Elon has a huge Hyperloop rival

[elhigh]

Originally Posted by RedDevil

I think the hyperloop system is viable; not in the West or China, but on the moon, if we ever get a large human presence there.
Moon bases need to be built in tunnels: away from cosmic radiation, extremes in heat and cold and super abrasive moon dust.

A hyperloop at over mach 2 could even be used as a launch system on the moon, throwing materials from the moon into space at very low cost.
if we want to explore the wider solar system and beyond we should seriously consider a moon base with factories and hyperloop launcher as a stepping stone.

A Mach 2 Hyperloop on Earth could be used as a launch system. There are a few things to deal with though: anything coming out of the end is going to make one hell of a *pop* so you don't want it near populated areas. And upon emergence from the tube it'll suddenly encounter all of the aerodynamic forces that the vacuum tube has isolated it from, so that's bound to be pretty bumpy. It would probably be best to reserve that kind of service for bulk goods like fuel and other consumables. Even then its utility for space industry would be gigantic.

Another thing to try would be to run that Hyperloop right up the side of Mt. Kenya. Conveniently, Mt. Kenya sits almost on top of the equator - the best spot for launches if you'd like to make the most of the planet's own rotation to make launches easier. Adding an affordable, fast turnaround space launch facility to the heart of Africa would do wonders for economies all around it, and of the various countries in that part of Africa, Kenya is a little less chaotic than some of its neighbors.

And Mt. Kenya is over 17,000 feet high, giving you a convenient three mile head start on getting out of the atmosphere when you do come out of the tube, in addition to there being no people to complain about the noise.

Yes, it's a national park. I'm daydreaming at this point.

Moon-based launch rails, AKA mass drivers, have been discussed at length. Once we have a stable base on the moon to build stuff, we'll be able to send packages of raw material pretty much anywhere we want on the cheap. Endless solar power and no existing ecosystem? Build what you want.

One important caveat: those packages might not have braking. If you don't mind meteoric impacts (for instance, creating a surface mine of lunar-sourced aluminum ore in a conveniently uninhabited place on Mars) then the costs, once it's up and running, are pretty cheap.

As to using it for launching manned missions, well. It'll pull high G's for launching bulk goods, but if you want to get an interplanetarily useful launch velocity for humans it has to be dozens, even hundreds of kilometers long. And even then, it'll be a pretty hard push.

[freebeard]

If you hollowed out the Moon and fired a proton torpedo into an exhaust port,

It would exit the other side, and if at lower than escape velocity would fall back as the Moon rotated the exhaust port out from under it.

[Xist]

Buseman's Biplane:


If your projectile is shaped like a weird soda straw, supposedly you do not create any shock waves.

You just cannot generate lift.

Or steer.

You better have good aim!

[RedDevil]

Originally Posted by elhigh

A Mach 2 Hyperloop on Earth could be used as a launch system. There are a few things to deal with though: anything coming out of the end is going to make one hell of a *pop* so you don't want it near populated areas. And upon emergence from the tube it'll suddenly encounter all of the aerodynamic forces that the vacuum tube has isolated it from, so that's bound to be pretty bumpy. It would probably be best to reserve that kind of service for bulk goods like fuel and other consumables. Even then its utility for space industry would be gigantic.

Another thing to try would be to run that Hyperloop right up the side of Mt. Kenya. Conveniently, Mt. Kenya sits almost on top of the equator - the best spot for launches if you'd like to make the most of the planet's own rotation to make launches easier. Adding an affordable, fast turnaround space launch facility to the heart of Africa would do wonders for economies all around it, and of the various countries in that part of Africa, Kenya is a little less chaotic than some of its neighbors.

And Mt. Kenya is over 17,000 feet high, giving you a convenient three mile head start on getting out of the atmosphere when you do come out of the tube, in addition to there being no people to complain about the noise.

Yes, it's a national park. I'm daydreaming at this point.

Moon-based launch rails, AKA mass drivers, have been discussed at length. Once we have a stable base on the moon to build stuff, we'll be able to send packages of raw material pretty much anywhere we want on the cheap. Endless solar power and no existing ecosystem? Build what you want.

One important caveat: those packages might not have braking. If you don't mind meteoric impacts (for instance, creating a surface mine of lunar-sourced aluminum ore in a conveniently uninhabited place on Mars) then the costs, once it's up and running, are pretty cheap.

As to using it for launching manned missions, well. It'll pull high G's for launching bulk goods, but if you want to get an interplanetarily useful launch velocity for humans it has to be dozens, even hundreds of kilometers long. And even then, it'll be a pretty hard push.

Thinking along the same lines

The mountain launch pipe cannot be vacuum, but we could superheat it and blow a lot of steam through.
That would create a hypersonic jet stream through which the capsule could be launced relatively easily; maybe the steam could actually double as propellant.
A tiny hydrogen/oxygen rocket could create a small amount of boost by itself and loads of superheated steam for additional pressure against the capsule in the launch pipe.
It would be a rocket powered self propelling steam cannon bullet. Far more efficient than a traditional launch system.

