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More New Details on NASA's CEV Launcher Studies
TheEqualizer writes "Continuing on the NYT story on NASA's current CEV launcher plans, spaceref has an even
more extensive look with detailed assessments of the available options. By all accounts, it looks like NASA is picking up where it left off with Apollo but also combining it with established Shuttle technology -- the capsule concept of the 1960s atop the shuttle boosters of the 1970s being the winning combination under the current budgetary limitations. However, is this coupling of
old technology and designs really the best we can do?"
To me, that's the problem.
The shuttle should have been a step towards true spaceplanes. It wasn't efficient, but it explored our prospects for fully reusable launch vehicles.
The next step was to be real spaceplanes. After that we could begin talking about things like commercial spaceliners, orbiting manufacturing facilities and all the other sci-fi dreams of my childhood.
Instead, we're finding that we can't (or won't: $$$) build on what we learned with the shuttle to create spaceplanes, so we're going back to rockets.
We went from sails to steam-driven paddleboats (which worked poorly) to propeller-driven steamships (which worked really well). The shuttle program is equivalent to saying "These paddleboats just have no future. Let's go back to sails."
Life is short: void the warranty.
I think here we're seeing the tension between development and production.
The shuttle has been a decent way to learn about the problems faced by reusable vehicles of a particular type. I'm glad that we did it, and that we have it. Yes, the next step, from a development standpoint, is to take what we learned and figure out how to do it more and better.
But meanwhile we have actual business in space and we need a way to get there and back again. We don't need it twenty years from now; we need it today. What we have today is (a) shuttles with a number of known problems (see above), and (b) big honkin' rockets with three decades of experience in interplanetary travel. Which can we have ready to go by next month? A design that's just been grounded again after two years of fixing, or a design that Just Works? Remember that it's for today, not next decade; we have plenty of time to work up something better for the twenty-teens and beyond.
We need *both* programs to keep the pipeline full today *and* tomorrow. Declaring a single winner sacrifices either today or tomorrow. I'm greedy: I want both.
.. space planes? Take off and land just like an airplane. Whatever happened to that idea?
The unforgiving results of the rocket equation when applied to the orbital velocity (as determined by the Earth's mass and radius) and the chemical energy available per lb of propellant. They all combine to make the task just barely possible. You get the impression that that some god wanted us to be able to get to space - but that it should be a serious challenge.
When your spacecraft must be made almost entirely of propellant it wants to be as close as possible to a sphere: lots of internal volume for propellant, minimum weight of the enclosing envelope. Airplanes really don't want to be anything like a sphere. They like un-spherelike protrusions known as wings. These weigh a lot, especially when you need to cover that much surface area with a heavy thermal protection system.
Landing with wings or lifting bodies can make sense in some circumstances but taking off with wings is ridiculous. The weight of the spacecraft at launch is much higher. If you size your wings for take-off weight you will pay the penalty of those big wings all the way to orbit and back (if it can even make it to orbit).
Just because the idea is intuitively appealing doesn't mean that it makes sense from an engineering point of view.
Weight happens.
Stop worrying about the risks of nuclear power and start worrying about the risks of not using nuclear power.
They are also attached to launch at a specific location and need yanked out of florida!
There are a number of factors to consider when launching a rocket and Florida provides the best launch location for the US. Here are the factors to consider...
- You have to launch east so you get the added help of the rotational velocity of the Earth.
- You want to launch over unpopulated areas (the ocean is pretty unpopulated for a long way). The Russians use the giant desert in their southern regions for this but don't care as much about the people living under the launch path (have you seen the pictures of rocket debris in Russian villages?). The Europeans also use the ocean (from French Guiana)
- You want to launch from the lowest possible latitute because you can only reach higher latitude orbits in one go (you can reach any orbit from the equator but you can't reach an equatorial orbit from the tropic of cancer without changing orbit in space)
- The ideal US launch facility from a physics standpoint would be Hawaii but the cost of getting the vehicle to Hawaii would be insane so we opt for a higher latitude, continental launch facility).
> Burt Rutan didn't go into orbit, he got up to 100 kms.
And going _up_ is the easy part; it's going sideways fast enough to orbit that is the tricky part. Energy is proportional to V^2.
(orbital_velocity/spaceshipOne_velocity)^2 =
(17,000mph/2,500mph)^2 =
=46x
So to become orbital, spaceShipOne needs *46*
times more energy, and needs to disipate *46* times more energy for re-entry.
So yes, spaceshipOne is cool and all that, but to say NASA is clueless is wrong.