GRYPHUS
USING AIR FOR ACCELERATION.
Project Gryphus focused on developing ducted rockets to collect data for studying thrust augmentation and air-augmentation on rockets that use commercial solid rocket motors. Thrust augmentation is the process in which the entrainment of a secondary flow mixing with a primary exhaust jet in a duct provide a higher thrust than the primary jet firing in isolation. For ducted rockets, the secondary flow consists of air entrained by an intake, duct, or shroud installed around the primary exhaust nozzle of the rocket. The goal of these modifications was to increase the specific impulse of the rocket compared to a non-ducted, conventional alternative, effectively increasing both power and efficiency.
The project started in the Fall of 2017 when the team has been able to design and construct its first test vehicle, Gryphus 1, which launched six times in the Spring 2018 semester ¬-- the most launches of any ERFSEDS rocket in a single semester. The data collected from these flights showed a 10 percent increase in the specific impulse of the vehicle.
Since then, the team has been able to design, build, and launch two more test vehicles, Gryphus 2 and 3. Gryphus 2, or G-2, started flying in the Fall of 2018 with the intent of continuing the mission of Gryphus 1 at higher velocities and studying the effects of different sized ducts. Gryphus 3 (G-3) began flight in the Spring of 2019 with the goal of demonstrating the possibility of thrust augmentation on a larger high-powered rocket. G-3 was ultimately retired in the Fall 2019 semester, having completed four flights testing differently sized ducts on each flight. In its penultimate flight, G-3 showed evidence of a 25-30% increase in specific impulse over the projected performance of its motor as the rocket experienced maximum thrust.
Project Gryphus concluded in 2021, having left its mark on the club and the rocketry community. Gryphus III is currently on display in the Lehman College of Engineering.