Transport plane - parachuting.

daveza

daveza

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Can't find answers on Google ( so maybe it's just a dumb question ).

I presume there should be a vacuum directly behind the plane - so why don't the guys get sucked out ?

jump.png
 
Bar0n said:
If you don't get a good enough answer here, try /r/askscience :p
Click to expand...

I only want to know why he thinks so, he should read how plane engines (and types) react to these vacuums and then he will have his answer more or less.
 
I just presumed as the plane moves forward there would be a vacuum behind the plane.

Perhaps only at a certain speed ?

( Science class was forty years ago ).
 
Fulcrum29 said:
I only want to know why he thinks so, he should read how plane engines (and types) react to these vacuums and then he will have his answer more or less.
Click to expand...

Care to give a nutshell answer?
 
Why would you assume a vacuum? There'd be a turbulent area of lower pressure, sure, but clearly not with a large enough differential to the interior of the plane to suck out anyone. Stories of people getting sucked out of airliners tend to be exaggerated, and remember that a cargo plane dropping paratroopers clearly wouldn't have its fuselage pressurised, so pressure inside and out would be comparable.
 
Its called aerodynamics. Just like a car, the plane can't have a low pressure behind it, its called drag. So the fuselage or car body is designed to have a smooth airflow around it and as little drag as possible. Now there can be turbulence behind the plane, but mostly heavy transports like the one used in Godzilla is designed to have as little turbulence as possible allowing you to drop out a team of pathfinders or some heavy cargo with a parachute.
(Maxim 11 of Marginally Effective Mercenaries - Everything is air-droppable, at least once.)

The faster you fly, the more turbulence. That is why the rear tailplane is mounted in a T shape on most modern heavy transports, instead of a normal layout like a Hercules. (Btw - turbulence behind a 747 can be so bad a guy jumping out could get ripped to pieces - note can - some madmen have done it)
 
So on those old planes with a drop-down set of stairs at the back - one could lower the stairs during flight safely ?
 
Bar0n said:
Care to give a nutshell answer?
Click to expand...

This was based on my initial question in this thread:

What will create the vacuum?

In typical condition, the only vacuum which can prove to be dangerous is the plane engines (pending on the type) and naturally the altitude.

I wanted to list some things here, but this link explains near everything:

http://science.howstuffworks.com/transport/flight/modern/airplanes.htm/printable

Then, as per layman.

Jet engines creates huge thrust, more energy (vacuum), sucked out.
Prop engines creates little thrust, less energy (vacuum), sucked out.

Remember their is many engine types, the pic in the OP is a C-130 Hercules powered by a turboprop which exhaust gases contains little energy as the majority of energy is used to drive the propeller.

I won't recommend jumping out behind a jet engine.
 
Fulcrum29 said:
This was based on my initial question in this thread:

What will create the vacuum?

In typical condition, the only vacuum which can prove to be dangerous is the plane engines (pending on the type) and naturally the altitude.

I wanted to list some things here, but this link explains near everything:

http://science.howstuffworks.com/transport/flight/modern/airplanes.htm/printable

Then, as per layman.

Jet engines creates huge thrust, more energy (vacuum), sucked out.
Prop engines creates little thrust, less energy (vacuum), sucked out.

Remember their is many engine types, the pic in the OP is a C-130 Hercules powered by a turboprop which exhaust gases contains little energy as the majority of energy is used to drive the propeller.

I won't recommend jumping out behind a jet engine.
Click to expand...

To be pedantic. That is supposedly a C5 Galaxy from the trailer of Godzilla.
 
Compton_effect said:
To be pedantic. That is supposedly a C5 Galaxy from the trailer of Godzilla.
Click to expand...

Checked a screenshot, yep that is a C-5 (or C-17 looking at the wings) used in Godzilla. Honestly never knew that they parachute behind these engines. Perhaps it is possible with a high-altitude HALO? Or perhaps it looks cool in a movie :p

France and Germany still uses the Transall C-160 to do high-altitude HALO, SA also had these. The US army uses the Lockheed C-130 Hercules to do near all parachute operations.

Edit: Correction made
 
Last edited:
Fulcrum29 said:
Checked a screenshot, yep that is a C-5 (or C-17 looking at the wings) used in Godzilla. Honestly never knew that they parachute behind these engines. Perhaps it is possible with a high-altitude HALO? Or perhaps it looks cool in a movie :p

France and Germany still uses the Transall C-160 to do high-altitude HALO, SA also had these. The US army uses the Lockheed C-130 Hercules to do near all parachute operations.

Edit: Correction made
Click to expand...

I also thought they wouldn't use a Galaxy for that. I know it can handle normal paratroops (380 flack magnets at a time:wtf:), but according to Google they can also do HALO. Some pretty impressive clips on youtube of the stuff they can drop from it.
 
Compton_effect said:
Its called aerodynamics. Just like a car, the plane can't have a low pressure behind it, its called drag. So the fuselage or car body is designed to have a smooth airflow around it and as little drag as possible. Now there can be turbulence behind the plane, but mostly heavy transports like the one used in Godzilla is designed to have as little turbulence as possible allowing you to drop out a team of pathfinders or some heavy cargo with a parachute.
(Maxim 11 of Marginally Effective Mercenaries - Everything is air-droppable, at least once.)

The faster you fly, the more turbulence. That is why the rear tailplane is mounted in a T shape on most modern heavy transports, instead of a normal layout like a Hercules. (Btw - turbulence behind a 747 can be so bad a guy jumping out could get ripped to pieces - note can - some madmen have done it)
Click to expand...

It is true that planes are designed for minimum turbulence, but that is with the cargo door closed. With the door open there will definitely be a lot of turbulence which creates a low pressure area behind the plane. The low pressure will however not be enough to pull somebody out of the plane. The higher risk is being buffeted by turbulence if you are close to the edge I think. The low pressure will also equalise with the inside of the plane when the door opens.
 
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