An algorithm of computation of airfoil drag in lower transonic domain

Abstract

Most of the modern airliners, civilian and military cargo aircraft and fighters, cruise at speeds slightly lower than the speed of sound, in the so called lower transonic domain. For many of these aircraft, relevant design conditions imply wing optimization exactly for this speed domain. In that case, one of the primary steps is selection or design of airfoils for the wing and other lifting surfaces, which produce the least possible shock wave drag. For that purpose, an algorithm, presented in this paper, has been developed. It enables the numerical calculation of wave drag both for the existing and newly designed airfoils for certain aircraft, primarily aimed for use in the operational aircraft design. This algorithm is fairly simple and very reliable, which has been proven by comparing it's results, obtained through the computer program Tranpro, with the experimental results for airfoils tested at a number of most competent aeronautical institutions throughout the world.