Sleipner participated in Spaceport America Cup's 10k COTS category in 2019, and was the first rocket built and developed by Propulse NTNU. Sleipner was also the first Nordic rocket to launch at Spaceport America. The 3U CubeSat payload was a collaborative project with Orbit NTNU, where 1 unit consisted of an information gathering and processing system developed by Propulse NTNU, and the remaining 2 units were developed by Orbit NTNU. Orbit NTNU’s unit contained several components of their SelfieSat satellite to be flight and stress tested during Sleipner’s flight, with emphasis on vibration and temperature endurance.
Sleipner had a length of 2.4 m, a diameter of 18.5 cm, a liftoff weight of 18.8 kg and a maximum velocity around 1000 km/h. The propulsion system for project Sleipner was a COTS Cesaroni Pro-98 4G motor. The airframe sections were made of carbon fiber, the nose cone was made of fiberglass, the couplers and boat tail were aluminium, and the fins were constructed by aluminium, carbon fiber and foam core. An air brake system was placed in the coupler section between the upper and lower airframe section to control the apogee of the rocket. The recovery system employed a dual deployment system consisting of a drogue and main parachute, located inside and directly below the nose cone of the rocket. The drogue was deployed using Hawk CO2 systems, and the main chute was deployed with a 3-ring release system. Sleipner had an SRAD flight computer to tie all the different electronic systems together. A custom PCB was developed, featuring a 32 bit processor, IMU and barometer sensors, GPS, Bluetooth, and SD card and a radio transmitter. Ground station software was designed to receive and display real-time data during flight.
Sleipner was launched successfully and had a stable flight until approximately 1500 m altitude. Instabilities occurring near the maximum velocity of the rocket, likely caused by fin fluttering, caused the nose cone to be ejected prematurely, and the rocket to quickly decelerate. The rapid ejection of the recovery system at such a high velocity caused the chords of the parachute systems to fail, and the rocket fell back to the ground without a parachute system. Sleipner was retrieved from the launch site afterwards, and video files and flight data could be assessed to further analyse the flight.
Out of the 121 teams participating at Spaceport America Cup 2019, Propulse was one of 20 teams to be selected for the poster sessions, where the airbrake control system was presented.
Sleipner received 188.5/200 points for the project technical report and 210/240 points for design implementation.