Generalization of turbojet and turbine-propeller engine performance in windmilling condition

Windmilling characteristics of several turbojet and turbine-propeller engines were investigated individually over a wide range of flight conditions in the NACA Lewis altitude wind tunnel. A study was made of all these data and windmilling performance of gas turbine engines was generalized. Although internal-drag, air-flow, and total-pressure-drop parameters were generalized to a single curve for both the axial-flow type engines and another for the centrifugal-flow engine. The engine speed, component pressure changes, and windmilling-propeller drag were generalized to single curves for the two turbine-propeller-type engines investigated. By the use of these curves the windmilling performance can be estimated for axial-flow type gas turbine engines similar to the types investigated over a wide range of flight conditions.