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Old March 13th 18, 01:20 PM posted to sci.space.policy
Fred J. McCall[_3_]
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Default BFR early next year.

JF Mezei wrote on Tue, 13 Mar 2018
04:39:45 -0400:

On 2018-03-12 20:37, Alain Fournier wrote:

Elon Musk said at South by Southwest that his Big Falcon Rocket
would start doing small test flights early next year.


"small test" ? a 1m high scale model with a tank of diet coke into which
a Mentos candy is dropped? :-)


Small test such as lift off, hover, land.


Space-X apparently has begun to test its new Raptor engines.

For commercial aircraft, they can mount a new engine on a 747 and test
it in flight. (same fuel, and sufficiently spaced pylons make it
possible to mount new engine)

What are Musk's options to test fly the new engines?


Why would he need to? He needs to test fly pieces of the actual
rocket. If you're just dinking with engines you can get most of your
data from ground tests.


Can they built a Falcon-9 with a few raptor engines and a methane tank
instead of Kerosene for a test flight?


They can, but why the hell would they do that?


Or must one assume that a test flight will be raptor engines on a BFR
stage 1 (even if it is topped by a cone instead of stage 2) ?


That's probably the simplest route. Or they could do BFS first.


From a light load point of view, is it a problem of the methane and LOX
tanks are only partly fueled since this is such a short flight?


Why would that be a problem? The rocket has to continue to work when
the tanks are partially empty, after all.


or would
this require smaller tanks? Or can the tank be fitted with a helium
filled balloon that fill's the otherwise empty tank space?


You REALLY don't understand this stuff, do you?


--
"Some people get lost in thought because it's such unfamiliar
territory."
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