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First of all is this question of best. In the case of human spaceflight (or just material for that matter), I would think it would be rather simple.
Whatever gets the most weight to LEO, with the lowest cost, would be best I would think.
I would then think that this would have to include having the most frequent number of flights as that spreads the developmental costs out over more launches. Another thing that would be important to bring the costs down is to have as small a launch crew as we could safely get away with.
It should also be remembered by all that every method has some advantages and some disadvantages. That is the nature of such complicated machinery.
Well, at any rate I have a sudden case of being very tired, so this is all for now, be back soon however, and thanks for the somewhat overwhelming response!!
Just keep an eye on Spaceships 3 and 4. Spaceship2 is for thrill seekers. Spaceship3 will be LEO and the only ? right now is whether he can give it docking capabilities. This is the only thing on the drawing board right now that will allow people without astronaut training to fly into space. The public interest in Spaceship2 has shown that this is the only method so far to be eccepted by the public for travel into LEO. Once at the LEO post another craft presently under development will pick up any workers and scientist and take them to Lagrange City and then to any other destinations. With the cargo being handled by the logistic center , Spaceship3's re-entry sheilding can be done with composits. An airliner type of flight into LEO is just a matter of time and money now. We are going to have a rapid expansion beyond LEO.
The best will be the simplest, and the simplest will be the smallest. In other words the crew launches with lunchboxes and toothbrushes and everything else goes on a cargo rocket.
I wanted to scream every time someone tried to claim the STS was a pickup truck to orbit - it is an 18 wheeler with a winnebago for a crew cab. With Orion NASA plans to drop the 18 wheeler's trailer but keeps the winnebago. We're still in need of a pickup truck (a minivan?) to get humans up and back safely, quickly and cheaply.
As for the technique used to get to orbit, I don't really think it matters - loose the chains and lets try them all.
For the catapult, look up Inductrak on wikipedia. Also, you probably want to come off the track at high subsonic speed unless the cat' goes up a high mountain - the aerodynamic stresses on the vehicle at high mach in dense atmosphere, and the engineering required to strengthen the vehicle to withstand them, may reduce the benefits of using a launcher in the first place. A vertical launch aligns those stresses pretty much parallel to the long axis of the vehicle. Trying to pull up from the horizontal to a vertical climb at multiples of supersonic speed would put a lot of lateral stress on the vehicle.
As for carrier aircraft, the aviation industry is currently looking at hybrid wing or blended wing/body vehicles that could be huge in size and payload capacity. Not fast, but capable of lifting significant mass to altitude.
SSTO is tough but we aren't actually that far away from it as the post that mentioned the Atlas proved and, it was also known during the Apollo era that the Saturn V's 3rd stage had a launch mass ratio that probably could have made it an SSTO, albeit without a useful payload - 40 years ago.
I think we should keep 2 ideas in mind:
1.) Keep the crew vehicle simple & small - it might be better to launch two 5-person craft than one 10-person vehicle, and put the bunk beds and the kitchen stove on a cargo rocket.
2.) Payload costs can be reduced dramatically and immediately if we embrace the idea that everything that makes it into orbit is potential payload - especially the tankage. As was mentioned with the Atlas post, that stuff has potential uses and we should treat it as payload. (If somebody can watch the videos of NASA throwing away a perfectly good External Tank during a shuttle launch without wanting to puke, you just aren't paying attention.)
Forgive me for being anal but what do you mean by "best"? Least expensive to manufacture? Most reliable? Safest? Shortest turnaround between flights? Shortest production time? Least $$$ per pound to orbit? Etc, etc, etc...
First, farranger is right--don't send up very much except the people themselves, in a small ascent stage. Even the descent stage can be sent up separately. And in the long run, the ideal would be to manufacture everything needed right in space (in LEO or elsewhere).
For getting 100 trillion delicate goo-filled cells up to orbit, how about this: Think initially of a long cannon pointed up at the sky (the angle to be determined), only instead of an explosive charge you have initially the capsule sealing against the barrel, and pressurized. As you launch, you continue rapidly pumping in gas from a large reservoir, providing a constant acceleration of a few g's. As the capsule nears the opening of the barrel, you ease up on the pumping, so that there is no pressure differential at the instant you exit the barrel (for the sake of a stable trajectory). Once you've exited, you jettison any structures that hold the seals. Then the capsule's own rocket engines take over for the rest of the way to orbit.
Note that the propellant gas does not need to be hot. Offhand, I don't know why plain old air wouldn't go just fine.
Note also that, unlike a catapult, this can be easily controlled throughout the entire launch.
A further refinement: Put the cannon barrel inside an existing, high mountain, with the mouth at or near the summit.
BTW re the DC-X, can someone explain the point behind this design? Why is it desirable to land vertically, when the difficulties are so obvious? The only advantage I can see is that landing could be done with the same hardware used to launch, but for that you would pay a formidable price in efficiency. (Of course, for landing on an airless body you don't have much choice.)
Gee, frodo, why haven't you been supporting my concept? Oh, well, never mind, this is bringing a lot of lurkers out of the woodwork.
And welcome to all of you quarks!
The only problem with the Delta and Atlas variants is that they just don't have the oomph to put manned capsules in any usable orbit. Which means designing a new rocket. Or, hiring the Russians to taxi us back and forth.
To whoever was saying that the early designs for the space shuttle were for vertical launching, we are talking back in 1968, when NASA was still golden. The engineers who got us to the Moon figured out that an air launched orbiter based on a lifting body design was the best way to go. Then, Congress decided that they were better at designing spacecraft than the engineers were, and we got the shuttle.
Why is it that people who are literate cannot understand that we are, at minimum, 100 years away from being able to build a space elevator? At least two folks have said the heck with this poll, lets live in fantasy land. Carbon nanotubes less than an inch long aside, we just don't know how to make a cable that will support its own weight when it is 23,000 miles long. PERIOD! Which means that we have to figure out how to accelerate our victims to 17,500 miles per hour, 5 miles per SECOND, to put them in orbit. And then de-accelerate them on the way back.
Just because the space shuttle didn't make it back when there was a big hole in the leading edge of the wing does not mean that there is an inherent flaw in the lifting body re-entry concept. It just means that we have to be careful with our spacecraft. Returning from orbit in a capsule may be the safest way to get through the hypersonic barrier, but it leaves you with the problem of landing. (Or watering, as was the case with the U.S. capsules.) And we have not even tried to land a capsule big enough to hold ten people.
Even though I am an advocate of using a catapult, I am not trying to create a meteor shower with the spacecraft. Which is what you will get if you accelerate a vehicle to a velocity at sea level, Denver level, or mountaintop level of one mile per second. Just cannot be done.
Everyone seems to think that we are looking at sending up a few people every few months for the next 20 years. Probably because they only think about going to Mars, and you don't need a bunch of people to go to Mars. When we go to Mars, it will be because so much money has been made from processing materials in space that developing the life support systems needed for a multi-year voyage will not seem expensive. We will not go to Mars because everyone thinks it would be cool, or because we could live there after a thousand years of terraforming. We will go to Mars because we will have so much money floating around that it will not be a big deal. In order to create all that wealth, we have to figure out how to get people, lots of people, into Low Earth Orbit, and to bring them back again. That is what I believe frodo is driving at; what launch system will be best for high volume launches (not loud, but frequent,) carrying 10 people into LEO. And by best I would assume that he means; cheapest, safest, and quickest.