WARR Rocketry

Building a next generation flight computer from scratch

We are WARR Rocketry. The scientific workgroup for rocketry and spaceflight (ger. Wissenschaftliche Arbeitsgemeinschaft für Raketentechnik und Raumfahrt) at the TU Munich. With our history going back all the way to the 60s and over 150 members we are one of the oldest and largest organizations of this kind in Europe.

We are currently working on three rocket projects:

• Project Cryosphere: hybrid rocket with 10 kN Lox / HTPB engine soaring to altitudes of 35 km+
• Project Nixus: Biliquid rocket with first student-developed 3.5 kN Lox / Ethanol regeneratively cooled engine in Germany
• Project WESP: Solid motor rocket with quick turn-around times for fast innovation and testing

The Rocketry Electronics Team and WARR Rocketry’s EX-4 biliquid rocket. It will be launched at the European Rocketry Competition (EURoC) in October this year.

All these rockets need a flight computer to deploy recovery parachutes at the correct times, gather scientific data during the flight and more. This is where our Electronics Team and our partnership with Eurocircuits comes in. Over the last 21 months, the Electronics Team developed what became to be the WARP flight computer from scratch. Having used expensive, unsatisfactory, commercial solutions before, the team had to be rebooted in October 2021, to start gaining the expertise on how to build a sounding rocket flight computer on their own. And it paid off! WARR Rocketry’s WARP flight computer can now be considered one of the most advanced sounding rocket flight computers in Europe.

WARR Rocketry’s WARP Flight Computer. A multi-PCB assembly consisting of six PCBs manufactured by Eurocircuits.

Bare power management board (PMB) and microcontroller unit (MCU) PCBs manufactured by Eurocircuits.

WARP consists of six in-house, iteratively developed, and tested PCBs manufactured by Eurocircuits. All the PCBs, except the backplane have a form factor of 60 x 85 mm:

• Backplane
• Power Management Board (PMB)
• Microcontroller Unit (MCU)
• Sensor Interface Board (SIB)
• High Current Board (HCB)
• Telemetry Board (TLM)

It boasts some unique features and specifications that sets it apart from the competition:

• Dual rail (5 V and 24 V) power management board with up to 12 A continuously on each rail
• Can interface with industry-standard sensors and actuators: 6x 24 V valves, 8x 4..20 mA pressure sensors, 8x thermocouple
• High-power telemetry: 3x 30 dBm radio outputs for high transmission ranges; up to 100 kb/s throughput
• Three pyrotechnic ignition channels with continuity monitoring
• STM32F4 microcontroller with real time operating system
• RS485 wired ground communication link
• Dual IMU, dual barometer, high-G sensor, 20 Hz GPS and more

To achieve all of this, we have worked with a number of PCB manufacturers over the last years, creating iterations of the different PCBs quickly. However, we considered none of them for the final version of WARP except Eurocircuits for the following reasons:

• Eurocircuits had the best price to quality ratio for us
• Eurocircuits offered the best and least confusing design-verification before ordering
• Impedance control and non-green solder mask is possible
• Best quality stencils, ensuring application of correct amount of solder
• Fast delivery times, configurable to our development timeline
• Least amount of manufacturing defects or quality control issues

With WARP, we have already successfully performed a range of exciting tests:

• EX-1B solid rocket launch to verify MCU firmware
• Helicopter drop test to verify parachute deployment
• Thermal Vacuum Chamber (TVAC) stress test under low ambient pressure (6 mbar) and high ambient temperature (60 °C)

EX-1B solid rocket avionics qualification launch in May of this year.

Now, of course, all of WARR Rocketry’s rockets have to be launched. The first launch occured on 8th of July this year, with a backup date on the 15th. The EX-3 Rocket of project cryosphere launched from the premises of Friends of Amateur Rocketry near the Mojave Desert in the USA. All the equipment has already been sent on its way and we are looking forward to giving you an update about it in our next blog post!

The EX-3 hybrid rocket in its final launch configuration. It was launched on 8th of July near the Mojave Desert in the US.