The Air Force Arnold Engineering Development Complex's Engine Test Facility test cells are used for development and evaluation testing of propulsion systems for advanced aircraft and missiles. These propulsion systems include turbojet and turbofan air breathing engines and ramjets. 

Ground tests of air breathing engines provide information such as performance, operability and reliability and can help cut development time and the number of flight tests required for manned aircraft or unmanned weapon systems such as cruise missiles and unmanned aerial vehicles. 

The tests may involve complete flighttype engines or heavier boilerplate versions in which inlets, compressors, combustors, nozzles or other components can be installed for experimental investigation. 

Engines are tested throughout their specified flight envelopes including critical areas which represent the limits of their performance. A wide range of flight conditions can be simulated but, generally, the limit for testing air breathing engines is less than Mach 3.8 at simulated altitudes below 100,000 feet. One specific cell, T-3, is designed for testing small engines and has the capability to reach Mach 4.0 at simulated altitudes below 70,000 feet and Mach 2.5 at sea level conditions. 

Some of the world's largest jet engines have been tested in the Aeropropulsion Systems Test Facility portion of the ETF. Those include the PW4000 series engines and Rolls-Royce Trent 800 used to power the Boeing 777 as well as the Rolls-Royce Trent 900 and Engine Alliance GP7200 used to power the Airbus A380. 

Engines for the development of the nation's most vital aerospace weapons systems have been tested in ETF. Among those are the Pratt & Whitney F119 engine used to power the F-22A Raptor and the Pratt & Whitney F135 engine used to power the F-35 Joint Strike Fighter. 

ETF's SL-2 and SL-3 sea-level test cells provide the capability to operate at either ambient sea level condition, variable temperature ram inlet conditions, or heated inlet sea level conditions without ram and to rapidly transition between those test configurations. 

These two cells are capable of testing up to 50,000 pound thrust engines at ram speeds up to Mach 1.2 and temperatures ranging from minus 20 degrees to 350 degrees Fahrenheit.

Another sea level test cell, SL-1, has the capability to operate at sea level conditions in an economical T-9 hush house configuration but is currently in an inertia status. These capabilities are especially critical for economically simulating flight conditions in a ground test facility and
rapidly accomplishing Accelerated Mission Testing or Accelerated Simulated Mission Endurance Testing. These tests evaluate engine durability by duplicating the types of missions the engine will actually fly in operational service. 

World War II ended with air power fully recognized as a controlling factor in warfare. Nearly one-half century had been devoted to developing and perfecting the conventional airplane. New technologies emerged from World War II shifting the world's aeronautical effort to high subsonic, transonic and supersonic flight.

At that time, the United States lacked the test facilities necessary to ground test the developing and envisioned high-performance jet engines.

The Germans recognized the need for special facilities for jet propulsion development. In 1944, they placed in operation the Bavarian Motor Works (BMW) engine test plant to test and develop gas turbine engines.

After the war, the BMW plant was dismantled and shipped to the U. S. In January 1949, AEDC's Engine Test Facility was approved by Congress, and in September 1950, the Air Force began reconditioning and installing the BMW equipment at AEDC.

The German equipment was modernized and expanded considerably during its installation at AEDC. Shakedown testing of ETF began in July 1953, and on May 3, 1954, the first turbojet engine test operation of a J-47 engine (later used to power the B-47 Stratojet bomber) began in ETF T-1 test cell.