Graham,
I heard today that the copper alloy AJR used was actually something a lot
more mundane than GrCop-84. It was a C182 Chromium Copper. IIRC both Masten
and XCOR have used these in the past for copper engine chambers. It's heat
treatable, has a pretty good thermal conductivity (I think they said it was
higher than GrCop84), while having decent softening temperatures. Nothing
amazing material properties wise, but nothing too shabby either.
FWIW,
~Jon
On Tue, Apr 4, 2017 at 7:43 PM, Graham Sortino <dmarc-noreply@xxxxxxxxxxxxx>
wrote:
I was looking at this article today as well and had a few observations...
According to the Rocketdyne <http://www.rocket.com/rl10-engine> website
the RL10C-1 is a pretty large ~25k lbf engine. It has a length of 86" and a
nozzle width of 57". It is an upper stage engine but judging by the picture
I'm guessing the version they tested more of a sea level nozzle. Even if
the engine doesn't have a full sized nozzle that is pretty impressive that
they printed such a large engine.
They mention using copper alloys and select laster melting (SLM). *Note-
this is different then DMLS*. I'm not as familiar with SLM but I did a
quick google and it lists a company called SLM Solutions
<https://slm-solutions.com/products/machines/selective-laser-melting-machine-slm-280-20>.
It sounds like SLM is similar to the EBM process that Arcam uses. Also, I'm
just guessing that the alloy they are printing is in GrCop-84
<https://ntrs.nasa.gov/search.jsp?R=20050123582>, which is sort of like a
high strength / high thermal conductivity copper alloy.
On Tuesday, April 4, 2017, 5:23:39 PM EDT, William Claybaugh <
wclaybaugh2@xxxxxxxxx> wrote:
Do (AR) nose tips see the kind of heating that would require inconel or
the like?
I've wondered if USC/RPL's titanium nose tips are justified for a Mach 5
mission w/ a very short heat pulse....
To be clear, I have not done my own analysis, I'm asking two questions.
Bill
On Tue, Apr 4, 2017 at 7:01 PM Ben Brockert <wikkit@xxxxxxxxx> wrote:
I visited Atlantic Precision a couple years ago, one of the few shops in
the US with multiple EOS DMLS machines, and they were actively printing
parts for the RL-10 even back then. Printing the chamber is big and flashy,
but there's a lot of utility in cranking out highly detailed inco or haynes
parts.
For any part with moderate complexity of the nickel alloys it's now
cheaper to print and lightly post-machine than to machine from solid
material, even at small production quantities.
That is of relevance to AR because a one-off printed and sanded nickel
alloy nose tip for a higher performance hobby rocket should quite
affordable, especially if you shop around and make it clear that you're not
in a rush for the part.
On Tuesday, April 4, 2017, Dave Klingler <davek@xxxxxxxxxxxxxxxx> wrote:
Ehhhh…one can always ask. Sometimes people like to talk about where
they’re headed. :)
Dave
On Apr 4, 2017, at 1:17 PM, William Claybaugh <wclaybaugh2@xxxxxxxxx>
wrote:
Dave:
Anyone privy to such information is likely subject to a non-disclosure
agreement....
Bill
On Tue, Apr 4, 2017 at 12:24 PM Dave Klingler <davek@xxxxxxxxxxxxxxxx>
wrote:
I just saw an article over at parabolicarc about AJR's first 3d-printed
thrust chamber firing. I’m trying to decide whether, from what I’ve read,
they’re substituting copper for stainless in a few spots.
I think design changes are probably unlikely this early, but at the very
least the new manufacturing process opens up the way for different
materials and more elaborate cooling passages that wouldn’t be possible
using the old tube benders. Is anyone on this list privy to what sort of
plans AJR has for higher chamber pressures or other improvements to the
RL-10? What’s the schedule for doing complete engine certification?
Dave Klingler
