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This paper presents the results of a study aimed at quantifying the effects of jet source noise reduction, increases in aircraft lift, and reduced aircraft thrust on the take-off noise associated with supersonic civil transports. Supersonic jet noise sources are first described, and their frequency and directivity dependence are defined. The study utilizes NASA's Aircraft Noise Prediction Program (ANOPP) in a parametric study to weigh the relative benefits of several approaches to low noise. The baseline aircraft concept used in these predictions is the AST-205-1 powered by GE21/J11-B14A scaled engines. Noise assessment is presented in terms of effective perceived noise levels (EPNL) at the FAA's centerline and sideline measuring locations for current subsonic aircraft, and in terms of audiologically perceived sound of people and other indirect effects.

The present paper discusses the NASA Langley Research Center stall/spin research program to improve the design and the evaluation techniques relative to stall/spin characteristics of general-aviation aircraft. The program encompasses model wind-tunnel tests, spin-tunnel and radio-control model tests, and full-scale airplane spin tests. Initial spin-tunnel results on models with several tail designs representative of light airplanes and several testing techniques are discussed.

The results of a total of 289 landings performed with a low wing airplane by a group of private pilots on a long and short runway have been analyzed to determine the landing performance of these pilots. Both the long and short runway landings show significant variation from straight or uniformly curved trajectories denoting considerable “jockeying” on the part of the pilot during approach. The long runway approach speeds were variable and higher than recommended. Considerable float followed by touchdown at speeds well above stall were noted. The short runway landings were quite similar except that approach speeds were slightly lower as a result of the use of 2/3 to full flaps, and touchdown occurred closer to the threshold.

This paper will present the scope of an NASA program aimed at improving the design and evaluation techniques relative to stall/spin characteristics of general-aviation aircraft. The program encompasses analytical studies, full-scale and model wind-tunnel tests, radio-control model, and full-scale flight tests. Initial spin-tunnel results of several tail designs on a representative light airplane will be discussed.

A fundamentally new approach to the aircraft minimum induced drag problem is presented. The method, a “viscous lifting line,” is based on the minimum entropy production principle and does not require the planar wake assumption. An approximate, closed form solution is obtained for several wing configurations including a comparison of wing extension, winglets, and in-plane wing sweep, with and without a constraint on wing-root bending moment. Like the classical lifting-line theory, this theory predicts that induced drag is proportional to the square of the lift coefficient and inversely proportional to the wing aspect ratio. Unlike the classical theory, it predicts that induced drag is Reynolds number dependent and that the optimum spanwise circulation distribution is non-elliptic.

The National Aeronautics and Space Administration (NASA) Aircraft Noise Prediction Program (ANOPP) Propeller Analysis System (PAS) is a set of computational modules for predicting the aerodynamics, performance, and noise of propellers. The ANOPP PAS has the capability to predict noise levels for propeller aircraft certification and produce parametric scaling laws for the adjustment of measured data to reference conditions. A technical overview of the prediction techniques incorporated into the system is presented. The prediction system has been applied to predict the noise signature of a variety of propeller configurations including the effects of propeller angle of attack. A summary of these validation studies is discussed with emphasis being placed on the wind tunnel and flight test programs sponsored by the Federal Aviation Administration (FAA) for the Piper Cherokee Lance aircraft.