Robert J. Mack

Studies of Leading-Edge Thrust Phenomena

A study of practical limitations on achievement of theoretical leading-edge thrust has been made and an empirical method for estimation of attainable thrust has been developed. The method is based on 1) a theoretical analysis of a set of two-dimension al airfoils to define thrust dependence on airfoil geometric characteristics and arbitrarily defined limiting pressures, 2) an examination of two-dimension al airfoil experimental data to provide an estimate of limiting pressure dependence on local Mach number and Reynolds number, and 3) employment of simple sweep theory to adapt the method to three-dimensi onal wings. Because the method takes into account the spanwise variation of airfoil section characteristics, an opportunity is afforded for design by iteration to maximize the attainable thrust and the attendant performance benefits. The applicability of the method was demonstrated by comparisons of theoretical and experimental aerodynamic characteristics for a series of wing-body configurations. Generally, good predictions of the attainable thrust and its influence on lift and drag characteristics were obtained over a range of Mach numbers from 0.24 to 2.0. b c c

Sonic‐Boom Pressure‐Field Estimation Techniques

Current theoretical methods of estimating the flow field surrounding airplanes in supersonic flight are based on Whithams solution for the flow about bodies of revolution and on other theoretical work that makes possible the representation of a complete airplane as an equivalent body of revolution. This paper presents a review of the fundamental theory and discusses the use of high‐speed digital computers in providing rapid and reliable analysis of sonic‐boom characteristics of complex airplane configurations. Application of the estimation techniques is illustrated in correlation with wind‐tunnel and flight‐test measurements.

Some Effects of Applying Sonic Boom Minimization to Supersonic Cruise Aircraft Design

This paper presents a discussion of an aircraft shaping method to control sonic boom overpressure levels along with the analysis of wind tunnel data which validated the method. The results indicate that the sonic boom minimization method can guide the design team choices of aircraft planform and component arrangement toward a low-boom-level configuration while permitting sufficient freedom and flexibility to satisfy other design criteria. Further, it is shown that off-design flight conditions do not drastically change the overpressure sonic boom shape and strength.