Validation of software for the calculation ofaerodynamic coefficients : with a focus on the software package Tornado

Abstract: Several programs exist today for calculating aerodynamic coefficients that with some simplificationsprovide fast approximations of the values for a real aircraft.Four different programs were analyzed for this report: Tornado, AVL, PANAIR and a handbook-typepreliminary method. In addition, ANSYS CFX was used for airfoil validation. For calculation of the zerolift drag, an approximation was computed in order to calculate the remaining values that were notcalculated by the software: drag contribution for fuselages, nacelles and some horizontal stabilizersand fins.Different types of aircraft were selected for trial: two commercial aircraft (Boeing 747-100 and 777-300), a TF-8A research airplane (with area rule application: some additions were made to the fuselageto prevent large variations in the cross-section when the contribution of the wing is added), a LockheedConstellation C-69 used as a military cargo airplane, a Boeing Stratocruiser used by the USAF withtwo configurations (basic and bomber), and an Aero Commander 680 Super, similar to a Cessna 162.Two airfoils (NACA2412, 0012) were also analyzed, to investigate the limitations of software designedfor three-dimensional calculations.The accuracy of the results showed that the validity of the software depends on the planform of theaircraft, as well as the simulation parameters Mach number and Reynolds number. The shape of thewing caused some of the methods to have serious difficulties in converging to valid results, orincreased the simulation time beyond acceptable limits.