Amy Williams's gold medal skeleton helmet (with vortex generators)

[aerohead]

Originally Posted by TimG

Speaking of the hit-with-large-hailstones look, this is a bicycling time trialing helmet recently introduced by Garneau:
Louis Garneau Superleggera Aero Helmet
Did they do the dimples correctly? It was my impression that their method of improvement was to keep laminar flow longer (greater angle) on the back of the object... so the ones on the front would mean more drag. It should have these just behind the chord around the sides as well as the top, no?

Any kind of turbulator will incur a skin friction penalty but allow a form drag reduction such that overall profile drag is reduced.
Proper placement is absolutely critical to their performance.A good place for windtunnels.

[aerohead]

Originally Posted by MetroMPG

I know! Mythbusters should do a fuel economy episode where they attach these helmets all over a car!

Or jump out of airplanes while 'inside' the helmets,and race each other to the ground!

[thatguitarguy]

Those few square inches of dimples are not likely to make you into Lance Armstrong.

The micro-fins on Amy's helmet might have some effect on speed, or they might just be there as a psyche job, but I remember when they were experimenting with vortex generators on the helmets of open cockpit race car drivers, it was more to reduce the buffeting that happens at +200 MPH. In Amy's case, with the helmet being a large part of her CDa, it might be for speed or buffeting. If you are going that fast lying on your belly down an ice chute, you are going to want to be able to see clearly and not have your helmet shaking around in the wind.