Question for a rocket scientist or an MITstudent:

[The Backlash Cometh]

Do you suppose that someday in the future, we may find a way for a helicopter/plane to make a journey from the east coast to the west coast by letting the revolution of the earth do most of the work? Or say, someday would we have the ability to set up an Atlanta-like "airport" in the sky where planes can reach by flying up, perpendicular to the earth, then wait for the earth to revolve to a predetermined spot and then glide down as quickly as the space shuttle manages to do?

What are the current obstacles?

[porphyrian]

1. I don't qualify, but you'd have to travel East and somehow counter gravity and static inertia.

Perhaps with electromagnetic control at an atomic level, so any day now.

[karlrschneider]

5. Traveling east is only advantageous when you're going into space.

Unless you're talking about prevailing winds. I guess the OP was thinking of something like
going 'straight up' and waiting for the world to rotate 'underneath' them. That could work if
you got out of the atmosphere but it would take a lot more energy than flying horizontally through it.
:-)

edit: Also, if your destination wasn't at the same latitude as the starting point, you would still
have to fly (glide?) north or south. Going from New York to Rio de Janeiro would be problematic.
:D

[The Backlash Cometh]

7. Yes, that's the box I was thinking in. I'm hoping there is something I

haven't read that might help us out of that box.

[porphyrian]

9. But what if you could counter both gravity and and the inertia that keeps us spinning?

If you could "turn off" the force holding us to the spinning planet, and the inertia generated by spinning with the planet, you could let the planet spin freely at any height, possibly even through the earth itself.

[The Backlash Cometh]

14. We do have some substances that are able to escape gravity.

Helium, for one.

[porphyrian]

17. Right, but that's a middleman I was thinking might be bypassed.

More like a white noise generator, but for gravity.

[The Backlash Cometh]

19. What is a white noise generator?

[porphyrian]

21. Sound is a type of waveform. A wave can be cancelled by combining it with a mirror image of itself.

A white noise generator reads the ambient noise then produces sound that cancels those soundwaves.

[muriel_volestrangler]

47. White noise is sound at all frequencies

It's completely different from cancelling out specific sound waves. See eg http://www.google.com/search?q=define%3A%22white+noise%22 - web definitions for "white noise".

[ProfessorGAC]

67. There's No Evidence That Gravity Is A Wave

While there have been many studies to determine the quantum nature of gravity, none has been established. To date, the mechanism of gravity is a curvature of space beyond the normal three dimensions. (Don't try to imagine it. We can't! Humans cannot really think past three dimensions. Well, Einstein could!)

The exact nature of the force that causes that curvature is not defined and no mechanism has been developed that passes muster of the mathematical models of either cosmological or quantum principles.

It would be cool if we could do it, but i fear we're centuries of knowledge away from it.
The Professor

[ret5hd]

31. Isn't that kinda like a fish saying that "air" escapes gravity...

just because bubbles float up?

Helium is affected by gravity, as all things are. It is less dense than air, so it rises to the top, but it is still affected by gravity.

[The Backlash Cometh]

32. A poetic mind, trying to work physics.

I'm outed.

[ret5hd]

36. will there be a backlash for outing backlash?

[The Backlash Cometh]

38. That all depends,

If you can indeed see straight into the distance to infinity and could see the back of your head, wouldn't you have all you needed to avoid the backlash?

[karlrschneider]

28. When someone figures out how to turn off gravity, he or she will rule the world.

:D

[karlrschneider]

2. Not for a very very very very very very long time.

;-)

[Prophet 451]

3. I'm neither

just a well-read amateur.

It's possible in theory but there's a whole heap of problems. Firstly, you're trying to get two moving objects to meet (akin to hitting a bullet with another bullet). Then you mave to work out inertia and how much deceleration time you'd need. Then you have to deal with the massive heat and friction caused by re-entry (the space shuttle has to be checked over in minute detail every time). It's possible but probably too much trouble to be worthwhile.

