Military AI Works

Observations by an ignoramus.

My observations in bold behind original text.

//----- MODEL PARMS

//0 Class
//1 Longitudinal Position (feet)
//2 Lateral Position (feet)
//3 Vertical Position (feet) Vertical distance at max extension (key frame 100)
//4 Impact Damage Threshold (Feet Per Minute)
//5 Brake Map (0=None, 1=Left, 2=Right)
//6 Wheel Radius (feet)
//7 Steer Angle (degrees)
//8 Static Compression (feet) (0 if rigid) Max compression, vertical distance between keyframe 100 to keyframe 200
//9 Max/Static Compression Ratio Distance of max compression devided by distance of static compression.
//10 Damping Ratio (0=Undamped, 1=Critically Damped)
//11 Extension Time (seconds)
//12 Retraction Time (seconds)
//13 Sound Type

[contact_points]
max_number_of_points = 21
point.0 = 1, 3.1, 0.0, -2.65, 10000, 0, 0.50, 90, 0.42, 2.0, 0.7, 3.0, 2.0, 0, 139.92, 187.07
point.1 = 1, -3.9, -4.5, -2.735, 10000, 1, 0.630, 0, 0.37, 2.0, 0.9, 4.7, 4.9, 2, 139.92, 187.07
point.2 = 1, -3.9, 4.5, -2.735, 10000, 2, 0.630, 0, 0.37, 2.0, 0.9, 5.0, 5.2, 3, 139.92, 187.07


These distances need to be measured in the 3d program, Gmax, FSDS or your program.

3. Vertical position. Vertical distance from bottom of wheel at max extension to plane of model centre. Keyframe 100

8. Static compression should be MAX COMPRESSION. Distance your animation moves up between key 100 to position at key 200.

To get static CFG height.
Move your animation slider in the 3d graphics program to where the gear looks correct for static.
Measure the travel upward from max extension (keyframe 100) to where you have it at keyframe X.

This distance is used to work out the Max/Static compression ratio. Devide the max compressiom travel by the distance you measured above to get the ratio.

The static CG height is the vertical distance between the bottom of the main wheel and the plane of the Centre of gravity, that you have decided, measured at this keyframe position. This is assuming the CG is above or below the centre of the model.

Static pitch. Use the tape measure function to measure the angle from the bottom of the main wheel to the bottom of the nose wheel. This angle is measured from the horizontal.

I hope this saves a huge amount of otherwise wasted time. Rant deleted.

John

Now I know why wise people talk less and listen more.

Correction to the above post

//8 Static Compression (feet) (0 if rigid) Vertical distance between keyframe 100 to keyframe 150.
//9 Max/Static Compression Ratio Distance of max compression (keyframe 200 - 100) devided by distance of static compression (keyframe 150 -100). Normally 2.0, unless you have animation other than default.

I have full extension at keyframe 100 and max compression at keyframe 200. Nothing in between.

John

JohnTenn wrote:Now I know why wise people talk less and listen more.

Yep.....

Looks to me as if you have already read the Microsoft SDK document inside the aircraft container folder. Lots of good info in that if you haven't.

John,

This is an area of AI aircraft model development that if understood and applied properly by more AI aircraft model developers would lead to much more realistic landing gear compression, less landing gear problems and much less trial an error when AI FDE developers like me develop AI FDE's for their AI aircraft models. I can count on one hand the number of AI FDE developers that I have ever received actual static compression, maximum compression and/or compression ratio values from.

I've attached below a document entitled "How to Configure Landing Gear Contact Points for FS2004" written by Jerry Beckwith that I refer to quite often while creating AI FDE's that you and others might find helpful.

The question becomes is it really worth it to add compression to an AI model's landing gear?? How many people will actually notice it if it does have compression? The C-135 series I made has compression but I've never heard a single person comment on it. To me it's one of those things that is wasted time and energy for an AI model.

Does it make the model behave better on landing if it does have compression built in??

I'm with Mike M on that one. The beauty of the gear compression is when the aircraft is moving on the ground and the nose dips when braking. If the nose oleo is considerably extended (like on an F-4 or a B-29) on approach to land, then it does look more authentic to include it.

I've generally found it a tricky thing to get right, even with Jerry's tutorial. I think there's some useful clarity in John T's post that I've copied for future reference. Thanks John for that post.

John Y

MIKE JG wrote:The question becomes is it really worth it to add compression to an AI model's landing gear?? How many people will actually notice it if it does have compression? The C-135 series I made has compression but I've never heard a single person comment on it. To me it's one of those things that is wasted time and energy for an AI model.

Certainly the return on the investment in time and energy is a very important consideration and as you say many if not most users will never even notice or comment on the results.

I'm certainly biased by both my passion for realism and my reluctant acceptance of the fact that most if not all of the realism that I build into my AI FDE's is seldom either observed or commented on. I guess I've gotten so used to it, it doesn't bother me that much any more.

Does it make the model behave better on landing if it does have compression built in??

Perhaps it is all in the eye of the beholder, but personally I think it does. However, it definitely makes taxiing, takeoffs and landings much more realistic when observed in spot view.

In the end of course it is always up to the discretion of the AI model developer what he chooses to spend his time on animating in his AI models.

As a novice to this discussion.

Personally, I believe the limits of what is possible has been pushed so far by may talented developers of all flightsim aircraft, that I have almost come expect a new model to have all the bells and whistles. That was until I tried to do it.

Have any of you seen the new FSpainter model for the A350-900?

Back to the original subject.

I figured that because the simulation is a mathematical model there must be defined parameters that give defined outcomes. I must be able to measure something, insert the data and get the expected result.

This was almost all true from my animation of the SF.260 gear. I made the positions I wanted the gear to be at, based on photographs. I then manipulated the position of full extension to where I wanted it. Then manipulated the 150 keyframe position and the doubled the travel to the 200 keyframe postion. The normal compression is always half way from 100 to 200, in my limited experience anyway.

Dispensing with realism, I plugged in the numbers and to my surprise it worked. The only challenge is when you change the static pitch, but then you are working from a known point. So much so than I even lowered the model by one inch to simulate the flattening of the tyre.

The damping ratio is very important in determining how far the oleo's compress while in the sim.

I have read my tutorials and found many to be contradictory or at least unclear, written I suspect for people trying to change the effects on models which they did not create.

Many thanks for this discussion and not kicking me to the curb after the first post. I feel like I was the self enlightened newbie who knew it all, or believed he did.

John

Gmax can be quite tricky when measuring the distance from the origin. View modes and making sure no objects are selected etc.