IL-76 contact points

S

SSI01

Charter Member
I'm having a little trouble with an Il-76 I recently downloaded. When loaded into the sim, the aircraft will appear on the tarmac but is sitting a little high. Of course, this results in an immediate crash. I've tried using contact points from two or three other Il-76s I have on the sim, but these turn the first -76 into a semi-submerged winged submarine. I figure I need to drop the bird about six or seven feet to get the wheels on the ground. Here are the contact points as provided in the config file:


point.0 = 1, -25.0, 0.0, -13.9, 1000.0, 0, 2.0, 70.0, 1.0, 2.7, 0.900, 12.0, 12.0, 0, 220, 250
point.1 = 1, -114.0, -18.0, -13.9, 2000.0, 1, 2.0, 13.0, 1.0, 2.7, 0.900, 17.0, 15.0, 2, 220, 250
point.2 = 1, -114.0, 18.0, -13.9, 2000.0, 2, 2.0, 13.0, 1.0, 2.7, 0.900, 17.0, 15.0, 3, 220, 250
point.3 = 2, -152.6, -103.5, 3.0, 700.0, 0, 0.0, 0.0, 0.0, 0.0, 0.000, 0.0, 0.0, 5, 0, 0
point.4 = 2, -152.6, 103.5, 3.0, 700.0, 0, 0.0, 0.0, 0.0, 0.0, 0.000, 0.0, 0.0, 6, 0, 0
point.5 = 2, 3.0, 0.0, 0.0, 700.0, 0, 0.0, 0.0, 0.0, 0.0, 0.000, 0.0, 0.0, 9, 0, 0
point.6 = 2, -222.7, 0.0, 4.0, 700.0, 0, 0.0, 0.0, 0.0, 0.0, 0.000, 0.0, 0.0, 4, 0, 0

I'd like to learn the theory and practice of changing contact points and use this as a learning opportunity, as this is bound to present itself again in the future. Does anyone know what needs to be changed, and what the number stand for?
 
If you open the cfg file for one of the default AC all the points are explained a bit more. As in what function does each column have etc.
The very first number on each line tells FS the basic function of the line ie wheel, float or scrape point.
The next three numbers position the bottom of the wheel from the design reference point. I may be incorrect in this one but I think this point can be anywhere in the model, it has nothing to do with the center of gravity or anything like that.
The first of the three is the longitudinal coordinate. So in this case 25 ft forward of the RP.
The second is the lateral coordinate. The first one is on the centerline and so it's zero. The other two are 18 feet left and right of center.
The third finally is the vertical coordinate. 13.9 feet below the RP in this case.

I guess that would be the one you may need to change. It's a bit strange that you get a crash though. I think there may be another issue.

Cheers
Stefan
 
Well Stefan, you learn something new every day. I'm a little tired right now but am planning on getting started on this in the morning. We'll see how things go and I'll let you know then. Thanks for the tips - will save what you gave me in a word file on the desktop.
 
OK, here's everything that's going on -
This is an AI IL-76, specifically the A-50 variant which is the AWACS version of the -76. There is no A-50 available anywhere I can find on the web that is purpose-made to be flown by a human in FS9, so I've had to settle for this. That being said, they have similar config entries to flyable aircraft so should be amenable to modification - I've done it in the past. I've tried playing with the third no. in the contact points section, even bringing it down to 0.0, but without fail the aircraft is always about one tire width above the tarmac no matter what mod is made. This situation occurs anywhere in the world the aircraft is taken - I did that to ensure it's not the terrain that's causing this. When it crashes, it always sinks to the same level - 1/2 way down the height of the fuselage. I've removed it from the sim until I can sort this out - also because another aircraft has begun displaying problems now. This didn't happen until this experimentation with the A-50. Hopefully the two are related and this fixed it. It they're not, the other aircraft, a JustFlight P-38, will be the subject of another thread. Is there to your knowledge a flyable A-50 available (I got this IA aircraft off avsim.rus)?
 
What's your static_cg_height (also in the contact points section)? Anywhere close to 14.0? And pitch?
 
mjahn said:
What's your static_cg_height (also in the contact points section)? Anywhere close to 14.0? And pitch?
Click to expand...

I've just looked at in ACM and the Static CG Height is 15.5, I suspect reducing that to 14.0 may do the trick. Pitch is zero btw, but that looks right.
 
AndyG43, Ah, the sweet smell of success. I'm missing just enough off the bottoms of all the tires to account for the "squash" you get with the bird's weight on them. You were dead on the money.

I will post on the other problem now, the one having to do with the P-38/F-4 from Just Flight. Getting scenery blurries and some other problems.
 
Manfred, please forgive me, I want to include you as well in my thanks.

BTW enjoying the Constellations very much indeed.
 
mjahn said:
What's your static_cg_height (also in the contact points section)? Anywhere close to 14.0? And pitch?
Click to expand...

That's what I was thinking of but could not think of the correct term and is what I meant when I said there has to be a different issue than just the third number.

Cheers
Stefan
 
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