[The Backlash Cometh]

8. Well, let's assume there are UFOs out there.

How would they have managed to do it for so long, undetected? What would they have had to control in order to make it work?

[Prophet 451]

25. Assuming aliens exist

(A UFO is not necessarily an alien).

They would have to be using systems of propulsion far in advance of our own and a system of fabricating craft which allowed them to withstand teh heat. The simplest way would be gravitic control i.e. some way of affecting to what degree you are affected by gravity. That way, you'd be able to make the descent without having to compensate for the earth pulling you in. The convex disc shape usually attributed to UFOs, while impractical for our methods of propulsion, is very good for making planetfall as it has very little drag factor.

The other possibility is jumpgating but that's well beyond our current level of technology and I'd hate to see what would happen if you opened a gate within an atmosphere.

The undetected part: It's not terribly difficult to baffle radar, we're learning how to do it now. The more interesting part is how they manage to avoid leaving a heat sig. We can figure out how to do that on a theoretical level but the engineering isn't up to it yet.

The major problem to control is actually time. It is impossible for any object with mass to exceed lightspeed (no, not "as far as we know", it's just flat-out impossible). Therefore, in order to cover the massive distances between their home system and here, they either need to find some way to skip the intervening distance (jumpgates being the most obvious example) or find some way to both keep the crew alive (suspended animation perhaps) on the journey AND, more importantly, establish communications with their home system. At conventional speeds, a communications signal wouldn't reach their home system for years. I'm sure there's a way around that but with our current tech, I'm damned if I can think of one.

[The Backlash Cometh]

30. "Not difficult to baffle radar"

You either fly in lower than the radar, or you send a signal which can confuse the radar, or you're made up of a material that can't be detected at all. And, we have atmosphere on earth, but space is a vaccum, correct? And we know how easy it is for an air-tight vessel to glide through that vaccum, doesn't take much energy at all.

I think that somehow, they use everything possible. Glide, when they're in a gravity type environment, which is why they don't produce heat. Maybe even understand the aircurrents better than we do, which is why they may know how to ride them? And maybe can produce elements at will, like helium, which would give them the ability to have a controlled ride?

Maybe their genius is that they're ship is adaptable to all kinds of environments, and their captains are prepared to handle various navigating factos and obstacles?

[Prophet 451]

60. Well

You can't create elements out of nowhere, the raw materials have to come from somewhere. Radar: There are materials which can't be detected by radar or, the technique that's used on stealth aircraft is to administer a kind of coating (and I'm afraid i know very little about it) which the radar signal sort-of "slides" off.

The rest: You may be correct.

[DavidDvorkin]

4. The winds would be fearsome

Because the atmosphere is rotating with the earth.

If you mean going into orbit and then reentering, the energy used would make the project impractical as a substitute for aircraft or high-speed trains.

[The Backlash Cometh]

10. That's what I'm thinking.

Unless there was a way to beam up and get through it all.

[Uncle Joe]

6. I don't qualify as either, but I have read of a space elevator concept,

I don't know the time feasibility of this but if it works, it could be a first step.

[The Backlash Cometh]

12. "Space elevator" I LIKE that!!

[Uncle Joe]

16. Yes, here is a link and column, there are others as well

http://www.space.com/news/060929_xprize_cup_elevator.html

"Admittedly, at least for now, the idea of a beanstalk-like space elevator connecting Earth and space is a stretch.

But next month’s X Prize Cup will host the Space Elevator Games, an unprecedented challenge for today’s engineers looking at ways to alter the future of access to space.

Teams from around the country will gather October 20-21 in Las Cruces, New Mexico to compete for $400,000 in prize money as part of NASA’s Centennial Challenges—the space agency’s program of prize contests to stimulate innovation and competition in solar system exploration.

No matter how you look at it—from the top down or bottom up—building a full-scale space elevator is an uphill battle. But at least physics is in your favor."

<snip>

[The Backlash Cometh]

20. Too cool.

Maybe we'll have a potential entry by the time this thread ends?

