[AR] Re: some interesting developments
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Wed, 30 Dec 2015 19:02:24 -0500 (EST)
On Wed, 30 Dec 2015, Thomas McNeill wrote:
Interesting rocket. The engines are forward and it appears to drop the
tank below it. Two stages and one set of engines.
"Note four rocket engine nozzles that power both the first and then second
stage after first stage propellant tank separates. Photo Credit DARPA."
My understanding -- not that I was following ALASA closely -- is that that
was the original plan, but they eventually decided that dropping the tank
gained them so little that there was no point. Mitch Burnside Clapp (who
is/was the ALASA project manager), at last spring's Space Access,
described it as "the only launcher whose stage count changed after PDR".
They decided to leave the engines where they were, partly because volume
constraints under the F-15E made it difficult to move them -- the payload
volume tapers toward the rear, and the engines can't be too close together
because ALASA uses differential throttling for control.
In any case, ALASA is grounded and probably dead. Two consecutive safety
tests of their N2O/acetylene mixed monoprop [aieee!! aieee cubed!!] went
KABOOM KABOOM a month or so ago, and that kind of spoiled the enthusiasm
for it; see <
http://spacenews.com/darpa-airborne-launcher-effort-falters>.
Mitch's comment on the monoprop last spring was "there are reasons why
this is not entirely insane", but apparently it was insane enough...
Henry
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