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Physics of Decompression in Aircraft.

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Ok to start with i don't really know if this should go here at all. But anyway, i have an idea for a 3rd person shooter, that i am trying to make a realistic as reasonablely possible, where the main protaganist escapes as a stowaway in a cargo plane, and i was thinking about some of the physics associated with aircraft decompression. I know as much that there are three types of decompression, Explosive Decompression, Rapid decompression and Gradual Decompression. I don't want Explosive Decompression because that would just ruin the scene.Please try to find the most realistic answers.
Here are my questions:
  • Firstly in the cargo hold part of the plane it is only going to be hand to hand combat so that the plane won't fall out of the sky straight away, but anyway i wanted to have a part where a jeep is in the back of the plane near the cargo door, and a group of enemies run up behind it as cover, so i thought you could open the door and shot the anchors holding the jeep in place ( not shooting the plane though ), so it rolls back through the door taking the enemies with it.[font="Verdana"] [color="#ff0000"]If i did this would the plane lose altitude or stay the same height (so i know if the door needs to be closed again afterwards), also would this cause decompression for the rest of the plane?[/font]
  • [color="#000000"]Secondly, when the level progresses to the seating area the enemies will start to use guns because they ain't afraid of taking their lives for yours. So i was thinking that i wanted the enemies to shoot the windows, i know that one bullet hole will cause gradual decompression, [color="#ff0000"]but how many will cause a big hole to form in the side of the plane?
  • [color="#ff0000"]Thirdly, when a hole is formed will objects such as seats and trolleys fly out the hole, but not people, because i wanted something to hit one of the engines?
  • [color="#ff0000"]Next, what type of decompression will this be?Sorry if this is in the wrong place and waffles on but i would really like some answers. Can you please be as detailed as you can, and send links if you know any?

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If i did this would the plane lose altitude or stay the same height (so i know if the door needs to be closed again afterwards), also would this cause decompression for the rest of the plane?[/quote]
There is no reason for the plane to lose altitude, unless the plane gets structural damage that impedes it from flying. The reason why planes lose altitude is because the pilot has to. He needs to equalise the cabin pressure to ensure the survival of the passengers.

but how many will cause a big hole to form in the side of the plane?[/quote]
Unless you use a minigun to saw the chassis in half, you won't see much effect. The hull of a plane is incredibly strong. It has many layers that prevent it from tearing. Even the windows are designed in layers for that very reason. I think Mythbusters did an episode on that - something worthwhile to chase up.

Thirdly, when a hole is formed will objects such as seats and trolleys fly out the hole, but not people, because i wanted something to hit one of the engines?[/quote]
If the hull blows out explosively (about the size of a car), yes maybe, but only nearby objects at the hole. If you have a window sized hole and the air flows out rapidly, probably not, except for light loose objects, such as paper, clothes, adjacent food trays at worst. The internal air pressure equalises quickly, and as soon as that happens, stuff won't be blown out.

There was a plane where an entire roof section got torn off due to structural failure of some sort. Almost all passengers were accounted for.

Google is a good friend. You should start reading up on this, here is a start:
https://secure.wikimedia.org/wikipedia/en/wiki/Uncontrolled_decompression
https://secure.wikimedia.org/wikipedia/en/wiki/Cabin_pressurization

If you want the scenario to be very realistic, then your protagonist should pass out in just 2 minutes upon loss of pressure, then die of asphyxiation. Especially because he won't have the privilege to access an oxygen mask in the cargo bay, like his fellow paying passenger do. Now, that wouldn't be much fun to play as a game.

Of course, depends what type of plane it is, I guess cargo planes would fly at much lower altitude as passenger airliners.

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Thanks for the answers!!! Ok so there is no way i can make it realistic as possible, except to a certain degree. Furthermore the type of plane i was thinking of was a Antonov AN 125, so something like that. [color="#ff0000"]So i could have the cargo door open then? But not without the main character just dropping dead. So i could have the main character grab a oxygen tank and mask on the way in, and the enemies have personal oxygen supplies thus maybe leading to a stealth section where you can take their masks off, i might have to look up more about asphyxiation for what the immedeate symptoms are. [color="#ff0000"]So would this happen before the door opened or after?
[color="#000000"]Next , i would be able to have a shooting section in the seating area, [color="#ff0000"]but what about if a window got shot out a things flew out would they make the hole bigger thus leading to the engine blowing out?[color="#000000"] I am not bothered about bending the truth a bit. [color="#ff0000"]Also would there be any use of the oxygen tank at this part, since the window is getting "blown" out?



[color="#000000"]I would be very thankful for your help again, and any ideas that you think would fit into this scene would be really appreciated. But please make it as realistic to a certain degree.

P.S I think that the plane is called that, but if you look it is just a cargo plane i am going to modify it to my needs by adding a small passenger deck and then a VIP lounge above that. Also if you look this plane opens up via all the back, i wanted only a ramp style door if you know what i mean.
[EDIT] The plane is the Antonov An-225.

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So i could have the cargo door open then? [/quote]
Antonov's are high altitude, so if your bloke tries to be heroic way up there, he won't go far. Also, opening the door that high could be problematic. Pressure difference could create an explosive decompression scenario... no idea. I don't know how the lock mechanism works on the Antonov, there might be heaps of safety measures preventing you from opening it in mid flight. These planes are so massive, that structural integrity depends on the doors being closed. Don't quote me on that, but if that is true, you can't open it while the plane is off the ground.

