WHEN operating the larger engine installations under marginal cooling conditions, considerable horsepower per nacelle is frequently expended solely on cooling instead of on improved airplane performance. The numerous development opportunities for reducing cooling drag are discussed briefly by Mr. Campbell.
Cooling fans offer performance gains which, in many cases, are startling to the uninitiated, yet which can be had today for the asking.
Determination of the degree of fan boost required, which is relatively small, and methods of calculating the net thrust horsepower gain to be had from fan application are provided by the author, who also discusses briefly the question of fan controllability requirements.
Finally, Mr. Campbell analyzes the published Schicht and Wattendorf contributions to blade design for higher pressure coefficient fans, and the application of these principles to a number of cooling fan projects.