[Uncle Joe]

22. Yea, that would be cool

;)

[SquireJons]

11. Geosynchronous Airports?

I'm not a rocket scientist, but I did sleep in a... oh never mind.

I have to say, it's an interesting concept. I think it would require orbital planes, meaning that they could escape earths atmosphere, like the satellites. And the Airport would have to be in outer space. But, seems to me that it could work. The down side would be fuel consumption. It takes much more fuel to reach orbit than it does to fly an aircraft anywhere.

Interestingly, the Germans were working on something like this (a bit) during WWII. The wanted to develop orbital air craft that could "skip" across the outer atmosphere and re-enter when they got to North America, so that they could attack American cities. According to their research, it would have been a very fast way of travel.

[The Backlash Cometh]

15. I just wonder, how far can a rocket be pulled up by a helium Zephr,

before it has to release, and can we start a rocket up in midair like that to break the gravitational field?

[karlrschneider]

29. Yeah, the geosynchronous altitude (Clarke Belt) is 22,000 miles up.

That's a long way to an airport. :D

[BrewerJohn]

13. Won't work

We share the motion of the earth by rotating with it. If one were to go "straight up", one would still be moving with the rotation. One would have to decelerate to get to rest with respect to the Earth's rotation. Deceleration takes as much energy as acceleration to the same speed would take.

[The Backlash Cometh]

18. How do we get that rotation to work for us?

What materials do we have available that can "break" the laws of physics?

[Prophet 451]

26. We don't

You can't break the laws of physics because if you can, it was obviously not a law to begin with.

[The Backlash Cometh]

33. Well, today we can bend light.

Yesterday, we couldn't.

[Prophet 451]

61. Which means

That the law saying we couldn't was incorrect. Scientific laws aren't like criminal laws, you can't "break" them. You can prove them incorrect though.

[SquireJons]

52. "You can't break the laws of physics because if you can..."

... you'd get a really big ticket! :+

[Solon]

27. There's a reason most rockets are launched from as close to the equator as possible...

They all go EAST, and use the Earth's rotation to give them an extra boost in angular velocity to attain orbit. Otherwise, spacecraft like the space shuttle would require more fuel.

You have to understand that all objects in orbit around the Earth have NOT escaped its gravity well, they just attained enough velocity to enter into a stable orbit. In fact, many satellites in low Earth orbit AREN'T in a stable orbit at all, and will fall, in time. Mostly this is because they are still close enough to the Earth to brush against the atmosphere, even if its extremely thin up there, and attain just enough drag to slow them down.

[The Backlash Cometh]

34. I could picture what you said. Nice details.

[Solon]

41. Here's an interesting little factoid for you...

The Moon is escaping Earth's gravity well. Every year, the Moon moves about one inch, on average, away from the Earth, its simply going a little too fast to stay in orbit around the Earth, its just taken about 4.5 billion years for it to get into it's current position.

We know this because the Apollo Astronauts position mirrors in certain locations on the moon, and scientists on Earth shoot a laser at those mirrors to measure the distance.

Also gravity is good for boosting objects to other places in the solar system, gravity increases in power the closer you get to the center of an object. Usually, when we want a probe to go to let's say Saturn, like Cassini, we will swing it by the Sun, as close as is safe for the probe, and then, on the way "out" to Saturn, it took another boost from the Earth's gravity well, it was moving fast, and moved even faster when it flew by at about 500 miles above the surface of the Earth.

This is how you increase velocity in the Solar system, and save on fuel, swinging around the planets is like going down a rollercoaster, using gravity to save on energy.

[The Backlash Cometh]

42. Is this the slingshot effect?

[Solon]

46. Yep...

When you have something going just a little too fast to stay in a stable orbit at a certain distance from the center of a massive body, that body's gravity then contributes to that object's velocity. There's a lot of dense math and stuff that goes along with this, but that's the gist of it.

I used the rollercoaster comparison because space probes "coast" so to speak, to their destination, after they are given a single boost. Most of the time, they will do corrective burns to make sure they stay on course, but that's about it.

