What would a plane with a propeller do in space?

[Yzzim]

Say they built it in space (non-combustible engine) and flipped the switch. What would happen?

 

[spaceghost21]

thinkin about this makes me head hurt.

 

[legoman666]

nothing.

 

[Nohr]

Spin itself around like a helicopter without a tail rotor, I'd guess.

 

[Brainonska511]

Nothing, since a propeller works by pulling air through it. You might have the aircraft start to spin due to a torque being created by the spinning propeller, but there would be no forward motion.

 

[newb111]

nothing to push against = no thrust

 

[Farang]

The vibrations may affect its movement but it wouldn't propel forward.

 

[Yzzim]

Originally posted by: Brainonska511
Nothing, since a propeller works by pulling air through it. You might have the aircraft start to spin due to a torque being created by the spinning propeller, but there would be no forward motion.

so the same could be said about a jet engine?

 

[Xylitol]

well there's tiny dust particles, so you'd move slightly

 

[skyking]

"space" is not entirely devoid of matter. The densities are very small when compared to the earth's atmosphere, but there are particles out there.
A couple of really large propellers counter-rotating around the same axis would produce some thrust. Not a useful amount, but a measureable one.

 

[CallMeJoe]

Originally posted by: Yzzim
so the same could be said about a jet engine?

Since you specified (non-combustible engine), you eliminate jets from the question. Assuming combustion, however (and an oxidizing source for the fuel), a jet would move since it is mass reaction propulsion.

 

[Jeff7]

The entire thing would rotate in place. The propeller would rotate rapidly in one direction, while the fuselage would rotate slowly in the other. The rates of rotation would depend on some polar moment of inertia of each body, and the mass, or something like that. Some moment of something-or-other of each component, or the mass distribution - if those were known, it would be possible to calculate how fast one would move relative to the other.

Forward velocity - as Xylitol said, yes, there are dust particles in space, though what you'd be more likely to find would be stray hydrogen atoms, and depending on your proximity to a star, you'd pick up some radiation pressure. The radiation pressure would likely be the main cause of any linear motion.

Originally posted by: CallMeJoe

Originally posted by: Yzzim
so the same could be said about a jet engine?

Since you specified (non-combustible engine), you eliminate jets from the question. Assuming combustion, however (and an oxidizing source for the fuel), a jet would move since it is mass reaction propulsion.

That being the case, it would really be little more than a rocket engine with a turbofan inside it.

 

[Agentbolt]

Originally posted by: newb111
nothing to push against = no thrust

I thought there was some property of empty space that made that not true. Otherwise how do rocket engines work? The thrust still needs something to push against to have force applied to the rocket to make it move forward.

 

[LargeGrue]

The correct answer is: it depends if it's on a treadmill or not.

 

[CallMeJoe]

Originally posted by: Agentbolt

Originally posted by: newb111
nothing to push against = no thrust

I thought there was some property of empty space that made that not true. Otherwise how do rocket engines work? The thrust still needs something to push against to have force applied to the rocket to make it move forward.

You misunderstand newtonian mass reaction propulsion. A rocket doesn't "push" against anything; it sends a quantity of matter in one direction, and as a result (for every action, there is an equal and opposite reaction) is propelled in the opposite direction.

 

[spidey07]

Originally posted by: Agentbolt

Originally posted by: newb111
nothing to push against = no thrust

I thought there was some property of empty space that made that not true. Otherwise how do rocket engines work? The thrust still needs something to push against to have force applied to the rocket to make it move forward.

There is no pushing, just force (although you can think of the rocket engines as a form of 'push', it's not really accurate). Newton would roll over in his grave but he's dead and he couldn't roll over in space anyway.

 

[Jeff7]

Originally posted by: Agentbolt

Originally posted by: newb111
nothing to push against = no thrust

I thought there was some property of empty space that made that not true. Otherwise how do rocket engines work? The thrust still needs something to push against to have force applied to the rocket to make it move forward.

