We did have an LN2 chilldown procedure, but due to some holds/recycles, we
ran out of LN2 ☹ Will bring a full dewar next time.
Carl Tedesco
-----Original Message-----
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On
Behalf Of Henry Vanderbilt
Sent: Thursday, February 22, 2018 2:38 PM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: L* for LOX/methane
Interesting issue there, RE keeping the injected propellant liquid from the
start in a LOX-methane motor intended to run liquid-liquid.
Yes, chilling down the LOX circuit before firing is routine for LOX-whatever
engines, but doing so for both propellant paths on a LOX-methane engine
could get WAY too exciting in terms of pad fires, hard starts, etc.
Maybe set up the LOX and methane circuits in good enough mechanical/thermal
contact so you can slowly pre-chill both with a trickle of LOX?
Or pre-chill the methane path with LN2 from a separate ground supply?
Henry
On 2/22/2018 3:26 PM, Carl Tedesco wrote:
Thanks Doug. That's shorter than I expected.
If C* were less than 18" I assume C*_eff would start to drop off.
Would you expect combustion instability. I'm asking because a LOX/CH4
motor we hot-fired a few weeks ago had a low L* and had a significant
low-frequency sound and obvious "sputtering/chugging". It had co-axial
injectors which were intended to be liquid-liquid, but were likely
gas-gas (or low-quality liquid at best), since the plumbing may not
have reached thermal equilibrium.
--- Carl Tedesco