Author Topic: Elevators may replace rockets, scientist says  (Read 7931 times)

Offline Hotol

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Offline Paul Howard

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RE: Elevators may replace rockets, scientist says
« Reply #1 on: 04/14/2006 06:10 pm »
It's a fine concept, but I do feel it's a long way off. They are still in the very early stages of creating nano tethers that will work in this senario.

Offline spacefire

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RE: Elevators may replace rockets, scientist says
« Reply #2 on: 04/15/2006 01:27 am »
carbon nanotubes could be put to use to sustain space exploration in a more acheievlable way than a space elevator.
Imagine a nuclear powered 'helicopter' with ultra-thin flexible, reelable,  up to 10mile long rotor blades.
At the tips of the blades are two payloads,each fitted with a rocket motor second stage. At altitudes of 100,000ft, the payloads, now spinning at speeds of thousands of miles per hour, are released and fire their rocket motors to achieve orbit.
Because the 'blades' at the release time extemely long, the centrifugal forces on the payloads can be kept relatively low while the speeds can reach signivicant fractions of the LEO Delta-V.

Offline modavis

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RE: Elevators may replace rockets, scientist says
« Reply #3 on: 04/15/2006 06:49 pm »
I'll be moderating a panel at ISDC on some of the challenges involved: debris avoidance, power beaming to the climbers, and of course the looooooong way to go before carbon nanotubes yield real bulk engineering materials. There could be breakthroughs in the latter next week... or it could take as long and cost as much as it took to get from the first transistor c. 1950 to an Intel fab plant c. 2000.


Offline Jim

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RE: Elevators may replace rockets, scientist says
« Reply #4 on: 04/27/2006 07:42 pm »
Quote
spacefire - 14/4/2006  9:27 PMcarbon nanotubes could be put to use to sustain space exploration in a more acheievlable way than a space elevator.Imagine a nuclear powered 'helicopter' with ultra-thin flexible, reelable,  up to 10mile long rotor blades.At the tips of the blades are two payloads,each fitted with a rocket motor second stage. At altitudes of 100,000ft, the payloads, now spinning at speeds of thousands of miles per hour, are released and fire their rocket motors to achieve orbit.Because the 'blades' at the release time extemely long, the centrifugal forces on the payloads can be kept relatively low while the speeds can reach signivicant fractions of the LEO Delta-V.

unworkable.

Offline publiusr

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RE: Elevators may replace rockets, scientist says
« Reply #5 on: 04/28/2006 10:43 pm »
To say the least.

Offline hop

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RE:
« Reply #6 on: 04/28/2006 11:13 pm »
Nanotube composites are likely to be of interest for conventional rockets long before they are suitable for space elevators. If you could create affordable composites with say 5x the strength/mass ratio currently attainable, it would open up some interesting options for launch vehicles. Pressure fed "big dumb boosters" or SSTOs with useful mass ratios both come to mind. Not to mention fighter aircraft and golf clubs :)

Of course, it remains to be seen whether they really pan out for structural composites.

Offline wannamoonbase

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RE: Elevators may replace rockets, scientist says
« Reply #7 on: 04/29/2006 10:50 am »
I would like to see an Elevator but there is obviously a very long way to go.  Even if their strength is really there in such a large application the practicallity of producting such a large volume of anything and assemblying it 100% vertically is a challenge to say the lease.

Once something like Kevlar is showing up in my living room and personal vehicle then I might think Nano tube production is coming closer.

I think 100 years for an elevator is on the short end of expectations.  Big works like the Channel Tunnel took hundreds of years of dreaming.  And digging a hole under the ground is alot easier than hanging a 24,000 mile long string.  

Of course if someone discovers a way to make money in space then all bets are off.
Wildly optimistic prediction, Superheavy recovery on IFT-4 or IFT-5

Offline rnc

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RE: Elevators may replace rockets, scientist says
« Reply #8 on: 05/06/2006 12:09 am »
Kevlar in the living room? My boat sails are made of it, as are the ropes and 20% of the weave of my deck coat. Kevlar, dyneema, spactra, vectran, PBO are all high strength materials. All are available in commercial volumes and all are used in the race yacht industry.  None are strong enough for a space elevator (sadly). Believe me, I would love to see an elevator - its probably ultimate solution to space access. Hard to do though.

On other hand, if it takes $10bn to build one, that does not equate to many years of CLV/CaLV launches.

Offline kraisee

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RE: Elevators may replace rockets, scientist says
« Reply #9 on: 05/06/2006 06:54 am »
Quote
Jim - 27/4/2006  3:42 PM

unworkable.

