The world’s first flight with a wedge-air rocket engine ended in crash

The demonstrator did not even have time to take off from the runway and start the KVR engine when it swerved to the side and, under the influence of a strong side wind, capsized and caught fire. In return for the destroyed copy, the developer promised to make two or larger sizes, and he received money for this from the budget.

About a year ago, Polaris Raumflugzeuge entered into a contract with the Federal Office for Equipment, Information Technology and Technical Support of the Bundeswehr (BAAINBw) to develop and build a full-scale prototype of a wedge-air rocket engine. CVRD engines were developed back in the 50s and there were even plans to install them on shuttles of the Space Shuttle program. But the project never left the laboratories. The flight of a German demonstrator with four conventional turbojet engines and one experimental CVRD engine was to be the first in history. But it hasn’t worked out yet.

Instead of the 4.25 m long MIRA I demonstrator destroyed in the accident, the company promises to build two – MIRA II and III, each 5 meters long. The engine configuration and airframe profile will remain the same: a wedge-shaped wing, four turbojet engines running on oxygen and kerosene, and one high-pressure jet engine on each.

Wedge-air rocket engines are interesting specifically for spaceplanes, where there is no room for first and second stage engines at the same time. The rocket can have two or more stages, when the bell-shaped nozzles are each designed to its own height. If there is only one nozzle, like a spaceplane, then it will be effective only at one altitude, wasting a lot of fuel at all other altitudes.

The nozzles of the CVRD engine are two halves of a bell connected on one side. The second missing side of the nozzle is formed by the incoming air flow. Thus, the nozzle profile changes, one might say, automatically throughout the flight from sea level to vacuum, on average ensuring effective operation at all altitudes. It’s a pity that this time the Germans didn’t succeed—it didn’t even get to the point of launching a high-pressure jet engine in the air. It would be interesting to see this technology in action in real flight conditions.