h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Say, you had a jet fighter and flew it up at an angle of forty five degrees. What happens eventually? (Assume it's flying at close to top speed, can't run out of fuel and has no pilot.) Does it get ripped apart? Does there come a stage when it eventually 'bounces' off 'something'? Or is it forced into flying horizontally?

I know that rockets have to reach a certain speed if they're to escape the earth's atmosphere but I've always wondered about the fate of a plane trying to escape.

I'd imagine that it gets to a point where there's not enough air to work the engines, then it'll either level off or start going down.

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I'd imagine that it gets to a point where there's not enough air to work the wings, then it'll either level off or just hang there thrusting up with no lift to go any further

Taff,

In that case, wouldn't the thrust from the engine continue to power it upwards?

Wings are mainly (as far as I'm aware) for (a) providing lift in flight and (b) providing something for the control surfaces which control changes in pitch and roll to hang off.

Yes, Yes, there's all the sticking fuel tanks (and possibly wheels)inside and hanging bombs or engines off them too.

plane at 45 degree angle

wing = lift Vs gravity.........no lift gravity wins

the engines are to move the plane
the wings fight gravity
if the engines were powerfull enough to counter garavity it would be a missile and not a plane

Yeah, the plane would stall (lose lift) at a high enough altitude due to the decreased air density. Jet fighters in particular become very unstable objects when they stall. Regardless of the engines still being on, without some sort of active input to recover the plane from the chaos after it stalls, it would likely crash eventually.

- JD

Most fighter planes have sufficient thrust to accelerate vertically, so the engines are the deciding factor at low altitudes, not the wings. But yes, the plane would level off as the air got too thin to produce enough thrust and became reliant on the lift supplied by the wings, which would also decrease, and so on...

If we assumed that the plane couldn't run out of fuel AND had unlimited oxygen, then it could keep going until it reached deep space. But then it would have to carry it's own oxygen, which makes it a rocket.

Escape velocity is not a fundamental constant, it's just a function of existing rocket technology. It's basically how fast a rocket needs to be going to achieve orbit before it runs out of fuel. Give it unlimited fuel, and it could rise at walking pace.

I believe it is something called the 'absolute ceiling' and involves, engine thrust, air density, air temperature, windg design, and lots of other complicated factors and obviously complex maths.

The end result of which is that all aeroplanes have a rated 'service ceiling' in which it is legally safe to fly up to with control. This is the legally rated maximum altitude for any particular plane, if a pilot goes above this he gets into trouble.

In reality it is a factor of safety to give a margin before the plane reaches its absolute ceiling above which is the height a plane will stall at. A stall is a complex aeronatuical term which in laymans terms means a crash that has not yet hit the ground.

Hence why pilots have to learn how to recover from a stall before it becomes a real crash...