Jim, isn't that fundamentally what most people said before all the major inventions throughout history though?   The steam locomotive, the motor car, the ironclad battleship, the aeroplane, the splitting of the atom and even manned space flight?

I'd agree that it is certainly unworkable today, but it's something we may be able to do *one day*.   I do not expect I'll live long enough to see any such thing practically used, but I'd never say its not going to happen.

Give us another 10,000 years of technology development and I think the human race will be doing an awful lot of the stuff which currently just appears in Sci-Fi.

"Imagination is the beginning of creation. You imagine what you desire, you will what you imagine and at last you create what you will."
-George Bernard Shaw, 1856-1950


I believe there are no real limits to what we can achieve if we just choose to make a concerted effort large enough to reach the stated goal.   It may take a very long time, but we can do anything if we just try hard enough.   I think the Apollo missions to the moon demonstrated that very graphically for us all.

My personal way to put it: "The human experience is only limited by the human imagination."
-Ross B Tierney, 1974-...

:)
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Offline kraisee

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RE: Elevators may replace rockets, scientist says
« Reply #10 on: 05/06/2006 07:08 am »
Quote
rnc - 5/5/2006  8:09 PM

On other hand, if it takes $10bn to build one, that does not equate to many years of CLV/CaLV launches.

But what if it takes $100,000Bn and five hundred years to develop?

Excuse the terrible pun, but exactly how long is this piece of string?   (no, not litterally) We obviously can't tell how long it will take to develop, or if it will simply be a flash-in-the-pan idea to be superseded by something entirely different again.

Rockets should continue to be the method of extending our reach further, at least until a better technology comes along.   When that happens, it will largely sweep the old technology aside anyway, just like the propeller aircraft replaced the derigible, and the jet replaced the prop.   One day, something will replace the rocket also.

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Offline Dana

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RE: Elevators may replace rockets, scientist says
« Reply #11 on: 05/06/2006 08:08 am »
"23,560th floor, hardware and electronics."

"D'OH! I was supposed to get off at Men's Wear on 19,450!"

And a certain Aerosmith tune comes to mind....
"Don't play dumb with me! You're not as good at it as I am!"-Col. Flagg

"'Second Place' is just the first loser."-Bobby Allison

Offline hop

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RE: Elevators may replace rockets, scientist says
« Reply #12 on: 05/06/2006 09:15 pm »
Quote
kraisee - 6/5/2006  12:08 AM
But what if it takes $100,000Bn and five hundred years to develop?

Excuse the terrible pun, but exactly how long is this piece of string?   (no, not litterally) We obviously can't tell how long it will take to develop, or if it will simply be a flash-in-the-pan idea to be superseded by something entirely different again.
There aren't really many fundamentally different approaches. Assuming no miracle breakthroughs in physics, you've got rockets (perhaps in combination with air breathing engines and wings), elevators,  various rotovator concepts, and that's about it. Even if you count fringe concepts like JP Aerospace's ATO, there's only a handful of basic methods.

The fundamental physics of space elevators is sound. What is lacking is materials, and with carbon nanotubes, we have a candidate. It is quite possible that they aren't ultimately suitable or economical, but the development of mass produced nanotube composites is likely to have large benefits anyway. While you can't predict how much effort and time it would take, it's hard to imagine that you wouldn't have a pretty good idea what was within reach, given a say few billions and a decade of serious research.

Offline BarryKirk

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RE: Elevators may replace rockets, scientist says
« Reply #13 on: 05/08/2006 03:10 pm »
Add to that laser launch and possibly a non rotating tether, kind of like a rotovator, but it's not rotating.

Offline josh_simonson

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Re: Elevators may replace rockets, scientist says
« Reply #14 on: 05/10/2006 07:48 pm »
We'll see LEO rotating tethers and lunar elevators before an earth one, IMO we should focus on building those incremental steps first.  That will build credibility for the concept, and it's something that can be done while waiting for material science to provide suitable materials.  The single stage to tether concept may actually end up being cheaper (certainly faster) than a full blown space elevator.

Offline BarryKirk

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Re: Elevators may replace rockets, scientist says
« Reply #15 on: 05/11/2006 08:39 pm »
Absolutly, I agree.  As an example, a low performance rotovator might be used to enhance the payload capacity of a small rocket for example a Falcon 1.

It doesn't have to be much.  If a rotovator could improve the payload capacity of a Falcon 1 by say 10%, that would be a good first step as a proof of concept.

Than gradually start improving the capacity.

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