The fastest objects anyone on Earth has ever launched are the Voyager probes, and they don't have anything beyond attitude thruster on them since they launched from Earth. They got big boosts in speed from slinging around Jupiter and Saturn, so much so, they are leaving the Solar System entirely, in fact, I think they just passed the Heliopause this year, and are in Interstellar space.

In fact, there is a "highway" of sorts, through the Solar System, a twisted course through interplanetary space, that, when a spacecraft takes it, can actually allow a craft to go to practically any major destination in the solar system with a low energy cost.

Here's a link:

http://en.wikipedia.org/wiki/Interplanetary_Transport_Network

[The Backlash Cometh]

48. I didn't know about that space highway.

I guess, it can't entirely be a vacuum. can it?

[Solon]

57. Well, there is no such thing as a PERFECT vacuum...

However, most of interplanetary space is quite empty, a couple of molecules per cubic meter, if that. Generally, space is empty enough for you not to worry about things like drag, and to be honest, anything larger than a dust grain would cause problems that would be catastrophic to spacecraft.

[OPERATIONMINDCRIME]

45. Yup. That's Why If You Throw An Object Westward It Will Go Further Then If Thrown Eastward.

For different reasons, but the same concept.

[The Backlash Cometh]

49. So, if you're playing soccer, it's always a good idea to know which

way is west? Assuming there is no wind factor, of course.

I don't know why, but this sounds like a Pelican fan gear.

[OPERATIONMINDCRIME]

51. Sorry, I Have To Edit Above. Just Realized I Reversed It. You Want To Throw West, Not East.

Truth be told though, it really is completely insignificant in measurement though lol

[muriel_volestrangler]

68. I think we're talking about the Coriolis acceleration, aren't we?

In which case it just about becomes noticeable for artillery shells, but nothing slower/smaller range. And air resistance will play a far larger part, for anything on Earth.

But I can understand having to think about the direction - I'm sitting here with pen and paper, and still can't convince myself I've got it right.

[HiFructosePronSyrup]

70. It's really quite simple.

We go up in the air, and thanks to the magic of Earth's rotation, we come back down in the same place we started from.

[Solon]

23. Technically, anything going west already does that...

Whether you are driving a car west, or flying a plane west, you are moving in the opposite direction as the Earth's rotation, so, you are already doing what the OP suggests, just that it does not save you any energy.

[The_Casual_Observer]

24. The darned atmosphere moves along with the earth.

And the plane has to lose the angular momentum that it has just by sitting on the earth too. It's an age old problem.

[not_a_robot]

35. I'm not even smart but,

There is a possibility of a vessel that has a lower or higher air density, as it can dive or rise based on the atmospheric pressure, much the way a submersible does (the atmoshphere is an ocean of gasses you know). If the vessel is shaped for a heavy glide slope as it descends (say some kind of rounded flying wing, with all around control surfaces), and the density is manipulated to maintain altitude, you could probably reduce the energy costs drastically by speed gliding to the destination. The process of creating a lighter than air craft that changes density (rather than using lighter than air gasses) might be a little too much though for us nearly hairless apes. The only design I've messed with looks like two deep acoustic diaphragms connected at the lip, as they are a shell for a rigid but still plastic diaphragm being pulled or let to change air density. Of course the shell would have to be lighter than anything i can make while resisting external and internal forces.



As far as using the rotation of the earth to change locations, well, no. Not unless you want to travel for a very long time by losing momentum via friction with particles beyond the exosphere.

[The Backlash Cometh]

39. Definitely a ship made stronger than steel, but of very light weigh

is an advantage. I just don't know why we haven't made as much inroads in that field, as we have with semiconductors.

