As the project manager for the 2017-18 student launch team, Koehler said his role is to facilitate the two sub teams, oversee everything, and manage the work and the reporting schedules. “One team works on the rocket and the other team works on the payload. This year, as far as the rocket goes, it was nearly a perfect flight. As far as the payload, unfortunately there was a small problem with the battery, but other than that, the system worked great.”
To participate, NASA requires quite a bit of documentation. There is a proposal to join the competition, a preliminary design review that’s due in November, and a critical design review that’s due in January. The team is also required to launch a sub-scale rocket and conduct a flight readiness review. The readiness review is the biggest report and due in March.
“All 30 of us worked on writing the big 300-page report,” he said. “My job was delegating the sections of the report to different people. The goal is to develop skills for our future in engineering. Writing technical reports in engineering is very important, and writing for the ISS competition has paid dividends for me. In senior design this past semester, I was able to dive in doing the technical writing because I had already done it before for ISS.”
Koehler said this year’s team overcame a lot of adversity with schedules, meeting deadlines, and some technical challenges. One example: flying too high. This doesn’t seem like it should be a problem in a rocket competition, but the rules for the NASA Student Launch are strict. Although the team normally only has one test flight in Illinois prior to the Huntsville competition, this year, the team was able to do two test flights and solve the height problem.
“All three of our main full-scale competition flights were successful,” Koehler said. “For our first flight, we just flew too high. It went to about 6,100 feet, which was too high for the altitude limitation of 5,600 feet. We adapted it by using a smaller motor and our second test flight flew just a couple of hundred feet under one mile.”
Illinois has participated in the competition for several years and each year is a little different. This year's competition allowed teams to choose between three payload challenges: Target detection, deployable rover, or landing coordinates via triangulation.
“All of the payloads are designed to be like real NASA missions,” Koehler said. “This year’s team chose a deployable rover payload. There’s a rover inside the rocket, like the Mars Curiosity. After it lands, the rover drives out of the rocket.”
A video of the initial testing of the team’s rover (MORRTE, which stands for Miniaturized Off-Road Remote Terrain Explorer) shows its mobility, speed, and ability to respond when faced with an obstacle. The rover design was inspired by the Boston Dynamics RHex rover, featuring an insect-like segmented body and flexible wheels.
Ultimately, battery failure was the team’s only real downfall.
“The rover is held inside the rocket with latches. There are batteries that hold the latches in place with servos. If the battery dies, the servo disconnects the latch, which is what happened during the descent in Huntsville at about 1,000 feet altitude.”
Koehler explained that the battery failure resulted from waiting too long to launch.
“At the competition, we’re about 300 to 400 feet away from the rocket and not allowed to go near it once it’s on the launch pad. There were about 10 rockets in the queue ahead of ours, so the rocket was out on the launch pad for about two hours. Next year, we’d like to get higher-quality batteries that will hold their charge for a longer duration. It’s a problem for real-world missions, too. Batteries and power often drive mission requirements—especially when you’re in outer space.”
In keeping with Koehler optimism, he described the silver lining in the failure.
“For the first two test flights, the rover stayed latched in. It didn’t fall out, but it wasn’t able to drive after it landed. At the competition, we were worried that when the rover fell out, it would be shattered into a million pieces, but because it had rained the night before, the ground was fairly soft so when the rover landed, it wasn’t broken. We recharged the batteries and it was still able to drive, so the team thought that was a success.”
One of the main reasons that the rover didn’t break on impact is the system of parachutes that deployed on schedule. An avionics suite on board the rocket controls the deployment. Altimeters on board the rocket take pressure readings through vent holes in the tube. When it senses a specific altitude, it sends an electronic current into an electronic match to ignite black powder and create a small explosion.
“The rocket is 11 feet tall and 6 inches in diameter with an L-1170 FJ-P motor—which is a large, solid motor. It burns for only a couple of seconds, then it coasts, reaches its apogee (its highest altitude), at about 4,500 feet. After that, we have black powder charges that explode to separate the rocket so that the parachutes can be deployed. There’s one parachute called the drogue parachute that comes out at apogee. It’s only 18 inches in diameter. It fell for several seconds. When it reaches 1,000 feet, the nosecone deploys and has its own 44-inch parachute. The rocket continues falling, tumbling. Then at 800 feet the main 96-inch parachute comes out and carries the rocket slowly to the ground. When the nosecone deployed, that was when the rover unfortunately fell out of the rocket. Everything else landed safely.”
Koehler said using several different parachutes of varying size is critical to control the speed of the rocket’s descent. “If we used the big parachute at the apogee, it would drift far away. The rockets are not supposed to drift more than about 2,500 feet. We use a smaller one at apogee so that it falls faster. Then the larger chute deploys at a much lower altitude so that it lands softly.”
Here’s where the benefit from the muddy field comes in: It provided a messy, but cushioned, landing for the rover.
“We went to recover the rocket and found that the parachute had dragged the rocket through mud, so it was muddy, but a very successful flight overall. We were a bit disappointed that the rover fell out, but were very happy that the fall didn’t destroy the rover and it was still able to drive.”
Koehler reflected on the strengths of this year’s team.
“I think this team learned a lot and were able to build on the experiences from the past few years,” Koehler said. “My freshman year, only the team leader knew a lot about rocketry before the competition. This year, we had 20 people on the team who already had good experience. And next year’s team will be very strong, too, as there are a lot of freshmen, sophomores, and juniors who will be continuing.”
Koehler described other team characteristics that others may see as disadvantages.
“Some of the other teams have big sponsorships and they are often senior design teams with a lot more experienced people. We started out as a smaller team, with humbler roots, and have grown. Some of the other teams have auto-body shops to professionally paint their rocket, but we paint our rocket ourselves. We take pride in doing a lot of the work ourselves even without big, corporate sponsors. All of our funding comes from the Illinois Space Society, which is a registered student organization in the Department of Aerospace Engineering.”
Koehler said the team requires about $5,000 each year, which includes all of the rocket parts and funds for the hotel rooms for the trip itself. “But we also take pride in the fact that we don’t charge our members to join the team. The Illinois Space Society just charges each member $10 annual dues to cover miscellaneous costs like pizza at general meetings. So, you really just have to show up and be interested in working on aerospace engineering problems. You don’t have to pay a high entry fee.”
“One of the biggest lessons I learned this year is that things aren’t always perfect, but they’re often still good,” Koehler said, whose big smile and positive attitude reflects a life with a glass that is definitely half-full. “We had lots of challenges that we were able to overcome. You don’t want to give up just when things get challenging or difficult. You want to keep trying, keep believing in yourself and in your team, that you have the skills and knowledge necessary to get the job done.”