Stetind was the first super-sonic rocket built and launched by Propulse NTNU. In June 2021, the team competed with Stetind in the digital Spaceport America Cup 30'K COTS class and won first place in its category, and 2nd place overall among all the 75 participating teams. 4 months later, in October 2021, the team launched Stetind at the European Rocketry Challenge and won the 9000 meter SOLID class, and breaking both the EuRoC velocity and altitude records.
Cesaroni Pro 98
Mach 1.8 (2205km/h)
in 0.24 seconds
Stetind launched on October 15th; the last launch day of EuRoC. After many setbacks, including two misfires just hours before, Stetind soared into the sky at Mach 1.8 - Propulse NTNU's very first super-sonic rocket.
The ascent was perfect, but at apogee the main chute deployed early. The forward airframe softly touched down after drifting downrange for half an hour, but the aft fell off right after apogee. We dedicated a page to all the schenanigans that happened the week prior to launch, and detailing how we recovered the rocket:
Team 2021 started the project with a new structure of the techical systems, it being divided into; Inner structure, Outer structure, Recovery and Avionics. Each of these systems have their role in the rocket which you can read more about below.
The team started conceptualizing the design of Stetind in September of 2020. Design continued to April of 2021 when after 3 design reviews, many iterations, tests and protypes, the final design was complete. Production of many of the components had started as early as February of 2021, and continued throughout the summer, with a full rocket reveal taking place mid August.
The rockets airframe consists of highly optimized parts for supersonic flights up to Mach 1.7. To minimize drag, a von Kármán shaped nosecone and aft section have been selected. The trapezoidal fins will ensure stable flight conditions during the ascent phase and increased ground clearance during impact from the recovery phase. The fins double wedge angle reduces drag from the shockwaves as well as higher lift performance in the supersonic regime, leading to better stability. The boat tail made of aluminium will lower the overall drag by reducing the wake generation downstream. Forward airframe is made of glass fiber to make radio communication with the ground station during the whole flight possible. Aft airframe, as well as the fins are made of carbon fiber due to the materials high strength to weight ratio.
These technical design decision have been made based on highly complicated numerical analysis using both empirical methods and software such as computational fluid dynamics. Detailed knowledge of both the flight and aerodynamic characteristics, such as pressure, energy and temperature, have been used in an iterative process to ensure that the rocket has the highest possible performance during flight.
Both forward and aft airframe have been produced using a method called winding, using a mandrel and a robot-arm, whereas the fins is CNC milled out of pre-produced carbon fiber plates. The latter production technique is also used for the fin brackets and the boat tail.