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FS2004 Proper Contact Points for Complex Gear

FSMuseum

FSMuseum

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232
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us-kentucky
Hi all,

Back again on my 747, I've found that I'm very dissatisfied with how the landing gear behaves on the ground and during takeoff/landing.

I am using the CLS 747 as the base model, and have been editing contact points for days now. I can't seem to get the behavior I want out of them. The wheels sink into the ground when rotating or touching down, and it seems like I can't find compression values that will make them sit nice and pretty on the ground when standing still or just rolling.

Also of note, I can't seem to get the ground steering quite right either, which I know is related to this. The nose gear can turn 70 degrees either way, and the center body gear can turn 13 degrees. This should give more than adequate turn radius according to my TWA 747-100 manual, but even at speeds below the manual's recommended 5 knots for tight turns, it just does not have the turning radius of the real thing. The nosewheel skids at high deflection even at speeds as low as 3 knots. The plane also seems to slow down far too quickly when taking curves.

I have been using MCX to manually extract values for the compression of the gear, and to verify my contact point positions.

What can I do to make this complex gear system work nicely?
 
hairyspin

hairyspin

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unitedkingdom
You can't get the main gear bogies to articulate at take-off rotation or landing using standard FS9 animations, which only assume a single wheel touching the ground. This can be done in FSX/P3D which let you animate almost anything at the cost of working out how to code ground proximity, pitch angle and similar considerations. I don't know if this is possible in FS9, but no doubt others will know.
 
tgibson

tgibson

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You can do almost all FSX "standard" animations in FS9. There are very few you cannot, and some can be worked around (like substituting prop animations for N1). The things that don't work for sure are related to SimConnect.
 
hairyspin

hairyspin

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unitedkingdom
What I meant was in FS9 you animate the gear oleo compression/extension, label it correctly and FS9 does the rest, but there's no bogie rotation label which will detect the conditions and keep the bogies flat on the runway as the co-pilot calls "Rotate!" A custom animation will be needed with code to drive it.
 
FSMuseum

FSMuseum

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232
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us-kentucky
The CLS model seems to have these animations in XML. I can partially rotate the 747 and even though the gear is sunk in the ground, it gives the appearance of being slightly tilted, as though the front wheel of the bogie should be off the ground while the aft wheel is not.

This leads me to believe that, if I set up the contact points correctly, I can make the wheels look really nice both in flight and on the ground. My questions then are how should I set up the contact points and suspension if it is possible, and also will I have to sacrifice ground maneuverability the make it look nice?
 
hairyspin

hairyspin

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unitedkingdom
There aren't any, but a custom-coded definition can be added to MODELDEF.XML to control a suitable animation. Such code might check the gear is extended fully, then calculate bogie angle depending on the aircraft's height above ground or the aircraft's AoA if on the ground. This would be separate from and in addition to gear extension/retraction animations, best applied to the wheel bogies themselves. The contact points would be as if for single wheels in place of the bogies, with a wheel diameter the same as the actual wheels.
 
tgibson

tgibson

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11,338
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us-california
Got it. These custom animations can be added to the makemdl.parts.xml file (in FS9 format) and used in FS9 as well.
 
Paul Domingue

Paul Domingue

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1,530
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us-california
Here is a thought, why not add a second set of gear, not modeled but using compression to activate the rotation of the bogies? In my mind that should work using dummies and reduce the complications of additional code. Might be worth a try.
 
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