Agreed. For us, safety is our highest priority especially now transitioning to
lox. In the end we do want a completely flight-worthy 10 kN engine but we
understand that will take many baby steps to achieve and we aren't expecting
complete success initially. We have the engine sized and are now trying to make
sure that our fluids system will work safely.
- Dillon
On Sep 13, 2016, at 2:07 AM, Randall Clague <rclague@xxxxxxxxx> wrote:
I am not advising the USC folks that they should try to achieve low
performance. I am advising them to focus on safety first, operability second,
and performance third.
If they pay attention only to safety and operability in steps one and two,
they will avoid the trap of premature optimization. Optimization is part of
step three.
When they start step three, they may well find that that their Isp is already
over 100 seconds. That's nice. They may find it already at 165 seconds.
That's nice. Right out of the gate, performance Does Not Matter. The horse
has to learn to walk first.
-R
On Monday, September 12, 2016, Troy Prideaux <troy@xxxxxxxxxxxxxxxxxxxxx>
wrote:
Well, to a point. Like everything in life, you need a balance. Any
performance outcome that’ll be under your propellant combination’s c* or
c*/g (in Isp terms - ~165sec for this combination say) must have sub optimal
mixing unless you have a gaping hole in your chamber. Nobody should expect
to hit optimal mixing in the early days of development, but … dunno… if the
mixing is too far out of whack, does that not potentially expose the chamber
to potential damage or hard moments?
Troy
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On ;
Behalf Of Randall Clague
Sent: Tuesday, 13 September 2016 12:37 PM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: LOX / IPA P&ID
If it works at all, it probably delivers 100 seconds or more. Fine. My point
is, forget about that. One step at a time. Premature optimization is the
bloodsworn enemy of success. Step two is Make It Work, success is defined as
supersonic flow. THEN, and only then, focus on the numbers.
-R
On Monday, September 12, 2016, Jonathan Goff <jongoff@xxxxxxxxx> wrote:
Randall,
While I agree with the general sentiment that getting something that fires
reliably and safely comes first, I think you'd have to try hard to get
LOX/IPA rocket that only delivered 100s Isp, even on a first try.
Jon
On Sep 12, 2016 4:28 PM, "Randall Clague" <rclague@xxxxxxxxx> wrote:
242 seconds is ambitious for a first effort.
First make it safe. Forget about Isp, your goal is making fire without
making shrapnel.
Then make it work. Forget about Isp, your goal is making supersonic flow
without making shrapnel.
Then make it work better. You probably hit 100 seconds in step two. Try to
hit 200 seconds, but remember, Reliability Is More Important Than
Performance.
-R
On Monday, September 12, 2016, Dillon Wessing <dillonwessing@xxxxxxxxx>
wrote:
Hi all. I am the lead of the USC Liquid Propulsion Lab. We’re developing a
LOX / IPA engine and wanted some input/advice on our ground testing P&ID.
Just some general specs for the engine. 10 kN of thrust. Total mass flow 4.2
kg/s (fuel: 1.91 kg/s, ox: 2.29 kg/s). Chamber pressure 350 psi. Pressure
going into the injector 437. 5 psi.
We are having channels milled into our combustion chamber for regen cooling
with the IPA and will have a separate reg for the ox since the IPA will have
higher pressure drops. Please comment on the validity of this design and any
concerns that we should keep in mind.
Best,
Dillon Wessing
