AI aircraft disappearing into ground when parked

[ailchim 206]

I have posted on this subject before, but didn't get a satisfactory answer: but I saw it again last night and it drives me nuts.Occasionally, I see parked AI aircraft tip nose down, tail up and disappear completely into the ground like a duck diving into a pond.This happens at different airports and when I'm flying different types. It happens immediately on arriving at the airport from the "Create Flight" menu or when altering the AI percentage so that the AI scenery is refreshed. It's too quick to say what type of aircraft, but I can say that it is always a smallish, rear engined, high tail commuter jet airliner - a CRJ, Fokker 70/100 or an ERJ, something like that. The rest of the AI population looks perfectly normal.I have a mix of PAI, Aardvark, ARNZ, CDAI and Martinez AI aircraft, so that doesn't narrow it down much.I have downloaded the Project Afcad files from PAI, so there is potentially a link between the airports, but I'm guessing it's a specific AI aircraft causing the problem, not an airport or the plane I'm flying.The most convincing argument I've heard is that it's something to do with contact points in the .cfg file.Has anyone ever had that happen?Does any one know if mixing .air files between aircraft can do this? Or copying parts of the .cfg file bewteen similar aircraft? I have to admit to having done that between similar aircraft from different "AI brand"s in an attempt to cure the particularly unsatisfactory landings some AI aircraft type perform.

[Guest Charlie Hall]

If it happens at stock airports then it shouldn't be the airports causing it. I too would suspect contact points or maybe even more likely the static_pitch and/or the static_cg_height settings in the same contact points section. Or it could be a combination of all the settings. I have PAI aircraft installed and have not seen that problem, so you might save time and look for one or more other add on AI aircraft as suspects. If you find which it is you might still be unable to fix it unless you can convert the airfile to make it flyable. If you manage to do that, then load the plane and see how it responds when the sim runs. If it sinks into the ground then you have found the problem. If not, go into slew mode and out again and see what happens. The static_ settings above are to do with how the aircraft acts when coming out of slew mode and also when first loaded. I would not recommend mixing and matching aircraft.cfg files and airfiles unless you know what you are doing.

[ailchim 206]

Thanks for the infoMy problem is they don't sink into the ground, they dive into it - and disappear entirely, all over in a second. I only see it if I happen be looking straight at the offending aircraft when FS loads.That's how I know what the tail of the aircraft looks like, its the only bit I see!I have altered static pitch and height before to fix those irritating aircraft which either float above the ground or have their wheels embedded in the tarmac.Can they be far enough out of kilter to pitch the plane right up on its nose and disappear completely?I have a few suspects, so I'll do a reasonableness check on those bits of code.Thanks again.If the static pitch is wrong, would t

[ailchim 206]

Mmmmm yes, checked the cg height and static pitch for the likely culprits and they look OK - pitch all small decimals e.g. -0.9, largest -1.2 I think, (degrees I presume) and height look right to be feet i.e. positive numbers between 7 and 10

[Guest drawlins]

I looked back at the previous post you'd made about this back in December. I still think you're looking at a contact point problem. And sooner or later you're going to have to narrow down which aircraft are doing it.One thing to think about if you've been mixing and matching various cfgs from other aircraft that no one ever mentions is the variablity of the reference data point. The ref data point is basically an arbitrary point from which all other data in the cfg that have location parameters are based. The location of the contact points for the wheels are all referencing that data point. You can move the ref data point around (weight_and_balance). but usually it's just left at 0,0,0. Here's the tricky part, where is 0,0,0 on the aircraft? A lot of times you'll find that it's more or less the center of gravity, centered about the wings somewhere. But that location is totally arbitrary. The location '0,0,0' is determined by where the model was in 3d space in gmax (assuming it came from gmax) and that becomes the center of the aircraft. Just by moving the model around in gmax, and then exporting it, I can have location 0,0,0 be 20 feet in front of the nose, or dead center in the fuselage, or at the very top trailing tip of the rudder if I want. (The ref data point for the default md83 is in the nose)Location 0,0,0 is completely arbitrary. It's probably never in the same location from model to model. And here's how that gets you into trouble when you start mixing parts from various cfgs.You keep your current contact points, and for the sake of arguement, we'll assume all cfg's had a ref data point of 0,0,0, and that on the model we're working with that 0,0,0 is also the center of gravity. We'll also assume that you're borrowing cfg data from a different model of the same aircraft type. Now you grab the engine parameters from a model where 0.0.0 happened to be in the nose. For that model, the longitudinal distance for the engine was -100. (meaning the engine's location is 100 feet behind the ref data point, the nose in this case) If you copy that engine info into the cfg for your ai model where 0.0.0 is at the middle of the wing, and not at the nose, now FS sees those new engines as being 50 feet further to the rear than the ones you replaced. And that's about all it takes to get your model to tip over on it's tail and start doing cartwheels.It's nice if you can visually see where the data point is located. If you're using the pay version of Aircraft Container Manager, you can, I don't know if there is another utility with this capability or not. But that will allow you to very quickly see where your contact points, engines, are all located in relation to each other as well as to the actual visual model.That said, I repeat what I said in my reply to your previous post about this, I've found FS2004 contact points to be extremely squirrely, even when they look dead on in ACM, I've still had planes bounce around like jumping beans when FS starts up.Hope that's not too discouraging,David R

