Simviation Forum - Project Opensky B747-400 nose gear collapse

May 23^rd, 2009 at 1:19am

flipside Offline
Colonel
Hello!
Minneapolis, MN

Gender:
Posts: 151

Why is it that the nose gear on Project Opensky's Delta B747-400 collapses when I taxi and apply the brakes at the runway threshold? What can I change in the aircraft.cfg to fix this?

bilben94@gmail.com

Back to top

IP Logged

Reply #1 - May 23^rd, 2009 at 4:13am

Travis Offline
Colonel
Cannot find REALITY.SYS.
Universe halted.
Dripping Springs, TX

Gender:
Posts: 4515

First off, flipside, I would steer clear of posting your email address on open message boards, since spambots troll for stuff like that.

Secondly, was this aircraft created specifically for FS9? Or is this an FSX model that you have gotten to work? Because I have noticed with some of the FSX models in FS9, the gear act a little weird.

If it isn't that, the fix is actually (I'm betting) fairly simple.

Open the file labeled "aircraft.cfg" in the folder of the 747 using Notepad. Scroll down until you see the following:

[contact_points]

There will be some information after that. Copy and paste it into your next reply and I'll see if I can fix your issue.

Back to top

IP Logged

Reply #2 - May 23^rd, 2009 at 6:27am

microlight Offline
Colonel
It's a bird...
Southern UK

Gender:
Posts: 2236

Hi flipside.

This is a well-known problem with the Posky 747s, and the latest FD Version 9.7, Revision D (FS9/FSX) can be downloaded from their site (downloads/747-400/FDE packages). This reputedly fixes the problem - let us know if it does.

Wink

BAe ATP for FS9 now available! www.enigmasim.com

Back to top

IP Logged

Reply #3 - May 23^rd, 2009 at 6:33am

flipside Offline
Colonel
Hello!
Minneapolis, MN

Gender:
Posts: 151

[contact_points]

   //0 Class <0=none,1=wheel, 2=scrape, 3=float>
   //1 Longitudinal Position    (feet)
   //2 Lateral Position (feet)
   //3 Vertical Position (feet)
   //4 Impact Damage Threshold (Feet Per Minute)
   //5 Brake Map    (0=None, 1=Left, 2=Right)
   //6 Wheel Radius       (feet)
   //7 Steer Angle (degrees)
   //8 Static Compression       (feet) (0 if rigid)
   //9 Max/Static Compression Ratio
   //10 Damping Ratio    (0=Undamped, 1=Critically Damped)
   //11 Extension Time    (seconds)
   //12 Retraction Time    (seconds)
   //13 Sound Type
   //14 Airspeed limit for retraction    (KIAS)
   //15 Airspeed that gear gets damage at (KIAS)

point.0 = 1.000, -30.333, 0.000, -13.833, 5181.102, 0.000, 2.042, 70.000, 0.300, 0.500, 0.880, 11.000, 11.000, 0.000, 240.000, 280.000 // Nose Gear
point.1 = 1.000, -110.583, -6.350, -15.403, 3574.803, 1.000, 1.917, -13.000, 1.620, 1.150, 0.741, 12.900, 14.900, 2.000, 240.000, 280.000 // Main Center Gear - Left
point.2 = 1.000, -110.583, 6.350, -15.403, 3574.803, 2.000, 1.917, -13.000, 1.620, 1.150, 0.741, 13.100, 15.400, 3.000, 240.000, 280.000 // Main Center Gear - Right
point.3 = 1.000, -102.083, -18.000, -15.403, 3574.803, 0.000, 1.917, -13.000, 1.620, 1.150, 0.741, 12.900, 14.900, 2.000, 240.000, 280.000 // Main Wing Gear - Left
point.4 = 1.000, -102.083, 18.000, -15.403, 3574.803, 0.000, 1.917, -13.000, 1.620, 1.150, 0.741, 13.100, 15.400, 3.000, 240.000, 280.000 // Main Wing Gear - Right
point.5 = 2.000, -146.000, -102.900, 7.000, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 5.000, 0.000, 0.000
point.6 = 2.000, -146.000, 102.900, 7.000, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 6.000, 0.000, 0.000
point.7 = 2.000, -189.667, 0.000, -2.000, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 9.000, 0.000, 0.000
point.8 = 2.000, -9.167, 0.000, -5.750, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 4.000, 0.000, 0.000
point.9 = 2.000, -229.667, 0.000, 55.500, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 8.000, 0.000, 0.000
point.10= 2.000, -106.400, -69.500, -5.000, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 9.000, 0.000, 0.000
point.11= 2.000, -76.300, -39.167, -9.000, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 9.000, 0.000, 0.000
point.12= 2.000, -76.300, 39.167, -9.000, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 9.000, 0.000, 0.000
point.13= 2.000, -106.400, 69.500, -5.000, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 9.000, 0.000, 0.000
point.14= 2.000, 0.000, 0.000, 0.000, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 4.000, 0.000, 0.000

