Why can't a regular airplane (like a boeing 777 ) go up to outer space?

Question

Since the airplane cruise at a high altitude already, doesn't it have enough power to go higher? I think I saw a movie on this once and was not sure about the science behind the constraints...

Answer 1

There's no air in space. A Boeing 777 needs air to go through it's turbines to give it thrust.

Answer 2

Okay...

Let's get right down to the basics...

1.) Airplanes like the Boing 777 are powered by Jet Engines which breathe air (especially oxygen) to combine with jet fuel and create the thrust of the exhaust gases for propulsion.
Without air (which gets thinner and thiner as you go higher and higher, no combusion can take place) the jet engines canot work above some limiting altitude - say 40,000 feet.

2.) Boeing Commercial Airliners are built to maintain internal atmospheric pressure for the occupants up to about 35,000 feet of altitude or so...Not into Outer Space.

3.) An airplane's basic manner of flight is based upon lift created by the wing's airfoil as it passes through the air. The less air you have (thinner atmosphere as you go higher and higher), the less "lift" you get, and finally the aircraft just falls out of the sky.

4.) For all of those reasons, space craft are much more strongly built and pressurized for zero atmosphere and heated internally for extreme cold conditions of high altitude or space flight. Propulsion systems range from solid fuels to liquid fuels powering rocket engines which do not have to breathe air. Since Outer Space lacks an atmosphere of air such as we have at the surface of the Earth, normal aircraft wings are not required. The only time you see them designed into a space craft is if the space craft is to be used for re-entry into the atmosphere.

5.) Lastly, the ticket you bought when you decided to ride on the Boing Jet Aircraft did not say "Destination Moon" or something like that. So the Jet can't go there.

Answer 3

There are three reasons that this would not be feasible, all of which have been discussed in one way or another:

1. The airfoils won't work. These include the wings and the control surfaces, as well as the engine compressor and turbine blades.

2. The engine fuel won't ignite. Since a commercial aircraft does not carry along an oxidizing agent like a rocket, it must depend on external air (compressed by the non-functioning airfoils) to mix with the fuel and create a combustible vapor.

3. Since the cabin air is provided by bleed air from the engines, the cabin pressure would quickly fall to near zero psia, creating a very uncomfortable situation for the passengers. Note that if the pressure could be maintained (e.g by lots of oxygen bottles on board), the aircraft could easily carry the structural pressure load, since the difference between atmospheric pressure at 40,000 feet and in outer space is pretty insignificant.

Friction heating would depend entirely on how fast you got going during steady flight or free fall. Since steady flight is not possible for the reasons stated above, and since a significant free fall would only be possible by turning the aircraft into a rocket, I think this is sort of a secondary concern.

Answer 4

Deuce is closest, so far. Here is a summary:

1. Airplanes fly because the wings hold them up in the atmosphere when they are moving fast enough.
2. Jet engines require oxygen from the outside air to work.

If a 777 could fly fast and high enough to coast to space (like the old X-15, which used a rocket) it couldn't control the direction it is pointed because directional control on aircraft relies on air passing over movable parts of the wings (ailerons, rudders, and elevators).

If the 777 still went up that high by getting a fast start and coasting the composite and aluminum body probably wouldn't stand the aerodynamic forces (including heat from friction) trying to get back down to earth.

In sum, airplanes are not designed to go higher than the altitude that their engines will cease to have enough oxygen to operate; in fact, they aren't designed to go nearly that high, for safety reasons.

The reason rockets can go high and fast is that rockets carry both fuel and oxygen (or an oxider). The payloads are designed to work in a vacuum, and if they are to return to earth they are designed to withstand all the aerodynamic and g-forces necessary to do so.

Answer 5

If a 777 went into space it was a science fiction story written by an ignorant author. It is not a matter of power, an airplane, by definition, needs air to fly in.

Answer 6

No problem. Refit the four engines with liquid fuel rockets, and include a bit of liquid oxygen stored somewhere.
Use a ram air intake to pressurize combustion air as the plane travels through the atmosphere, then switch to LOX as it departs the atmosphere.
It ain't about power, but there is a concept called "ballistic thrust". As the plane moves out of the atmosphere, its wings do less and less lift, so the rockets must end up doing all the lifting. Without ballistic thrust greater than the weight of the plane, it drops.

-oh, did I mention that the rockets have to be on gimbals, to be moved to steer?

Also, this configuration gets it into space. To get it to orbit, the rockets must accelerate the plane up to about 17,000 miles per hour.

Answer 7

I think it's pretty logical...

What generates lift on an airplane?
Air flows over the wings to generate lift.

What generates the thrust that forces the air to flow over the wings?
The jet engines, compressing air and igniting jet fuel with it creating a hot plume of gas which thrusts backwards propelling the aircraft forwards.

What is required for combustion and lift?
Oxygen gas is needed to combust the compressed air, air particles generate the high and low pressures on the wing for lift.

Is there oxygen and air in space?
No, hence there will be no lift and no thrust - hence no flight. Should it reach space it would fall right back down to Earth as its engines would fail.

Answer 8

Here is the thing, the higher you get the less atmosphere there is. Since airplanes fly using lift from there wings they can't get to space, because there is just not enough air to create lift if you had enough power (like a rocket) you could but then that wouldn't be a normal airplane.

Answer 9

I think some confusion comes from the shuttle, which looks and behaves like an aircraft.

But I think people forget that it is injected into space with huge expendable rockets. It is only on the return that it glides in like a regular aircraft.

We have had people on here ask why the shuttles don't fly to the moon, not knowing that shuttles do not fly anywhere - rockets take them to orbit.

Then of course they don't realise that a shuttle could not glide into the moon (no atmosphere), has no nice runway to land on, and no huge rockets to get it off again.

It is precisely this kind of ignorance that feeds those infernal moon landing conspiracy theories.

Answer 10

A certain amount of speed is required to actually break free of the Earth's gravity. Way more than the 600 mph the average airliner can fly at. It's called 'Escape Velocity'. I think it's about 25, 000 mph for Earth.

Answer 11

There's no life support systems,people would die.The airplane uses jet turbines,which force air at a high speed.With no air space,it could not move.