From d04dc451fd981e0ead59aa473911af27f2e7147c Mon Sep 17 00:00:00 2001 From: Bdale Garbee Date: Thu, 2 May 2019 21:24:27 -0600 Subject: [PATCH] add write-up of my first APCP test stand burn --- rockets/research/2019-test-1.mdwn | 41 +++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) create mode 100755 rockets/research/2019-test-1.mdwn diff --git a/rockets/research/2019-test-1.mdwn b/rockets/research/2019-test-1.mdwn new file mode 100755 index 0000000..d40aadb --- /dev/null +++ b/rockets/research/2019-test-1.mdwn @@ -0,0 +1,41 @@ +# Test 2019-1 # + +This was my first test burn of an APCP motor using grains I cast myself. + +2 grain 54mm Everclear motor with #24 nozzle, using one of Terry's igniters, +on the test stand in Hartsel at the first Tripoli Colorado launch of the year. +The grains used were from teh 7 January 2019 batch: + +* Grain 1, 2.990" long, 163.7g gross, 5.50g casting tube, 158.20g net propellant +* Grain 2, 2.992" long, 163.8g gross, 5.51g casting tube, 158.29g net propellant + +Used abou 7.5" of ARR liner, the grains were definitely "loose" in the +case. The buna-n o-rings were lightly lubed, but the liner was put in without +any grease. + +Tested without simulation, using the "standard" EX nozzle for a 2-grain 54mm +case according to the Loki Research data table. Tapped forward closure for +pressure sensor, buna-n o-rings. + +Simulation says ... + +## Results ## + +Test stand data logged as sn 3634, flight 16. Note that the sensor calibration +was re-done after the weekend, at which time we observed that the load cell +wasn't really linear unless another 10 lb or so were added to the arm vs what +we were running with. So all thrust values from this and all prior test +sessions are suspect. Chamber pressure numbers are with fairly high confidence +but not great resolution due to reduced output on the 2500psi sensor used. + +No measurable erosion of nozzle throat. The liner was pretty well cooked, but +no signs of burn-through or case damage of any kind. The o-rings on each end +looked relatively undamaged, but were of course discarded after use. + +This motor burned very cleanly. Almost no visible flame, just some yellow-ish +flashes near the end of the exhaust plume. The 2.8 second burn was slightly +progressive, starting around 117 N, peaking at 212 N. Peak chamber pressure +was around 740psi. + +These results make me think it would be "safe" to fly more grains as long as +I stick with the Loki recommended EX nozzle throat for each grain count. -- 2.30.2