From: email@example.com (Mark Drela) Organization: Massachusetts Institute of Technology Date: 02 Jun 96 16:20:13 References: 1 2 3 4 Followups: 1
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In article <airliners.1996.831@ohare.Chicago.COM>, firstname.lastname@example.org.TU-Berlin.DE (Burkhard Domke) writes: |> The flow of engines pod-mounted beneath a wing counteract the |> circulation of the wing, thus reducing lift, whereas engines mounted |> above the wing would enhance lift. Careful here. You cannot relate the lift directly to the circulation if blowing is used. The derivation of the Kutta-Joukowsky relation between lift and circulation... Lift/span = rho V Gamma the circulation "Gamma" describes the flow behavior in the farfield of the airfoil (i.e. from far away, the airfoil looks like a point vortex). A jet of air is not a potential flow, so you get different values for Gamma depending on how you draw the contour. Also, the derivation of the above formula assumes that there are no momentum sources in the flowfield. A jet engine is a momentum source. Mark Drela First Law of Aviation: MIT Aero & Astro "Takeoff is optional, landing is compulsory"