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Old March 18 2013, 04:09 AM   #271
Crazy Eddie
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Re: SpaceX is a go for April 30th: 1st commercial launch to space stat

publiusr wrote: View Post
sojourner wrote: View Post
Wait, you're saying a KKV doesn't need a high t/w ratio? Dude, you might want to think on that a little. That KKV is doing exactly what it's supposed to do.
No, it is launched by a missile to hit a warhead
And in order to do that it has to be able to accelerate under very tightly controlled parameters, holding a relative position in the path of an oncoming target that is also moving very very quickly. From the seeker's point of view, it is stationary and everything else around it is moving; it is programmed to keep its target stationary in its field of view no matter where that target actually moves.\

I'm thinking the guys who did this net test expected the actual KKV to use less thrust during an intercept than it did doing this hover.
They did not. The specific point of the test was to see whether or not the MKV had enough precision to follow a pre-programmed test fire routine simulating an actual intercept (with a theoretically high divert trajectory). They performed a similar test with the KKV (which your video does not depict) in which they added a small thruster fed by a pressure hose because the smaller unit's thrusters weren't powerful enough to hover for any amount of time.

The ideal test of the system, of course, would be for it to hold a stationkeeping attitude in freefall -- on a vomit comet or something -- but there's no way anyone's gonna let them actually test that thing on an airplane.

Now the anti-missile defense arguements puzzle me a bit. They say striking a warhead with a KKV is all but impossible
Nobody says that. What they say is that the interceptors that currently exist can't quite pull this off under battlefield conditions because both their timing and their tracking requirements are infeasible under those conditions.

It's a bit like saying it's impossible to do a kick flip on a skateboard during a hurricane. That statement tells you less about kick flips than it does about hurricanes.

Put that another way: how would you assess the feasibility of a Mars Sample Return mission if the Martian government started shooting at your return vehicles?
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