The team successfully completed a hot fire of the rocket engine in March of 2026, following a complete redesign and rebuild of the test stand piping after an anomaly that occurred during the Fornax campaign. This test marks the first time in four years that DanSTAR has turned on their engine.

The engine, Gnome Child MK IV is 3D printed in steel by Danish industry partners and is the same design as the previous rocket Valkyrie. The re-use of the engine design would allow us to skip the hotfires, but ultimately a hotfire campaign was conducted anyway. This was done primarily for educating the team, since it was a very different team than those who participated in 2021. A static fire was also planned to take place before EuRoC.

The “brain” of the rocket – the flight computer – consisted of a backplane with five slot-in boards, each of which had unique jobs to control and monitor the entire rocket. Besides the custom flight computer, we designed battery boards to monitor and charge the battery, a switch board to easily turn off power, a black box to store the valuable flight data, and a middleman board to take the outputs (pyro channels) of both of the COTS flight computers to deploy the recovery system. We used two COTS computers to ensure deployment of the parachutes.

Valkyrie used the fourth iteration of DanSTAR’s Gnome Child biliquid rocket engine as its propulsion unit.
Like its predecessors, Gnome Child Mk IV used nitrous oxide and a custom isopropanol fuel blend, and produced 3.1 kN of thrust at a chamber pressure of 19 bar with a specific impulse of 195 seconds. This put it at the forefront of efficiency among student rocket engines, and to our knowledge was the only flight-proven student-developed liquid engine in all of Europe at the time of launch.
After the successful launch of Dragonfly in 2020, the engine underwent several design improvements, saving 1.5 kg of mass and reducing the pressure drop in the cooling channels. Due to its regenerative cooling system and well-tested injector design, the engine achieved an extremely high combustion efficiency during operations. Gnome Child Mk IV was the culmination of three years of engineering, designing and testing, and is still a testimony to DanSTAR’s ambitiousness and dedication.

The Rack was the flight computer that controlled the Valkyrie rocket. It was the successor to the Stack, which was used in the Dragonfly rocket. While the Stack consisted of seven unique PCB boards stacked on top of each other, the Rack consisted of six unique PCB boards which were slotted into a backplane PCB, in much the same way RAM is slotted into a motherboard on a computer.
This slotting system allowed for boards to be independently added, removed, iterated, replaced, and tested easily throughout the entire design process of the Valkyrie rocket.
Each PCB in the Rack had a unique purpose, including controlling the flow of propellants with servo motors, measuring pressures and temperatures in the engine, and wirelessly communicating with Mission Control via on-board antennas.
Each of the six PCBs was equipped with STM32 microcontrollers, all of which communicated with each other using CAN-FD protocol, a protocol used in modern high-performance vehicles. This ensured that data and information about the rocket was gathered, stored, and transmitted to where it needed to be at all times before, during, and after the flight. Many of the Rack boards were also controlling other peripheral PCBs in the rocket which were not a part of the flight computer; the Actuator board was controlling three different Servo boards, the Main board controlled the Ignition board, and the Power Supply board monitored four different Battery boards.
The Rack was designed and programmed entirely by DanSTAR’s electronics and embedded software teams, making every aspect of it specialized for the operation of the Valkyrie rocket.

Gnome Child is the name of the rocket engine that propelled Dragonfly upwards for the approximately 16 second long boost phase. During this period, the rocket saw an acceleration of more than 3G as the fuel tanks emptied. Around 18 kg of pure propellant was burnt in this period.

The engine was kept cool with an advanced regenerative cooling system, meaning all of the fuel is circulated around the combustion chamber immediately before being injected into the engine. This has a two-fold advantage in that the engine is kept cool, but the fuel is also heated up, reducing the energy needed for evaporation.

This was, and is still, done in close cooperation with Danish Technological Institute who gracefully offered us the opportunity to 3D print the engine out of metal. 3D printing is a new and emerging technology within rocketry that allows for complex designs of cooling systems within the actual engine itself that could not be manufactured with traditional methods. This means DanSTAR is on the forefront within actual rocketry development, and it allows our students to get hands-on experience with state-of-the-art technology before graduating.

RICHARD is short for Robust Internal Controller for High Altitude Rocket Dragonfly. This was our internal flight computer, which additionally also controlled the test stand. Sometimes refered to as the flight stack for its many stacked PCBs, it utilised STM32 microcontrollers for a low learning curve and reliable platform to work with. The stacked PCB design allowed for easy iterations of individual computer models and made adding new features a breeze.

The internal communication was done with a modern CAN interface, the same also used in the automotive industry, which allowed the boards to communicate quickly and easily among each other, ensuring information was where it was needed when it was needed.
The multi-board design consisted of an actuator board, temperature sensor board, pressure sensor board, telemetry board, high-power board, low-power board, and lastly the main board. This configuration had all the functionality that was needed within Dragonfly during flight and recovery, and controlled everything from the auto-ignition sequence to recovery events.
When used on the test stand, a test stand board was added to the stack, which increased the amount of connected sensors and valves that could be controlled.

The launch rail is a quarter ton heavy and 13 meter tall, behemoth structure that DanSTAR had to develop from scratch to facilitate launching a rocket the size of Dragonfly. The launch inclination can be adjusted down to a single degree because of its special hinge construction. This means DanSTAR can carefully decide the rocket flight direction, which is helpful for safer launch events.

The structure itself consists of a steel center piece and legs with an aluminum mast. This ensures most of the weight is located at the bottom of the structure, making it stable even in windier conditions. The mast is in constant tension because of the steel wires which keep it firmly in place when the launch rail is deployed.
The launch rail is able to be completely disassembled, which is a requirement for shipping it to the US, in order to distribute the shipping weight throughout several flight cases.

The test stand's fluid system is intended to emulate the one as seen in Dragonfly. This provides a test bed with close to the same conditions present as in the rocket itself, and build on the principles of 'test as you fly, fly as you test' laid out by Copenhagen Suborbitals.

Similar to the rocket, it contains three large volumes. A 10 L tank for storing the 300 bar dinitrogen, a 35 L insulated nitrous tank, and a 15 L fuel tank. This is approximately three times as large as seen on the rocket, allowing for quick turnover times between hot-fires by reducing fueling time as well as enabling longer duration engine burns to be test.

The demo engine is outfitted with a thorough sensor suite, capable of sensing feed pressure for both the oxidizer and fuel as well chamber pressure. It has 6 thermocouples located deeply inside the chamber wall to measure temperature at critical locations.