A Fix for the Bouncing B-52H

[Guest]

I'm not the first one to say this, but my hat is off to Kotaro Akikawa for his marvelous B-52H design for FS2002. Behind this work of art is a huge amount of technical data and, not surprisingly, a few problem areas. Needless to say, beta testing doesn't always catch all of the problems.During the past year, I've read about (and experienced) the "Bouncing BUFF" problem in FS2002. For me, it occurs on the ground at partial fuel loads of about 60% or less. During the landing roll or the start of takeoff, the tail of the B-52 will bounce high in the air, over and over, with the aircraft often ending crosswise with the runway with its nose on the ground and the fuselage in the air. Not a pretty sight.The problem is in the contact_points section of the Aircraft.cfg file. The contact point for the Rear main gear is missing. This missing point is not visually obvious because the aircraft looks normal on the ground. However, the aircraft is actually only supported by the Front main gear and the two outriggers. At lighter fuel weights, the center-of-gravity apparently shifts enough to cause this "tripod" arrangement to become unstable. That, I believe, is what has happened and why it was not easy to discover. Because of concerns over ownership, I contacted Kotaro by email on June 10 with my description of the problem and the proposed solution. In his response he stated that he would not be able to verify my findings due to some PC issues. He also said he would be pleased if I would post the fix and share it with the community. I appreciate his confidence.The fix shown below is rather easy, but if you're unfamiliar with file editing be sure to back up the original file before trying to do any revisions. Any text editor should work. I use Notepad. Open the Aircraft.cfg file with your text editor. Locate the (contact_points) section (in square brackets). Copy all of the data for point.0 and paste it just after the data for point.6. Edit this new line so "point.0=1.000000,16.000000, . . . . . . . ." now reads "point.7=1.000000,-34.000000, . . . . . . . ." Save the file. The new contact point should read as follows:point.7=1.000000,-34.000000,0.000000,-12.083333,3750.081701,0.000000,3.941352,41.520000,0.861471,2.500000,0.916691,10.000000,10.000000,0.000000,0.000000,0.000000 That's it. This fixed it for me and made the BUFF usable again. It now rolls normally regardless of the fuel load. I hope this fix works as well for anyone else who tries it.Cheers,JerryHThis message will also be posted on other FS2002 forums.

[Guest]

You should submit a copy of the full "patched" aircraft.cfg on the File Library. That way more people will know about it.The only thing that is needed to make Kotaro's B-52H perfect would be a fix so she can fly over 18,000 on autopilot with her going into a "Dutch Roll"

[Guest]

Thanks for your comments, Simlock.I'm not certain if Kotaro gave me permission to upload a patched aircraft.cfg file. In any event, I'm reluctant to do that because many simmers may have already customized or revised their files for other reasons. I felt that a simple editing fix would be more useful.With regard to Dutch Roll with the AP, I believe that problem is solved by moving the center-of-gravity of the wing-tip fuel tanks. For some reason, these tip tanks were originally located 400 feet from the aircraft centerline. They should be located at 75 feet. Sorry that I can't cite a reference for this, but its rather obvious that 400 feet is an error. To be more specific, in the (fuel) section of the aircraft.cfg file, the second value for LeftTip should be changed from -400.0 to -75.0; RightTip should be changed from 400.0 to 75.0.Regards,JerryH

[WebbPA 0]

I've applied this fix and it doesn't work for me. I want to make sure I did it right. I now have a new line: contact_points ... point.7=1.000000,-34.000000,0.000000,-12.083333,3750.081701,0.000000,3.9 41352,41.520000,0.861471,2.500000,0.916691,10.000000,10.000000,0.000000, 0.000000,0.000000 (Cut & pasted from the .cfg file) Tested at 25% and 50% fuel and various flap configurations (50-100% extended) the ac nosedives into the runway at about 125 kts. Anyone else?

[Guest]

Jim (WebbPA), I'm as disappointed as you are. Yes, your new contact point is identical to what I have. Having the rear gear added was like night and day for me which is why I shared my find with you and others. I'll go back and flight test some more conditions to see if I can duplicate your problem. Incidently, I am not affiliated with Kotaro or his beta testers. Just a stubborn retired Boeing guy who knew there must be an answer for a misbehaving B-52. I just remembered another thing that I learned during my detective work. Fuel consumption is carefully managed for this aircraft. In other words, 50% fuel remaining doesn't mean all nine tanks have 50% fuel in them. Fuel is drawn from the tanks in a specific sequence in order to control the position of the center-of-gravity. I flew the aircraft for many hours (in slew mode to save time), stopping every half hour or so to note the status of each fuel tank. My numbers for each tank are shown below for a total fuel load of about 50%: Left Aux, 0% Left Main, 41% Center 1, 100% Right Main, 41% Right Aux, 0% Center 2, 100% Center 3, 6% Right Tip, 100% Left Tip, 100% You might try these to see if it makes any difference. Good luck. Looking forward to hearing some better news. Regards,JerryH

[WebbPA 0]

Jerry, I think I have an "ID Ten T" error. I should have seen it when I saw your fuel configurations. I had been changing the first 5 tank levels, never bothing to move the slider to see that there were 4 more tanks. Leaving C2 and C3 at 100% seem to account for my problems. And this may account for some or all of my landing problems. In my defense I note that there are only 5 gauges visible in the panel. Thanks for your help.

[Guest]

I'm bumping this message one time to give it a few more days of life.JerryH