static_pitch= 1.000
static_cg_height= 12.500
gear_system_type=0

// Nose gear
//point.0= 1.000, -30.333, -1.500, -13.750, 2181.102, 0.000, 2.000, 70.000, 0.300, 0.500, 0.880, 11.000, 11.000, 0.000, 240.000, 280.000
//point.1= 1.000, -30.333, 1.500, -13.750, 2181.102, 0.000, 2.000, 70.000, 0.300, 0.500, 0.880, 11.000, 11.000, 0.000, 240.000, 280.000
//
// Main Wing Gear (left)
//point.2= 1.000, -104.583, -18.000, -16.533, 1574.803, 1.000, 2.000, -13.000, 2.602, 2.500, 0.551, 12.900, 14.900, 2.000, 240.000, 280.000
//point.3= 1.000, -104.583, -14.000, -16.533, 1574.803, 1.000, 2.000, -13.000, 2.602, 2.500, 0.551, 12.900, 14.900, 2.000, 240.000, 280.000
//point.4= 1.000, -99.583, -18.000, -16.533, 1574.803, 1.000, 2.000, -13.000, 2.602, 2.500, 0.551, 12.900, 14.900, 2.000, 240.000, 280.000
//point.5= 1.000, -99.583, -14.000, -16.533, 1574.803, 1.000, 2.000, -13.000, 2.602, 2.500, 0.551, 12.900, 14.900, 2.000, 240.000, 280.000
//
// Main Wing Gear (right)
//point.6= 1.000, -104.583, 18.000, -16.533, 1574.803, 2.000, 2.000, -13.000, 2.602, 2.500, 0.551, 15.100, 16.400, 3.000, 240.000, 280.000
//point.7= 1.000, -104.583, 14.000, -16.533, 1574.803, 2.000, 2.000, -13.000, 2.602, 2.500, 0.551, 15.100, 16.400, 3.000, 240.000, 280.000
//point.8= 1.000, -99.583, 18.000, -16.533, 1574.803, 2.000, 2.000, -13.000, 2.602, 2.500, 0.551, 15.100, 16.400, 3.000, 240.000, 280.000
//point.9= 1.000, -99.583, 14.000, -16.533, 1574.803, 2.000, 2.000, -13.000, 2.602, 2.500, 0.551, 15.100, 16.400, 3.000, 240.000, 280.000
//
// Main Center Gear (left)
//point.10= 1.000, -115.583, -8.000, -16.533, 1574.803, 1.000, 2.000, 0.000, 2.602, 2.500, 0.551, 13.400, 14.900, 2.000, 240.000, 280.000
//point.11= 1.000, -115.583, -4.000, -16.533, 1574.803, 1.000, 2.000, 0.000, 2.602, 2.500, 0.551, 13.400, 14.900, 2.000, 240.000, 280.000
//point.12= 1.000, -109.583, -8.000, -16.533, 1574.803, 1.000, 2.000, 0.000, 2.602, 2.500, 0.551, 13.400, 14.900, 2.000, 240.000, 280.000
//point.13= 1.000, -109.583, -4.000, -16.533, 1574.803, 1.000, 2.000, 0.000, 2.602, 2.500, 0.551, 13.400, 14.900, 2.000, 240.000, 280.000
//
// Main Center Gear (right)
//point.14= 1.000, -115.583, 8.000, -16.533, 1574.803, 2.000, 2.000, 0.000, 2.602, 2.500, 0.551, 11.500, 17.500, 3.000, 240.000, 280.000
//point.15= 1.000, -115.583, 4.000, -16.533, 1574.803, 2.000, 2.000, 0.000, 2.602, 2.500, 0.551, 11.500, 17.500, 3.000, 240.000, 280.000
//point.16= 1.000, -109.583, 8.000, -16.533, 1574.803, 2.000, 2.000, 0.000, 2.602, 2.500, 0.551, 11.500, 17.500, 3.000, 240.000, 280.000
//point.17= 1.000, -109.583, 4.000, -16.533, 1574.803, 2.000, 2.000, 0.000, 2.602, 2.500, 0.551, 11.500, 17.500, 3.000, 240.000, 280.000
//
//Scrape points
//point.18 = 2.000, -146.000, -98.900, 7.000, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 5.000, 0.000, 0.000
//point.19 = 2.000, -146.000, 98.900, 7.000, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 6.000, 0.000, 0.000
//point.20 = 2.000, -189.667, 0.000, -2.000, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 9.000, 0.000, 0.000
//point.21 = 2.000, -9.167, 0.000, -5.750, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 4.000, 0.000, 0.000
//point.22 = 2.000, -229.667, 0.000, 55.500, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 8.000, 0.000, 0.000
//point.23 = 2.000, -106.400, -69.500, -5.000, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 9.000, 0.000, 0.000
//point.24 = 2.000, -76.300, -39.167, -9.000, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 9.000, 0.000, 0.000
//point.25 = 2.000, -76.300, 39.167, -9.000, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 9.000, 0.000, 0.000
//point.26 = 2.000, -106.400, 69.500, -5.000, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 9.000, 0.000, 0.000
//point.27 = 2.000, 0.000, 0.000, 0.000, 787.402, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 0.000, 4.000, 0.000, 0.000

