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The way an aircraft sits...

ndicki

ndicki

Charter Member 2016
On the ground is governed by which elements in which file? I thought it was the "Contact Points" in aircraft.cfg, but it doesn't seem to be the case after all. Can anyone point me in the right direction?
 
contact points and static_pitch=
static_cg_height=
in the aircraft cfg
H
 
Static pitch and static CG height only decide the attitude of the model when it's spawned before the physics kick in (meaning how high and in which angle it's "dropped"), after that it's pure contact points.
 
OK, but when I copy the air file and aircraft.cfg from model A to model B, and
change the contact points and static cg height to those of model B, then it shoukld sit on the grass correctly - in my book at least. The thing is, it doesn't... If you want to think about what I'm doing, imagine fitting the FM of the AvH/ETO Spit MkI to the AH model, for example.
 
ndicki said:
OK, but when I copy the air file and aircraft.cfg from model A to model B, and
change the contact points and static cg height to those of model B, then it shoukld sit on the grass correctly - in my book at least. The thing is, it doesn't... If you want to think about what I'm doing, imagine fitting the FM of the AvH/ETO Spit MkI to the AH model, for example.
Click to expand...
you are correct it should
H
 
Bdp. I have. Very odd. It sits with its tail in the mud up to the tailplanes, when I use the alternative FM but with the original contact points.

Never mind, it looks better unmodified, even if the main wheels are an inch off the grass...
 
What the guys have told you is correct...except the xdp/bdp bit.
Nothing in the damage profile that affects the contact points.

On the a/c your trying to fix the contact points...one thing you should understand.

'In the book' measurements are many times right. But, those measurements are taken from 'where' on the a/c? No say. Possibly from factory drawings.

In gmax/CFS3 the contact points measurements are taken from the model's 'center'...as it's built in gmax. The two are not particularly the same. So the numbers for one a/c might not work for another like a/c.

Contact points are in the Aircraft.cfg. You can look at a few of the stock a/c, and in their .cfg file, some have added notes on the contacts points, and what each one is.
If the a/c's mains are only inches off the ground, probably only a change of .05 might be needed. That's something you simply play with to get it right. Of course, it helps if all the other numbers are at least within reason! The measurements are in meters.
 
Thanks - the thing is, the aircraft sits correctly using the "issue" aircraft.cfg. Transfer the contact points to the replacement aircraft.cfg and it sinks in. odd. Or does the 0,0,0 point have something to do with it?
 
This is a stupid question for sure but have you accounted for the differences in modelling, like the ETO Spitfire Ia and the AH Spitfire Ia? While they're both modelled after the same aircraft the contact points can be quite different. If you're going for a certainly similar model, like Spitfire XIV and Spitfire V, this is probably not the reason. Is it possible that the new model has a more rearward weight distribution and the tail wheel is simply on the limits of its strength in the old model and now taking damage thanks to higher stress when the landing gear is compressed?
 
greycap.raf said:
This is a stupid question for sure but have you accounted for the differences in modelling, like the ETO Spitfire Ia and the AH Spitfire Ia? While they're both modelled after the same aircraft the contact points can be quite different. If you're going for a certainly similar model, like Spitfire XIV and Spitfire V, this is probably not the reason. Is it possible that the new model has a more rearward weight distribution and the tail wheel is simply on the limits of its strength in the old model and now taking damage thanks to higher stress when the landing gear is compressed?
Click to expand...
that makes sense to me
i use acm for the civil sims
but acm does not see cfs3 models
btw soooory for the xdp/bdp confusion
you knew what i meant:isadizzy:
H
 
ndicki said:
Thanks - the thing is, the aircraft sits correctly using the "issue" aircraft.cfg. Transfer the contact points to the replacement aircraft.cfg and it sinks in. odd. Or does the 0,0,0 point have something to do with it?
Click to expand...

Exactly!!

Even between two different models of the same a/c, there can be vast differences. It depends on how it was built in gmax, which no-one but the builder has control of.

Your 'issue' aircraft.cfg is your best starting point...unless it's just totally out of wack. That one doesn't seem to be, so just fine tune it.
But...it can get a little more complicated. LOL.
Wheel size is in there, besides the 0,0,0 location of each wheel, that affects how the a/c sits, rolls, etc. Get the picture? It's all a package deal, and works together. The more accurate it all is, the more accurate it acts.

One other IMPORTANT point, that some might be reading this, might not understand...
The FM (airfile) AND the aircraft.cfg are matched sets. But, the aircraft.cfg entries over-ride the same entries in the airfile. So, they are not meant to be inter-changed. Don't mix 'em!
There's alot of entries in both files, that greatly affect how that a/c flies, most un-seen, unless you know what to look for.

No such thing as a dumb question. Just some of us have been fooling with this stuff so long (groan), things get taken for granted.

Cheers to ya.
 
Thanks - it does look as though it's going to be a bit less simple than I'd thought...
I'd already understood about the link between the two files, don't worry - one day when I forgot, I found myself hurtling towards the ground the moment I appeared in the flight! :pop4:

To put it bluntly, what I really want it a 2.XX FM for Craig's D.520. I've been fiddling round with the Firepower one, but it's far too optimistic, I think. GregoryP's got it pretty well right - the D.520 had the reputation of being a temperamental, highly-strung bit-ch to fly, and the 4.00 one really is. But in the meantime, I'd still like to fly it myself...
 
Editing contact points for a model when you don't have access to the mesh in gmax is a total pain since there are no visual tools to help, like ACM for FS8/9.
I've been fiddling with the XDP and AvH light effects to reproduce Jerry's very useful option of putting lights at each contact point with AirWrench (this doesn't work with CFS3 afaik). This isn't simplified by the effects using metric sizes, while aircraft.cfg uses feet! And the coordinates are not in the same order! :isadizzy: Hopefully I'll get a useful tool out of it yet - I'd post a picture, but it's dancat's Mosca and I've caused enough trouble...

The model centre can certainly vary a great deal. Look for the reference datum entry in aircraft.cfg, it's in the [weight and balance] section, to see if the models have their centres at the zero point, and at the empty_weight_CG_position to see where that is by comparison. The stock Tempest V has its model centre at the tip of the spinner as far as I can work out, so the CoG is 9.2 feet aft of this.

If the tailwheel contact point is below ground level, even when fully compressed, then the tail will drop until the next contact point at the tail touches the ground. We've all heard of moling, I call this problem Pershing!
 
hairyspin said:
This isn't simplified by the effects using metric sizes, while aircraft.cfg uses feet!
Click to expand...

Ah! Ya caught me, hairyspin.
Yes, aircraft.cfg is in feet.

Apology on that one. Too many files floating around.

Appreciate you catching my error.
 
ok I know it has nothing to do with contact points but that´s also an issue that sometimes arises...and is a annoying one: why and what could be done with airplanes showing up half sunk in the airfield?
It happens with some airplanes only but it´s very unpleasant!
Could someone here address me to the right direction letting me modifying those (not so many luckily!) airplanes?
Crossram gave at the beginning of december an answer saying it could be solved using an hex editor but it does not explain why this happen only to spawning aircraft in the preflight standby!
Once selected from the menu, that same aircraft shows up normally....

Thks a lot guys, Gianluca
 
According to the modellers here submarining can not be solved. There was a work around on one of the former italian aircraft websites that had modified .bdp files for specific models that would prevent sinking. However that did not fix the model directly and if you accidently deleted or lost that .bdp file then the problem was still there. If it was as easy as a hex edit, then it would be a published tutorial somewhere on this site. Unfortunately unless this has recently changed then there is no such fix!
 
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