By Peter Schurke, March 2010
Saturday morning at 0600 we piled almost a dozen teenagers and a passel of family and friends into a veritable caravan of vehicles and started the trek over the mountains to the hallowed grounds of Mansfield for the test/control launch of my students’ Student Launch Inititative project. Our project mentor, WAC Secretary Carl Hamilton, was able to arrange an opening of the club’s waiver for us for a one-off launch to get the test flight in before our Flight Readiness Review in two weeks.
We arrived about an hour later than planned (one vehicle decided to take a different route and found the “slow” way.), held a safety briefing and then the kids got to work prepping their vehicle.
As they were using this test flight as a control experiment, the plan for this launch was to fly with their Gyroscopic Stabilization package installed, but inactive.
Immediately, a major problem cropped up: The backup altimeter–a Perfectflite MAWD–would not power up. The students spent 30 minutes trying to diagnose the problem, and finally had to declare the MAWD “Dead” and adjust the flight plan to proceed without it.
Problem two cropped up when the students could not find their package of shear pins. Carl had a package in his range box, but they appeared to be made of a different material than the ones the students had ground tested with. This led to another moment of decision-making crisis: Could they risk using untested shear pins with no backup ejection charge? What would be the consequences of failure if the charge did not shear the pins and separate the airframe (ballistic re-entry and likely vehicle destruction), versus the potential consequences of not using shear pins at all (drag separation, main out too early)?
After 15 minutes of debate, the students decided to forego shear pins altogether for this flight and trust that the fitment of their couplers would keep things together during the flight.
They finished their launch prep and proceeded to the pad. Their checklist of procedures made things much smoother (actual time to get the rocket on the rail and ready for flight was about half their ususal dawdling…but that was then lost to a lot of time picture-taking….)
The software for the telemetry system decided to start acting up a little, but after a 5 minute countdown delay that was resolved and the kids were ready to launch their vehicle.
Ascent was gorgeous–laser beam straight. Apogee was 5978 feet–almost 700 feet above predicted. Then things started to go a little sideways.
The apogee charge separated the airframe and pushed out the drogue as planned, but the nosecone also slipped off and allowed the main to begin coming out as well. This is the point where mistake number three (heretofore unknown to all of us) came out to bite them in the @$$.
The harness for the drogue wrapped itself around the part of the main that was sticking out of the airframe. The team that had packed the main had inexplicably rolled the harness around the parachute instead of using the method they had practiced in advance. the combination of the two sets of recovery harness wrapped tightly around the main turned our recovery in to “drogue with supplemental nylon wad” recovery.
Luckily, the kids overbuilt the snot out of the airframe, so the closest thing to damage suffered was some minor damage in the avionics bay the epoxy holding one of the bulkhead stops sheared because they did not properly sand the parts before epoxying them together so that they would get a good hold). That and the airframe got a little muddy when it landed.
Not a complete success, but not a total failure either. They have their mandatory test flight in the books, they have some lessons to learn, and they have data to report to NASA.
For their own peace of mind, they intend to go back out there in three weeks for the March WAC launch and re-fly so that they get all the deployment correct. Once they have that done, they can proceed to the final launch in Huntsville with a confidence that their vehicle will do what it is designed to do.
Thanks go out to Carl Hamilton for all his help getting the behind the scenes stuff, including the waiver and all the 10,000 phone calls he had to make to assure that this went off as smoothly as it did! Thanks to Puget Sound Propulsion, who donated the motor for our test flight! Thanks to all the members of the list who have unknowingly given great advice to my students over the last few months as they have lurked on the list and picked up on ideas and techniques that have found their way into the vehicle.
More to come when they give it another try in three weeks.
Science and Engineering Teacher, Lead Advisor
Ingraham Aerospace Sciences Academy
Ingraham High School
1819 N 135th St.
Seattle, WA 98133