07 Nov 07
1 edit
Let's say you have a car (or an airplane) powered by a propeller. Your original design featured a large wall, attached to the car (or airplane), behind the propeller, which is hit by the air coming from the back of the propeller. Your friend says you should remove the wall, because it'll make the car (or airplane) go faster. You say it doesn't make a difference. Who's right? Explain your reasoning.
08 Nov 07
The air molecules are being pushed backward by the prop which pushes the plane forward. These fast moving molecules then hit the wall pushing the wall backwards, which of course pushes the plane backwards. So yeah, removing the wall will speed it up. Seems too simple... am I missing something???
08 Nov 07
Originally posted by XZantothno, u got it
The air molecules are being pushed backward by the prop which pushes the plane forward. These fast moving molecules then hit the wall pushing the wall backwards, which of course pushes the plane backwards. So yeah, removing the wall will speed it up. Seems too simple... am I missing something???
08 Nov 07
Originally posted by ark13simple. The wall has mass. By removing the wall you are removing mass so your speed will increase.
Let's say you have a car (or an airplane) powered by a propeller. Your original design featured a large wall, attached to the car (or airplane), behind the propeller, which is hit by the air coming from the back of the propeller. Your friend says you should remove the wall, because it'll make the car (or airplane) go faster. You say it doesn't make a difference. Who's right? Explain your reasoning.
Anytime you reduce weight you will increase speed.
08 Nov 07
Originally posted by XZantothAll good answers.
The air molecules are being pushed backward by the prop which pushes the plane forward. These fast moving molecules then hit the wall pushing the wall backwards, which of course pushes the plane backwards. So yeah, removing the wall will speed it up. Seems too simple... am I missing something???
It was supposed to be easy; maybe even deceptively easy. People tend to over-think this sort of thing.
08 Nov 07
Originally posted by ark13What is the wall made out of?
Let's say you have a car (or an airplane) powered by a propeller. Your original design featured a large wall, attached to the car (or airplane), behind the propeller, which is hit by the air coming from the back of the propeller. Your friend says you should remove the wall, because it'll make the car (or airplane) go faster. You say it doesn't make a difference. Who's right? Explain your reasoning.
IRNG 24
10 Nov 07
Originally posted by ark13I don't see any thrust being developed at all, seems to me the wall would deflect the air trying to leave the vicinity of the prop which would produce thrust if all the air goes in the same direction. But when a wall is there, the air is all forced sideways, downwards, upwards and diverting the thrust to 90 degrees from the original direction of unimpeded air flow. Now if the wall had a piece sticking out from it in such a way as to block the flow of air in certain directions, you could get a twisting force or possibly a lifting force if the air was directed straight down but with just a wall it seems to me the thrust would be vectored off in all directions, think of a stream of water from a hose hitting a wall, its going to splatter all sideways and will try to move the wall a bit but that would be in the opposite direction. It would be like trying to put a giant electric fan on a sailboat, no net thrust. If anything it looks to me like it might go backwards.
Let's say you have a car (or an airplane) powered by a propeller. Your original design featured a large wall, attached to the car (or airplane), behind the propeller, which is hit by the air coming from the back of the propeller. Your friend says you should remove the wall, because it'll make the car (or airplane) go faster. You say it doesn't make a difference. Who's right? Explain your reasoning.
11 Nov 07
Originally posted by ark13how can the pilot see with a huge wall infront of him? assuming that the prop is in front of the driver, and the wall is behind the prop, we have bigger problems than how fast it will go.
Let's say you have a car (or an airplane) powered by a propeller. Your original design featured a large wall, attached to the car (or airplane), behind the propeller, which is hit by the air coming from the back of the propeller. Your friend says you should remove the wall, because it'll make the car (or airplane) go faster. You say it doesn't make a difference. Who's right? Explain your reasoning.