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Better nort crash

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Better nort crash

Postby StuartC » Thu Jun 05, 2014 9:46 pm

Because this will happen, soon.......


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Re: Better nort crash

Postby radi » Thu Jun 05, 2014 10:27 pm

Nice job, especially keeping the structure almost intact for the 'flat drop' :D
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Re: Better nort crash

Postby Hooray » Thu Jun 05, 2014 10:46 pm

that's pretty cool, is that a static animation, is it scripted, or does possibly even use JSBSim submodels ?
Also, check out: Subject: Visualising crashes in FG
Gijs wrote:
mattt wrote:Would it not be highly groovacious if we could take events like this as they are reported and model them as accurately as the data we could obtain and release the results to the media (or other interested parties, like accident investigators, etc)?

That came up in my mind aswell, back in 2009 after the Turkish crash at Schiphol. We can easily visualise flightpaths, which would be cool for (local) news stations. Visualising, the damaging/actual crash is a "little" harder though, but stuff like this might increase the development of crash simulation in FG...



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Re: Better nort crash

Postby StuartC » Fri Jun 06, 2014 8:47 am

Thom has been working away on the Damage systems ( like code in the V1 he did ), and this is the latest upcoming expansion for the damage system. Its Nasal, not JSBsim, and will eventually work/be seen over MP as well. Being Nasal, it should be adaptable to most aircraft in the end.
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Re: Better nort crash

Postby KL-666 » Fri Jun 06, 2014 1:05 pm

This will be very educational for all the people flying subsonic jetliners faster than mach 1. But it will be of the utmost importance to get the limits right. Do the planes only explode, or is there also minor structural damage possible? Little overspeed, or pulling flaps a little early, do not normally completely destruct the aircraft.

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Re: Better nort crash

Postby StuartC » Fri Jun 06, 2014 1:15 pm

It should be scalable eventually. Its only part of a number of systems thats being put together.


How about a bird strike knocking out one or more engines ?


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Re: Better nort crash

Postby Johan G » Fri Jun 06, 2014 1:36 pm

StuartC wrote in Thu Jun 05, 2014 9:46 pm:Because this will happen, soon.......

It is a good start, but I think that it disintegrates a bit much. :wink:

Having looked at about an hour of aircraft crash videos and compilations on YouTube now (from GA to aerobatics to high-performance military aircraft) I notice a few things:
  • Most aircraft hold together better than that, and when they break apart they tend to do that in larger sections (for example wings, nose, tail, engine nacelles) and with things still attached to parts breaking off.
  • That being said, hitting the deck from higher angles (like 30 degrees and upward) and with higher than merely stall speed they do indeed tend to break apart like that.
  • When hitting the deck at very low angles and at lower airspeeds (in essence failed landings) they are more or less intact, but often bent.
  • Failed take-offs are worse than failed landings due to higher airspeed and altitude and the aircraft will almost always at least bend or loose a wing or two (or worse if the airspeed and/or altitude is higher).
You have probably not started on the fireball, but I made some observations there as well:
  • Pretty much any airspeed higher than stall speed tend to produce a fireball, even if the aircraft does not break apart (hint: over-stressing wings and airframe ruptures fuel tanks).
  • High-performance and/or larger aircraft have bigger engines that needs more fuel and will produce a larger fireball. In essence small GA aircraft will only burn, while a fully fueled jet fighter or a cargo plane will more or less explode in a most spectacular way.
  • The fireball tend to mushroom at impacts with low horizontal speed and form a "fluffy cone" at higher horizontal airspeeds (something like spheres expanding along the impact path that rises in approximately the same rate as the expand).
  • The fireball quickly (within a few to some ten seconds, probably depending on the fuel available) settles to an red to orange inferno close to fuselage and wings (where the fuel is) and produce completely opaque dark gray to black smoke.

EDIT:
StuartC wrote in Fri Jun 06, 2014 1:15 pm:How about a bird strike knocking out one or more engines ?

Ooh, nice. :D

Brings this to mind: "Hit birds. We've lost thrust on both engines. We're turning back towards LaGuardia." :wink: Time flies, it's already five years ago.

