Hey Richard
Nice work! Would love to give it a shot with some calibrated altimeters ...
Maybe bring it to Roctober?
Thanks
-James
Sent from my iPhone
On 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.
<Test Chamber.JPG>
