Aerodynamics of Formation Flight

TLDR

The study reports wind‑tunnel test results evaluating the aerodynamics of aircraft in formation flight. A vortex‑lattice model and wind‑tunnel tests in echelon, chevron, and in‑line formations examined how horizontal and vertical offsets between leading and trailing wings affect aerodynamics. Results show that the leading aircraft’s offset and angle of attack strongly influence the trailing aircraft, producing lift‑to‑drag gains, shifts in CLmax and stall angle, and altered CL‑α curves.

Abstract

Reported are the results of wind-tunnel tests conducted to evaluate aerodynamics characteristics of aircraft in formation flight. A vortex-lattice numerical scheme was used to investigate the effect of spatial offset (horizontal and vertical) between the leading and trailing wings. The wind-tunnel test configurations consisted of echelon, chevron, and in-line formations. Analysis of the data revealed that the spatial offset and the angle of attack of the leading wing had significant impact on the trailing aircraft. For some test conditions an increase in lift-to-drag ratio of the trailing aircraft was measured. Variation in C Lmax and/or α stall was observed as well. At higher angles of attack of the leading wing, the C L-α curve of the trailing aircraft was significantly altered.