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Author Topic: Help required  (Read 1137 times)

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Stainless

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Help required
« on: November 03, 2017, 03:09:28 AM »

I have changed the way the flight dynamic model works to make it more realistic.

The system that most people use (including JBSIM and YASIM used in flight gear) makes approximations about key elements. Like fuel tanks. A fuel tank is basically modeled as a cylinder as far as the physics is concerned. This is better than just ignoring it and just treating it as part of the aircraft's mass, but is pretty crude.

I also want to have a lot of realistic damage effects. So fuel tanks can be holed, hydraulics damaged, radio, engine and radar can take hits.

I realised yesterday that it is easy to do both things.

The physics engine I am using can handle objects as meshes. So you add a collision mesh to the msh file that defines the shape and location of a fuel tank, I pass that into the physics system and it calculates the inertia tensor from the shape. I just need to play with the mass and the shape as the fuel level decreases.

With the addition of other collision meshes as well it removes the randomness in the damage code. So you can actually target weak points in an aircraft and get the results you expect. Also if your aircraft gets hit, you have to manage the damage. Pumping fuel from damaged tanks to undamaged ones. Using the MFD HUD repeater if the HUD gets damaged. Anything we can think of.

Of course that does mean that someone has to add these collision meshes to the aircraft.

At the moment the only two I need doing are the F16 and something for it to go up against. I can't see a modern mig in the list, but anything would do.

Once I have something to work with it other aircraft can wait until I have released something you can play with.

Anyone interested?
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Pursuivant

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Re: Help required
« Reply #1 on: November 05, 2017, 03:08:38 PM »

Very cool that you are planning these things, it will go a long way to making the flight and and damage models more realistic, and might eventually allow for more realistic simulation of fluid dynamics for things like leaking tanks or deliberate fluid ejections like fuel dumping, sprayed liquids, or in-flight refueling. It would also allow for realistic calculations of things like fuel starvation for planes which don't have fuel injectors or pressurized fuel systems.

If you wanted to get even more complex with the damage modeling, please possibly consider some mechanism for modeling the mechanical properties different materials as well as the basic physics of hydrostatic shock on fluid-filled containers. That would allow the damage absorption capacities and fluid loss properties of a "self-sealing" fuel cell to be modeled differently from those of a bullet hitting a solid metal tank. (More simply it would allow correct "damage decals" to be applied to hits on external parts made from different materials - splintering for wood or composites, tears and flapping material for canvas, punched holes for metal.)
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Stainless

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Re: Help required
« Reply #2 on: November 06, 2017, 11:46:06 AM »

Damage application based on materials is already planned..... well actually started would be a better phrase.

Fuel tanks have a type specifier, which ranges form ... well .. bucket, to self healing synthetic.

I haven't got around to the code yet, but it's in the pipeline.  :D

I am only mortal, but I am a damn good mortal.  8)
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Dimlee

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Re: Help required
« Reply #3 on: November 06, 2017, 12:26:40 PM »

Just wonder would it be possible to simulate different effects of a bullet penetration of:
- full tank - fuel leaking as the only result
- empty/almost empty tank full of vapours - immediate detonation
- empty tank equipped with inerting system - no other result than holes.
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Stainless

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Re: Help required
« Reply #4 on: November 06, 2017, 11:11:25 PM »

Just wonder would it be possible to simulate different effects of a bullet penetration of:
- full tank - fuel leaking as the only result
- empty/almost empty tank full of vapours - immediate detonation
- empty tank equipped with inerting system - no other result than holes.

Yes. I have also built in a fuel type variable. So a tank filled with modern avgas behaves differently from a solid rocket booster, or exotic fuels like HTP etc.
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