The duty of the altitude cell is to do connected testing on any engine at altitude exhaust
conditions, at any inlet temperature, but with the ram air supply normally at atmospheric pressure
or below. The cell is not primarily intended for high density or supersonic inlet testing.
The cell itself is a steel shell 20 ft. in diameter and 80 ft. long. It lies in a deep cutting at
right angles to the supply and exhaust mains, to which it exhausts through a diffuser and cooling
system. The cutting walls and superstructure building contain a variety of the smaller services. The
larger services lie outside the cutting; the cold-air plant occupies a site between the main
compressor-plant hall and the cell, while an air heater will stand on the other side of the supply
mains from the cell. A central control and instrumentation building also stands beyond the pressure
mains where it can serve both the new test cells and in certain respects the ramjet cells also.
The test cell is divided into two compartments by a bulkhead about 20 ft. along the cell. Each
compartment has a 14 ft. wide removable cover or hatch for loading engines and gear into the cell.
The upstream compartment serves both as the site for propeller-turbine engines on test and also as a
plenum chamber in which supply air is maintained at the desired ram conditions of simulated flight.
The down-stream chamber is the site of turbojet engines on test and in operation is maintained at
the altitude exhaust pressure. Processed air enters the plenum chamber from an external ring main
through a series of connecting ducts and ports.