I should add, the numbers in my advice are based on as-flown vehicle
performance, in vehicles that emphasized safety and operability over
performance so strongly that the engine(s) could explode in flight without
jeopardizing public safety or flight safety or the ability of the crew
to return to base for a normal landing. As-tested numbets of just the
engine will be higher than I have advised.
-R
On Tuesday, September 13, 2016, Lloyd Droppers <ldroppers@xxxxxxxxx> wrote:
Oh yeah forgot this, nitrogen will work for pressurization, but it will
eat nitrogen about 2-3x the rate you expect, and pressurization will take
twice as long. A good diffuser will help, so will letting your LOX warm
some before filling(this will change you lox density), but be ready for it.
Helium is the best to use if you can get it, and GOX will also work, but
you would obviously have to redo the pressurization system to make that
change.
Lloyd
On Sep 13, 2016 12:03, "Lloyd Droppers" <ldroppers@xxxxxxxxx
<javascript:_e(%7B%7D,'cvml','ldroppers@xxxxxxxxx');>> wrote:
Dillion, seems reasonable for a first cut. I would change
-pressurization solenoid downstream of the regulator so you can set and
adjust pressure without pressing the tank.
-regulators in parallel rather than series. This way you have more
flexibility in testing.
-i'm not familiar with the two overlapping arrow symbol on the propellant
feed lines. If it is a flow control device like an orifice that is good. If
it is a flowmeter that would work as well.
-if you can add another pressure transducer between the cooling jacket
and injector on the fuel side that would be nice but not necessary.
- on this or another p&id draw in the lox and fuel loading/draining
connections.
-i would filter propellants on the way into the tank rather than in the
feed lines, but that might be personal preference.
As far as valves go check out http://www.magnatrol.com. I think they
have valves that will work for your test stand. But they are massive and a
bit pricey for your pressure/flow rate/fluids.
You should also look at coaxial shell cooling schemes (SP-125 on pg 107
in my version) instead of milled channels. It is an older technology, but
it should be cheaper / easier to fabricate than milled channels.
And I'm with Randall, run a little fuel rich, and use reasonable size
injector orifices, and create a robust first engine. Something that just
works at 210s with a 15-1 thrust to weight will be much more useful than a
finicky high performance engine.
You can always go improve the engine later, and that process will be much
easier if you know how to get one engine up and running and your test stand
is all ironed out.
Good luck, and let us know how it progresses.
Lloyd
On Sep 12, 2016 15:57, "Dillon Wessing" <dillonwessing@xxxxxxxxx
<javascript:_e(%7B%7D,'cvml','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
