From: Bdale Garbee Date: Mon, 29 Jun 2015 04:16:24 +0000 (-0600) Subject: more text X-Git-Url: https://git.gag.com/?p=web%2Fgag.com;a=commitdiff_plain;h=a14ba311ab903887ab759c867464c5cea1a0a608 more text --- diff --git a/rockets/research/test5.mdwn b/rockets/research/test5.mdwn index 1c82653..23f80a1 100755 --- a/rockets/research/test5.mdwn +++ b/rockets/research/test5.mdwn @@ -69,6 +69,14 @@ Little John at Tripoli Colorado Spring Fling 2015. We used a Slim Gem igniter from Quickburst. Great flight! The motor seemed to come up to pressure quickly, and burned brilliantly. +The airframe weighed 1200 grams ready to launch, and 982 grams post-flight, +of which 1g or so was BP in the ejection charge, and a few grams were in +the Aerotech delay grain. + +Post-flight measurement of the phenolic nozzle showed approximately an +0.330" throat, which clearly indicates some erosion from the 0.291" starting +point. + ![flight acceleration data](test5-altosui.png) ## Observations ## @@ -80,3 +88,11 @@ the others, all of which had some evidence of propellant sticking to the cap and leaving an uneven top surface. This resulted in some quick trim work with a knife, ergo final grain masses not matching all that well. +We were totally stoked that the burn time matched simulation (once we factor +in a tenth of a second or two before the motor came up to pressure!). We +were also pleased that the max pressure was "right on time" at about 0.4 +seconds after coming up to pressure. The regressive curve seems a bit +exagerated in the flight accel data, which seems completely explainable by +the nozzle throat erosion causing pressure to faill during that period. + +Pretty cool for our first real flight test!