Regarding The Earth's Orbit As It Relates To Aircraft

I've got a couple of random questions regarding flying and stuff that hopefully some people can answer:

1. When a plane takes off, why does the ground stay stationary under it, when the Earth is rotating? Is this because of Newton's 1st Law "Objects in motion stay in motion" and since it was thrown off a spinning Earth it just continues, or because the atmosphere of the Earth is also rotating at the same speed as the Earth. If so, how are the gases rotating? I can understand how the solid mass of the Earth would be spinning, but not the atmosphere as much.

2. If it were theoretically possible to stop a helicopter somehow and get it out of this rotation such as a collision with something (something not from Earth since then it would also be spinning the same way), would the helicopter be able to simply hover while the ground moves underneath it and thereby cover half the world much faster than conventional flying? Or would it immediately be picked up into the spin of the Earth again?

3. Could you make a space station independant and outside of Earth's orbit, and then extend a giant rod down to the Earth's surface. Have someone start at the space station and make their way down the rod, and then finally take the last few inches of the jump. Would they land on solid ground, or would the Earth be spinning ridiculously fast below them and when they landed they would be sent flying similar to jumping out of a moving car? Theoretically.... obviously quite tough to make a giant 30 million foot rod.


[edit on 1-8-2006 by Yarcofin]

Originally posted by Yarcofin
3. Could you make a space station independant and outside of Earth's orbit, and then extend a giant rod down to the Earth's surface. Have someone start at the space station and make their way down the rod, and then finally take the last few inches of the jump. Would they land on solid ground, or would the Earth be spinning ridiculously fast below them and when they landed they would be sent flying similar to jumping out of a moving car? Theoretically.... obviously quite tough to make a giant 30 million foot rod.
[edit on 1-8-2006 by Yarcofin]

Well I think you could use this theory in global travel - the space station would be within Earth's orbit field but have to use some thrust to counter the effect.

It could be a good idea if the station headed in the opposite direction to the earth's spin because I guess it would take half the effort to travel the required distance. For example, you want to travel from Hawaii to London; in a plane that will take you x hours, but you could ascend to a point above Earth where gravity's pull is halved and travel the same distance in x/2. I guess thats why Richard Branson is so interested in selling space travel to us.

Cool post

Good thread!

Originally posted by Yarcofin
I've got a couple of random questions regarding flying and stuff that hopefully some people can answer:

1. When a plane takes off, why does the ground stay stationary under it, when the Earth is rotating? Is this because of Newton's 1st Law "Objects in motion stay in motion" and since it was thrown off a spinning Earth it just continues, or because the atmosphere of the Earth is also rotating at the same speed as the Earth. If so, how are the gases rotating? I can understand how the solid mass of the Earth would be spinning, but not the atmosphere as much.

I think it's combination of both the things you're saying as far as aircraft. Winds are created by both the Coriolis Effect and the uneven heating of the Earth by the sun.

2. If it were theoretically possible to stop a helicopter somehow and get it out of this rotation such as a collision with something (something not from Earth since then it would also be spinning the same way), would the helicopter be able to simply hover while the ground moves underneath it and thereby cover half the world much faster than conventional flying? Or would it immediately be picked up into the spin of the Earth again?

I think anything that would hit the helicopter that hard would destroy it...sorry that's my best answer to this question

3. Could you make a space station independant and outside of Earth's orbit, and then extend a giant rod down to the Earth's surface. Have someone start at the space station and make their way down the rod, and then finally take the last few inches of the jump. Would they land on solid ground, or would the Earth be spinning ridiculously fast below them and when they landed they would be sent flying similar to jumping out of a moving car? Theoretically.... obviously quite tough to make a giant 30 million foot rod.


[edit on 1-8-2006 by Yarcofin]

Yeah, at least theoretically, I think you're basically describing a Space Elevator. Except it's better to build from the ground up than from orbit down.

What hes describing is cetainly not a space elevator. For a space elevator to work it must be in a geosynchronous orbit ie. always above the same point on the earth and therefore its definately not "independant and outside of earths orbit".

It may be theoretically possible to have the space station in an orbit around the sun at a very slightly further distance than the earth, but you would only be able to jump off the "rod" at a very specific point as the surface of the earth is not flat. Therefore to stop the rod destroying things on the ground etc. it would have to be only a few feet off the ground at the highest point on earth at that lattitude.

Also the earth isnt stationary under a flying plane!! You really need to think about relativity when asking these questions ...

Originally posted by Yarcofin
1. When a plane takes off, why does the ground stay stationary under it, when the Earth is rotating? Is this because of Newton's 1st Law "Objects in motion stay in motion" and since it was thrown off a spinning Earth it just continues, or because the atmosphere of the Earth is also rotating at the same speed as the Earth. If so, how are the gases rotating? I can understand how the solid mass of the Earth would be spinning, but not the atmosphere as much.

The atmosphere spins along with the earth due to friction. It follows similar characteristics of fluid mechanics. The same as you can use a spoon to stir the cream in your coffee and get all of the liquid turning. Even though the molecules are not tightly bound like the earth, there is still friction that makes it move as a whole. That is until you bring in the heat convection part that creates winds. In northern latitudes the winds are faster than the earth’s rotation, and near the equator they are slower. Winds have more of an effect on an airplane than the rotation of the earth, but depending on the latitude it can take longer to fly to a destination than the return trip.

Here is a good explanation, if you scroll down to Global Weather.

www.phy6.org...

2. If it were theoretically possible to stop a helicopter somehow and get it out of this rotation such as a collision with something (something not from Earth since then it would also be spinning the same way), would the helicopter be able to simply hover while the ground moves underneath it and thereby cover half the world much faster than conventional flying? Or would it immediately be picked up into the spin of the Earth again?

The chopper would still have to fly through the atmosphere because the same friction is acting on it. With a rotational speed of 1,000 MPH at the equator, that would be some collision.

3. Could you make a space station independant and outside of Earth's orbit, and then extend a giant rod down to the Earth's surface. Have someone start at the space station and make their way down the rod, and then finally take the last few inches of the jump. Would they land on solid ground, or would the Earth be spinning ridiculously fast below them and when they landed they would be sent flying similar to jumping out of a moving car? Theoretically.... obviously quite tough to make a giant 30 million foot rod.

As DJ said, if the station were placed in geosynchronous orbit you could, and have a space elevator, then you can anchor it to the ground, and don't need to jump off. I think this would be very cool if they built it. Otherwise it depends on the relative speed, for example the International Space Station is around 18,000 MPH.

Maybe it would work if you start running before you jumped off.

Good questions.

Cheers

[edit on 8/1/2006 by Hal9000]

Thanks for the replies everyone. I appreciate it.

The space elevator idea sounds crazy (in a good way ). I can't imagine what it would be like to look up and see it extend on 'forever' into space. I imagine that would probably be the most expensive construction project mankind would undertake up to that point.

What I was describing initially wasn't a space elevator, but that sounds pretty cool as well.

Looks like I have some reading to do.

Originally posted by Yarcofin
I've got a couple of random questions regarding flying and stuff that hopefully some people can answer:

1. When a plane takes off, why does the ground stay stationary under it, when the Earth is rotating? Is this because of Newton's 1st Law "Objects in motion stay in motion" and since it was thrown off a spinning Earth it just continues, or because the atmosphere of the Earth is also rotating at the same speed as the Earth. If so, how are the gases rotating? I can understand how the solid mass of the Earth would be spinning, but not the atmosphere as much.

When you jump the earth is repulsed, but only a little. The Law of Conservation of Momentum applies to cases like this. Basically, taking off will take force off the surface of the earth, but without forcing on the earth to take off (lift) it won't do anything to the earth. For every action, there is an equal and opposite reaction. You'll shift the center of mass, but not by much.

2. If it were theoretically possible to stop a helicopter somehow and get it out of this rotation such as a collision with something (something not from Earth since then it would also be spinning the same way), would the helicopter be able to simply hover while the ground moves underneath it and thereby cover half the world much faster than conventional flying? Or would it immediately be picked up into the spin of the Earth again?

