Hi Dave,
Quote:
Originally Posted by DaveBirkenstock
. . .
The one thing not clearly identified on that blimp image is the suction inlet, just upstream of the concave tailcone. By adding energy in the form of suction, the mechanism can generate what Fabio Goldschmied called "fuselage self-propulsion."
Goldschmied proved a significant reduction in total power used for streamlined bodies (his baseline body was the rigid blimp, USS Akron) by exploiting pressure thrust. . . .
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I remember NASA has done a lot of work on boundary layer control using perforated panels or slots and a suction pump. I see some similarity with 'pressure thrust', which appears to be pulling in a larger fraction of the air flow. Is there a rough rule of thumb about what fraction of the flow needs to be pulled in and at what velocity relative to the high-speed flow?
I just finished reading "A History of Suction-Type Laminar-Flow Control with Emphasis on Flight Research" by Albert L. Braslow. This report mentions problems with rain, ice and other surface contamination. I get the impression 'pressure thrust' pulls in more than just the boundary layer. However, I'm wondering if rain and snow might cause problems?
Bob Wilson