the PMDG MD-11 from A42 at Zurich, and it went very smoothly, with no bumps or head shake.

Could you post what you've got for Contact Points in the aircraft.cfg, and what the gsx.cfg should be for the PMDG MD-11? I might also be a case of weight being an issue. I tested all the pushbacks at just below MTOW.

[virtuali]

Could you post what you've got for Contact Points in the aircraft.cfg

[contact_points]
max_number_of_points = 8
point.0 = 1,  -28.838,   0.000, -17.330, 1181.1, 0, 1.67, 70, 1.10, 0.8, 0.725,  7.1,  7.3, 0, 260, 300
point.1 = 1, -113.443,   0.000, -17.350, 1574.8, 0, 2.25,  0, 1.10, 0.9, 0.747,  8.5,  8.7, 1, 260, 300
point.2 = 1, -113.443, -17.500, -17.350, 1574.8, 1, 2.25,  0, 1.10, 0.9, 0.747,  8.8,  8.9, 2, 260, 300
point.3 = 1, -113.443,  17.500, -17.350, 1574.8, 2, 2.25,  0, 1.10, 0.9, 0.747,  9.0,  9.1, 3, 260, 300

point.4 = 2,   -2.862,  0.000,   -3.716, 1574.8, 0, 0.0,  0, 0.00, 0.0, 0.000, 0, 0, 4, 0, 0
point.5 = 2, -165.988,  0.000,   -5.661, 1574.8, 0, 0.0,  0, 0.00, 0.0, 0.000, 0, 0, 9, 0, 0
point.6 = 2, -145.983, -86.091,  -4.097, 1574.8, 0, 0.0,  0, 0.00, 0.0, 0.000, 0, 0, 5, 0, 0
point.7 = 2, -145.983,  86.091,  -4.097, 1574.8, 0, 0.0,  0, 0.00, 0.0, 0.000, 0, 0, 6, 0, 0

static_pitch = -0.27
static_cg_height = 13.985
gear_system_type = 0   


My installed version is the retail CD from Aerosoft, I don't know exactly which version is, don't remember having installed any patches.

and what the gsx.cfg should be for the PMDG MD-11?

You don't need one, because it's a natively supported airplane. However, even if you had one with a wrong pushback distance, it won't affect the Pushback other than the longitudinal position of the truck, but it would be a visual issue only.

[Noble.]

Yeah, I've got identical values for the contact points. I just tried pushing back again at MLW (205 tonnes or so) and the pushback was flawless. It's obviously related to the "bouncing" present on the MD-11 and NGX when you're near the MTOW (which you can invoke quite easily by cycling through the views). Obviously this isn't an issue with GSX what-so-ever, but do you have any advice on the best way to remedy this? I'd imagine it's going to be a case of trial and error with the contact points of the MD-11? It's a bit odd it happens at higher gross weights but fine at the lower weights, as I'd have thought contact points were contact points regardless. Also, if I modify the values in contact points in the aircraft.cfg will I need to modify the gsx.cfg for the MD-11?

Thanks for your help.

[virtuali]

Obviously this isn't an issue with GSX what-so-ever, but do you have any advice on the best way to remedy this?

You might try playing with the 9th, 10th and 11th parameter of the contact point, which are: Static Compression, Ratio of Maximum Compression to Static Compression and Damping Ratio

In the PMDG MD-11 they are set to:

1.10, 0.8, 0.725

for the nose gear, and

1.10, 0.9, 0.747

for all the other gears

Also, if I modify the values in contact points in the aircraft.cfg will I need to modify the gsx.cfg for the MD-11?

No, the contact points in the aircraft.cfg are physical values, GSX.CFG values are related only to the visual model, and you are not changing that. As I've said already, there's no need for a GSX.CFG file with a fully supported airplane like the MD-11.

[Ricochetv1]

It's not clear if or what fixed this issue. I'm having the same issue, el except that as I'm taxiing after having to slew the plane back to where it was after sliding across the ground, the brakes go into a permanent overheat condition.