RL-10s are tested at sea level with just a diffuser. The far end of the
diffuser is closed with a door that opens outward, and the entire system is
pumped down to a good vacuum before the engine start. The door slams open
pretty hard...
For better performance use a STED, Second Throat Ejector Diffuser.
Supersonic Flow in the Second-Throat Ejector-Diffuser System
https://sci-hub.se/10.2514/3.26411
On Wed, Mar 22, 2023 at 2:51 PM <eric.pillai01@xxxxxxxxx> wrote:
Somewhat related to this topic - if I had an engine with a very large
expansion ratio and low exit pressure, are there any scrappy ways to test
it on the ground? Could always truncate the nozzle but since the entire
nozzle is regen cooled, there would be a pretty meaningful part of data
missing since the test nozzle would be way shorter.
I imagine that wrangling a professional scale vacuum chamber for engine
testing would be expensive and slow to arrange. Lack of ground test
capability is a huge bummer so I’m very interested in ways to mitigate the
problem.
Thanks,
Eric
On Mar 22, 2023, at 10:21 AM, Norman Yarvin <yarvin@xxxxxxxxxxxx> wrote:of
On Sun, Mar 19, 2023 at 11:48:19AM -0700, roxanna Mason wrote:
John, when I was privileged to work with Bob Truax he taught me many
rocket and other related things including his Sea Dragon which had a
compensating nozzle on stage 2. It was merely a tubular shaped section
corrugated sheet metal which would expand as altitude increases.
So a single sheet of metal that would bend into shape, starting out
corrugated and ending un-corrugated? Was there to be some sort of
actuator doing the bending, or just internal pressure? (Or was it a
more complicated thing with multiple pieces of metal?)
At any rate, the first stage is where an altitude-compensating nozzle
is most useful, but in this case it was on the second stage, which is
puzzling. Too flimsy to handle the rigors of water launch, perhaps,
to be put on the first stage?
