The most powerful solid propellant motor ever test fired in an AEDC altitude cell was the 300,000-pound thrust second stage of the Air Force's Peacekeeper missile . Because of the effects of gravity, liquid fuel rockets usually are tested in a vertical position. Engines are mounted on the vertical thrust stand in the cell above ground level. Test Cell J-5 is a horizontal cell for testing rocket engines at simulated altitudes to 100,000ft. The cell is 50-ft in length with an internal diameter of 16 feet.
Water is used to cool and scrub exhaust gases in all of the rocket test cells.
A sombrero-shaped deflector at the bottom turns the exhaust upward along the cooling chamber walls. The dry gas exhaust is then pumped to atmosphere by the ETF rotating machinery. The significance of some test results particularly emphasizes the value of ground test facilities for system evaluation prior to flight testing. It was quickly fixed, preventing a thirteen-million dollar launch failure. This equalled the original cost of the test cell in which it was tested.