Research studies focusing on jet engine test cell aerodynamics, acoustics, and cell flow characteristics as affecting engine performance can be conducted with scale models for a variety of test cells. Such studies require the simulation of a number of jet engines in rather accurate detail, both as to geometry and as to flow characteristics. It has been demonstrated that simulators of low-bypass afterburning turbojets, high-bypass turbofans, turboshaft engines (without propellers), and unducted fan engines can be designed, fabricated, and successfully operated using either high-pressure air ejector systems or turbine driven systems for the motive power. Specific components of a test cell such as inlets or exhaust sections alone may be tested independently by employing a vacuum source and bellmouth to simulate engine inlet flow or compressed air and scaled nozzle to simulate engine exhaust flow. The peculiar problems associated with scale model testing and engine simulators and the methods which can be used to attack these problems are described. This SAE Aerospace Information Report (AIR) has been written for individuals associated with ground level testing of turbofan and turbojet engines and particularly for those who might be interested in investigating the performance characteristics of a new test cell design or of proposed modifications to an existing test cell by means of a scale model test.