Motorcycle helmets...

[SystemParanoia]

Why are they not dimpled like golfballs to reduce drag/noise ?

[Alfanatic]

They're made to be slippery on tarmac / dirt / car roofs, not in air.

[Munter]

SystemParanoia said:

Why are they not dimpled like golfballs to reduce drag/noise ?

I asked the same question about F1 cars. Apparently it's the spin and the dimples on the golf ball that reduce the drag. Without the spin you don't get the effect. So unless you can spin the helmet really fast around on your head....

[Mr Gear]

Alfanatic said:

They're made to be slippery on tarmac / dirt / car roofs, not in air.

Exactly. The best ones are smooth to prevent twisting forces in the event of an accident.

[SystemParanoia]

ahh.. that makes sense.

as for the spin, im sure a perspex 360 deg electric setup could be configured

[OnTheOverrun]

Dimples on a sphere only reduce the thick wake of a smooth sphere to the thin wake of a dimpled sphere if indeed, it is a sphere. For the principle to work well on a helmet, you would need to not have a visor and the rider would need to not have a neck, which is impractical.