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[web/gag.com] / rockets / research / test5.mdwn

diff --git a/rockets/research/test5.mdwn b/rockets/research/test5.mdwn
index 1c82653f01fe13213c13ba70bdd4a5c18faa0409..23f80a1ce2cf9c9f5b539fd5786ea198a1d65595 100755 (executable)
--- 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!