I hope that you can figure this out.

Back to top

IP Logged

Reply #4 - May 23^rd, 2009 at 7:34am

Travis Offline
Colonel
Cannot find REALITY.SYS.
Universe halted.
Dripping Springs, TX

Gender:
Posts: 4515

Wow. Okay. All that stuff that has the "//" in front is stuff that is ignored by FS. So those don't matter. You'll want to keep that in mind for future reference, since adding stuff to CFG files is pretty much important information for FS.

But I would follow what microlight said and try the fix. If that doesn't do the job, then come back and I will describe how to fix the issue from what you posted.

Back to top

IP Logged

Reply #5 - May 23^rd, 2009 at 6:18pm

flipside Offline
Colonel
Hello!
Minneapolis, MN

Gender:
Posts: 151

I downloaded the FDE from the Project Opensky site and installes the Air and cfg files into the offending aircraft and it didn't work. The nose gear still collapsed on the runway threshold. I am approaching the motivation to dump the aircraft and search out another that works. Angry

Back to top

IP Logged

Reply #6 - May 23^rd, 2009 at 7:47pm

Travis Offline
Colonel
Cannot find REALITY.SYS.
Universe halted.
Dripping Springs, TX

Gender:
Posts: 4515

Before you do that, take a look at what you posted above:

point.0 =

1.000

, -30.333, 0.000, -13.833,

5181.102

, 0.000, 2.042, 70.000, 0.300, 0.500, 0.880, 11.000, 11.000, 0.000, 240.000, 280.000 // Nose Gear

The red number is what tells you that the point is a gear point. The first one is usually the nose gear, but they also tell you on this one at the end of the entry.

The green number is how hard (in ft per second) you have to hit the gear point for it to fail. Since this is a function of multiplying the actual weight of the aircraft for the speed at which it is moving, this number may be too low. Try increasing it to something like 8000. If that doesn't work, then other factors may come into play.

Back to top

IP Logged

Reply #7 - May 27^th, 2009 at 5:47am

flipside Offline
Colonel
Hello!
Minneapolis, MN

Gender:
Posts: 151

The nose gear sinks into the ground when I am taxiing in spot view. (I taxi this way to park precisely-my nose wheel on the guide line and stopped at the cross mark) If I am stopped and switch to spot view it looks alright. The nose gear sinks into the ground the instant I start to move.

Back to top

IP Logged

Reply #8 - May 27^th, 2009 at 8:53am

Travis Offline
Colonel
Cannot find REALITY.SYS.
Universe halted.
Dripping Springs, TX

Gender:
Posts: 4515

That means there is more wrong. It means that the compression ratio is off, which I could only help you fix if I had the aircraft. Look at the table of numbers preceding the point.* section and you'll see "Static Compression" as well as "Max/Static Compression Ratio". These numbers must be manipulated to fix this issue. Unfortunately, it's something you MUST have the aircraft in front of you to accomplish, and I don't. However, look at the following document, which describes in detail every entry in the aircaft.cfg file. Look at the entries pertaining to the compression areas, and it should give you some idea of how to fix this.

