The September Black Rock XI launch saw an enthusiastic group of newcomers to high power rocketry: satellite designer-builders from Japan, Arizona and California. Their visit was the outcome of a challenge issued by Prof. Bob Twiggs of the Stanford University Space Development Laboratory, at the Japan-U.S. Science, Technology, and Space Applications Program (JUSTSAP) conference in November, 1998. Professor Twiggs challenged JUSTSAP members to fit a functional space satellite inside a standard twelve-ounce Coke can (hence the nickname "CanSats"), for a boost into orbit in 2000. Space development programs at the University of Tokyo, the Tokyo Institute of Technology, and Arizona State University joined Stanford in design and construction of miniature satellites with some pretty powerful features, including the ability to network in space. Designers of the Iridium satellite system also began a CanSat mentoring program with students at the Kennedy Middle School.
Aeropac member Tom Rouse heard about the CanSat program during discussions of his CATS project at Stanford. (Good luck on your space launch this month, Tom!) Professor Twiggs joked that CanSats were tested by placing them in a 30-gallon galvanized garbage can and tossing it from the 4th floor balcony of the SSDL building. Tom said, I have an idea.... I know some folks who can actually launch these gadgets for you.
By February, 1999 a few Aeropac members had volunteered to be guinea pigs, and in monthly meetings at Stanford began to define the parameters of the project. The objective was to give the students hands-on experience in the life cycle (one year or less) of a space project. We agreed on the form factor: each rocket would be capable of lofting three CanSats 2-3 miles, the CanSats would each have about 15-20 minutes "hang time" under parachute for experiments, simulating a low-orbit pass, and construction would be standardized so that payloads would be interchangeable between launch vehicles.
The plan: boost on an M1419; at apogee the booster recovers under an R-12 chute, while the payload section quickly falls clear of the booster with a deliberately undersized R-7 chute. Six seconds after apogee, a secondary pyro charge separates the nose cone with its own chute, retained until now by four shear pins, and ejects the CanSat Carrier. When the carrier reaches the end of its 30-foot kevlar tether, the CanSats slip free and begin their descent under 36" parachutes. Now about 7 pounds lighter, the payload section slows to a descent rate of 15 fps under the R-7.
Our prototype rocket was a beautiful 6" dia. graphite airframe volunteered by Pius Morozumi, who also built the prototype CanSat "Carrier." We selected a custom-modified G-Wiz Deluxe flight computer for avionics (thanks, Rob Briody and Larry Lynch-Freshner), Vaughn Brothers parachutes for the CanSats (thanks, Mike and Jerry), rail launch system and fins by Black Sky Research (thanks, Scott Bartel) and Aerotech propellant to get it all up in the air (thanks to Karl Baumann and Aerotech).
Rain and mosquitoes notwithstanding, we launched this contraption at Mudrock and were pleased to see every component perform flawlessly.
With a proven design, we began building. I chose to wrap my airframe with carbon fiber, using John Coker's excellent online resource as my bible, Pius settled on Kevlar lamination, Jim Green went with pure canvas phenolic from Black Sky Research, and William Walby concealed his secrets under his trademark Perfect Paint Job. We were careful to make the CanSat Carriers interchangeable between all four launch vehicles, just in case. As it turns out, this was a good thing.
Professor Twiggs inaugurated his first visit to Black Rock by getting his son's brand new pickup truck stuck in Pius' Cove, a mudhole of ill repute named after it's first victim, an anonymous member of the Rocket Bunch. Much later that day Dr. Twiggs and Dr. Morozumi were observed salvaging mud from the truck and weighing it on a gram scale for use as ballast in dummy CanSats for the next day's launch.
Pius' graphite bird flew twice again at Aeronaut in July. The first flight was to test the system on an M1419 motor. We learned that the Vaughn Brothers 'chutes keep a 12-oz satellite aloft for a Very Long Time. Even with radio beacons, recovery took 5 hours. William cored the chutes with a hot coffee can and obtained an acceptable descent rate.
We also found that 3 grams of 4f was ejecting the CanSat Carrier too forcefully, and that Kevlar is indeed stronger than the steel eye bolt.
The second test was flown with an undersized motor substituted at the last minute. The airframe failed to achieve separation at apogee for reasons not determined, and the rocket made an aerodynamically perfect core sample. With both success and failure in our minds, we resumed construction for the September launch.
September 10 found the Rocket Bunch back in Gerlach preparing their machines, with a half-day break to volunteer for a BLM clean-up project.
Professor Twiggs, wearing a t-shirt proclaiming "I Survived Pius' Cove" made numerous Playa crossings escorting student groups, visiting professors, a film crew, a reporter, plus four Porta-Potties (thanks, Bob).
On the afternoon of the 10th, the CanSats arrived, with their builders from the University of Tokyo (my group), the Tokyo Institute of Technology (William's bunch), Arizona State University (Pius) and Kennedy Middle School (Jim and Becky). This afternoon had been scheduled as a time to test fit the CanSats in the Carriers reserved for flight. They were all fine, but a mismatch of another kind cropped up instead: U Tokyo's experiments required radio transmission during ascent, and my carbon-fiber airframe was radio-opaque. Because we had standardized the form factor in the planning stage, it was quick and easy to trade payloads with Pius and accommodate the needs of both groups.
Tom, William, Ranny, Griffin, Pius, Jim and Becky.
Launch conditions were perfect on Saturday, and the Rocket Bunch turned in four flawless flights. Jim Green's 40.3 pound rocket took honors for altitude at 12,342 ft. AGL at T+28.4 seconds.
Paul Campbell was Aeropac's finest ambassador that day, shepherding a dozen or more Kennedy students through construction and launch of their first model rockets. All four CanSat teams were busy tracking satellites, running experiments, and downloading data and images. The student teams were awake most of Saturday night summarizing their data for a breakfast presentation at Bruno's on Sunday morning.
Six weeks after the launch, data analysis continues - the work by the students is truly outstanding. Links to the latest results plus photographs and video clips of the launch are posted on the ARLISS index page.
The Rocket Bunch will return next season. Tom Rouse and John Coker served in an advisory capacity this year, and are now stepping in to fill Stanford's request for two additional rockets. CanSat builders next year will be assigned payload slots, not a specific vehicle, distributing the product (and the risk) of the university teams among several rockets. There will be a few other minor tweaks to the program, but otherwise we'll concentrate on emulating William's paint job.
The Stanford Space Development Lab's 30-gallon galvanized test vehicle can now be laid to rest. Do you think they'd donate it for use at the LCO table?
- Randolph Mitchell
