DLR launches sounding rocket to test reusable booster technology – Parabolic Arc

Launch of the STORT in-flight experiment. [Credit: DLR (CC BY-NC-ND 3.0)]
  • The DLR flies a three-stage sounding rocket for the first time.
  • Component structures, measurement methods and evaluation algorithms tested for the re-entry phase.
  • A modular and distributed data acquisition system allowed the efficient recording of data from the different experiments.
  • Focus: space travel, aerodynamics, sounding rockets.

ANDOYA, Norway (DLR PR) — Reusable support systems are exposed to high loads and temperatures when returning to the surface. The German Aerospace Center (DLR) has now successfully tested component structures, measurement methods and evaluation algorithms for the re-entry phase with the flight experiment STORT (Key Technologies for High Energy Return Flights load-bearing floors).

In the early morning of June 26, 2022, the three-stage rocket experiment was launched from the Andøya Space launch site in northern Norway. At the top of the trajectory at an altitude of 38 kilometers, the upper stage reaches a flight speed of about 9,000 kilometers per hour, which corresponds to a Mach number of more than eight. It then fell into the Atlantic Ocean more than 350 kilometers from the starting point.

“In order to achieve higher flight speeds, for the first time we used a DLR sounding rocket with three rocket stages instead of two,” says Dorian Hargarten of the DLR Institute of Space Operations and Astronaut Training. “In addition, the third stage with the various science payloads followed a particularly flat trajectory at an altitude of 38 kilometers at Mach numbers up to eight. Here, analogous to the development of heat during re-entry into the Earth’s atmosphere, various high-temperature experiments were conducted at the high heat loads to be studied.

Testing ceramic segments and lamellae

Materials that resist high thermal loads and dissipate them are crucial for heat development in the re-entry phase. Robust heat sensors that closely monitor temperature changes are also essential.

“In STORT, the third-stage rocket pre-body consists of five ceramic segments,” explains STORT project leader Prof. Ali Gülhan of the DLR Institute of Aerodynamics and Flow Technology. “We have fitted the pre-body with numerous heat flux sensors, thermocouples and pressure sensors every 90 degrees along the four longitudinal lines and are now very excited about analyzing the data.”

To carry out the thermal management experiments, the researchers used three stationary canards with ceramic outer shells on the rocket, which were developed by the DLR Institute of Structures. While one duck was actively cooled, the second duck was passively cooled. The third reference canard (without cooling) was also used to study the impact-boundary layer interaction. The three ducks showed different structural responses in flight under the same thermal load.

STORT Rocket [Credit: DLR (CC BY-NC-ND 3.0)]

A modular and distributed data acquisition system allowed the efficient recording of data from the different experiments. In the previous ATEK project, a standard module made of aluminum alloys was replaced by a hybrid module consisting of a CFRP structure with metal flanges to reduce the weight of the cylindrical payload segments. In the STORT project, researchers are currently testing a significantly lighter module made entirely of CFRP.

Next to the DLR is the Technical University of Munich involved in the STORT flight experiment by manufacturing the CFRP module. Another international partner is the University of Arizona, which performed simulations for the “Impact-Boundary Layer Interaction” experiment on the duck. Mission planning and execution was the responsibility of the Mobile Rocket Base (MORABA) department of the DLR Institute of Space Operations and Astronaut Training.

The preliminary body was designed and manufactured by the DLR Institute for Construction Methods and Structure Technology. The DLR Institute of Aerodynamics and Flow Technology, also responsible for the prime contractor, contributed to the aerothermal design, active thermal management, payload instrumentation and their modular data acquisition.

About the STORT project

The flight experiment, which has now been completed, is part of the STORT research project. The project is part of the DLR sub-program “Reusable space transportation systems”. It aims to develop selected technologies and methods for thermomechanical analysis and evaluation of load-bearing systems. For this purpose, the component structures, measurement methods and evaluation algorithms, which were developed in the basic investigations, are adapted for flight experience and ultimately qualified with flight. In addition to ground experiments, flight data provides validation data for physical modeling, numerical simulations, and system analysis, enabling reliable design and evaluation of future carrier systems.

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