Others could probably give you more help if you can't seem to get it to work right. Just let us know.

Never give up! Never surrender! Grin

Back to top

IP Logged

Reply #9 - May 29^th, 2009 at 11:59am

microlight Offline
Colonel
It's a bird...
Southern UK

Gender:
Posts: 2236

flipside,

I have tried to reproduce the sinking nose gear on the V4 Posky 744 and cannot make it happen (this is using the RR variant of the FD). I've tried full fuel down to 30% fuel and all kinds of rapid ground acceleration, violent braking etc etc, and the nose wheel moves on its suspension but doesn't sink. The figures for static compression (same as yours) seem to work OK for me. Can you check some things for me, like the nose gear position, reproduced from my aircraft.cfg below:

point.0 = 1.000,

-20.333

, 0.000, -13.833, 5181.102, 0.000, 2.042, 70.000, 0.300, 0.500, 0.880, 11.000, 11.000, 0.000, 240.000, 280.000 // Nose Gear

The figure highlighted is the nosewheel longitudinal position and is the same here as in the most recent Posky FD download, which is ten feet forward from the figure you quoted in your post: -30.333. In the Posky download, only one of the many aircraft.cfg files has the -30 figure so this must be a typo. In practical terms this makes no difference; I tried it and my nose wheel would still not collapse.

Also, the 747 FD has always been sensitive to weight distribution, and the CG location hasn't always been in the right place - please check yours (visible on the fuel/payload menu) and confirm that it's in the performance envelope just behind the stylised cockpit.

Good luck!

Wink

BAe ATP for FS9 now available! www.enigmasim.com

Back to top

IP Logged

Reply #10 - May 29^th, 2009 at 5:12pm

flipside Offline
Colonel
Hello!
Minneapolis, MN

Gender:
Posts: 151

It seems to be only in Spot view that if you stop and start to move again the nose wheel sinks into the ground.

Back to top

IP Logged

Reply #11 - May 29^th, 2009 at 11:47pm

MiltonShupe Offline
Colonel
Fly FS

Gender:
Posts: 55

Gentlemen,

You are all around the issue but not quite on it.

The issue is the max-static ratio. This number should never be less than 1.0 and in this contact point, it is 0.500.

point.0 = 1.000, -30.333, 0.000, -13.833, 5181.102, 0.000, 2.042, 70.000, 0.300,

0.500

, 0.880, 11.000, 11.000, 0.000, 240.000, 280.000 // Nose Gear

For an aircraft this size the suspension is very hard if you can call 4" (.300') suspension.

Change the the max-static ratio to 2.0 and try it, like this:

point.0 = 1.000, -30.333, 0.000, -13.833, 5181.102, 0.000, 2.042, 70.000, 0.300,

2.00

, 0.880, 11.000, 11.000, 0.000, 240.000, 280.000 // Nose Gear

This is the only obvious thing I see in the contact point data.

Back to top

IP Logged

Reply #12 - May 30^th, 2009 at 4:20am

flipside Offline
Colonel
Hello!
Minneapolis, MN

Gender:
Posts: 151

Never mind. I dumped the aircraft. Angry

Back to top

IP Logged

Reply #13 - May 30^th, 2009 at 6:09am

microlight Offline
Colonel
It's a bird...
Southern UK

Gender:
Posts: 2236

Hi Milton,

Good to see you in your new identity! Wink

Thanks for the information regarding this parameter, the FS9 aircraft container SDK doesn't give much information on what this value should be. I tried the increased value on my Posky 747 V4, and although it didn't make any difference (as the nosewheel didn't collapse originally) it's another area to try when it does happen.

flipside,
worth a try as this is otherwise a great plane.

Wink

BAe ATP for FS9 now available! www.enigmasim.com

Back to top

IP Logged

Reply #14 - May 30^th, 2009 at 8:44am

MiltonShupe Offline
Colonel
Fly FS

Gender:
Posts: 55

Thanks. I have done several tutorials on suspension setup and although this one is directed at modelers, reading it may help. There are couple of nice links for reference as well.

http://www.sim-outhouse.com/sohforums/showthread.php?t=944

Back to top

IP Logged

	Search the archive: