Elevator to space?

[Chalo]

Now to your "question-answer". My question was: "I will enjoy reading your detailed explanation of how you plan to avoid Gravity Drag." Or something like that, because in your post it sounded like you thought an Orbit Elevator could avoid it. You have so far failed to explain how an Orbit Elevator traction system turns off gravity. You did by fiat say that gravity does not drag the elevator down, but I already had it figured out that you believe that.

Then you don't understand what aerospace engineers mean by "gravity drag". It's not the force of gravity, or the work required to raise a mass against the force of gravity. It's the work a flying machine has to do before being able to rise away from the ground. A rocket first must burn enough propellant to hover, and then must add more thrust to move upward. The amount of thrust required to hover is gravity drag, and an elevator-- the space kind, the regular kind, or a funicular-- does not have any. It has mechanical traction instead.

It's all irrelevant because we don't have the materials for a space elevator cable, nor the will to throw that much treasure at a project even if the materials were available.

 

[doctorGONZO]

Now to your "question-answer". My question was: "I will enjoy reading your detailed explanation of how you plan to avoid Gravity Drag." Or something like that, because in your post it sounded like you thought an Orbit Elevator could avoid it. You have so far failed to explain how an Orbit Elevator traction system turns off gravity. You did by fiat say that gravity does not drag the elevator down, but I already had it figured out that you believe that.

Then you don't understand what aerospace engineers mean by "gravity drag". It's not the force of gravity, or the work required to raise a mass against the force of gravity. It's the work a flying machine has to do before being able to rise away from the ground. A rocket first must burn enough propellant to hover, and then must add more thrust to move upward. The amount of thrust required to hover is gravity drag, and an elevator-- the space kind, the regular kind, or a funicular-- does not have any. It has mechanical traction instead.

It's all irrelevant because we don't have the materials for a space elevator cable, nor the will to throw that much treasure at a project even if the materials were available.

Than' yuh vurra much for your mistaken and condescending guess about my knowledge. FYI I have known about what you say the aerospace engineers mean by "gravity drag" since the time I recognized it on my own while flying my motor powered model aeroplanes (in aer, not in ospace!) when about 12. Sometimes I would "hang one on the prop" and I reasoned it out. That was close to 60 years ago. Probably before what you say the aerospace engineers call "gravity drag" was even a gleam in your ears.

It did make an interesting attempt for you to divert the conversation.

So, now, not to forget your assertion and subsequent lack of acceptable response to my query: How do you expect to avoid what you say the aerospace engineers call "gravity drag" in your understanding of an Orbit Elevator? Or did you just have a lapse and simply mis-speak?

I do agree somewhat with your last sentence. The cost and also the panorama of serious practical problems should put the Orbit Elevator completely off the table for any foreseeable chance of reallyattempting to do it.

It may, however, serve as a good vehicle to relieve enthusiasts of a bit of change in contributions and donations and even pie in the sky investments. I can easily imagine it becoming another hot fusion type eternal government funded project. Always going to be successful in only another 20 years.

 

[Chalo]

So, now, not to forget your assertion and subsequent lack of acceptable response to my query: How do you expect to avoid what you say the aerospace engineers call "gravity drag" in your understanding of an Orbit Elevator? Or did you just have a lapse and simply mis-speak?

Why do you think a wheel-driven vehicle would suffer gravity drag? Just curious. From where I sit, elevators don't use up energy just hanging there. If you mean gravity losses incurred while launching the system, then granted, there will be those. But operationally, I don't see what you are talking about. A space elevator would have no more gravity drag than a truck climbing a hill.

I didn't learn aerospace principles as a hobbyist. I was employed by Blue Origin for more than five years, from the beginning.

 

[doctorGONZO]

So, now, not to forget your assertion and subsequent lack of acceptable response to my query: How do you expect to avoid what you say the aerospace engineers call "gravity drag" in your understanding of an Orbit Elevator? Or did you just have a lapse and simply mis-speak?

Why do you think a wheel-driven vehicle would suffer gravity drag? Just curious. From where I sit, elevators don't use up energy just hanging there. If you mean gravity losses incurred while launching the system, then granted, there will be those. But operationally, I don't see what you are talking about. A space elevator would have no more gravity drag than a truck climbing a hill.

I didn't learn aerospace principles as a hobbyist. I was employed by Blue Origin for more than five years, from the beginning.

" I don't see what you are talking about. A space elevator would have no more gravity drag than a truck climbing a hill."


Uhhh, a truck climbing a hill suffers gravity drag. Why do you think it is easier for you to pedal down a hill and harder to pedal up a hill?

Everything moving up in a gravitational field suffers gravity drag. Every microsecond that it is moving up it is suffering gravity drag. True for a rocket, a space plane, a Orbit Elevator, a truck climbing a hill, even true for a Chalo pedaling up the foothills of the Sierra Nevada..

