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Contact Points Question

I downloaded this aircraft and fixed the front wheels in the aircraft.cfg. The ground layer was above the top of the wheels. Only the front. Rear were correct. Then I open SAMM and select the new aircraft.
When finished, the static model front wheels were below the ground layer again. Is there a way to correct this?
 

gadgets

Resource contributor
By fixing the front wheel, I assume you mean you edited the static pitch and c/g height.

If so, it would seem that SAMM didn't see the revised aircraft.cfg when it generated the static model. (Do you have more than one copy of this aircraft?) Fortunately, you can fix this with the Static Position editor, initiated from the Main Panel.

Alternately, make sure SAMM is "pointed" to the aircraft with the edited aircraft.cfg file and regenerate the static model. Be aware, however, that, depending on how the model is designed, you may need to tweak the c/g height anyway for the static model to sit properly on its wheels

Don
 
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Thanks for the reply. This is what I did. I lowered the 22.166667 to 19.166667.
[contact_points]
point.0=1.000000,22.166667,0.000000
I will try to lower this static_cg_height thing. Never tried this before.
static_cg_height=4.917881
I had both a copy of the aircraft.cfg and the default aircraft.cfg. Can this cause a problem? Many Thanks.
 

gadgets

Resource contributor
I don't think adjusting the contact point locations is going to correct the problem within flightsim. Such changes wont even be seen by SAMM - which is why your static model didn't "react"

The proper way to adjust how the aircraft sits on the ground is to adjust the static_pitch and static_cg_height entries in the [contact points] block.

Don
 

gadgets

Resource contributor
So static aircraft models don't use the contact points themselves? Interesting!
Why do you think they should? The static model is essentially the aircraft model with all the animations removed to make execution more efficient?

Don
 

hairyspin

Resource contributor
I'm an animated aircraft builder Don, but always looking to understand more. Thanks for the reply: it makes sense to me. :cool:
 
Contact points are not an accurate way to calculate the model location, altitude above ground and pitch because they are subject to slight variations depending on the aircraft loadings (fuel, payloads, etc.) If one is to take those into account, he/she has to build an entire engine to handle that (almost the same as FS) and/or know well about each model behaviour (their gear compression system) to be converted in a static one (how the gears were 3D modeled and how their compression would affect pitch and CG height)
^^ so, it's a "no-go" due to the thousands of aircraft out there that may be processed through SAMM, and all have their own slight differences.
Although I don't know much about SAMM because I don't make static aircraft out of models I download, I guess the CG heigth and the static pitch are the best alternative to keep things simple for everyone. The other way around, if you were to explain to each SAMM user that gear strut anim compression goes from keyframe 100 to 120/125 for immediate compression, and 120/125 to 200 for maximum load compression, and ask them to check the induced pitch depending on how much "loading" they would like to have, no one would sort it out... Best would to select an arbitrary keyframe in between where to freeze the gear compression animation state, and let user provide CG Heigh and static pitch on their own, by simply editing the Aircraft.cfg..

I may be wrong here, knowing almost nothing about SAMM, of course. :)
 

gadgets

Resource contributor
Thanks, Karl

if you were to explain to each SAMM user that gear strut anim compression goes from ...
I'm a little skeptical about how successful that would be. Basically, SAMM isolates each animation, creates a static transform reflecting the default (or user-selected optional position) for that animation and then discards the animation. For the gear, SAMM sets gear compression to the default on-ground value and positions the static model at the aircraft.cfg value for static pitch and static_cg_height.

SAMM also provides an editor allowing the user to easily adjust those static parameters (for the static model).

So, I don't think there's a problem or deficiency - other than a user attempted to adjust aircraft static position by editing the contact point locations which SAMM doesn't read and I doubt would have the desired effect withing FS..

Don
 
Gadgets, just a bit of a update. After trying a few times with the static_cg_height, now all three wheels are below ground level.
So I will continue to work with this. Viewing the aircraft in MCX looks very level. Hopefully, I will go back to the aircraft.cfg and raise the complete aircraft. Many thanks to all for the reply's. See what happens.
 

gadgets

Resource contributor
If the aircraft sits OK in FS, I suggest you do your adjustments with SAMMs static position editor. If you do adjust the static position in aircraft.cfg, make sure the aircraft sits properly in FS before tryting to create a static model.

Don
 

hairyspin

Resource contributor
This is more fun than first met the eye! For a SimObject model like an aircraft, static height and pitch determine where the model first appears in the sim. Then gravity takes over and the aircraft drops until it settles to its contact points on the ground, but in FSX we usually don't see this settling while scenery, autogen and static models are being loaded. In older FS versions and especially in CFS3 you would see this. Where static height is wildly wrong and can be seen to be wrong is in Slew mode when static height and pitch determine where the model starts before engaging warp drive. I sometimes suggest people try setting static height to a couple of thousand feet in the .cfg to see how long their model takes to crash on the runway.

For SAMM it makes sense that a static model is placed with the static numbers. It's not even going to move around like AI models.

Default gear compression for FSX is at keyframe 150, btw.
 
Hi folks,
I hope this is not piggybacking onto a separate topic;
[edited:]

Thanks for the comments below Don,

I've deleted the extraneous material so I can find a better place for it. After I do a little more experimenting that is.

Larry
 
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gadgets

Resource contributor
Larry, if you are asking with regard to flying aircraft, you might have better luck in another forum.

As regards SAMM, contact points aren't considered. I simply set the model at the static CofG and pitch parameters from the aircraft.cfg file. If the user is not happy with the result, the he/she can adjust both from SAMM's main panel. Generally there are wide variations in the accuracy of these two aircraft.cfg values. I suspect some designers don't take static gear compression into account.

Hopefully, others can shed more light on the topic.

Don
 

Paul Domingue

Resource contributor
Please excuse this question because it's out of ignorance but isn't static aircraft just another piece of scenery and shouldn't be placed the same as any other scenery object?
 
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