The US Air Force's Arnold Engineering Development Center (AEDC) has announced completion of a hot flow test on a dual ramjet and scramjet hypersonic engine for the Falcon combined cycle engine technology (Facet) programme.

Facet's goal is to test the combined-cycle technology at up to Mach 4 so a future vehicle could accelerate itself to the point where the scramjet can propel it at hypersonic speeds. When it completes its mission the vehicle can decelerate to the subsonic regime and return to base. Testing is to begin at M3 and be increased to M4.

The test was completed at the AEDC's Aerodynamic and Propulsion Test Unit (APTU). Matthew Bond, APTU manager, says: "The most critical issue in a turbine engine or a ramjet is making sure you can manage the airflow [from subsonic to supersonic]. For example, with a ramjet, even though the vehicle is going at Mach 3 or Mach 4, when the air comes in the inlet it actually gets [slowed] down to subsonic flow."

Falcon dual ramjet/scramjet hypersonic engin
The Defense Advanced Research Projects Agency's Falcon Combined Cycle Engine was successfully ground tested April 9 for the first time in the Aerodynamic and Propulsion Test Unit at Arnold Engineering Development Center, Arnold Air Force Base, Tenn

The right flow will ensure that the fuel/air mixture in the combustor can be ignited and that combustion can be maintained.

APTU can only run a test at one Mach number at a time, but this nevertheless allows users to confirm their calculations. The Pratt & Whitney Rocketdyne-developed propulsion system is a key component of the Defense Advanced Research Projects Agency/USAF Falcon hypersonic vehicle programme. Lockheed's vehicle design for Falcon employs the Facet hypersonic engine and a Rolls-Royce Liberty Works turbojet for subsonic and low-supersonic flight.

Source: Flight International