Mystery Steve wrote:I've never seen shark skin up close...
That's because you have not read this thread:
Inspiration From Nature???. There you go, true shark skin (all the notes in white letters scribbled over the picture are pure science fiction, written by me):
Shark skin, coloured by a Ferrari fan, I guess. Are those little Ferrari F1 noses?
I wouldn't call that dimples. I believe (yeah, I know somebody will correct me) that the flow regime is different (viscosity is higher in water, so Reynolds number is different). So, in air, I think that the skin has to be considerably rougher than the one used in swimming. In the end, you don't notice they exist: they don't look like shark skin nor like dimples.
Ferrari serrated Gurney Flap, posted by the millionth time
I also posted recently in a thread by Green Power Dude Reloaded a picture about the Ferrari cockpit shield around 2003, also with the same kind of serrated Gurney Flap. You have to look closely to notice it.
... it's the little thing with holes in front of the steering wheel
In that same thread somebody suggested to GPDR to use vortex generators around the cockpit entrance of his Green Powered car, if I remember well. I did not understand all what GPDR and the fella said, but they also seemed to agree on something that didn't looked like golf balls, there were more like
entire winglets.
Some aircraft, with similar speeds (and thus Reynolds numbers) to the ones of F1 cars have used the concept, for example, the Junkers J-I, like this:
Junkers J-I sole surviving airplane. Top speed: 170 kph, the same exact aerodynamic regime of Toro Rosso, Force India and McLaren, all of them Junkers in a sense
Now, is this kind of skin sensitive to yaw? I bet.
Vortex generators in airplanes (that have little aerodynamic yaw) are there to delay stall, like this (link to image courtesy of Dave Killens):
Dave explained to us that you shouldn't allow a bunch of little snakes with arrow shaped heads to dance on top of your wing, I think
... and of course that's nothing critical in Formula One cars. So, the problem, I think, would be to find a skin that's corrugated but it's insensitive to yaw, something that the Junkers wing corrugations seem unable to do.
For example, look at this row of black things on the dropped trailing edge of this airplane:
Seem pretty similar to winglets to me. Check this two huge winglets on top of the wing, for example (yeah, also vortex generators):
So, I'd say that the shark skin is there (in a sense), only that the bumps are so large that we don't
see them.
Finally, I conccur with qw56q. We posted
some time ago and
not so long ago this image, a little more specific (it
could help to clarify qw56q post, if needed):
The squares to the right of the images represents drag: the white one represents the drag because of low pressure at the back of the shape, the black one represents the skin drag of the shape
As you can see, when you have an aerodynamic shape, like a wing, the pressure drag is very small. So, if you put dimples on top, you don't "get back" enough "wake energy" from the increase in drag caused by a rougher skin. This only works for blunt objects (or for wings in stall, which have a low back pressure).
Of course, if you have a blunt enough car, you can put some VGs on top of it, but, as I said, the bumps are
large, like this:
Now, if your car is a piece of old junk, you could start to test your own designs, like this:
True shark skin: is this the future of Formula One?