Maybe not true for one of those captured antigravity flying saucers outta A51.

 

[Chalo]

OK, still not getting it. One more time:

What aerospace engineers call "gravity drag" is not the same as the work required to rise against the pull of gravity. It is the work required to maintain altitude against the pull of gravity.

A truck parked on a hill is doing no work. A climber hanging in his harness is doing no work. A motionless elevator is doing no work. A hovering helicopter is doing all kinds of work, and so is a rocket, even when it isn't moving anywhere.

The truck on a hill, or the climber on a rope, or the elevator, begins to do work when it ascends. That work is storing potential energy that can be recovered later upon descent. The helicopter or rocket will only ascend when it adds more work than what is required to hover. That fraction of the energy, the part that adds altitude, can be recovered by descending. The fraction used just to keep it from falling down-- the gravity drag-- can't be restored to the system by any means.

Do you get it now?

 

[Starson]

Well, why not build it at one of the earth's poles, so that it isn't moving at 17,000 miles per hour. And how about using readily available material to create a tower, which would reach way up there? Oh yeah, the material would be seawater, frozen in massive layers, one on top of the other. It could be solid or hollow. In case you think that I'm joking, I'm not. A couple of weeks ago, I thought of this and was really wondering if this could work? By the way, I have no idea of the physics involved, obviously ... just trying to think outside of the box.
Gary

 

[Alastor]

lets see how they will fail this time

 

[doctorGONZO]

OK, still not getting it. One more time:

What aerospace engineers call "gravity drag" is not the same as the work required to rise against the pull of gravity. It is the work required to maintain altitude against the pull of gravity.

A truck parked on a hill is doing no work. A climber hanging in his harness is doing no work. A motionless elevator is doing no work. A hovering helicopter is doing all kinds of work, and so is a rocket, even when it isn't moving anywhere.

The truck on a hill, or the climber on a rope, or the elevator, begins to do work when it ascends. That work is storing potential energy that can be recovered later upon descent. The helicopter or rocket will only ascend when it adds more work than what is required to hover. That fraction of the energy, the part that adds altitude, can be recovered by descending. The fraction used just to keep it from falling down-- the gravity drag-- can't be restored to the system by any means.

Do you get it now?

LOL Chalo, don't quit your day job.

"Do you get it now?"

I'll type s l o w so maybe you can get it now. I already got it 60 years ago. When I figured it out on my own as a young boy. You are going round in circles conversationally like a cat chasing its own tail because you have not understood that I have understood it. But FYI you don't really understand it.

You claim to have owned an aerospace corporation or something like that. And now you are a bike mechanic (not that there is anything wrong with that) and apparently a lounge lizard performer or something like that. And I have figured out why you are not presently the billionaire CEO of a company competing with Spacex or Virgin Galactic. It is because you seem to chronically grossly misunderstand people and then fly it into the ground to try to prove that you are right.

You could piss off Jesus. Even if He was in a good mood.

 

[Chalo]

You claim to have owned an aerospace corporation or something like that. And now you are a bike mechanic (not that there is anything wrong with that) and apparently a lounge lizard performer or something like that.

Alright, here's the nickel version, since a crazy old crackpot won't remember it anyway:

Over twenty years ago, I embarked on a career as a prototypist and machinist. I worked making video and film equipment at a startup called R&D Unique Devices, then technical ceramics for the semiconductor industry at the company now called CoorsTek, then flywheel-based energy storage with Active Power. Then I had a five and a half year gig getting the private space program Blue Origin rolling. We considered and vetted a lot of ground-breaking technologies for launch systems, including tethers/elevators. But we made a rocket before I left.

Then I took three years off because I'd had enough. When I returned to work, I chose to do what I liked best rather than what moved my career forward, so I took a job working on bikes. I qualified myself for all of this not with the art degree that I never actually finished, but with proven ability.

I joined up with Austin Bike Zoo and built some noteworthy pedal powered contraptions.

In the meantime, my wife started a cool band that I joined, which gives me an excuse to dress in ways I normally don't.

[youtube]yVQAY-_ixHU[/youtube]

So yes, my life is so awesome it's sort of hard to believe, but that's the truth.

You? Let me guess. "I watch a lot of teevee and hassle people on the internet."

 

[melodious]

I used to grow up near and around the Lawrence Livermore Laboratory. There were times during Reagan's Star Wars Initiative, they were developing lasers. They'd shoot a laser straight up into the sky, not sure where. You could see it from very long distances on a nice clear night. Anyways, I was still just a pup learning music and happened to play in a big band from my area as a tenor sax player. The leader was an airplane hobbyist and had a few airplanes sitting in a garage being built. It turned out that quite a few of the other players (including the damn trombone section :wink: ) were physicists, astrophysicists, aeronautical engineers, and such. You couldn't tell until you struck up a conversation with them. Couldn't solo worth a lick, but I guess one in such a position has to focus their mental energy to shooting down missiles and things of that nature...