[Jonathan50]

37. Orient Express

http://www.fas.org/irp/mystery/nasp.htm

X-30 National Aerospace Plane (NASP)
There is also the possiblity that the SR-71 follow-on was hidden in plain sight. The program to develop what is called the National Aerospace Plane (NASP), designated the X-30, had its roots in a highly classified, Special Access Required, Defense Advanced Research Projects Agency (DARPA) project called Copper Canyon, which ran from 1982 to 1985. Originally conceived as a feasibility study for a single-stage-to-orbit (SSTO) airplane which could take off and land horizontally, Copper Canyon became the starting point for what Ronald Reagan called:<1>

"...a new Orient Express that could, by the end of the next decade, take off from Dulles Airport and accelerate up to twenty-five times the speed of sound, attaining low earth orbit or flying to Tokyo within two hours..."

The next stage of the program, called Phase 2, with Copper Canyon being Phase 1, was intended to develop the technologies for a vehicle that could go into orbit as well as travel over intercontinental ranges at hypersonic speeds. There were no commitments to undertake Phase 3, the actual design, construction and flight testing of the aircraft. The decision to undertake Phase 3 based on the maturity of the requisite technologies, originally planned for 1990, was currently been postponed until at least April of 1993.<3>

There were six identifiable technologies which are considered critical to the success of the project.<3&g; Three of these "enabling" technologies are related to the propulsion system, which would consist of an air-breathing supersonic combustion ramjet, or scramjet. A scramjet is designed to compress onrushing hypersonic air in a combustion chamber. Liquid hydrogen is then injected into the chamber, where it is ignited by the hot compressed air. The exhaust, consisting primarily of water vapor, is expelled through a nozzle to create thrust. The efficient functioning of the engine is dependent on the aerodynamics of the airframe, the underside of which must function as the air inlet mechanism and the exhaust nozzle. Design integration of the airframe and engine are thus absolutely critical to project success. The efficient use of hydrogen as a fuel for such a system is another crucial element in the development of the X-30.

[The Backlash Cometh]

40. Hmm...sounds like the exhaust would be a better alternative to

help out with our global warming problem.

[Redstone]

43. Uh, the "obstacles" would be a little inconvenience known as "physics."

Redstone

[The Backlash Cometh]

50. That's the box we're trying to break out of.

[Redstone]

54. Nah. the laws of physics are a strong enough box that you're NOT going to break out of it.

Sorry about that, but it's the way things are.

There's no perpetual-motion machine. There's no 200-mile-per-gallon carburetor. There's no secret anti-gravity drive for rockets.

There just isn't.

Redstone

[originalpckelly]

55. "There's no secret anti-gravity drive for rockets."

You never know. :rofl: Never say never.

[The Backlash Cometh]

62. Hey, on DU we live for the chance to budge an immovable object.

Impeach Physics!

[OPERATIONMINDCRIME]

44. Not Physically Possible Unless You Go Into Orbit And Re-Enter, Like We Do Already.

Current obstacles? Elementary physics.

[originalpckelly]

56. Actually, that doesn't have a thing to do with it...

it's all about the fact that we are traveling as fast as the speed of the Earth's surface, so there is no relative motion between us and it.

[OPERATIONMINDCRIME]

58. Ummmm, Buddy, That's Why You'd Have To Escape The Atmosphere And Then Re-Enter.

I'm sitting here shaking my head from side to side and laughing a little out loud as to your attempt to sound smart. And don't get hung up on the word orbit. The whole point is that you have to basically break free of the earths full rotation first, then re-enter, much like we do already.

:freak:

[originalpckelly]

59. That doesn't have anything to do with it when it comes to motion relative to the Earth's surface...

only in achieving a stable orbit.

There is no way practically to use the energy of the Earth's rotation to move from one point on it to another, because the motion of the Earth's surface and anything on it due to the Earth's rotation are the same. There is no relative motion between the Earth's surface and anything on it (or above it for that matter) because the Earth and whatever object we are talking about are rotating at the same speed.

