Vidar II is our second iteration of the single stage Vidar launch vehicle, and the third iteration of our self-built hybrid rocket engine. The highlights of this vehicle are the feed system and recovery module. Since last year's design, we have moved on from our HyperTEK style feed system to a custom pyrotechnic valve. There is only one moving part in our system, which simplifies production and significantly increases its reliability. Our recovery systems have also been upgraded, this time featuring a two-ring release system and separation of the booster and payload modules during descent.
Wet Mass: 70 lbs
Dry Mass: 55 lbs
Fuel: Aluminized HTPB
Oxidizer: Nitrous Oxide
Peak Thrust: 430 lbf
Average Thrust: 330 lbf
Burn Time: 9 s
Motor Classification: N
Drogue Chute: Dome
Drogue Chute Diameter: 5'
Main Chute: Toroidal
Main Chute Diameter: 8'
The payload of Vidar II served only to fulfill the requirements of IREC, meaning that it is a 10 pound dead weight. In the future, we plan to develop our own functional scientific payload. However, we currently place our focus on engine development.
The avionics of Vidar II, like all other major components, are designed by members of our team. Our primary flight board is the "Zenith", a student built altimeter, although we also operate a commercial Raven PCB as a redundant parallel for safety. Furthermore, there are two GPS modules on the rocket for recovery purposes.
The recovery module is sheltered by a shell of fiberglass. Inside this module are housed both a drogue and primary parachute. When deployment is signaled by the avionics, CO2 canisters pressurize the module and break shear pins. The drogue chute is deployed, which stabilizes and slows the rocket. At a predetermined altitude, a secondary electrical signal cuts a line which allows the main parachute to deploy. The drogue pulls the main parachute out from the recovery module, and carries the storage bag away. The main parachute, therefore, will support the engine section, and the drogue parachute will independently support the payload and avionics.
Our run tank, like most of the rocket, was also constructed from aluminum. The tank wall works dual purpose as the structural airframe, saving weight and increasing stability. The run tank is designed for pressures to around 745 psi. It is attached on each end by a machined aluminum bulkhead. The top bulkhead has a permanent vent installed to cool the oxidizer, as well as a dip tube to control tank ullage to prevent failure due to over-pressurization. The run tank is filled from the bottom bulkhead, where a hose can connect to the rocket through the outside of the bulkhead.
Our combustion chamber is very similar to our previous design. We still employ a six sided star-patterned fuel grain of HTPB rubber. The HTPB is cased in an ABS tube, which is itself held within the aluminum outer shell. The nozzle is machined from graphite.
The fin can was constructed from aluminum, with dimensions determined from a flight simulation in OpenRocket.