Undercarriage drag prediction for a fixed undercarriage light aircraft

The following paper presents undercarriage drag predictions for a light aircraft with fixed landing gear. A Scottish Aviation Bulldog 120, operated by the National Flying Laboratory Centre (NFLC) at Cranfield University, is considered as the test case for this study. Taking advantage of a recently developed laser scanned model, computational fluid dynamics (CFD) techniques are exploited to investigate the undercarriage drag. Results via standard theoretical and empirical methods are compared to the CFD results. It is found that the established empirical methods matched the CFD predictions to within the stated error bands for moderate angles of attack. However, due to the aircraft flow field at higher angles of attack, some discrepancies in the level of drag predicted are observed. Further flight test data is recommended to confirm these findings