[ailchim 206]

Thanks for the info, I have my suspicions which aircraft may be involved - unfortunately it was quite a while after I'd fiddled with the .cfg and .air files before I realised I had a problem - the "divers" appear so fleetingly that it's a matter of luck whether you see them at all.To make matters worse, I just replaced a old, single traffic file with MRAI flight plans - which are one per airline - so I can't easily use something like AI Traffic Mover to analyse which aircraft should be at the airport where I have seen the problem.I'll go back and download the original models for the doubtful aircraft and make sure they are running on the original data.Thanks for the help by the way. I was rather hoping someone else would have had this problem and know which aircraft was at fault - but maybe I have caused the trouble myself by meddling!

[Guest drawlins]

After thinking about it overnight, I think I should change part of my original reply. I'm not certain that the engine location scenario that I described would cause a plane to tip over since I don't know if the engine location has any "weight" associated with it.However, if where I said "engine" before you instead substituted "Center of Gravity", you could get a plane to tip over. In the example I described this would result in the CoG ending up way behind the main landing gear, and the plane would just tip over to the rear. I know this works, I've done it before. Could you use MS's traffic toolbox to narrow down the cart wheeling planes? If you're at an airport and see planes flipping over, immediately pause the game, and then open up the traffic toolbox thing (I can't remember the name of the utility right now) and sort all the traffic by the airport you are at. Make a note of the planes present. Then unpause the game and let the planes keep flipping till they eventually crash and dissappear. Then open up the traffic toolbox again, and see what's missing. That 'might' work. Payware solution would be to use ACM and look at all your planes and see if you can find a CoG out of place.David R

[jvile 1]

There are other areas within FS9 that can cause your AI Plane to disappear on startup the way that you are describing. If you have checked the aircraft .cfg specification settings (Contacts, CoG, etc.) and have a good matched aircraft .air file then follow through with this additional check. In the Options/Settings/Display menu locate the slider for the Terrain Mesh Complexity percent. If it is set at a high percent value this will include more points (lower settings drop less-significant points) for the hills, valleys, mountains, and canyons. Even though the airport is suppose to be flat it is not perfect in some locations (Ramps, Taxiways, Runways, etc.). This can be seen when AI Planes taxi and bounce so severe at some airports that are close to very steep elevations that the effect (unit of sprites) will generate tire smoke and leave tread marks on ramps and taxiways. If you lower the Terrain Mesh Complexity percent slider to 50 or 60 percent this will eliminate some of the points and the AI Planes will not bounce severely but will be able to keep their foot print on the hard elevation floor of the Ramp/Taxiway/Runway.Another option is to use a program like AFCAD and move the parking spot a small amount so on startup of FS9 the AI Plane is not sitting directly on the points which are causing it to bounce and disappear into the tarmac.These options are work arounds and do not solve the problem but helps to desensitize the model of that particular offending AI Aircraft. The Aircraft designer must ensure that the model has enough stability so when the AI Plane encounters these imperfection areas the plane does not bounce to the point it disappears either on startup (sitting at the parking spot) or in taxi mode.