Yes, the LR-101 is reliable so long as you keep the O/F within limits never
exceeding 1.9 or the wall immediately upstream of the throat will burn out.
Even Rocketdyne pooched a few as I've found burned out chambers in the
surplus store. I recommend cavitating venturis to maintain O/F and M-dot
with a good regulator/dome loader to maintain steady and balanced ullage
pressure.
Yes, they're made of nickel plated 4130 steel for strength over a thin wall
for good heat transfer since high carbon steels are relatively poor
conductors.
Being of double wall construction, the inner wall is not supported by the
outer wall like other engines are. So the fuel coolant could collapse the
hot wall
if made out of high conductivity but lower strength metals like copper..
All that said, the LR-101 is cosmetically pretty and a fun engine to test.
Ken
On Mon, Oct 11, 2021 at 5:00 PM Jonathan Adams <jonadams2002@xxxxxxxxx>
wrote:
I should also mention it would run at a fuel-rich ratio, and we're looking
at using film cooling so that the steel can withstand the rigors of
operation. The 101 seems like a nice design to look back on for amateurs,
even if it wasn't a very high performance engine and wasn't very resilient.
I've seen it mentioned on AR a number of times that their walls burned
through easily...
On Tue, Oct 12, 2021 at 10:28 AM Jonathan Adams <jonadams2002@xxxxxxxxx>
wrote:
It's interesting you say that, as later on we (my team and I) are looking
at making a steel TCA using the same 4130 steel that the 101 used. Maybe
then we could take a good look at aluminum.
Jon
On Tue, Oct 12, 2021 at 9:23 AM roxanna Mason <rocketmaster.ken@xxxxxxxxx>
wrote:
The LR-101 Vernier engine ran off ratio,i.e. 1.8 so aluminum worked but
at 2.3 it would be under significantly higher heat flux,
Ken
On Mon, Oct 11, 2021 at 1:56 PM Henry Spencer <hspencer@xxxxxxxxxxxxx>
wrote:
On Tue, 12 Oct 2021, Jonathan Adams wrote:
The engine I'm working on now runs Jet-A and LOX at 350 psi and r =2.3
(when operating at its limit). For reasons relating to cost I've sofar
been looking at 6061-T6 aluminum, but I'm now wondering whetherthat's
the right choice... Can aluminum get the job done?
Yes, but. It's certainly been done; it's seen significant use --
mostly
with slightly cooler-burning propellant combinations, but if I recall
correctly, the LR-101 (Atlas vernier) injector is aluminum. The
downside:
it's unforgiving -- the cooling must be just right -- because it loses
strength so rapidly with even mild heating. With an aggressive
oxidizer
like LOX, it can even ignite. Most likely not a good choice for early
experimental work.
Is there a grade of copper that is preferable for something like this?
C145, aka half-hard tellurium copper, seems to be what people like --
properties much the same as pure copper but a lot easier to machine.
Henry