B, I'm talking about the bumps along the leading edge of the fins, not the bumps onm the back and body and such. Appreciate someone trying to understand what I feel might be a great idea.
I mistyped when I said increasing stall, I meant increasing stall angle.
The greater the stall angle attainable, the more effecient the wing is, and is able to produce downforce at lower speeds then wings with lesser stall angle.
The marine biologists and CFD guys were at first confused as to how the whales were able to use their pectoral fins to swim up almost vertically while releasing massive amounts of air. The angles of climb were beyond what should be attainable with standard smooth fins that dolphins sharks and other whales posses.
Traditionally, modern fighter jets are impossible to fly without a computer translating the fighters requests for control. The aerodynamics of modern jets are more akin to a dart being thrown backwards with a computer keeping it pointed that way, as it alsways on the edge of changing direction. These knife edge wings offer the air the option of going either above or below the wings, but some air takes a moment to 'decide', and needs to be foced over and under, creating some chaos at the leading edge.
If there are round bumps staggered on the leading edge, the air has the option to go around the bumps in 360 degrees of freedom, so when the air hits the broad wing surfaces, it has already been conditioned, and is easier to control.
Here is a link about the bumps (tubercles!!!)
*From the article*
The group built two model humpback whale flippers, one with a smooth leading edge and one with a wavy edge approximating the usual spacing of tubercles. They tested the scaled-down fins in the Naval Academy's wind tunnel by matching the Reynolds number of a swimming humpback, around 500,000, and measured the steady lift and drag forces on the fins at a variety of angles to the oncoming flow, ranging from –2° to 20°.
The smooth-edged flipper behaved much like a standard airplane wing, although its shape gave it a few advantages over a normal wing. As the angle of attack increased, the lift force increased until the flipper stalled out at around 12° when the lift dropped and the drag increased substantially. This performance is very similar to a standard wing, but the lift did not drop as much as the group expected, possibly because fins are tapered towards the tip. The taper might let different parts of the fin stall later than others, leading to a more gradual drop off in the lift force.
"The really impressive results, however, came from the flipper with tubercles. The fin did not stall until it reached an angle of 16° and produced up to 6% higher lift and as much as 32% lower drag than the smooth fin. Over nearly the entire operating range of angles the bumpy flipper performed better.
Summarizing the performance of the flipper models as an aerodynamic efficiency – the ratio of lift force to drag force – they found that tubercles increased efficiency at almost any angle, and particularly augmented the efficiency at high angles. Maximum efficiency jumped from 22.5 to 23.5.
The group hypothesizes that the tubercles function like vortex generators, speeding up the flow in the gaps between bumps. The energized flow stays attached to the flipper better, helping to prevent stall at high angles and increasing the lift force. These increased forces probably contribute to humpbacks' surprising agility."
