POLARIS Spaceplanes announced a deal with Germany’s BAAINBw to develop an experimental hypersonic aircraft for the development of reusable hypersonic platforms.
POLARIS is to develop a two-stage hypersonic reusable aircraft for a more sustainable access to space under the contract signed with Germany’s military acquisition agency BAAINBw. A prototype is set to fly in 2027.
The company describes the aircraft as a hybrid-powerplant platform with the size of a fighter jet, carrying a spacecraft to high altitude and hypersonic speed.
According to the concept, the main aircraft, powered by a pair of turbofans and an aerospike rocket engine, carries the rocket-powered spacecraft carrying the payload, mainly satellites. While the turbofans work for takeoff and initial climb, the aerospike engine takes over at high altitudes to provide the rest of the required push.
As to why an aerospike is used for the ‘mothership’ aircraft, it stems from the fact that aerospike engines with an open nozzle can operate at maximum efficiency inside the atmosphere. In conventional rocket engines with closed nozzles, the efficiency varies with the changing atmospheric pressure, which results in efficiency losses. Additionally, compared to a scramjet engine, which takes more effort in terms of design and testing due to the involvement of an air intake and combustor to operate at extreme speeds, aerospike as a rocket engine is overall simpler in these regards.
Whereas conventional rocket launches for space-based payloads fully or partially expend expensive equipment, this concept provides full reusability, with the only main resource spent being the fuel. However, the challenges, such as thermal management under hypersonic speeds and propulsion constraints, have kept the idea from being implemented despite the multiple instances of projects from the Cold War era to today.
Author: Kaan Azman
Editor: Özgür Ekşi
