Cooper–Harper rating scale

The Cooper-Harper Handling Qualities Rating Scale (HQRS), sometimes Cooper-Harper Rating Scale (CHRS), is a pilot rating scale, a set of criteria used by test pilots and flight test engineers to evaluate the handling qualities of aircraft while performing a task during a flight test. The scale ranges from 1 to 10, with 1 indicating the best handling characteristics and 10 the worst. The criteria are evaluative and thus the scale is subjective.

Background

Development

After World War II, the various U.S. military branches sent different models of their operational aircraft to the Ames Aeronautical Laboratory located at the Moffett Federal Airfield in Mountain View, California for evaluation of the planes' flight performance and flying qualities. The laboratory was operated by NACA, the predecessor of NASA. Most of the flights were conducted by George Cooper, Bob Innis, and Fred Drinkwater and took place at the remote test site at the Crows Landing Naval Auxiliary Landing Field in the central valley area east of Moffett Field.

What may be the most important contribution of the flying qualities evaluation programs and experiments conducted on the variable stability aircraft at Ames was George Cooper's standardized system for rating an aircraft's flying qualities. Cooper developed his rating system over several years as a result of the need to quantify the pilot's judgment of an aircraft's handling in a fashion that could be used in the stability and control design process. This came about because of his perception of the value that such a system would have, and because of the encouragement of his colleagues in the United States and England who were familiar with his initial attempts.

Cooper's approach forced a specific definition of the pilot's task and of its performance standards. Furthermore, it accounted for the demands the aircraft placed on the pilot in accomplishing a given task to some specified degree of precision.