I did not have a copy of this original thread but fortunately Felix had copied it over to the FFDS Tips forum. Thank you Felix.
Introduction
I struggled with suspension for a long time before I figured out the simplicity of it. I have been asked and have helped many others with suspension setup and thought maybe this would help here.
There are really only four aspects to this:
1. Provide an ample distance for suspension animation from frames 100 to 200 (tire height~)
2. Vertical distance to ground is the "hanging" (in the air) suspension measured at frame 100 (from Reference point to bottom of tire).
3. Static compression should be measured at max gross weight on the ground and be 75-80% of total animation.
4. Max to static ratio = total animation distance / static compression
Aircraft have more total suspension movement than meets the eye on the ground. Just like with a car on a jack, suspension hanging is quite a distance relative to what you see when it's on the ground. Important: To setup aircraft suspension to improve visuals on takeoffs and landings and eliminate stiffness on the ground, ensure you animate suspension movement to at least 3/4 the height of the tires, more is usually better depending on the aircraft.
Setup in the contact points then becomes critical so that your animation is used fully and responds correctly. For a fully loaded aircraft (which is how I set my suspension visuals), I typically use 75-80% of total suspension movement for static compression. Think about it. Hanging gear plus full gross weight = most of the available suspension movement. Then divide the total distance by the 75-80% ... you get about 1.2 - 1.4 for max-static ratio. This allows all that suspension to be used at gross, allows the suspension to drop on takeoff and gives you a nice, softer landing. Carrier landings are greatly improved with lots of suspension travel.
For a really nice basic graphic explanation of hanging gear, static compression, and fully compressed gear, read this by Jerry Beckwith: http://www.mudpond.org/contact_points.pdf
Setup
Basic steps to suspension setup can easily be accomplished with the design tool and aircraft.cfg open.
Before you start, ensure you have the aircraft properly positioned in your design program so that CoG/FS Reference are where you need them. Example:
http://www.flightsimonline.com/tutorials/s0.JPG
See Lou "Firestriker" Holland's tutorial for more examples: http://www.oregon-coast.net/Tutorials/CofG/index.htm
The suspension setup steps are:
1. Determine vertical distance from CoG/Ref point to fully extended (hanging) gear (keyframe 100)
This is also the distance to the ground when landing and is critical to proper suspension setup.
2. Determine suspension travel distance between frames 100 and 200 (total suspension travel)
3. Convert the vertical distance in meters to feet and update the aircraft.cfg contact point vertical distance to ground.
4. Calculate static and max-to-static ratio and update cfg.
Set the damping to your preference between .7 -1.0. I recommend at least .8 for these suspensions.
You may have to adjust vertical distance to ground by a tenth or so for proper tire-on-ground appearance.
Repeat the steps for the center gear but use around 40% of animated travel
When done, set static height and pitch so the aircraft tires are just a bit off the ground in slew mode, and drops gently when loaded.
If this is done correctly, your suspensions will be more realistic, wheels stay on the ground during rollout, and gear will drop when you depart the runway.
Hope this helps a bit.
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