U.S.-Norway THOR-ER Hypersonic Rocket Engine Completes Critical Test

A hypersonic rocket engine jointly created by the U.S. and Norway known as the Tactical High-speed Offensive Ramjet for Extended Range (THOR-ER), completed an important developmental test on August 17, the Pentagon confirmed today.

In April 2020, the U.S. Department of Defense and the Norwegian Ministry of Defense jointly announced their partnership to develop advanced technologies applicable to long range high-speed and hypersonic weapons.

At Andøya in northern Norway, the test vehicle “successfully fired several times, showing the viability of ramjet propulsion technology and demonstrating significant increases in effective range.”

The recent tests satisfied the THOR-ER Phase 1 objectives of demonstrating jointly-developed propulsion technologies in flight, including new high energy fuels, advanced air injection, and throttling methodologies which will be essential for mission flexible SFRJ systems of the future.

“The SFRJ flight vehicle was accelerated to above Mach 2 with the help of a solid rocket booster, and transitioned to ramjet mode. The flight phase was a resounding success with stable flight, robust ramjet operation, and a high thrust-to-drag ratio,” said Executive Vice President of Aerospace Propulsion at the Nordic Ammunition Company (Nammo), Stein Erik Nodeland. “The flights performed in accordance with pre-flight calculations, demonstrating a high-speed long-range trajectory. All in all, this is a real milestone. While not the first ramjet vehicle, it is the first modern ramjet, with a potential for a great improvement in range, time to target, and agility.”

The first flight, conducted on August 17, demonstrated an unguided vehicle with robust SFRJ operation across a wide range of altitudes and speeds. The second test, which focused on a high thrust flight profile, took place the following day. Both flights were considered successful, having demonstrating high supersonic speeds prior to ramjet burnout and splashdown. Program officials will continue to evaluate system performance based upon telemetry and other data obtained during the test.

The THOR-ER program builds upon collaborative research efforts involving the Office of the Undersecretary of Defense for Research and Engineering, the Joint Hypersonics Transition Office, NAWCWD, the Norwegian Defence Research Establishment, and Nammo.