Influence of low-speed aerodynamic performance on airport community noise

Abstract

Properly assessing proposed aviation policies requires a thorough trade study of noise, emissions, fuel consumption, and cost. Aircraft low-speed aerodynamic performance is an important driver of all these impacts, and this thesis presents the development of an aerodynamic tool capable of accurately estimating key low-speed performance characteristics using aircraft geometry information typical of that available in the preliminary phase of aircraft design. The goal of this thesis is to use the low-speed aerodynamic estimates to present the sensitivity of aircraft noise to aircraft configuration and operational procedures, and then to identify improved procedures to reduce the cost, fuel use, and noise of current aircraft. The low-speed aerodynamic method developed in this work is comparable to aircraft manufacturer initial design tools. It requires about fifteen seconds on a modem computer and has been developed to a sufficient level of accuracy through a calibration study using Boeing flight test data, NASA wind tunnel results, and an empirically-tuned Lockheed method. The low-speed method is generally capable of predicting a drag polar, drag as a function of lift, to within one-percent. It also determines the changes of the drag polar due to high-lift devices, both slat and flap deployment, to within about three-percent. In addition, the method contains correlations to predict the variations of lift with angle of attack and the maximum lift coefficient; these predictions have errors around ten-percent and five-percent, respectively. The estimates produced by the method are of appropriate fidelity to properly model aircraft flight trajectories for fuel bum and noise estimates within larger environmental impact assessment models.

(cont.) The results of simulations of the mandated takeoff and landing noise certification procedure show that noise is reduced insignificantly by small modifications to the airframe. This is largely because, for the current aircraft fleet, engine noise dominates both takeoff and landing noise, and only methods to reduce the required thrust or increase the aircraft altitude will significantly decrease noise. For landing, significant reductions in noise, on the order of 12%, were found by increasing the approach speed, which decreases required thrust, and by steepening the approach path, which keeps the aircraft higher above the ground when outside the airport boundaries. The results of an optimization study estimating the Pareto Frontier of departure procedures for a 747-200 aircraft show that compared to the standard departure at maximum takeoff weight, a reduction in time to climb of two minutes, in fuel consumption of 1,300 Ibm, and in land area exposed to a sound level 55 EPNdB of 100 square miles can be mutually achieved.