North American - Rockwell (NAR) built the shuttle we know today, right ?
This picture
http://history.nasa.gov/SP-4221/p333.jpg show what NAR shuttle looked like at the beginning (= 1969-1971)
At the beginning there was no external tank. The tanks were within the orbiter. So it was much, much bigger.
Current orbiter is 37 m long * 24 m span. Internal-tanks orbiters were 60m long*35m span! They were also much heavier, even empty.
difference number two: the booster or first stage.
The little trick which explains why the shuttle drop its tank as of today:
when you drop the orbiter tank, you save weight, so the booster can be smaller and less efficient.
Because of the big orbiter, the booster was so big it could not be parachuted down on the sea as of today.
The only way of recovering it was to turn it into a giant aircraft, and land it on a runway. So the already big booster had wings, crew, turbofans, undercarriage, tail
Imagine a Boeing 747 crossed with a X-15, and having twelve SSMEs.Or a piloted Saturn V S-IC !
http://history.nasa.gov/SP-4221/p355.jpg
Last difference: today the shuttle starts its SSME on the pad, not in flight. This help at take-off, but also mean a bigger tank.
At the time the booster being bigger and more efficient the orbiter didn't needed to fire its own SSMEs at take-off. They started during the flight.
Designers used to say the shuttle dimensions were "something like a Boeing 707 riding a 747"
Whatever happened, the monster shuttle was way too complex and expensive to built.
So NASA asked an economic institute called Mathematica to find a less expensive shuttle. Mathematica answer was called TAOS - Thrust Assisted Orbital Shuttle - a barbaric acronym covering the shuttle as we know it today.
- External tank, smaller orbiter
- SSME started on the pad (not in flight)
- thanks to the two "tricks" above smaller, unefficient, and unexpensive booster could be used: the SRBs.
So we consider the actual shuttle a compromised thing; BUT the original design was not better. It would have been a much worse disaster! Heck, there were two crews, one in the booster, the other in the orbiter.
The orbiter and booster were enormous. The booster maximum speed was something like 3km/s - 10 000kph ! Kind of flying an A380 faster than a X-15
The orbiter was twice as big, so the heatshield - which already doomed the smaller Columbia orbiter - would have been even more extended, on a larger area.
So the question is, what design was best for the shuttle at the time ?
Well, the answer is, the technology was not to date. The shuttle was kind of too big... Endeavour (no pun
) for the 60's -70's. Well, it still is as of today in fact.
General consensus as of today (with 30 years insight)
- Reusable Launch Vehicles are justified only if very high flight rate. This mean a very large number of satellites to launch, or a moon base to feed. We have neither, so RLV are not of interest of today
- NASA should have continued a X-series after the X-15; kind of X-20 DynaSoar instead of trying to built the shuttle right from the start
- what works from a technical point of view : Kistler K-1. Unmanned, two stages, parachutes, airbags.
http://www.rocketplanekistler.com/k1vehicle/k1vehicle.html
This thing has no wings, nor pilots; it is recovered by parachutes and airbags. Not glamourous, but that would works. This would have been the best option in 1970, alas airbags were not mature at the time.
A pity: a Kistler K-1 with an Apollo CM capsule ontop would have made a perfect space shuttle for NASA.
Of all the shuttle concepts examined from 1968 to 1972, my favourite these days is the Triamese.
http://www.astronautix.com/lvs/triamese.htm
Alas, even this one doesnt work, for reasons explained here
http://www.spacekb.com/Uwe/Forum.aspx/space-flight/236/Multiple-Engines
Nope, in an alternate history world, the Triamese would work.
And NASA would have had a fully-reusable,
viable space shuttle.
