Hey Matt,
Just wondering, for pyrodex what is the difference between well contained and
too contained.
Over the line it is not a gas generator...
Thanks, Cliff
On July 28, 2016 12:30:28 PM PDT, Lakestake Rocketry <lakestake@xxxxxxxxx>
wrote:
Dave Flynn and I were using the vacuum chamber in testing Pyrodex as a
less
regulated ejection charge material. It turned out that Pyrodex does
just
fine if well contained. People have reported poor performance and lack
of
performance. We found that when held in a rigid container it fired
just as
energetically as black powder with a lot less mess. When loosely
contained
(like in a gallon ziploc bag Kurt) it would not burn completely nor
produce
the desired impulse.
One note, you can use a lot less Pyrodex than BP. My first test
ejected
itself from the test container and bounced off the warehouse roof...
YMMV
so test early and test often.
Matt
On Mon, Jul 25, 2016 at 3:51 PM, R Dierking <applerocketry@xxxxxxxxxxx>
wrote:
Hello Mark.a
The problem with the mobility of my set-up is that the vacuum pump is
couple hundred pounds. Otherwise, I would like to bring it to alaunch.
Perhaps when I get my utility trailer at the end of the year.complicated
My head is kind of spinning right now, because this could be a
conversation depending on what the objectives where. For example, ifwe
were interested in the accuracy of the barometric altimeters we areusing
for rocketry, then we would need a precise instrument that wastraceable to
a standard, or maybe check a few of them at the same time to see thevacuum)
variation.
Unfortunately, accurate instruments for low pressures (i.e. high
are expensive. It would be nice to have something more accurate thana
standard vacuum gauge I’m currently using.altimeters
There have been some interesting discussions on this chat regarding
altitude determinations using barometric altimeters vs. gps units.
For me, the current objective is reassurance that barometric
will fire the drogue and main charges correctly, and if a sidedeployment
bay will not prematurely open on ascent. To have accurate altitudethe
readings would be a plus.
I’ll be installing 4 more electrical connections through the end of
vacuum chamber for drogue and main charge connections.something
I live in Temecula, and anyone that is interested in testing
using the set-up I have is welcome to visit. Just contact me offchat.
to
*From: *Mark Woods <mark@xxxxxxxxx>
*Sent: *Monday, July 25, 2016 1:40 PM
*To: *roc-chat@xxxxxxxxxxxxx
*Subject: *[roc-chat] Re: Vacuum Chamber for Ground Testing
Hi all,
I'm new to this community but an electronics engineer and would offer
help if that's useful...altimeters
Thanks,
Mark
On Jul 25, 2016, at 12:43, James Dougherty <jafrado@xxxxxxxxx> wrote:
Hey Richard
Nice work! Would love to give it a shot with some calibrated
... Maybe bring it to Roctober?wrote:
Thanks
-James
Sent from my iPhone
On Jul 23, 2016, at 4:27 PM, R Dierking <applerocketry@xxxxxxxxxxx>
for
This is a follow-up on an earlier post on creating a vacuum chamber
testing altimeters and other rocket-related equipment. I’ve attacheda
photo of the chamber that measures 3” square and 12” long.¼”
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
polycarbonate ends for the o-ring seals was more difficult thanimagined.
Also, it took a couple tries to create electrical connections throughthe
end to connect a switch. Unfortunately, the 2nd stage on the vacuumpump
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-100a
couple times and it recorded about 102,000’. So, I think that’sadequate
for awhile. 😊the
The next chamber will be 6” square and about 40” long to accommodate
upper half of a rocket I’m working on.as
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
PSIA, Inches Hg, Torr, mbar, and microns. A Torr is 1/760atmospheric
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>