3 of 4
3
Space Elevator
Posted: 28 July 2010 07:57 AM   [ Ignore ]   [ # 31 ]
Administrator
Avatar
RankRankRankRankRank
Total Posts:  601
Joined  2008-03-13

I don’t see myself a multi-load tether as a solution without improving the concept because it means that the strength of the tether must be increased to accommodate more load. 
Actually I even wonder: what is the advantage of using a tether? Basically the only problem it addresses is avoiding reaction mass.
I would love to compare different lifting concepts on efficiency and see their advantages:fanned lifter vs plane vs balloon vs tether.
I think probably balloon would be the most efficient method for lifting.
Of course it would work only until the edge of atmosphere where you would need either a tether or reaction mass (balloon gas?).
That could reduce tether strength requirements and allow for multi-tethering or maybe produce a totally new orbital lifting concept combined with some innovative propulsion concept (dpf?).

Profile
 
 
Posted: 28 July 2010 08:03 AM   [ Ignore ]   [ # 32 ]
Administrator
Avatar
RankRankRankRankRank
Total Posts:  601
Joined  2008-03-13

Just to point out that weather balloons can go as high as stratosphere
http://upload.wikimedia.org/wikipedia/commons/f/f9/Atmosphere_layers-en.svg 
Definitely a SSTO vehicle :D

Profile
 
 
Posted: 28 July 2010 04:34 PM   [ Ignore ]   [ # 33 ]
Old Croaker
Avatar
RankRankRankRankRank
Total Posts:  999
Joined  2009-02-20

The quick trip is to the “off-shore” activities that will pop up around 60 miles. That’s where I expect the first tourist stops to be, followed by commercial access fees to use any or all of the tether as a launch system. The less reaction mass that you have to leave the ground and or orbit with, the smaller, lighter, and cheaper your launch vehicle gets. This also pays dividends in smaller thrusters and shorter burns, which also contribute to lower reaction mass requirements.

The tether is easy to “understand”, which makes it easier to sell than a pendulum or a balloon (why hasn’t somebody done this before?). The tether concept also eliminates the need for heat shielding and a retro-burn to re-enter the atmosphere. While this all will probably seem quaint to an “enlightened” reader in less than 50 years, its about the best we can do right now and is still light years ahead of what most people think is possible.

 Signature 

“The Power To Get Things Done”

Profile
 
 
Posted: 29 July 2010 03:45 PM   [ Ignore ]   [ # 34 ]
Old Timer
Avatar
RankRankRankRank
Total Posts:  463
Joined  2009-12-13
Breakable - 28 July 2010 11:57 AM

Actually I even wonder: what is the advantage of using a tether? Basically the only problem it addresses is avoiding reaction mass.

reaction mass is the single largest problem in rocketry!

it’s time for new physics; i want that reactionless thruster now, please. there may be no other way to get to the stars

Profile
 
 
Posted: 29 July 2010 04:37 PM   [ Ignore ]   [ # 35 ]
Old Croaker
Avatar
RankRankRankRankRank
Total Posts:  999
Joined  2009-02-20
vansig - 29 July 2010 07:45 PM
Breakable - 28 July 2010 11:57 AM

Actually I even wonder: what is the advantage of using a tether? Basically the only problem it addresses is avoiding reaction mass.

reaction mass is the single largest problem in rocketry!

it’s time for new physics; i want that reactionless thruster now, please. there may be no other way to get to the stars

The tether also eliminates the need for multi-G force liftoff and re-entries, which opens space tourism to almost anybody. Just as reaction mass has geometric multipliers, minimizing it has geometric dividers. The less mass of any type that you need, the better off you are.

I’d like to see at least one variation of a tractor beam. One pushes against mass, the other pulls toward a large mass.

 Signature 

“The Power To Get Things Done”

Profile
 
 
Posted: 29 July 2010 10:19 PM   [ Ignore ]   [ # 36 ]
Old Croaker
Avatar
RankRankRankRankRank
Total Posts:  1429
Joined  2007-11-01
Aeronaut - 29 July 2010 08:37 PM

...

I’d like to see at least one variation of a tractor beam. One pushes against mass, the other pulls toward a large mass.

I’d like to chide you for wanting “spooky action at a distance”, were it not that that’s actually a good description of every field and force in physics. Phagh!  cheese  grrr

 Signature 

Help Keep The Planet Green: Maximize Your CO2 and CH4 Output!

Profile
 
 
Posted: 30 July 2010 04:18 AM   [ Ignore ]   [ # 37 ]
Old Croaker
Avatar
RankRankRankRankRank
Total Posts:  999
Joined  2009-02-20
Brian H - 30 July 2010 02:19 AM
Aeronaut - 29 July 2010 08:37 PM

...

I’d like to see at least one variation of a tractor beam. One pushes against mass, the other pulls toward a large mass.

I’d like to chide you for wanting “spooky action at a distance”, were it not that that’s actually a good description of every field and force in physics. Phagh!  cheese  grrr

I’d also like to add a transporter to my wish list. Flip Phone’s already accomplished.

