Starstreak+ Couplers

We are BEARS e.V., the student space club of the TU Berlin (Technical University of Berlin). We provide motivated students the ability to work on space related projects, like sounding rockets, rovers or experiments. BEARS is a nonprofit organization and all of our projects are financed by sponsorships and donations.

The following project is from the rocketry team of BEARS. The rocketry team builds sounding rockets, which fly about 3 km high and can give their payloads their necessary heights or micro gravity.

The current aim of the rocketry team is to participate the European Rocketry Challenge 2027 (EuRoC) in Portugal. EuRoC is a yearly rocketry competition of student clubs all over Europe. We already participated at EuRoC 2025 and achieved the 4th place. We also plan to launch a lower Rocket named “Starstreak” in November 2026 to test all the new systems.

The system

The rocket is divided in multiple compartments for easier assembly. In general, each compartment contain the necessary components for one area of responsibility. From bottom to top, we have the following compartment:

Motor Compartment

Contains the motor and fins of the rocket. Starstreak will use COTS solid motor. We currently design a hybrid engine, which is planed to fly at EuRoC 2027.

Avionics Compartment

Contains the bulk of the PCBs and controls the entire rocket. Also houses batteries and a cooling system. We also use long, slim PCBs along the entire rocket to connect everything and reduce the use of cables.

Airbreak Compartment

At EuRoC, the aim is to have your apogee as close to 3 km as possible. To achieve this, we aim to fly a bit higher and slow the rocket mid flight using the measured flight data. The compartment contains retractable plates, which can increase the drag of the rocket.

Payload Compartment

This compartment will only fly at EuRoC 2027. We plan to eject a drone at apogee, which will film the descending rocket and fly to a target provided by EuRoC.

Recovery Compartment

Contains the parachute of the rocket. Starstreak is using a reefing system. The parachute will be deployed at apogee to slow the descend and fully open at the last 300m for a soft landing.

Nose Compartment

Important for aerodynamics and contains most of the antenna for communication with the ground station.

This picture is from the previous rocket and uses a different payload.

The couplers

Each compartment uses a body tube and two couplers. The couplers are the connection between all the compartment. They hold the rocket together and ensure a stable force flow.

We have two main designs for our coupler. The couplers for the top of the compartments are relative simple. They have a conical interface with M4 screw hole. The conical design has the advantage of being easy to assemble and direct force flow, especially for the screws. The other side of the coupler is glued to the body tube.

Additionally, the top coupler has screw hole for the PCBs. They are important for correct positioning of the connectors between the compartment.

The bottom coupler uses the same design elements as the top coupler, but has some additional functions.

First of all, it is the counterpart for the top compartment and has recesses for the M4 screws.

In addition, the bottom coupler multiple countersunk screw holes and 3.5 mm holes. The countersunk screw attach a plate internally. Every compartment uses this plate to secure all the different parts to the structure of the rocket. The 3.5 mm holes are used for venting. It is important to have the same pressure inside and outside the rocket, otherwise things like the barometer do not work.

Lastly, the Airbeak Compartment needs its own, specialized couplers because it’s structural requirements makes the use of a body tube sub optimal. The design of these couplers is still in progress and will be provided at a later date.

The design of the couplers make a 5-axis CNC or alternatively metal 3D printing necessary. We at bears lack the capabilities for these procedures. Therefore we need the help of PCBWay to produce the couplers.

We hope to cooperate with PCBWay for the upcoming Starstreak rocket in November and the rocket planed for EuRoC 2027. The current designs will be used Starstreak rocket, which will be adjusted after its launch.

Our social media:

Website: https://www.bears-space.de/

Instagram: https://www.instagram.com/bears.space/

LinkedIn: https://www.linkedin.com/company/bears-ev/

YouTube: https://www.youtube.com/@BEARS-Space