The new laboratory at McCook Field for the examination and destructive testing of propellers for airplanes was put in commission on October 1, 1918. In planning the dynamometer and calibration apparatus and their foundations, it was necessary to perform engineering of a pioneer character, in which the element of magnitude of forces to be handled not only exceeded anything heretofore provided for in this type of apparatus, but in which provision also had to be made for testing aeronautical units much greater than now actually in existence in practical flight.

One of the striking features of the new laboratory is the complete enclosure of the propeller rotating apparatus within a streamlined housing of sheet iron. The contour of this housing was laid out with the idea of approximating as closely as practicable the lines and fairing of the fuselage, so that the propeller under test is subjected to conditions that resemble as nearly as possible actual flight conditions, in an aerodynamic sense. This feature is further emphasized by the placing of this streamlined housing in such a position in relation to adjacent structures that the slipstream air is afforded an unobstructed path for a considerable distance away from the propeller. Were there an obstruction in the slipstream near the propeller, the lie thrust registration would be higher than the true reading for that particular rotative speed of the propeller being examined.