Could someone please explain the mystery/calculation of the "static_cg_height" setting of the [contact points].

[Downwind66]

This setting should not be "off Limits" to those of us who are NOT developers/flight sim aircraft designers. This setting is not a "one size fits all" and the setting

itself is very critical in allowing the ground spoilers to automatically work or not work. In so many cases I see people posting for help stating their spoilers will not

deploy and they either get no answer or solution(s) or an answer that might be more complicated than need be!

 

I will say this and more!  I do appreciate the work and effort that the flight sim developers put into their work, making our enjoyment more affordable and 

enjoyable! What I see is very nice add-on aircraft being produced with aircraft configured with what appears to be "one size fits all!" I continue to modify

aircraft entries to make the freeware flyable. Such items are Manufacturer = Project Opensky, Project Opensky is not a manufacturer, they might be a created by,

but the manufacturer is an entry such as Boeing, Airbus and the list goes on! We, who have been doing this for awhile know what to look for when trying to get a freeware aircraft to fly! The newbie out there isn't that knowledgeable in this and when they finally get their answer, they probably wonder why the developer

can't get this right! I often ask the same question, but it happens over and over and over! Same goes for aircraft ground spoilers, you could get them to work if 

you had the knowledge to recalculate the "static_cg_height" entry? But, for some reason, this mystery almost gets to the point of being off limits to the

end user! When you get some experience under your belt and manage to take good notes over old issues, you will not have to ask, you can make the corrections yourself and life goes on. I've been simming for a long time and know most of the items to look for, if not, I have to ask for help (like I did yesterday). Some issues are easily fixed, others you have to "seek out" those who know the answers or know where to go to find the answer!

 

Believe me, not judging developers, just asking for help in solving an age old problem. Just get us the calculation, we'll figure it out!

 

Downwind66 (Rick)

 

 

[jgf]

In the cfg file you will find:

"empty_weight_CG_position = 0, 0, 0"

 

This is the coordinates of the center of gravity relative to the physics model (often, but not always, set to 0,0,0).

 

The "static_cg_height" is the distance of this point straight from the runway when the plane is sitting normally.  If this is too high the plane, when loaded, will appear above the runway and drop onto it, if too low the plane will appear with the gear somewhat buried and usually spring into the air;  this setting also works in conjunction with the compression and damping settings of the gear (the cause of the infamous bouncing aircraft or vibrating aircraft). 

 

"static_pitch = " also factors into this as it defines the angle of that line containing the CG position relative to the ground.  (The CG position is always a vertical line measurement.)

 

None of this is easily computed from data in the cfg or air files;  there is a util which will read data from the mdl file from which you can get or compute these values.  Otherwise it is a matter of trial and error and luck to find them.