Runway Tracking After Landing

[Guest ricere]

Can anyone provide some

[Brian Doney 127]

This is because PSS modeled main gear steering in the FDE (IIRC, I no longer have it installed, but I seem to remember it being one of the first changes I made long ago). In the real aircraft, this would be locked out above a certain speed, but in FS, no one seems to have figured out just quite how to do this properly.This can make rollouts particularly tricky as the main gear will steer opposite rudder input, compounding any deviation from the centerline.Check the steering angle values in the contact_points section of the aircraft.cfg. If memory serves the main gear have a negative value here, (~ -20.0 or so, I believe). Set this value to 0.0 and try again.

[Guest franksalot]

Hi ricere, good point, after a nice touchdown the whole experience is ruined by having to 'chase' the aircraft all over the runway.Brian, I can't find the 'steering angle' section in my PSS B772LR, here is the Contact Points section from my T7[contact_points]static_pitch = 0.1static_cg_height = 17.56tailwheel_lock = 0gear_system_type = 1max_number_of_points = 17point.0 = 1, 85.43, 0.00, -17.10, 1181.1, 0, 4.521, 68, 0.70, 2.5, 0.723, 13, 14, 0, 270, 270point.1 = 1, -4.76, -20.0, -18.40, 1574.8, 1, 4.521, 0, 1.91, 2.5, 0.747, 13, 14, 2, 270, 270point.2 = 1, -4.76, 20.0, -18.40, 1574.8, 2, 4.521, 0, 1.91, 2.5, 0.747, 12.9, 13.9, 3, 270, 270point.3 = 2, 30.86, -31.6, -14.14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0point.4 = 2, 30.86, 31.5, -14.14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0point.5 = 2, -102, -36, 9, 787.4, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0point.6 = 2, -38.4, -105, 12.5, 787.4, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0point.7 = 2, -102, 36, 9, 787.4, 0, 0, 0, 0, 0, 0, 0, 0, 9, 0, 0point.8 = 2, -38.4, 105, 12.5, 787.4, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0point.9 = 2, -102, 0, 44.12, 2787.4, 0, 0, 0, 0, 0, 0, 0, 0, 9, 0, 0point.10 = 2, -88.3844, 0, 0.0661, 787.4, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0point.11 = 2, -57.091, 0, -6.708, 787.4, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0point.12 = 2, -44.38, 0, -8.6234, 787.4, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0point.13 = 2, -102.1003, 0, 3.9805, 2787.4, 0, 0, 0, 0, 0, 0, 0, 0, 9, 0, 0point.14 = 2, 50.4709, 0, 13.0267, 787.4, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0point.15 = 2, 105.0852, 0, 0.4276, 2787.4, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0point.16 = 5, 0.0, 0.0, -10.0, 1600, 0.0, 0.0, 50.0, 0.0, 0.0, 1.00, 1.0, 1.0, 0, 0.0, 0.0Which line/s need to be changed? Would it be Items 1 and 2.Ken

[Brian Doney 127]

Well, if that's the 772LR .cfg as installed, then I am wrong, as the steering angle is already set to 0.NOSE GEARpoint.0 = 1, 85.43, 0.00, -17.10, 1181.1, 0, 4.521, 68, 0.70, 2.5, 0.723, 13, 14, 0, 270, 270MAIN GEARpoint.1 = 1, -4.76, -20.0, -18.40, 1574.8, 1, 4.521, 0, 1.91, 2.5, 0.747, 13, 14, 2, 270, 270point.2 = 1, -4.76, 20.0, -18.40, 1574.8, 2, 4.521, 0, 1.91, 2.5, 0.747, 12.9, 13.9, 3, 270, 270Maybe it has been addressed since I last had it installed, or maybe I'm imagining things.The only curiosity I see there is point 16, a water rudder ?

[Guest franksalot]

Hello Brian, thanks for your reply.Yes, that is the PSS B772LR .cfg as installed - in fact I re-installed the T7 only last week; I admit to 'tweaking' it slightly but not the Contact Points."Water Rudder".....? Beats me :)I made a Recording of a landing I did this morning, when I played it back, looking 'nose on', I noticed that the T7 'tracked' fairly straight until I disengaged the AP (I could tell by the loud klaxon horn sound). By then the nose wheel had made contact and it 'slid' all over the place. That must be where the problem lies?Ken

[Brian Doney 127]

If you want to experiment a bit, try reducing the nose gear angle to ~50-55 degrees, from 68, and comment out point.16 with a couple of forward slashes.The only thing I can figure is that this is how they attempted main gear steering, instead of setting it directly in the main gear definitions. It has been given a 50 degree steering angle, and I'm at a loss as to any other purpose that would serve. The same problem would still apply though, AFAIK, in that it could not be locked out properly at high speed.EDIT: I'm really not 100% positive anymore, obviously, but I do know that something I did back then did rectify this issue, and it's in my head that it was a contact points problem.

[Guest ricere]

Ken/Brian,Gents,Thanks for narrowing the focus as to where to begin adjusting values. What works well for me was this:reduction in the static_cg_height from 17.56 to 17.50point.0 = nose wheel turn angle reduced from 68 to 50point.16 = edited in the beginning of the string with //Aircraft is firmly planted to the runway when the "mains" touchdown and very little if any rudder pedal corrections are required to maintain runway centerline. This problem is fixed...next?Cheers all!Rich

[Guest franksalot]

Hi Brian and Rich,Yep, tried that and it's made a fantastic difference; the whole rollout was well under control. Being a Nit picker !st Class :) I'm going to reduce point .0 just a little more....say to 45 - my nose wheel is still 'flicking' too much for my liking. (as noted from another of my recordings).Now that's sorted, how about 'smoking tires/tyres' on touchdown, another of my hang ups. I'm told that this effect is controlled by Fs9 .cfg file, but I can't find any reference to it there. My PMDG B738NG has this effect, see attached .jpg.Ken

[Guest franksalot]

Hello Brian and rich,That last small adjustment was just about right, suits me anyway :) Makes turning tight bends/corners a little difficult, but I've got used to it, a work of art :)Thank you for your help.Ken

[Guest franksalot]

Forgot to say; also sorted the touchdown 'smoke'.One more refinement, then I'll quit and do more flying :)'Next' Wing Views' - anyone have any ideas?Ken

[Guest franksalot]

Hi, Update on touchdown smoke - fixed that one as well :)Just one more query about the FMC, but that is being sorted by Tech. Support. Then we're 'home and dry' with a great aircraft.Ken