Nope. Not at all how rockets work, otherwise they wouldn't work in space. They don't need anything to push off of.
It has to do with mass being forcibly ejected out the back. Action vs reaction. Simple as that.
Propel a small amount of stuff out the back at high velocity.
Momentum = mass * velocity.
Small mass * high velocity = large mass * small velocity.

If a large spaceship fires a small amount of mass out the back at very high speed, it will in turn move in the opposite direction, but at a slower speed.





Darn. Beaten to it.

 

[Agentbolt]

Originally posted by: spidey07

Originally posted by: Agentbolt

Originally posted by: newb111
nothing to push against = no thrust

I thought there was some property of empty space that made that not true. Otherwise how do rocket engines work? The thrust still needs something to push against to have force applied to the rocket to make it move forward.

There is no pushing, just force (although you can think of the rocket engines as a form of 'push', it's not really accurate). Newton would roll over in his grave but he's dead and he couldn't roll over in space anyway.

Give me a break, I'm on my third 20 hour day and I've admitted to nearly failing geometry in the past. I'm clearly not very smart.

 

[Born2bwire]

Originally posted by: spidey07

Originally posted by: Agentbolt

Originally posted by: newb111
nothing to push against = no thrust

I thought there was some property of empty space that made that not true. Otherwise how do rocket engines work? The thrust still needs something to push against to have force applied to the rocket to make it move forward.

There is no pushing, just force (although you can think of the rocket engines as a form of 'push', it's not really accurate). Newton would roll over in his grave but he's dead and he couldn't roll over in space anyway.

Well, if he was buried with a pair of coins for the ferryman he could flip one of them and that would impart an angular momentum.

 

[spidey07]

Originally posted by: Agentbolt

Originally posted by: spidey07

Originally posted by: Agentbolt

Originally posted by: newb111
nothing to push against = no thrust

I thought there was some property of empty space that made that not true. Otherwise how do rocket engines work? The thrust still needs something to push against to have force applied to the rocket to make it move forward.

There is no pushing, just force (although you can think of the rocket engines as a form of 'push', it's not really accurate). Newton would roll over in his grave but he's dead and he couldn't roll over in space anyway.

Give me a break, I'm on my third 20 hour day and I've admitted to nearly failing geometry in the past. I'm clearly not very smart.

Don't worry about it, I failed German.

Twice.

Barely passed the 3rd time.

 

[blackdogdeek]

the plane takes off.

 

[soccerballtux]

Originally posted by: Xylitol
well there's tiny dust particles, so you'd move slightly

this.

 

[Born2bwire]

Originally posted by: spidey07

Originally posted by: Agentbolt

Originally posted by: spidey07

Originally posted by: Agentbolt

Originally posted by: newb111
nothing to push against = no thrust

I thought there was some property of empty space that made that not true. Otherwise how do rocket engines work? The thrust still needs something to push against to have force applied to the rocket to make it move forward.

There is no pushing, just force (although you can think of the rocket engines as a form of 'push', it's not really accurate). Newton would roll over in his grave but he's dead and he couldn't roll over in space anyway.

Give me a break, I'm on my third 20 hour day and I've admitted to nearly failing geometry in the past. I'm clearly not very smart.

Don't worry about it, I failed German.

Twice.

Barely passed the 3rd time.

How's that even possible, next to Ireland they've got the best drinking songs.

Im Himmel gibt?s kein Bier,
Drum trinken wir es hier.
Denn sind wir nicht mehr hier,
Dann trinken die andern unser Bier.

 

[Eli]

It would float around.

lol

 

[spidey07]

Originally posted by: Born2bwire
How's that even possible, next to Ireland they've got the best drinking songs.

Im Himmel gibt?s kein Bier,
Drum trinken wir es hier.
Denn sind wir nicht mehr hier,
Dann trinken die andern unser Bier.

This is how it's possible...
In himmel there is no beer
We drink here
Then we aren't drinking here
then you can drink another beer

Es tud meir lied, ich habe viel zu viel zu trinken.