Out of Pod Experience

Sorry but I'm not whining or stating a personal opinion. It's just fact based on history, sorry if you can't deal with it.

No it doesn't. Unless you have the ability to manufacture the entire spacecraft in space (including obtaining the raw materials), you still have to launch the stuff you're going to build it with. We aren't even close to that kind of space construction capability, and there are no (plausible) plans to develop it within the foreseeable future.

Sure, doing the final assembly (of components manufactured on earth) in space allows you to launch a large spacecraft on a series of smaller rockets instead of all at once, but let's consider two very simple numbers that kill the possibility of an air launch for this:

AN-225 (heaviest cargo aircraft ever built) maximum takeoff weight: 1.4 million pounds.

Space shuttle external fuel tank, fully loaded: 1.7 million pounds.

Forget about the spacecraft itself, or the cargo mass, or the aerodynamic issues involved in carrying something that big externally, there are no aircraft capable of even lifting the fuel required to reach orbit.



No, it's based on marketing material and science fiction. In the real world, you can't just make the engineering problems disappear with wishful thinking.



The Scaled Composites Model 339 SpaceShipTwo (SS2) is a suborbital, air-launched spaceplane, designed for space tourism.

SUB. ORBITAL.

For those of you who don't understand what this means, it's an expensive toy for letting rich people pretend they went to "space". It has no useful payload capacity, and it can't even reach orbit.

The old space shuttle was built for a ground takeoff and needed a massive payload bay. Any new shuttle will be much smaller and perfectly able to launch from a 747 sized plane or at worse, an antanov. These aircraft have carried much heavyer loads. The shuttle will not need a massive external tank because it would already be flying at high altitude and wont have a payload of several tonnes. Getting to the inernational space station is all it needs to do.

As far as building large structures in space goes, we do have a little experience with this kind of thing

RAM jets dont work in space

A chemical rocket will do the job just fine.

Oh I meant the multistage system, since it won't need as much fuel for the carrier ship, it's less weight to get that high : ) But yes, doh, I said something silly >.<

Ok, so you slash payload capacity. Congratulations, now it takes you a lot more launches to get anything useful into orbit, and puts a severe limit on the size of the largest component you can launch.

PS: here's an actual small-payload air launch rocket: http://en.wikipedia.org/wiki/Pegasus_%28rocket%29 . Good luck carrying people with that.



Wrong. "High altitude" for a plane is a small fraction of the altitude and speed required for orbit. The main advantage isn't the altitude itself, it's the fact that you can do your acceleration where the air is thinner. http://en.wikipedia.org/wiki/Air_launch_to_orbit

In the equation below, it is indicated that high speeds can reduce delta-V requirements up to 15% over the vertical launch case.

That means that you still have to provide the other 85%, even as a theoretical ideal. It's a nice fuel reduction, but it's not going to magically make the fuel requirements go away.



Obviously there are advantages, my point is that we're nowhere near being able to do this kind of stuff. Getting there would involve a massive effort over long periods of time, not some magical "let's go to space" project by a private company within the next decade.

The whole point would to to launch people not materials. NASA is already experimenting with sending up satalites using this kind of technology because it is so much cheaper. Spaceship one is already proof the technology works, it simply requires a larger engine and fuel which will easily fit on the back of a 747. The new Heavy Orion rocket can take up the heavy stuff and it can all be built at the international space station.



And given that you wont be needing to launch vertically from the ground or will be anywhere near as heavy the craft wont need anywhere near as much fuel or power that the shuttles required..

People are heavy. Well, not just because they're fat, but because you have to include all those wonderful life support systems (unless you don't care if you deliver a load of corpses). For example, the Mercury capsule had an empty weight of almost 2400 pounds, or more than double what a Pegasus can put into orbit. And that's for one person.

You might be able to cut some weight with modern electronics, but then you're going to add a lot of weight right back to get the kind of reliability and safety that would be acceptable for commercial spaceflight.

Also, remember that the context of this is commercial travel. Launching a couple passengers to your orbital factory is entirely different than what is being discussed here. If you want to send people up at a useful rate, you're going to need something a lot larger and heavier.



Err, no. A "larger engine and more fuel" is a huge difference. We're not talking about swapping the engine in your car for a better one, it would require a completely new design with a massive increase in size and weight. Could it be done? Maybe, but it's not going to happen for a long time.



Not launching vertically from the ground IS the 15% fuel reduction. You don't get any fuel reduction beyond that.

Carry, yes, but that's not good enough.

1) Maximum altitude is reduced to 15,000' with the shuttle attached, compared to 40,000' for a Pegasus launch.

2) The 747 can only carry an empty shuttle. Add another 60% to that for a full load of fuel/cargo/etc and see how well the 747 flies. While you're at it, don't forget that the shuttle only works because it has that massive external fuel tank which by itself is more than the 747 can carry.

Yes, because distance needed to travel into space doesn't come into the equation anymore *rolls eyes* That's a 15% reduction on top of the reduction in fuel needed due to a shorter escape path.

Now if it's not obvious allready Space ship three will be a 3 stage system. The 1st jet will be conventional 747 type aircraft but smaller and light weight due to it's lack of having to carry people. Will look like Spaceship 2 and use a scram jet engine. Under Spaceship three's main lift will be a Ram/turbojet system with minimal fuel.

In general, craft that suck material directly from the atmosphere to use for oxidation offer superior specific impulse to traditional chemical rockets

The third jet once in sub orbit will blast off using a chemical rocket, a few things happen here.

1.Vertical reduction fuel needed to take off.
2.Shorter distance to escape gravity pull results in a shorter burn time and less fuel on top of the vertical take off.
3.The 2nd stage jet is a gilder that goes back down without fuel


NOw the end all idea is to build a better system to get up high, which includes a conventional airship, a permanent sky base, followed by a helium-filled, solar-powered ascender unit that slowly accelerates horizontally untill it reaches sub orbital levels, thus making a jet brust into space easy and cost effective.

In fact the solar-powered ascender unit is basically done.