Elliot:
My home machine shop can turn a part that will look like what Ed is doing
up until he starts closing out the cooling channels; that last can’t be
done with a machine tool.
Ed gets, ultimately, a monolithic part with no seems or joints which can
only be alternatively made by additive manufacturing.
Bill
On Fri, Jul 12, 2019 at 11:17 PM Elliot Robert <elliotr@xxxxxxxxx> wrote:
I take it this is the process that you and the late Charles Pooley talked
about in the later chapters of your book? Compliments on an excellent basic
introduction to those competent in the basic prereqs btw. I'm about to drop
a trivial amount of money on a custom built 4-axis cnc machine so maybe now
is a good time to ask, what exactly is the advantage to this process if you
have a 4-axis cnc that can produce regen cooled liquid rocket engines in
far less time? You seem to indicate a cnc is required anyway.
On Fri, Jul 12, 2019 at 10:07 PM Ed LeBouthillier <codemonky@xxxxxxxxxxxxx>
wrote:
On Fri, 2019-07-12 at 15:01 -1000, David Summers wrote:
That looks really good! How complex is the design? Are you leaving
the chamber walls that thin?
This was just a first experiment. I wanted to establish the rate of
deposit. My goal will be 0.015" wall thickness, 0.015" cooling channel
thickness and 0.015" closeout thickness, for a total thickness of
0.045" inches. At my current amperage level, that'll take a 60 hours
per layer (per 0.015"), or about 240 hours total. There is some benefit
to plating slower; the quality of the deposition is better. If one
increases the amperage, then spikes and trees will form. I had no
spikes or trees so I feel that I shouldn't try to speed things along.
The design was pretty simple. My goal is to test it with Butane and Gox
at about 70 PSI. It should produce about 5 pounds of thrust (presuming
the combustion is smooth enough). This first engine is intended to be
water cooled to establish heat flux. I'm currently not optimistic about
closing the regeneration cycle, but I'll know more after testing.