So i could have the main character grab a oxygen tank and mask on the way in, and the enemies have personal oxygen supplies thus maybe leading to a stealth section where you can take their masks off, i might have to look up more about asphyxiation for what the immedeate symptoms are. [/quote]
Cargo planes could have emergency masks dotted around the place. I have no idea where, you actually need to research the plane itself. In most cases they are affixed to the plane (al least in passenger airliners), so no portable O2 bottles.

but what about if a window got shot out a things flew out would they make the hole bigger thus leading to the engine blowing out?[/quote]
Check my previous post. A simple window blow-out does nothing significant.

Also would there be any use of the oxygen tank at this part, since the window is getting "blown" out? [/quote]
As i said before, some planes do not have O2 tanks lying around. When the cabin pressure drops, you have masks dropping down from the ceiling over the passengers.


This is what you should do. Pick a plane make and model you want to base the game on, which in this case is the Antonov. Research and study it's capabilities. What it can carry. Where the internal components are, such as masks, fuel tanks, compartments, windows, etc, etc. Research how the plane was built, what materials it uses, what the windows are made of. Once you get all that info, you can plan your scenario in the game.


But you know what? Do something that it's fun. The setting doesn't have to be 100% replica of the plane.

You want the window to blow out and take out an engine due to a passenger falling into it?
Do it.

You want the protagonist to survive more than 30 minutes after decompression?
Do it. Just make up a background story that the protagonist is an experienced mountain climber and was on Everest many times before.

You want to open cargo doors, 2 km in altitude?
Do it.

You want to alter the plane's design and specs for your game?
Do it. Just pretend that the Antonov is a custom plane for a particular purpose. Perfectly plausible in the real world.

At the end of the day, who cares if some events are not physically accurate. It's perfectly ok to ignore some minor technical details for the sake of supporting the story and the game play, as long as you don't do blatant obvious violation of physics (visually at least). But even then, players will forgive you, as they seen dodgy physics in many other games before. The main thing is, whatever happens in that plane, it should look and feel believable. You want to give the player a fun experience.

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Thank You again for all the help!!! I am going to make the plane a custom plane anyway. I should have told you more of the backstory of the game. It is going to be a Third Person Shooter, and you take control of a agencys best Spy. The game is based around global conspiracy, so it has corrupt presidents, officials and terrorists.So anyway at the airplane scene you get chased out of a airport (Miami International to be exact)by secret service after trying to find your wifes killer, and heading to Shanghai you stowaway on a customised Antonov AN-225 which is coincidentally heading to Shanghai.

If you would like to tell me your ideas for the plane scene go ahead.

Furthermore because he is like a top spy/killer he has training for situations so he can survive longer in the plane.

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Interesting concept - will there be any snakes on the plane? :P

You could do other scenarios, such as crippling the plane. For instance, if there was a blow-out, the damage could affect other subsystems on the plane, such as hydraulics, cabling, etc. So the plane is crippled, and crash landing is imminent, unless something is done about it. You could add other things, such as dangerous special cargo, which makes the crippled plane situation more perilous. Just don't make it a nuclear weapon, cause that has been done a million times before. If you go with the custom plane scenario, you could pretend the plane was converted to a military weapon (like this one, more here).

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LOL snakes! I was going to have the plane crash land in the Grand Canyon leading to a Stand Off in the Visitor Centre, a bit like Homeland Security on Modern Warfare 2. So i was thinking the engine could blow out leading to the plane listing to a side and producing a new angle of cover, this could also lead to the systems crippling. The cargo is going to be some kind of weapons/ammunitions/munitions sort of stuff, what would a triad gangster lord have? Highly volatile! The thing has six Turbofan Thrusters so it should be able to hold up after a couple of engine blowouts. Also i was thinking of have jeeps and that in the cargo hold.[color="#ff0000"] I was wondering would someone be able to survive in the cargo hold normally, with no doors open? [color="#000000"]I was thinking of having a ingenious cover system where the cover gets destroyed in real time, and so that bullets can go through things like stud walls or wooden crates, but then if the character was behind a metal sheet for along time after so much wear from the constant shooting,the bullets would eventually go through. Do you think this is a good idea? Obviously it would depend what difficulty it was on for the amount of time it takes to destroy cover, also in the harder difficulty the enemies and you could get harmed realistically, for example a shot in the leg causes the enemies to fall to the ground but still be able to hide behind cover and shoot, just to make it harder, this could maybe happen to the main character as well. What do you think?

thanks for the feedback, its cool to have people enjoy your ideas and that.

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If possible, it might be more fun if the plane would land(on the edge of some.. coral reef? And you have to do stuff like kill enemies and maybe search some item while trying to get away before the plane starts sinking... Like you might have to dive a few times... The water level could rise slowly.

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I like the idea of the coral reef, but i thought of the grand canyon because it is on the way to shanghai (u will need to know the story to understand) but also i could include that you begin in the plane wreckage and have to shoot your way out, before it explodes, e.g. a door blows across your path and you have to take an alternative route.

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