# I Novel Launch Method

1. Mar 21, 2016

### udtsith

I know magnetic launch tracks on the side of mountains has been proposed before but what if...

you vacuum the inside of the launch track on the side of the mountain and extend the tube up from about 5K meters to 30K meters? The tube on the side of the mountain would be made of a strong metal but the tube that isn't supported would be something like kevlar film. The tube that goes beyond the mountain wouldn't be responsible for accelerating anything or even supporting the launch vehicle. The only purpose of the tube beyond the mountain would be to keep the vacuum so that the launch vehicle isn't slowed (much) by air friction. At 30K meters the atmosphere is about 5% at the surface. If it could go to 50K the atmosphere is only 1% of surface. Before a launch any air that seeped in from the sides of the kevlar would be vacuumed out to match the opening pressure at 30K/50K meters. The launch vehicle would then leave the top of the mountain at escape velocity or...it would carry an additional booster that is also accelerated...or a tunnel could be dug into the earth to extend the launch track if needed.

The advantage of having this 'floating tube' beyond the top of the mountain would be so that the launch craft doesn't have to face or smash into the atmosphere. And it would be alot easier to support a tube that goes to just 30K meters than one that goes all the way to space

2. Mar 21, 2016

### Borg

It's a lot cheaper to strap a rocket to the bottom of a 747 and launch it that way.

3. Mar 21, 2016

### udtsith

The difference though is that all the energy needed for launch is given at the ground. Whereas for a 747 you are only 20K meters up and you still have 300K meters to go against gravity. So imagine the space shuttle ... most of the weight is with the fuel needed to accelerate the fuel.

4. Mar 21, 2016

### Borg

I didn't notice that you were referring to meters. Mount Everest is only 8850 meters high. How do you propose to build something an additional 20 - 40 thousand meters above that?
You still have to overcome gravity with your idea.

5. Mar 21, 2016

### udtsith

Yes, you overcome gravity by inputting all the kinetic energy required into the launch vehicle before it leaves the side of the mountain. Yes, the greatest technical challenge/impossibility would be extending a tube an additional 30K meters into space but when I think of the forces they don't seem insurmountable. For example, you don't have to pull as you would a space elevator (which would also need to go much farther)...and you don't have to deal with accelerating the craft. All you have to do is (somehow) get a material to keep a low pressure environment until launch. Maybe rings of balloons? or maybe the interior of the kevlar tube is heated air or helium/hydrogen?

6. Mar 21, 2016

### Borg

That's an awfully lot of hand waving of immense technical challenges. It sounds like a design for the worlds most expensive explosion as the payload strikes the interior of your tube due to movement or thermal differentials. I stick by my original post. Launching a rocket from a 747 is far cheaper with a much higher chance of success.

7. Nov 5, 2016

8. Nov 5, 2016

### DrStupid

Borg already explained why a tube from 5K to 30K meters is not a good idea. But how about using a giant plasma beam to drill a tunnel into space?

9. Nov 9, 2016

### Staff: Mentor

With magnetic levitation for the tube, this concept is known as StarTram. It works on paper, but no prototype of relevant scale has ever been tested. The gigantic plasma window looks like the most problematic part, but levitating ~200 km of vacuum tube is not easy either.
There is nothing to match. If your opening at the top is at atmospheric pressure, then every part of the tube is at the outside pressure corresponding to its height is due to hydrostatic equilibrium. You have to keep the whole tunnel under a better vacuum and develop some shutter system to let the spacecraft leave without air entering.

10. Nov 9, 2016

### 256bits

Not sure of the implementation of your idea.

One thing to consider is that the viscosity of a gas, which a plasma can be considered, increases with temperature.
A rocket would experience more friction moving through a plasma at high temperature, in comparison to air at STP for example.

11. Nov 10, 2016

### DrStupid

The rocket would experience less friction because the higher temperature reduces the density and the rocket could be accelerated by the friction if the plasma is faster.