Effects of wake rollup on formation-flight aerodynamics

Götz Bramesfeld, Mark D. Maughmer

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


The aerodynamic performance of two high aspect-ratio wings flying in formation is investigated with particular interest in the importance of considering wake rollup in making aerodynamic predictions. For this purpose, formations of various separations were investigated using a drag-free, fixed-wake model as well as a force-free, relaxed one. In all cases the aircraft were trimmed for roll and the follower aircraft pitch attitude was adjusted to match the lift coefficient of the lead aircraft. Both wake representations result in similar induced-drag minima for the follower aircraft which result when the lateral overlaps of the two aircraft are around 10% of a wingspan. Computations with the fixed-wake model, however, predict a wider region of lateral separations having the lowest induced drag than do the simulations with wake rollup. A small performance difference due to the wake model also exists when one aircraft follows directly behind the other. Independent of the wake model used, trimming the aircraft in roll and pitch can have a significant influence on their performance, although the required control-input solutions for trim are essentially not affected by the choice of wake representation.

Original languageEnglish (US)
Pages (from-to)1167-1173
Number of pages7
JournalJournal of Aircraft
Issue number4
StatePublished - 2008

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering


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