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Chute movement

An exciting "new" option in FlightGear, that includes reflections, lightmaps, the particle system etc.. A lot is yet to be discovered/implemented!

Chute movement

Postby Thorsten » Tue Dec 06, 2016 11:21 am

Doesn't really come out in a still of course, but I've started work on a shader for chutes. It's based on displacement functions (like the dragon wing animation) and delivers very natural and organic motions.

Image

What you can see here at the edge is a deformation mode of the circular shape (the small see-saw pattern...) - basically this goes into some flapping motion under speed while the centroid of the chute swings in somewhat irregular sines around.

I'm going to try for a fold mode next when the chute is separated (my current idea is to pass a force parameter to the shader that indicates whether there's something heavy pulling at it - that would also give a gross deformation of the chute - and if there's nothing pulling it goes flat and eventually folds into something non-chute. Let's see how this goes...
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Re: Chute movement

Postby Thorsten » Tue Dec 06, 2016 5:46 pm

Here's a short sequence to show a bit better what I'm after:

Drag chute under high load:

Image

Under reduced load, diameter widens:

Image

Just after release, diameter widens to near full, chute goes into a wobble as it is no longer pulled into shape...

Image

... and starts to flutter around as it moves away:

Image
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Re: Chute movement

Postby wlbragg » Tue Dec 06, 2016 7:14 pm

Oooh, that looks really good, exciting stuff!
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Re: Chute movement

Postby Necolatis » Tue Dec 06, 2016 8:42 pm

Very cool.
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Re: Chute movement

Postby Josh_grtuxteam » Wed Dec 07, 2016 12:52 pm

Hi Thorsten,

Would be great , as soon as the process is available i'll give it a try against the SR71 chute, but if it does not work with a specific chute shape, which is at least the case for SR71 .

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Re: Chute movement

Postby Johan G » Wed Dec 07, 2016 2:52 pm

I could bet that NASA has some data that could be useful later on. :wink:

Side note: IIRC they did some studies on parachutes at high altitude supersonic conditions back in the 50's or 60's that has been used as recently as when they sent one of the rovers to Mars.
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Re: Chute movement

Postby Thorsten » Wed Dec 07, 2016 3:19 pm

but if it does not work with a specific chute shape, which is at least the case for SR71 .


It requires a specific arrangement of your model coordinate system. Which you can always do with your 3d modeling software - and then rotate/translate via animation into desired position in FG. And it requires to pass 3d-model specific parameters. Which you have to measure.

And it's for radially symmetric chutes (no paragliders) - which the Blackbird has.
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Re: Chute movement

Postby Josh_grtuxteam » Wed Dec 07, 2016 5:39 pm

But misunderstanding about "radially symmetric" i am not sure this will answer the feature

here the real one

Image

here the model one

Image




right now animated with conventional animation pitch, heading, translate horizontal/vertical and scale

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Re: Chute movement

Postby Thorsten » Wed Dec 07, 2016 5:52 pm

Good enough I guess.
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Re: Chute movement

Postby wkitty42 » Thu Dec 08, 2016 1:47 am

looks close enough to radial symmetry for government work ;)
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Re: Chute movement

Postby Thorsten » Thu Dec 08, 2016 10:12 am

I've now pushed a first fully integrated version of the animation (including jettison sequence) to the Shuttle repository for testing and refinement.

Wayne, you managed to make a video of the dragon - think you can shoot one of this? It really doesn't come out well in still images.

(I've found saving the state a few seconds before touchdown and then simply resuming that and deploying gear quickly rather useful for testing)
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Re: Chute movement

Postby Thorsten » Fri Dec 09, 2016 8:01 am

Just tested the shader effect with the Lightning drag chute - after adapting the geometry of the model to the required coordinate system, it seems to work 'as is', i.e. without any additional scaling or control parameters required.

(Sorry, since the SR-71 didn't make it to FGAddon, I can't use it as second test case)

So I'll prepare it for FGData over the next days.
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Re: Chute movement

Postby Thorsten » Sun Dec 11, 2016 8:42 am

Pushed to FGData, some documentation on the wiki.
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Re: Chute movement

Postby Thorsten » Thu Dec 15, 2016 7:38 am

Wayne captured this (not the best quality) - it gives an impression of the movement:

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