[AR] Re: [AR] Re: [AR] Re: [AR] Re: “Transitioning space propulsion to a nitrous-based industry standard”
- From: Alexander Mikhailov <alexander.mikhailov@xxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Tue, 4 Apr 2023 23:09:55 +0000
(The LLNL piston-pump guys, who switched from hydrazine to peroxide for their
experimental work, were surprised and impressed by just how much easier it
made everything -- for example, they could do quick tests on the lab bench,
instead of having to go out to a hazmat test site every time.)
I'm researching that piston pump project, and can't find anything from
LLNL after approx. 2005 :( . Did they stop working on that? Where's
that information about comparative simplicity of HTP vs. N2H4 comes
from?
Alex
On 4/4/23, Matthew JL <prmattjl@xxxxxxxxx> wrote:
Why not hydrogen peroxide in monoprop or one of the various alcohols that
it’s hypergolic with?
On Tue, Apr 4, 2023 at 5:47 PM Henry Spencer <hspencer@xxxxxxxxxxxxx>
wrote:
On Tue, 4 Apr 2023, Norman Yarvin wrote:
...The industry has moved away from hypergolics for launch,
but not for precise orbital maneuvering, likely because it's a big
advantage to be able to just release a blip of fuel and oxidizer and
know they will combust immediately: no having to wait for a torch
igniter to fire up.
For precise orbital maneuvering, there's no reason why you need anything
more than a torch igniter! At least one of the innumerable proposals for
a nontoxic-propellants Shuttle RCS/OMS system envisioned eliminating the
RCS vernier thrusters in favor of igniter-only operation of the main RCS
thrusters.
Setting that aside, bear in mind that torch igniters don't necessarily
have to add a lot of complexity or delay. The Apollo SM/LM RCS engines
used a "preigniter" scheme, with the plumbing arranged so that propellant
flow through the main valves reached the preigniter chamber first, so it
would light (hypergolically) and pressurize the main chamber before flow
reached the main injector, minimizing (hypergolic) ignition delays there.
You could presumably do the same thing with a spark-ignited torch, so it
would still need the spark system but wouldn't have its own valves etc.
(That does lose one advantage of separate valves: verifying torch
ignition before committing to main-chamber flow, so the control system
can
abort startup if the igniter malfunctions.)
Henry
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