A numerical study of airplanes flying in proximity

Abstract

During an emergency such as an unsafe landing gear indication, a second aircraft is often used to perform an airborne visual inspection of the landing gear. The chase airplane may be quite dissimilar in size and wing loading and consequently experience unexpected aerodynamic forces and moments caused by the other airplane. A numerical study of the inherent danger involved with the aerodynamic interaction of aircraft flying in proximity was made using the low-order panel code PMARC (Panel Method Ames Research Center). PMARC validation was made by comparing wind tunnel and analytically derived stability data for T-34 and F-14 models with PMARC results. A T-34 was then placed at various distances underneath an F-14 to determine changes in lift and pitching moments on the T-34. Color illustrations of pressure coefficients were used to highlight the changes in aerodynamic forces and moments as vertical separation between the two aircraft was decreased. PMARC showed that 4.5 deg. of elevator trim change were required as a T-34 approached to within its semispan of an F- 14