I realized that a bird strike script could sample the terrain land class and increase the possibility for a bird strike in certain conditions, like where water and land meets, along beaches and over wetlands, as well as increase the possibility at lower altitudes. Something for the future I guess.
Last edited by Johan G on Fri Jun 06, 2014 2:00 pm, edited 1 time in total.
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Re: Better nort crash

Postby StuartC » Fri Jun 06, 2014 1:42 pm

Someone mention fireball, lol

Image


That WAS an SU-47. Crash explosion, fireball and sound etc are currently just ported from the V1 at the moment but Algy thinks it should be possible to scale it depending on aircraft size/fuel/payload eventually.
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Re: Better nort crash

Postby Johan G » Fri Jun 06, 2014 2:30 pm

Regarding bird strikes I stumbled upon this again:

Bird Aircraft Strike Hazard / Dangerous Encounters - 1974 US Air Force Educational Documentary (22 minutes)


Note that there is also some statistics (11 minutes in), like time of day, time of year and altitude (AGL I guess) where the probability of a bird strike increases.
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Re: Better nort crash

Postby Hooray » Fri Jun 06, 2014 4:10 pm

StuartC wrote in Fri Jun 06, 2014 8:47 am:Thom has been working away on the Damage systems ( like code in the V1 he did ), and this is the latest upcoming expansion for the damage system. Its Nasal, not JSBsim, and will eventually work/be seen over MP as well. Being Nasal, it should be adaptable to most aircraft in the end.


thanks for clarifying, good to know - I agree, that using Nasal here makes sense if it's supposed to work with different FDM engines.


StuartC wrote in Fri Jun 06, 2014 1:15 pm:It should be scalable eventually. Its only part of a number of systems thats being put together.

This being implemented in Nasal, I suggest that you post your code here (or use gitorious) so that others can provide feedback.
Also, you should be aware of galvedro's work which is probably going to be available in 3.2: http://wiki.flightgear.org/A_Failure_Ma ... FlightGear

How about a bird strike knocking out one or more engines ?

A long time ago, I actually put together a simple Nasal script (based on tanker.nas) that would allow AI-controlled bird strikes: Subject: bird

Hooray wrote:We already have some birds - that are used by glider pilots to find thermals. If you are looking for something a little more sophisticated, you can use the AI traffic system, which is fully scriptable using Nasal - FlightGear really doesn't care what type of 3D model you are using, so it doesn't matter if it's a tanker, fox2 missile, f14b or the 3D model of a bird:

Subject: Bird strikes script

Hooray wrote:Just to prove my point: It really doesn't take any longer than say 2-3 minutes to open the tanker.nas script, change the model file name to point to the 3D model of a bird, what you end up with is a "funny bird" flying at 330+ kts ground speed at 17000 ft AMSL (I took the first freely available bird model that I could find...):

Image

As a next step, one could change the heuristics that move the bird (assuming that you don't want it to keep flying refueling patterns...), making it search actual thermals (local weather) would also not seem too complicated - it would just involve calls into the local weather code.

Probably, you'll want to add some collision detection code then.
Once this is working, you may want to animate the whole thing and probably change its size, too.

Like I said, it's all perfectly possible with the tanker.nas script.

Also, please do let me know if you need help creating "effect contrails" out of feathers and blood, okay :lol:


I realized that a bird strike script could sample the terrain land class and increase the possibility for a bird strike in certain conditions, like where water and land meets, along beaches and over wetlands, as well as increase the possibility at lower altitudes. Something for the future I guess.

those are the kind of heuristics made possible through geodinfo(), and implemented by AW
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Re: Better nort crash

Postby StuartC » Fri Jun 06, 2014 4:41 pm

Actually, we have the feathers since that video was taken...............
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Re: Better nort crash

Postby Algernon » Sat Jun 07, 2014 9:58 pm

As yes, the birdstrike code does definitely have a cloud of feathers, that was the whole reason I started work on it!! I should point out that in the video of the Victor engine being struck, the bird had a titanium skeleton and was packed with explosives (the severity of the strike was multipled several times in order to cause an explosion for dramatic effect) - one Victor engine once ingested 11 seagulls and kept turning (obviously they shut it down just in case). Exhaust product modelling is, of course, most welcome!

For info, the damage system seen in operation in the birdstrike video is running alongside a modified version of generic-yasim-engines.nas, which then interacts with FG's existing failures system to trigger unservicabilities (in the video, the engine is pretty much destroyed, but light engine damage results first in RPM and thrust loss, then loss of oil pressure, without which the likelihood of failure goes up.
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Re: Better nort crash

Postby Thorsten » Sun Jun 08, 2014 5:15 am

I think that's a really neat feature - I like how the different impact scenarios lead to a very different debris dispersion! Keep it up!
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Re: Better nort crash

Postby HJ1AN » Sun Jun 08, 2014 5:44 am

Love the crashes. The 'flat drop' is a bit unrealistic though... i mean it droped what about 3-4 feet and the wings broke like styrofoam lol. Hopefully that is just demo and you can make the breaking limit higher so we can perform belly landings and whatnot.
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Re: Better nort crash

Postby Algernon » Sun Jun 08, 2014 9:21 am

Yes, the flat drop is just a demo I think, I know that belly landings are on the cards as we've been talking about how to achieve this in YASim using small (obviously invisible) wheels underneath the fuselage.
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