I enjoyed that Minor Mishaps video very much. Most of the time, I'm not a real big fan of hip-hop because usually it involves taking the human musician out of the equation (i.e. DJ, overdubs, etc.). You did a marvelous job of keeping it real. And the audience enjoyed it, which is just icing on the cake.

 

[John in CR]

Damn, just when I was about to offer money to charity for a video of his Elvis act.

 

[parajared]

I was watching Modern Marvels today and they featured the space elevator.

Modern Marvels: Carbon

 

[deronmoped]

Chalo,

If I interpret this gravity drag thing correctly, may it should be explained this way.

A rocket needs to overcome two things, lifting its weight into space and obtaining orbital velocity to overcome gravity drag. For if a rocket is shot straight up, it will come right back down because it will not have reached "orbit".

A elevator to space only needs to move the weight of itself up the tether. Since it's still attached to the Earth though the tether, the orbit will be provided by the Earth imparting "it's" spin into the elevator.

Could that be correct?

 

[Chalo]

Chalo,

If I interpret this gravity drag thing correctly, may it should be explained this way.

A rocket needs to overcome two things, lifting its weight into space and obtaining orbital velocity to overcome gravity drag. For if a rocket is shot straight up, it will come right back down because it will not have reached "orbit".

A elevator to space only needs to move the weight of itself up the tether. Since it's still attached to the Earth though the tether, the orbit will be provided by the Earth imparting "it's" spin into the elevator.

Could that be correct?

That's not what aerospace engineers are talking about when they say gravity drag.

Here is what they are talking about: For as long as it takes for the launch vehicle to escape Earth's apparent gravity (until it reaches a truly orbital combination of altitude and tangential velocity), the rocket must hold up its own weight using thrust. The elevator doesn't have to do this. If you take the rocket halfway to orbit and then slow to a stop and hold its altitude steady, it will burn up its fuel until it falls. If you do the same thing with an elevator, it just sits there consuming no energy and never falling.

If both vehicles are ascending, the elevator is spending as much energy as it takes to ascend, and no more. The rocket is spending that much energy, plus the energy it takes for the rocket to just hang there. It's a big difference whose proportion varies according to how fast the rocket accelerates, and thus how long it remains under the effect of apparent gravity.

 

[deronmoped]

Chalo,

If I interpret this gravity drag thing correctly, may it should be explained this way.

A rocket needs to overcome two things, lifting its weight into space and obtaining orbital velocity to overcome gravity drag. For if a rocket is shot straight up, it will come right back down because it will not have reached "orbit".

A elevator to space only needs to move the weight of itself up the tether. Since it's still attached to the Earth though the tether, the orbit will be provided by the Earth imparting "it's" spin into the elevator.

Could that be correct?

That's not what aerospace engineers are talking about when they say gravity drag.

Here is what they are talking about: For as long as it takes for the launch vehicle to escape Earth's apparent gravity (until it reaches a truly orbital combination of altitude and tangential velocity), the rocket must hold up its own weight using thrust. The elevator doesn't have to do this. If you take the rocket halfway to orbit and then slow to a stop and hold its altitude steady, it will burn up its fuel until it falls. If you do the same thing with an elevator, it just sits there consuming no energy and never falling.

If both vehicles are ascending, the elevator is spending as much energy as it takes to ascend, and no more. The rocket is spending that much energy, plus the energy it takes for the rocket to just hang there. It's a big difference whose proportion varies according to how fast the rocket accelerates, and thus how long it remains under the effect of apparent gravity.

Now the force that overcomes the energy needed to just hang the rocket there, is when the rocket is in orbit around the Earth. As long as the rocket has orbital velocity, it will remain in orbit, not falling back to Earth. If then the rocket accelerates more, it will achieve a higher orbit and then remain at that orbit. To come out of orbit, the rocket needs to use energy to slow itself down so gravity is allowed to drag it back to Earth.

Or am I talking about a different force?

 

[Chalo]

Now the force that overcomes the energy needed to just hang the rocket there, is when the rocket is in orbit around the Earth. As long as the rocket has orbital velocity, it will remain in orbit, not falling back to Earth. If then the rocket accelerates more, it will achieve a higher orbit and then remain at that orbit. To come out of orbit, the rocket needs to use energy to slow itself down so gravity is allowed to drag it back to Earth.

Right. So "gravity drag", in the aerospace engineering sense, only applies when a vehicle hasn't yet reached a stable orbit, and must use energy to keep from falling down. Once it reaches a stable orbit, it requires no continuous application of thrust to stay in orbit.