P.S. My chamber was just a bit of large diameter ABS pipe. It worked fine
and was cheap and easy to make but it has the drawback that you can't see
what is going on inside. The bright side is that you won't either after a
couple of uses ;).
Matt
On Mon, Jul 25, 2016 at 12:18 PM, Lakestake Rocketry <lakestake@xxxxxxxxx>
wrote:
Nice work Richard.
Matt
On Sat, Jul 23, 2016 at 4:27 PM, R Dierking <applerocketry@xxxxxxxxxxx>
wrote:
This is a follow-up on an earlier post on creating a vacuum chamber for
testing altimeters and other rocket-related equipment. I’ve attached a
photo of the chamber that measures 3” square and 12” long.
Mike Kramer suggested that I make a smaller test version to work out
potential bugs, and it turned out that cutting the grooves in the 1 ¼”
polycarbonate ends for the o-ring seals was more difficult than imagined.
Also, it took a couple tries to create electrical connections through the
end to connect a switch. Unfortunately, the 2nd stage on the vacuum
pump isn’t getting as low as specification. I’m still working on that, but
so far achieved about 29 ½” of vacuum *. I tested a PerfectFlite SL-100 a
couple times and it recorded about 102,000’. So, I think that’s adequate
for awhile. 😊
The next chamber will be 6” square and about 40” long to accommodate the
upper half of a rocket I’m working on.
This vacuum chamber project has been kind of a distraction to my L-3
project, but I’m still glad for the time spent. Always fun building
something different and learning more about atmospheric pressure for
amateur rocketry.
Richard Dierking
* There are many different ways to denote atmospheric pressure such as
PSIA, Inches Hg, Torr, mbar, and microns. A Torr is 1/760 atmospheric
pressure and there’s about 1 Torr at 150,000’. I have an inexpensive (aka
cheap) vacuum gauge so it’s really only good for low vacuum.
