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View Full Version : A classic. . . Airport 77



Wally
2005-Jan-07, 01:28 PM
Caught the tail end of this the other day. To jog your memory, this is the one where the 747 crash lands in the ocean, then sinks to the bottom some 50 or so feet below the surface. The passengers get dramatically saved at the end when they use big inflatables to lift the aircraft back to the surface. I remember seeing it as a kid as well, and being amazed at the special effects.

This time though, I just couldn't get myself to believe a 747 would sink in water. Wouldn't it be essentially a big ol' (sealed) tin can out there??? Even if the wings/underbelly were still full of fuel, I'm thinking jet fuel would be lighter than water and would simply add to the buoyancy. Sure, the engines weigh a heck of a lot, but I wouldn't think it'd be enough to counteract the water displacement of a "can" so huge, would it???

Moose
2005-Jan-07, 01:46 PM
Caught the tail end of this the other day. To jog your memory, this is the one where the 747 crash lands in the ocean, then sinks to the bottom some 50 or so feet below the surface. The passengers get dramatically saved at the end when they use big inflatables to lift the aircraft back to the surface. I remember seeing it as a kid as well, and being amazed at the special effects.

Is that what that movie was? I remember catching a bit of that when I was a kid. The scene where the passengers watch the sea water "rise" past the windows (or more accurately, when they watched the plane sink) freaked me right out as a kid. (I've been a little hydrophobic since my cousins (intentionally) rolled a canoe I was in when I was six and was still learning how to swim.)

kucharek
2005-Jan-07, 02:30 PM
Funnily I also saw the tail end of this flic a few days ago (it's the type of movie they cram into the tv schedule between xmas and Epiphany...

Was also my first thought: It would never sink as long as no water gets inside.
A 747 has a maxiumum take-off weight of 450 tons. Lets say the fuselage is 60m long and has a diameter of 6m. This would be a cylindrical volume of 1700m^3, which would give four times the buoyancy than the mass of the jet.
And the fusalge is larger than my rough numbers.

Harald

PS: And I don't know how well the pressure hull of a jet would deal with outside overpressure - normally, the pressure inside is higher than outside in a plane.

Donnie B.
2005-Jan-07, 02:52 PM
Even though this thread is not in Bad TV / Movies :wink: , I'll comment...

The real problem in any airplane ditching is that it's virtually impossible for the fuselage to remain intact.

Any large airplane is moving fast when it touches the water surface. Typically, whatever touches the surface first (usually a wingtip or engine) experiences a huge and sudden drag force, imparting a torque to the airframe -- possibly ripping off one or both wings, or even breaking the fuselage in half. No airplane is designed to withstand those forces.

So it almost never happens (outside of Hollywood) that a fuselage retains integrity in a water crash. Therefore, it's moot to question whether an intact airframe would float, or how long it would float.

Wally
2005-Jan-07, 05:08 PM
Even though this thread is not in Bad TV / Movies :wink: , I'll comment...



I debated whether to put this thread there or not, but then figured since it has nothing to do with astronomy, it fit better here. . . 8)