Hey all,

I had a brainwave a week ago of how to build a structure the 100KM to space.

Part one is the design which resembles a tripod more than a single spire.
Part two is the construction of each leg.

If you look at a camera tripod, it can acheive great stability over long distances with relativly lightweight materials. A tripod is also a lot easier to keep upright than say a single post. A tripod also allows for a more interestng form of construction as construction can occur on the ground and not up in the air/space.

Building a tripod using normal construction methods however is impractical as the shear weight of the structure would cause it to bow and snap. I have a solution however.

Bamboo grows with large air pockets which allows it to acheive great strength while remaining lightweight. I propose a similar construction for such a structure. Large, inflateable blocks I think would solve almost all material delemas. Each block is tied together to form the legs of the tripod on the ground, deflated. Each component could then be inflated using normal oxygen in sequence from the middle. As each segment is inflated, the structure would rise higher into the air. Furthermore, as it rises into the air, the pressure inside increases and makes the structure even stronger. (Pressure release valves would be needed on each component and as air escapes as it rises, it becomes lighter)

Benifits of this structure include that few materials are used, the main support of the structure is pressurised air, the erection of the structure is relatively easy, it provides multiple paths to get to the top, maintenence is also simple and best of all, it will bend and sway with the weather as necessary.

Thoughts anyone?

The reasons for using oxygen is that it is cheap to obtain and doesn't weight too much. Also it pressurises well.

I'm not sure if this method would work well for buildings as it is self-supporting, but I don't think it would take too much additional weight. However as a spacelift only needs to be self supporting and take a small amount of additional weight, iI think it would work. Getting to the top is also easy as a climber could go up the legs with little trouble.

I could see the structure bending, but the construction of using small high pressure compartments would help prevent twisting and bending (Exactly the same as bamboo), but would allow it to sway and bend back with the wind. The construction material is also flexible, probably a plastic or kevlar like material so it could puncture but not shear, snap or bend out of shape. As each compartment would bend, the pressure would increase and force it to spring back into its original shape.

I can't believe that this hasn't been done before or investigated.

What is very interesting is that each component will physically get lighter the higher it is. The reason is that you require less air to maintain the pressure and equal strength as the atmosphere around it becomes lower in pressure. I can't think of another material that the higher it is the less mass it has, nor one that keeps its strength even though it is lighter. Cool huh?

Well it has been 3 years! Lots has changed, but it looks like this idea's not so stupid after all...

http://www.newscientist.com/article/mg20227117.000-inflatable-tower-could-climb-to-the-edge-of-space.html

15km instead of 100, but I'm glad to hear someone's followed up on the idea!