Students Build Rocket for Project OlympusBy George Ipe
On Tuesday, a rocket engine with 20 pounds of thrust roared to life, spewing white flame in a test firing chamber at an astronautics laboratory in Building 31. Though the technology in this engine is not new, its design has not been accepted by much of the rocket industry. Project Olympus, a three-year-old student group, will try to change that when it launches a small payload with a hybrid rocket engine in 1994.
"The idea behind Olympus is to put about a 5- to 10-kilogram scientific payload into low-earth orbit at a reduced cost. A real interest of mine is the development and commercialization of space. One way to achieve this is by providing greater accessibility to smaller and cheaper rockets. Olympus might point the way," said Andrew W. Lewin G, who thought up the project during his sophomore year.
The heart of the Olympus rocket is a hybrid engine which uses a safe but non-volatile fuel, polybutadiene, a rubbery material which goes into the making of, among other things, labels for Levi's jeans. This is burned with liquid oxygen to provide thrust for the rocket. The rocket is considered a hybrid because it uses both solid and liquid fuel.
"The hybrid rocket was worked on during the 1930s and '40s, and especially in the '60s. But they fell by the wayside to stable solid-fuel rockets, which are well-suited for military purposes and high-performance liquid-fuel rockets used especially for large-scale civilian rockets. Neither group wanted to compromise their rocket fuel, so both solids and liquids have developed over the years and have become entrenched in the industry. Interest in hybrids is only now being revived," Lewin said.
"The performance of hybrids is slightly better than solids, though not as good as liquids. But I think hybrids have their real niche in booster applications and orbital maneuvers because you can stop and restart these engines. This cannot be done with solids," he added.
Lawrence M. Smilg '93, a member of the design team responsible for the engine's pressurization systems, said, "It is environmentally conscious to use hybrids rather than solids in the space shuttle. A full 10 percent of exhaust from the solid-motor engine of the shuttle is hydrochloric acid. That is bad." Smilg is experimenting with a new method of pressurizing liquid propellants suggested by group faculty advisor Manuel Martinez-Sanchez, professor of aeronautics and astronautics.
"The technique is based on a series of nozzles and injection systems used in pressurizing water in old locomotive engines. This concept has never been tried before. If this system works, we will have made a real contribution to hybrid technology," Smilg added.
Third-stage test in '94
The complete rocket's preliminary design will be worked out this term, Lewin said. The tentative designs call for a three-stage rocket weighing about 5,000 kilograms with a 20,000-pound thrust first-stage engine. Lewin estimates the rocket will be about 40 feet high and 4 to 6 feet wide. "Our goal is to test launch the third and final stage, which houses the payload and autonomous guidance and control systems, by the summer of '94, money permitting. Modifications will be made based on the results of this sub-orbital test firing."
Funding for Project Olympus comes from the federal Space Grant program, the Undergraduate Research Opportunities Program, the Department of Aeronautics and Astronautics, and alumni. Lewin estimates the total cost of the project to be on the order of $1 million.
"Olympus provides an avenue for enterprising students to learn by doing. This is positive and we at the aero-astro department are very supportive," Martinez-Sanchez said.
Lewin, who was awarded a Marshall Scholarship earlier this year, said, "The spirit and atmosphere for innovation here at MIT makes it unique. Usually at other universities, professors initiate projects and students follow. It is not necessarily the case that students elsewhere can easily start technical projects on their own and get good support from their school."
Lilac Muller '93, a design team member responsible for the guidance system, said, "Olympus works like an actual company would. I had worked at the Jet Propulsion Laboratory last summer, and the way our project runs is very similar to the way theirs worked. We as students are given great responsibility to work individually and with other students."