Quote:
Originally Posted by ChazInMT
Your “Stalled Wing” is not a fair comparison, and, your statement that it has very high drag is not quite correct. The wing, in fact, has its highest drag just before it stalls, that's what is keeping the airplane aloft. When the flow detaches from the wing in its stalled state, the low pressure area drops dramatically, the lift goes away, The Dynamically Created Low Pressure Area No Longer Exists.
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I have to say that
you have a few misconceptions about aerodynamics.
The stalled wing is a fair comparison and the wing does NOT have its highest drag "just before it stalls." Quite the contrary. See the graph below. The Clark Y stalls at about 18 degrees. After that the lift drops and the drag
increases dramatically due to flow separation. The drag does not "keep the airplane aloft," lift does. And the lift does not "go away" after the wing stalls, it just decreases.
Quote:
Originally Posted by ChazInMT
The flat area behind a car is not always a turbulent, drag producing thing.
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Yes it is, and we should try to minimize it as much as possible. The closer we get to the "ideal" shape, the lower the Cd is, due to the elimination of the flat area.
Quote:
Originally Posted by ChazInMT
The website where the flow diagrams in Post 1 were retrieved from show the “Raw data” in the form of tuft tested VW’s, the air flow is doing what's depicted in that diagram.
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And what Cds did they get with the stock car vs. the "detached" airflow? Or did they not test that? Are you just assuming that the car would have a lower Cd with detached flow? You know what they say about the word assume.
Quote:
Originally Posted by ChazInMT
I have a pickup truck with big ol side rearview mirrors on it, when I put my hand close to the mirror in the air bubble formed behind there, my hand is not buffeting about wildly from the turbulent air, same thing on the back of a car, the air just puffs about a bit, no huge drag creation.
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Your hand is in the low pressure area, and the drag is there, even if you cannot "feel" it. There is at least one graph on this website showing the huge amount of drag a flat plate creates.
Quote:
Originally Posted by ChazInMT
Do you think this car is creating a huge amount of drag behind it??
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No, not a
huge amount of drag, but some nonetheless, and it is due to the separated airflow. The car is not the optimum shape for low drag, but Toyota did the best they could within the other constraints for the car (styling, overall length, utility, etc.). Would it have lower drag with a full boattail and fully attached flow? Certainly.
Under your theory, the Prius would have lower drag if we deliberately cause airflow separation up by the B or C pillar. I disagree.