Aerodynamic Development of a Refueling Pod for Tanker Aircraft

Abstract

Computational fluid dynamics (CFD) was utilized for the aerodynamic design/development of an aerial refueling pod for installation on KC130J tanker aircraft. The computational work was conducted using the full aircraft geometry (including several flap settings) along with propeller and engine exhaust effects. Several refueling pods were designed/analyzed using CFD and later flight tested. Numerous CFD solutions were generated to develop aerodynamic loads on the pod/pylon over the desired flight envelope. Pressure data on the pod/pylon were obtained during two flight tests and were used to validate the CFD predicted loads. The excellent correlation between the predicted and measured pressures permitted the use of CFD alone to develop the aerodynamic loads for the structural analysis, eliminating the need for expensive testing. This computational design/analysis effort led to the development of a refueling pod design that was successfully flight tested over the entire flight envelope and is currently in production for all KC-130J tanker aircraft. INTRODUCTION Advances in computational power and numerical prediction capabilities have led to increased utilization of computational fluid dynamics (CFD) for aircraft and component design. One such recent application at Lockheed Martin was the aerodynamic design of a refueling pod for installation on the KC-130J aircraft used by the United States Marines Corps. This aircraft utilizes a hose and drogue type system for refueling high performance aircraft at high speed conditions as well as helicopters at low speed refueling conditions, as depicted in Figure 1. The large variety of operating conditions greatly increases the complexity of the aerodynamic design problem.