Numerical investigation on the weight, speed, and installation location effects on fuel tank separation trajectory

Abstract

A numerical survey coupled with six degree-of-freedom flight simulation have been undertaken to study the fuel tank separation trajectory, released from a trainer airplane. Two different spanwise release points for the tank, near and farther from the fuselage under the starboard wing with full and empty fuel were considered. The studies were performed at two free stream Mach numbers of 0.23 and 0.42 at zero angle of attack. Dynamic unstructured tetrahedral mesh approach combined with spring-based smoothing and local remeshing was applied with an implicit, second-order upwind accurate Euler solver. A six degree-of-freedom routine using a fourth-order multi-point time integration scheme was coupled with the flow solver to update the payload trajectory information at each time step. According to the results, the payload installed farther from the fuselage falls down with a higher forward velocity than that located closer, once released from the wing. The spanwise installation point was also found to have a strong impact on the pitch attitude of the released payload. The payload weight has been shown to play a vital role in longitudinal-lateral coupling behavior and the associated moments on the released payload.