Design, Construction, and Supersonic Wind Tunnel Testing of an Aerospike Rocket Nozzle

Abstract

Every rocket that has ever launched a payload into orbit has used the same shape to direct the exhaust - it looks like a bell, and it is inefficient. For a rocket, small inefficiencies translate into greatly amplified costs in sending things to space. Inefficiencies mean it is more expensive to launch the satellites that enable TV broadcasting, weather forecasting, GPS, and other technologies that we use every day on Earth. One replacement for this bell-shaped nozzle that might perform better is called an "aerospike," which is a concept that has existed since the 1950s, but has yet to propel any rocket into orbit because of a lack of experimental data to support the decades of theory of its operation. Simply put, it seems that few people are building aerospikes because few people have before, leading to a cycle in which the development of the concept has stagnated and space companies are unwilling to take on the risk of using this "unproven" technology.

This senior thesis aimed to provide some of that experimental data and renew interest in the aerospike. Two scaled-down rockets were designed, one with the classic bell-shaped nozzle and one with an aerospike, and a supersonic wind tunnel was used to simulate their launch. The driving hope was that the data provided by these experiments would support the theory that aerospikes can operate more efficiently than bell nozzles and encourage other research and industry groups to use aerospikes on full-scale rockets. The results of this study did indeed provide general support for the hypothesis that aerospikes should be more efficient than bell nozzles. Future work will attempt to replicate and extend the results and resolve some unexpected features of the data that was gathered.