Best launch point imho would be Mount Chimborazo, a 6310 meter high dead volcano in Equador, just a hundred miles south of the equator; the top of the mountain is the point furthest removed from the center of the earth.
Mount Everest is higher compared to sea level, but as the earth flattens out because of its own rotation, the added circumference at the equator makes Chimborazo the winner.
As it is 0.1 % further away from the center of the earth than sea level it reduces the power needed for the launch ever so slightly, but the lower air resistance by taking off at altitude is more important.

A mass driver system could not only launch stuff, it could also brake goods coming in - but it would require great precision and a safety bailout system (side rockets?) if the lineup gets botched. The driver could best be situated horizontally over the surface so it would indeed require but a small correction to miss it and not crash.

To send stuff back to earth: I think moon rock may be great heat shield material. Weight is no problem and it is single use, no deposit. Just build the mass driver launcher so that it aims directly at earth - the moon keeps the same side towards earth all the time - and it would not need rocket fuel at all.

The human body can endure large G forces when it is floating in water. As it weighs the same as water it could endure almost limitless G forces - except for air and gases in the lungs and bowels
Rather than building swimming pools aboard spacecraft there could be hard shelled G force suits lined with soft watery gel pads. Like a body shaped tank with just an inch of play all round.
If one can endure 10 G for 23 seconds you'd be at the escape speed for the moon; 2300 meter per second. That would 'just' need a 13.2 kilometer or 8.3 mile launch track.

[redpoint5]

Originally Posted by RedDevil

The mountain launch pipe cannot be vacuum, but we could superheat it and blow a lot of steam through.

The human body can endure large G forces when it is floating in water. As it weighs the same as water it could endure almost limitless G forces - except for air and gases in the lungs and bowels.

Is a tube even necessary? Couldn't a maglev railgun accelerate at practically any rate, or is the tube the cheaper option?

I can't see a vacuum tube being feasible or practical.

Having the rocket use onboard propellant while being accelerated defeats the purpose of the accelerator; to reduce the required mass of onboard fuel. Rockets are already about 85% fuel, by weight. Of that fuel, something like 85% of it is used to accelerate the remaining fuel.

Providing ground based acceleration logarithmically reduces the amount of fuel required to take a vehicle to orbit or escape velocity.

Can the body really withstand sustained 10+ G acceleration rates if surrounded by water? The brain is encased in fluid, and yet people get concussions fairly easily.

[freebeard]

Ramps on the western slopes of big mountains is the type of geo-engineering I could get behind, but...

Sobolev Spaces, Schwartz Spaces, and a Definition of the Electromagnetic and Gravitational Coupling

ABSTRACT
The concept of multiplicity of solutions was developed in [1] which is based on the theory of energy operators in the Schwartz space S-(R) and some subspaces called energy spaces first defined in [2] and [3]. The main idea is to look for solutions of a given linear PDE in those subspaces.
[snip]
The last example is the derivation of the Woodward effect [4] with the variations of the EM energy density under strict assumptions in general relativity. It finally leads to a theoretical definition of an electromagnetic and gravitational (EMG) coupling.

This is the work to explain how Shawyer's EM drive doesn't falsify physics. The long trail from From The Earth To The Moon to Gerald Bull and Saddam Hoos-sane's Project Babylon is reaching the end.

[RedDevil]

Originally Posted by redpoint5

Is a tube even necessary? Couldn't a maglev railgun accelerate at practically any rate, or is the tube the cheaper option?

I can't see a vacuum tube being feasible or practical.

Having the rocket use onboard propellant while being accelerated defeats the purpose of the accelerator; to reduce the required mass of onboard fuel. Rockets are already about 85% fuel, by weight. Of that fuel, something like 85% of it is used to accelerate the remaining fuel.

Providing ground based acceleration logarithmically reduces the amount of fuel required to take a vehicle to orbit or escape velocity.

Can the body really withstand sustained 10+ G acceleration rates if surrounded by water? The brain is encased in fluid, and yet people get concussions fairly easily.

Track it back to what stirred the discussion.
If you are to launch something with a rail gun it will produce a massive bang if you go supersonic; you cannot do it in vacuum.
Super heated steam however is much less dense than air because it has lower molecular weight and the molecules will be further apart.
A steam jet from a launch tube can reduce the friction and the initial bang in the atmosphere and even double as propellant.

The rocket comes in because it does 3 things at once: it produces thrust (though not enough to launch the capsule by itself), pressure pushing the capsule up and a jet of supersonic steam punching a channel through the air above the launch tube.

Would it be safe, or even possible, to fire a rocket inside a tube? I'm not sure... but it will produce more thrust than a rocket in open air.
Nuclear subs launch their ICMBs with compressed air, afaik, which only fire their rockets when well clear of the sub. But a tube bored in a volcano should be able to withstand a rocket blast. My concern would be whether the capsule itself can withstand it all.
But then the tube improves the performance of the rocket at the start - where its conventional efficiency is worst. It might even do away with the need of staged rockets.

As thread jacks go, this one is over the moon

[freebeard]

Hyperloop to the Moon!

If anyone wants to do their homework, I'd suggest Isaac Arthur

Episode 7: Launch Loops

Episode 8: Space Towers

Episode 9: Orbital Rings