Hiho, Hiho, It’s Off to Launch We Go!

AAVGBlog3:11DSC_0236.jpg Yeah, we know, there’s some catching up on the blog to do.
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Saturday S&T’s AAVG rocket team braved high winds and an oncoming monsoon to test Sagitto*, their ’11 entry in NASA’s University Student Launch Initiative scheduled for Huntsville, Alabama next month. Sagitto, a two-stage rocket packed with four explosive charges, has two stiff challenges; carry an instrumentation payload one mile in altitude, and have the ‘payload’ section remain upright when it descends to earth.
That means one black powder charge must deploy a drogue parachute at apogee to keep the rocket from becoming a streamlined brick**. Half way to earth the second charge fires ejecting the payload stage, which a mere 100 feet lower sets off its own main parachute blast and deploys three folding legs designed to “land” the payload like the “Eagle” back in 1969. The main rocket body continues to fall away from the instrumentation package before popping its main parachute at 900 feet. Or, you can see a much simpler flight profile version here.
Three of the four charges fired correctly so the main chute didn’t deploy, sending the rocket body plunging to the ground a little faster than planned. They think they didn’t pack the explosive tight enough to get the required force, but thanks to the Spring thaw the ground was soft so damage was minimal. The payload section floated to earth properly but strong cross winds pulled the payload stage over on its side. Nevertheless it was an excellent test flight. Just needs some tweaking.
AAVGTestDSC_0175.jpgSpeaking of explosive charges, these aren’t random fire crackers or cherry bombs. The AAVG crew measures out specific grains (not grams)of black powder to determine the minimum charge necessary to split the sections into only two sections. Rumor has it that during last week’s on-campus testing someone mis-estimated the charge by a factor of nearly two. It separated, alright, much farther (and louder) than expected, but that’s OK. No snakes were harmed in these experiments.
* Latin for “I shoot arrows!”
**The Southern California Soaring Association has a real-life “Streamlined Brick” award; Astronaut Alan Shepard was one of the recipients.