Quote:
Originally Posted by theunchosen
The pressure contour map is the same as what an airfoil is(like if you put an airfoil next to those two cd maps you'd see the flow tendencies over the back of the concavity is the exact same smooth hugging without any complex vacuum or suction schemes.)
The only advantage I can see is you can kind of create the shape you want and then apply this technique for "free"(using air intake or some other naturally occuring engine process(by natural I mean something that it does under normal circumstances)).
Other than that I'm sticking with my foil-prism for my custom build CF sketches.
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But this would screw with volumetric efficiency, since the engine would have to work harder to draw in the air it needs. So you're still trading efficiency.
Looking at this from both sides, I'm thinking that it's more like a novelty aero-experiment than something viable for right now.
Dave has openly stated that the gains are there to be had, and said that an aero shape was not a valid opponent to this "design"... yet just stated that the achieved Cd of the capsule, which can only be achieved with help, is still higher than the airfoil.
By the way guys, the vacuum needs to occur in the concave area for this to work... that would mean there would have to be a pressure vent somewhere else... like at the tip of the tail cone.
Saying that you're re-issuing drag to another area is a false statement.
The efficiency loss comes from the necessity to drive a vacuum pump to keep the boundary layer attached at the concave region. The idea that the flow slows down so dramatically to stay attached there is what causes the pressure to rise in that area compared to other areas.