[OPERATIONMINDCRIME]

63. Listen Dude, No Fucking Shit. I'm Not Sure What You're Not Getting Here.

No fucking shit that "the motion of the Earth's surface and anything on it due to the Earth's rotation are the same. There is no relative motion between the Earth's surface and anything on it". That's grade school fucking physics. Not sure why you're acting like you know that and I don't. The whole fucking point I'm making is the same goddamn one you're making. I'm saying it's goddamn impossible. I'm saying the only way to get the earth's rotation to come into play, hence breaking the lack of relative motion, is to literally completely go beyond the atmosphere. Then, as the earth fucking rotates, you can come back down in a different goddamn spot. We do this already, every goddamn time we go into space.

So I'm on the same logical side as you. Will you please stop responding to me as if I'm not, or as if you're actually saying something that isn't completely obvious?

Sheesh!

[originalpckelly]

64. Well, it really doesn't matter if we go into space or not...

:-)

:rofl:

I love fuckin' with people sometimes.

[originalpckelly]

53. The only time we can effectively use the motion of the rotation of the Earth...

is when the frame of reference is not the the Earth itself. Since we are traveling at the same speed as the surface of the Earth, for the purposes of this discussion we are not traveling at any relative speed. Any translation across the surface of the Earth is within that frame of reference.

The only time we can practically use the energy of the motion we all have because of the Earth's rotation is when we talk about energy levels and escape velocity (going into orbit.)

[eppur_se_muova]

65. Sounds like a 'rotovator' bolo, a sort of variation on the space elevator concept.

http://en.wikipedia.org/wiki/Space_Elevator

(In reference to the OP, this device exploits the orbital motion of the device more than the rotational motion of the Earth.)

In a rotovator, a large mass in orbit has long tethers attached, rotating at such speed that a tether end comes very close to the planetary surface. The end of the tether traces out a 'cycloid' curve (IIRC). During closest approach, an atmospheric or ballistic vehicle can rendezvous and dock. The tether then lifts the payload into orbit, and drops it off at a later rendezvous at another point near the planetary surface.

(A 'bolo' may also refer to a similar device in Solar orbit, used for momentum transfer to change orbits. See http://www.amazon.com/Web-Between-Worlds-Charles-Sheffield/dp/0671319736/sr=1-1/qid=1171551093/ref=pd_bbs_sr_1/002-0058968-0320840?ie=UTF8&s=books
for a 1979 story which was largely responsible for giving the idea popular exposure, together with Arthur C. Clarke's "Fountains of Paradise".)

Don't know who to credit for first suggesting this, but a number of SF authors now take it for granted that various species of tether-based devices are legitimate background for stories set in the future, particularly on airless bodies (Moon) or Mars. In Earth orbit, the immersion of the tether into the atmosphere would lead to energy dissipation, and some source of energy input would have to be provided.

edit: ref to bolo in http://en.wikipedia.org/wiki/Space_habitat

http://www.islandone.org/LEOBiblio/SPBI122.HTM which credits Robert L. Forward with the 'rotovator' concept:



http://www.strangehorizons.com/2003/20030414/rope.shtml

http://www.medianet.pl/~andrew/SPBI114.HTM

[AngryAmish]

66. Physics

When on the surface of the earth we are traveling at the same speed as the surface of the earth. It just appears that we are standing still (normal relativity). If the helicopter (apparently) shoots straight into the air the momentum of the speed of the earth is not lost so the helicopter would still be traveling at the same rate of speed as the surface.

[Sequoia]

69. I used to think things like this as a kid.

I would think, why can't I suspend myself in the air and let the Earth turn under me so that I could be in China (Cultural Revolution then...eat your meat, there are children starving in China). Then I thought, well the atmosphere might carry me along so maybe I should be higher up but then I wouldn't have any oxygen.

[The Backlash Cometh]

71. I had a deprived childhood.

So I'm in La Segunda Juventud.

[Sequoia]

73. Is that another planet?

[The Backlash Cometh]

74. Second star to the right, and sail until the morning.

[Sequoia]

75. I love you Peter Pan. Let's go to Neverland.

[alfredo]

72. I did something like that on peyote.