Well, all the air and everything that can reasonably considered the earth moves at about the same speed. At the equator you'd have to move at about 1000 mph to remain stationary above the ground. To stay stationary you'd have to move pretty fast not to mention the propogation of the earth around the sun to do that. To hit a helicopter that fast, it's dead

3. Could you make a space station independant and outside of Earth's orbit, and then extend a giant rod down to the Earth's surface. Have someone start at the space station and make their way down the rod, and then finally take the last few inches of the jump. Would they land on solid ground, or would the Earth be spinning ridiculously fast below them and when they landed they would be sent flying similar to jumping out of a moving car? Theoretically.... obviously quite tough to make a giant 30 million foot rod.

The space station would have to be in GEOSTATIONARY orbit. It's a special case of geosynchronous. Geosynchronous means that it will pass the same point at the same time every day. At this time, we cannot build a space elevator like this. You've got all the weight of the stuff going down to the earth pushing down on the structure below. At 42241 km, this is kind of a tall structure, it would fail from the stress placed on it by the weight.

If you build this in LEO, ignoring atmo effects, you'd be spinning so much faster than the earth. Orbital periods tend to be measured in minutes there instead of hours (around 88 minutes at the low end, I have no idea where I saw that but can run the numbers pretty fast). It would be like jumping out of a moving car at hypersonic speeds (oh say Mach 30 or so). The Apollo missions pegged the atmosphere at about M38. LEO velocity is around 8 kilometers per second (space is metric :roll. There are no non-earth orbits in which you could do this. Maybe the Lagrange points, but those are even farther out than geostationary.

When you jump the earth is repulsed, but only a little. The Law of Conservation of Momentum applies to cases like this. Basically, taking off will take force off the surface of the earth, but without forcing on the earth to take off (lift) it won't do anything to the earth. For every action, there is an equal and opposite reaction. You'll shift the center of mass, but not by much.

What would happen if you got everyone on earth, or at least a few million, to all stand in a giant crowd in one place and all jump simultaniously? Would anything slightly noticable/measurable occur?

It would be like jumping out of a moving car at hypersonic speeds (oh say Mach 30 or so).

Sounds painful. PS: What is 'LEO'. My guess is "lunar equator orbit".

Originally posted by Yarcofin
What is 'LEO'. My guess is "lunar equator orbit".

Low Earth Orbit

Thanks djohnsto. I didn't know there was such a thing. I figured you were either in orbit or you weren't, and it was all the same. Guess I still have a bit to learn. It makes sense now that I think about it though.

Since everyone seems pretty focused on the idea that a helicopter would crash, what if there was a way to make the impact as soft as possible. Say some kind of very elastic polymer/foam/rubber of some sort that would catch the helicopter (or plane for that matter). This way it wouldn't be a sudden 1000 mph impact, it would gradually go from being in the Earth's spin to a standstill, instead of instantaniously hitting a wall. Imagine the stretching of 'Silly Putty'. It would be a series of elastic barriers and/or nets that would gradually slow the aircraft down in sequence. Each would absorb a certain amount of speed and break, and then the craft would continue on to the next one. Or possibly just one very gradual, very strong barrier.

And it would all be held in place by a giant rod from the non-orbiting (or possibly geosynchronous) space station. Obviously this wouldn't be the most financially feasable undertaking for commercial travel. haha. It would be worth doing once to achieve a new speed record which equals the rotation speed of the Earth though. Basically it would just be cool to have the Earth move around you, rather than having to move around the Earth, for a change.

"Yay. We travelled.... exactly as fast as we would have normally just by sitting on the ground. D'oh."

[edit on 2-8-2006 by Yarcofin]

Originally posted by Yarcofin
because the atmosphere of the Earth is also rotating at the same speed as the Earth.

Dude, you've answered the question yourself!!

1. I think solid surfaces on the earth stay stationary (to some degree) when the mass of the sold surface is pulled towards the center of the earth and pressure is enacted on all sides of the surface from other solid surfaces. Then in some cases, the surface does move, such as in the case of a volcanic eruption or an earthquake. But I do not understand the significance of the airplane.

2.

3. Yes