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physics of an aeroplane crash

physics of an aeroplane crash

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s
Fast and Curious

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Originally posted by robbie carrobie
why does everything get pulverised when an aeroplane crashes? Is it a transference of energy when the aeroplane meets something more dense than itself, like a mountain or a tall building? Can anyone explain it in really clear and simple terms? Also why can aircraft flight not be made more safe as in providing parachutes for passengers or protective airbags that go off on impact?
There is work going on developing parachutes that can slow down a massive jetliner but it sounds like nothing would have helped this latest crash tragedy. They hear the pilot, captain, maybe, leaving the cockpit, then the door is locked when he tries to get back in, trying to break down the door, then the plane hits the mountain at pretty much full speed, way too much kinetic energy for the thin skinned plane to handle just running full tilt into a forest of rocks. It wouldn't have mattered WHAT safety measures they had, air bags, parachutes, gel foam, none of that would have helped that particular flight. RIP all 150 people on board.

twhitehead

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Originally posted by sonhouse
It wouldn't have mattered WHAT safety measures they had, air bags, parachutes, gel foam, none of that would have helped that particular flight.
Assuming the flight hit the mountain. However, safety measures that would have prevented the crash in the first place, would have been effective.
One report said that a ground proximity alarm was heard on the black box recording. A possible change would be to let the autopilot have more control and actually avoid the ground. But the issue there is whether computers or human pilots are more reliable and what overrides are put in place.

wolfgang59
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Originally posted by Soothfast
Hmm...

Escape pods?

Tractor beams?

Inertial dampeners?

Heisenberg compensators?

This is the Science Forum. Surely any problem can be solved!
You are over thinking this - just make the front of the plane from rubber.

D
Losing the Thread

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Originally posted by robbie carrobie
you would not need to give training if they were ejector seats, simply strap the passenger in and if the aeroplane was in difficulty the entire fuselage could by jettisoned and the passengers and cabin crew ejected safely.
How much weight are your fuselage sections going to add? It's not feasible to do this. The thing has to get in the air and not separate in flight due to stresses. Aside from that this is a huge levels of complexity you are adding. It's worth mentioning that ejector seats have cost quite a few lives when they've gone off incorrectly, typically killing ground crew. Cutting out ways the plane can fail in the first place is a better way forwards.

s
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Originally posted by DeepThought
How much weight are your fuselage sections going to add? It's not feasible to do this. The thing has to get in the air and not separate in flight due to stresses. Aside from that this is a huge levels of complexity you are adding. It's worth mentioning that ejector seats have cost quite a few lives when they've gone off incorrectly, typically killing ground crew. Cutting out ways the plane can fail in the first place is a better way forwards.
I was in the USAF for 4 years and we had an incident like that on the flight line where this bomber jet I was working on (not ATT!) had this co-pilot seat that ejected downwards instead of up as in most jets. So somehow this guy activated the eject rocket and slammed into the tarmac which happened to be about 8 feet below. Killed him instantly.

googlefudge

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Originally posted by twhitehead
Assuming the flight hit the mountain. However, safety measures that would have prevented the crash in the first place, would have been effective.
One report said that a ground proximity alarm was heard on the black box recording. A possible change would be to let the autopilot have more control and actually avoid the ground. But the issue there is whether computers or human pilots are more reliable and what overrides are put in place.
http://www.bbc.co.uk/news/world-europe-32063587

Yeah, it's difficult to introduce systems to prevent a person deliberately crashing
the aircraft.

The only solution to that is to have the aircraft able to auto-override the pilot.
Which is possibly where we will eventually go, but it's a very fraught subject as
pilots understandably don't want to have the plane countermanding their actions.

And incidents like this [assuming that this is what it currently looks like] are incredibly
rare.

rc

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Originally posted by DeepThought
How much weight are your fuselage sections going to add? It's not feasible to do this. The thing has to get in the air and not separate in flight due to stresses. Aside from that this is a huge levels of complexity you are adding. It's worth mentioning that ejector seats have cost quite a few lives when they've gone off incorrectly, typically killing ground crew. Cutting out ways the plane can fail in the first place is a better way forwards.
it wouldn't weigh that much, simply keep the top of the fuselage on with hydraulics. Safety measures could be built in to ensure that they cannot jettison without deliberation. The hydraulics could be situated in the aeroplanes frame no problem.

rc

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Originally posted by sonhouse
There is work going on developing parachutes that can slow down a massive jetliner but it sounds like nothing would have helped this latest crash tragedy. They hear the pilot, captain, maybe, leaving the cockpit, then the door is locked when he tries to get back in, trying to break down the door, then the plane hits the mountain at pretty much full speed, w ...[text shortened]... s, gel foam, none of that would have helped that particular flight. RIP all 150 people on board.
is that what happened? they locked the cockpit door and couldn't get back in? really? ouch!

rc

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Originally posted by twhitehead
I did. It was my idea you silly man.
lol, we are trying to think of ways of preventing the aircraft from crashing , how does making the wings fall off accomplish this?

rc

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can someone please tell me where all the energy goes?

googlefudge

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Originally posted by robbie carrobie
can someone please tell me where all the energy goes?
Sound, heat, deforming the rocks, deforming the air-frame...

All kinds of places.

s
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Originally posted by robbie carrobie
can someone please tell me where all the energy goes?
Mainly heat. It heats the parts by crushing them and all the pieces inside.

If you had a sensitive thermometer and the plane did not explode, you could work out the amount of kinetic energy involved, at least a decent estimate by noting the temperature of the rocks and/or the pieces left over versus the temperatures of the plane chassis and wings, etc., and the rocks before the collision.

Everything will be very hot for a while anyway, till wind and/or rain sucks the heat away.

googlefudge

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Originally posted by robbie carrobie
it wouldn't weigh that much, simply keep the top of the fuselage on with hydraulics. Safety measures could be built in to ensure that they cannot jettison without deliberation. The hydraulics could be situated in the aeroplanes frame no problem.
Hydraulics are heavy, as are the structural reinforcements needed to make
the airframe strong enough to do this.

Weight is bad.

rc

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Originally posted by googlefudge
Sound, heat, deforming the rocks, deforming the air-frame...

All kinds of places.
amazing, do all the fragments carry some energy when they splinter?

rc

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Originally posted by googlefudge
Hydraulics are heavy, as are the structural reinforcements needed to make
the airframe strong enough to do this.

Weight is bad.
they would not need to be very heavy, after all their function is merely to clamp and release.

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