 Signature 

“The Power To Get Things Done”

Profile
 
 
Posted: 30 July 2010 04:36 AM   [ Ignore ]   [ # 38 ]
Old Croaker
Avatar
RankRankRankRankRank
Total Posts:  1429
Joined  2007-11-01
Aeronaut - 30 July 2010 08:18 AM
Brian H - 30 July 2010 02:19 AM
Aeronaut - 29 July 2010 08:37 PM

...

I’d like to see at least one variation of a tractor beam. One pushes against mass, the other pulls toward a large mass.

I’d like to chide you for wanting “spooky action at a distance”, were it not that that’s actually a good description of every field and force in physics. Phagh!  cheese  grrr

I’d also like to add a transporter to my wish list. Flip Phone’s already accomplished.

Sorry.  Transporter: if it can send to one location, it can also send to 2 simultaneously, and perhaps leave the original intact.  How many of you arguing about which you is the you-est do you want?

 Signature 

Help Keep The Planet Green: Maximize Your CO2 and CH4 Output!

Profile
 
 
Posted: 30 July 2010 04:16 PM   [ Ignore ]   [ # 39 ]
Old Croaker
Avatar
RankRankRankRankRank
Total Posts:  999
Joined  2009-02-20

Does it have to send to multiple locations?

 Signature 

“The Power To Get Things Done”

Profile
 
 
Posted: 30 July 2010 04:37 PM   [ Ignore ]   [ # 40 ]
Old Croaker
Avatar
RankRankRankRankRank
Total Posts:  1429
Joined  2007-11-01
Aeronaut - 30 July 2010 08:16 PM

Does it have to send to multiple locations?

How would you stop the transmitted matter transport info from being “mirrored” at 2+ receivers? It’s like trying to enforce copyright on digital copies.  cheese 
So far, the only physics that even hints at matter transport is very brief and carefully pre-arranged entanglement events, AFAIK, however. The matter transporter is more like a “creation machine” than an actual physics possibility.  Viz the “replicator”, which materializes gizmos and cordon bleu meals at the touch of a button.

 Signature 

Help Keep The Planet Green: Maximize Your CO2 and CH4 Output!

Profile
 
 
Posted: 30 July 2010 08:28 PM   [ Ignore ]   [ # 41 ]
Old Timer
Avatar
RankRankRankRank
Total Posts:  463
Joined  2009-12-13

okay i apologize for letting this topic off the rails by mentioning a reactionless thruster.

keeping it real and in the twenty-first century,
colossal carbon tubes have the specific strength needed for a space elevator.

if a climber could accelerate as it goes up, then at a modest 1.1g it would reach high subsonic speeds in five minutes.. at which point it would be ~44 km out.

at 300 m/s top speed, total travel time from surface to 30,000 km out would be ~28 hours. but after reaching space, it could perhaps go faster?

Profile
 
 
Posted: 30 July 2010 11:29 PM   [ Ignore ]   [ # 42 ]
Old Croaker
Avatar
RankRankRankRankRank
Total Posts:  1429
Joined  2007-11-01

Perhaps a lower G-number, with constant accel/decel throughout, using inductive braking to recapture some of the energy, would make for a shorter trip. The seats etc. would of course have to rotate to cushion the decel. after turnaround.

 Signature 

Help Keep The Planet Green: Maximize Your CO2 and CH4 Output!

Profile
 
 
Posted: 31 July 2010 03:24 AM   [ Ignore ]   [ # 43 ]
Old Croaker
Avatar
RankRankRankRankRank
Total Posts:  999
Joined  2009-02-20

The stuff I was reading several years ago was based on a fairly constant 120 MPH velocity in both directions, powered by laser(s). That’s plenty fast enough for tourists only going around 62 miles to get their astronaut wings and join the zero-g club. The vast majority of the 69,000 mile tether would be used as spaceports to various destinations in both launch and recovery modes.

 Signature 

“The Power To Get Things Done”

Profile
 
 
Posted: 15 August 2010 05:29 AM   [ Ignore ]   [ # 44 ]
Newbie
Rank
Total Posts:  3
Joined  2010-08-05

Hello.

I found this discussion because … to keep things short without anecdotal stuff, I was looking for candidate technologies for my own space elevator project and its stabilization.

Yes, I take advantage of discussion forums to advertise my much less sexy space elevator, namely the SpaceShaft so my apologies for this action. Of course there are other reasons why I do this besides the advertising, (which I do since I have no budget for such things,) but very importantly because of the concentration of gray matter in forums like this.

For now I will just place a hyperlink to some descriptions of what I am proposing, I hope you find it interesting since it answers a lot of the outstanding questions being discussed. I really hope you try to demolish my idea.
 
http://spaceshaft.org from where you will be redirected to the temporary page at http://spaceentrepreneurs.ning.com/profile/NeslonSemino since the SpaceShaft website is being redesigned.

Live long and prosper

Profile
 
 
Posted: 15 August 2010 10:47 AM   [ Ignore ]   [ # 45 ]
Administrator
Avatar
RankRankRankRankRank
Total Posts:  601
Joined  2008-03-13
spaceshaft - 15 August 2010 09:29 AM

Hello.
... I really hope you try to demolish my idea. ...
Live long and prosper

Just want to point out to you that without cheap energy space travel is too expensive wink

Profile
 
 
   
3 of 4
3