Blue Reaper was a significant leap in technical capabilities from the team’s previous rockets. The rocket is 91.2“ tall, and is 6“ in internal diameter. The larger inner diameter (as compared to previous years’ 4“ internal diameter) was chosen to increase space allowances for payload and advanced avionics. The airframe weighs approximately 64 lbs ready-to-fly on the rail.
The rocket utilizes a dual-recovery system, where a small 4’ drogue parachute is housed just aft of the payload, and a large 14’ main parachute is housed aft of the avionics section. Section separation is achieved with two 35-gram CO2 charges per event, mounted in Tinder Rocketry Raptor units. Blue Reaper is powered by an Aerotech M2500T COTS rocket motor.
For the first year, the team developed an innovative 3U CubeSat payload and deployer system actuated at 2,500 ft to eject the payload from the rocket. The deployer mechanically retained the CubeSat through flight and apogee until its deployment. Once the CubeSat was deployed, it released a parachute and recorded video until it reached the ground. A seed dispersal system was triggered to simulate interplanetary terraforming operations when it neared the ground.
The team implemented advanced composites to form the rigid structure of the rocket. The airframe was constructed using prepreg carbon fiber sheets to increase ease of manufacturing and increase strength while decreasing weight. Molded carbon fiber was used on the fin mounts and airbrake petals. A two-part fiberglass mold was used to form the composite nose cone, and the nose cone tip was machined in-house.
Blue Reaper contained Duke AERO’s first SRAD flight computer, “Eris.” Eris was developed in-house, using third-party sensors and electronic components. It is controlled by a pair of microcontrollers: a Teensy 4.1 and an Arduino ATMEGA chip. Each chip is designated a certain set of responsibilities to optimize performance in all aspects of flight. The team developed all of the Arduino code placed onto each microcontroller to handle all sensors, flight functions, and airbrake control.
Blue Reaper flew with Duke AERO’s Variable Drag Airbrake System (VDAS) to enable high-precision apogee targeting and showcase the team’s capability to create high fidelity GNC systems. During the coast phase of flight, the system actuates a servo to deploy three forged carbon blades to increase drag and guide the rocket to within one foot of the target apogee. The linear deployment design maximizes drag efficiency while minimizing vertical space required for mechanics within the rocket. The control of the system is a simplified version of model predictive control handled by the Eris Gamma. The team created a modified simulation software in Python, using OpenRocket as the basis for the code. During flight, a series of flight plans is created based on the conditions at burnout, and the computer continuously performs PID control around the chosen flight plan until 10,000 feet.
Integrating the rocket at Spaceport America Cup 2023 proved to be difficult, due to the added challenge of passing wires through the aluminum airbrake housing. Despite these complications, Blue Reaper was launched on the second day of the launch window and had a completely nominal flight. Due to an overly high polling rate in the controls, the airbrake system overestimated the necessary drag and was fully deployed for the entire coast phase. This caused the rocket to fall roughly 1,500 feet short of the target apogee, proving the effectiveness of the airbrakes to cause significant apogee reduction. Blue Reaper had successful separation and parachute deployment at apogee and drogue. Every component was recovered in flight-ready condition, scoring Blue Reaper full recovery points in the competition.
Blue Reaper performed well in its competition category at Spaceport America Cup 2023 and had the fourth highest overall design and build score. Duke AERO celebrated a nominal flight, successful competition, and the design of a rocket built almost entirely in-house.