Alternate Space Elevator Design

Tom Ligon · Post by **Tom Ligon** » Fri Dec 11, 2009 3:43 pm

Monkees with typewriters are not the answer. Clearly you have not read the Probablilty Zero piece in the March 2010 Analog, written by a family member with some help by me. It is called "Ten Thousand Monkees", but really is about a better alternative.

alexjrgreen · Post by **alexjrgreen** » Fri Dec 11, 2009 4:05 pm

Thanks for the heads up!

MirariNefas · Post by **MirariNefas** » Fri Dec 11, 2009 7:56 pm

Aero wrote:But don't you still have the strength of materials problem? Whatever you inflate it with, the horizontal forces on the tower (radial outward) will be vastly more powerful than the vertical forces, it seems to me. And if the vertical forces are enough to hold it erect, then the horizontal forces should be enough to rip it apart. Unless I misunderstood what it is that holds the tower up.

But what if it is lighter than air for the bulk of its mass? Any lighter than air section doesn't need vertical force to hold it up, and can be dedicated to holding up the sections above it which are above the atmosphere. So the bottom, where it is widest, only needs to support the top, where it is narrowest.

ndelta · Post by **ndelta** » Fri Dec 11, 2009 9:10 pm

Last month I was trying to figure a way to make a vacuum airship work without the added weight of heavy structural members inside of it. It is easier to keep the weight of materials down by having everything in tension as opposed to compression. I thought that you would need some way to keep pressure inside the "balloon" without a lighter-than-air gas. The only thing that I could come up with was to somehow have a negative charge inside a non-conducting flexible envelope. The negative charge would expand the envelope displacing enough air to float. I never got around to calculating if it would work or not. This sounds like that only on steroids. (120,000 km tall balloon) This guy obviously has thought about this a lot longer than I have.

AcesHigh · Post by **AcesHigh** » Tue Dec 15, 2009 9:57 pm

what exactly will impeach this tower of tearing apart? You know, the proposed space elevator needed Carbon Nanotube´s strenght is NOT needed to avoid the cable falling... but to avoid it splitting!

hanelyp · Post by **hanelyp** » Wed Dec 16, 2009 6:47 am

Tom Ligon brings up a very good point, a negatively charged tower will collect positive ions. In addition to lightning discharges, such a tower reaching above sensible atmosphere would have a steady ion collection from ambient ions. If the envelope was conductive there would be a constant contest between keeping the tower charged up and discharging to the environment. If the envelope is insulating charge would build up on either side until breakdown voltage was reached. Any estimates on how fast the tower would discharge?

Another thought I had is that any electron gas inside a cool envelope would tend to condense on the envelope as a static charge. I wouldn't expect this to be a killer to the idea, but it might change the dynamics.

djolds1 · Post by **djolds1** » Sat Jun 12, 2010 3:25 pm

ndelta wrote:Last month I was trying to figure a way to make a vacuum airship work without the added weight of heavy structural members inside of it. It is easier to keep the weight of materials down by having everything in tension as opposed to compression. I thought that you would need some way to keep pressure inside the "balloon" without a lighter-than-air gas. The only thing that I could come up with was to somehow have a negative charge inside a non-conducting flexible envelope. The negative charge would expand the envelope displacing enough air to float. I never got around to calculating if it would work or not. This sounds like that only on steroids. (120,000 km tall balloon) This guy obviously has thought about this a lot longer than I have.

Would this idea be useful for the Airship to Orbit concept? An ATO should achieve orbit well "south" of the ionosphere.

Stoney3K · Post by **Stoney3K** » Sat Jun 12, 2010 5:33 pm

hanelyp wrote:Tom Ligon brings up a very good point, a negatively charged tower will collect positive ions. In addition to lightning discharges, such a tower reaching above sensible atmosphere would have a steady ion collection from ambient ions. If the envelope was conductive there would be a constant contest between keeping the tower charged up and discharging to the environment. If the envelope is insulating charge would build up on either side until breakdown voltage was reached. Any estimates on how fast the tower would discharge?

You could, of course, line the entire tower with a Magrid and keep the structure itself charge-free.

rjaypeters · Post by **rjaypeters** » Thu Aug 26, 2010 4:20 am

Thin-walled pressurized structure needed to resist longitudinal loads? One need look no further than the Atlas rocket.

MSimon · Post by **MSimon** » Thu Aug 26, 2010 3:37 pm

Why do the last two comments remind me of sex?

It must be those male and female mating connectors I've been playing with.

jrvz · Post by **jrvz** » Thu Aug 26, 2010 5:20 pm

According to TFA, the tower has no net charge - there's a layer of positive charge to balance the charge of the electron gas. They're separated by a very good insulator.

However, it seems to me that the electrons would not fill the volume, but (due to the attraction of the positive charges) would instead plate the inside of the insulator. Then you'd have a cylindrical capacitor containing a vacuum, which would instantly collapse due to air pressure.

If you give the electrons so much energy they can't remain on the insulator, then I expect the whole thing gets too hot to survive.