Amy Williams's gold medal skeleton helmet (with vortex generators) - Page 2 - Fuel Economy, Hypermiling, EcoModding News and Forum

Peter7307 · 02-21-2010, 07:11 PM

Didn't see or hear about the potential protests but the Skeleton amazes me...face first at 140+ on a platform smaller than a seat cushion.

These guys are even nuttier than the luge riders !

Great to watch though.

Pete.

orange4boy · 02-21-2010, 09:55 PM

Much of the skill in this sport is reducing drag as you ride. I just saw a set of pics of the US team testing in a wind tunnel. I remember thinking... " Why don't they boattail those helmets?" Probably regs.

I'll put money on the VG's making a big enough difference to win all else being the same.

Christ · 02-21-2010, 11:41 PM

I tend to agree, although without enough experience to say for sure, that you don't need to exit the boundary layer to affect it. I say this because even if you're inside the turbulence, it has to "adjust" it's depth to the new shape. This requires a change in flow patterns, which could be enough to affect flow in general.

My own thought is that level with the edge of the boundary layer is probably ideal, although nearly impossible on an object that sees constant changes in speed/density of the fluid medium.

MetroMPG · 02-22-2010, 06:12 PM

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

Christ · 02-22-2010, 06:15 PM

*muffled chuckling*

luvit · 02-22-2010, 07:35 PM

Quote:

Originally Posted by MetroMPG

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

um.. i've only watched 2 episodes of mythbusters.
who could guess mythbusters could cram so much disappointment in 2 episodes.

Peter7307 · 02-22-2010, 07:39 PM

They have had a lot of practice !

Pete.

aerohead · 03-06-2010, 04:49 PM

The VGs make sense to me.If she holds her head steady,the VGs could allow the air to follow a 28-degree tangent angle off the top and sides of the helmet,instead of 22-degrees,reducing the wake and its base-pressure behind the helmet,cutting o0verall profile drag.
There'd be a slight skin-friction penalty due to the VGs,but the form drag reduction would trump it.Clever!
I can already see the 2014 Winter Games,with boat-tailed neck brace/humpbacks between helmet and shoulders.

TimG · 03-09-2010, 09:48 AM

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?

orange4boy · 03-09-2010, 04:20 PM

My question is if they work why are they not on the sides as well?

Marketing gimmick. Looks cool though.

It had to happen. Enough people have seen the mythbusters episode to now believe the dimples work on a large/slow scale.

I'm still on the fence. I want to see a real study before I'm sold. But I won't say it does not work till I see that proof either.