Dimpled Helmet - Hang Gliding Org - Worlds largest Hang Gliding community, discover Hang Gliding

Search

  • Sorry...You must register to activate searching









Post new topic   Reply to topic    Hang Gliding Org Forum Index -> Hang gliding general->Dimpled Helmet
BURY this topic
View previous topic :: View next topic  
Mavi Gogun
1 thumbs up
1 thumbs up


Joined: 26 Jun 2009
Posts: 978
Location: Istanbul (not Constantinople)

PostPosted: Thu Apr 12, 2012 11:51 pm    Post subject: Dimpled Helmet Reply with quote #1   
http://university.tri-sports.com/2012/03/29/garneau-vorttice-helmet/





from the article wrote:
The golf ball dimples disturb the flow of air around the helmet, called the boundary layer, to make it easier for the object to move through using less energy. As with golf balls, this increases travel with given energy, especially at low speeds. The truncated shape has been adopted by Trek, Cervelo and other manufacturers to make shapes more effective over wider yaw angles. The “strakes” or raised, sideways ”V” protrusions on the helmet are oriented where the helmet’s laminar boundary layer begins to “depart” or detach, potentially creating drag. These strakes prevent the resulting vacuum from boundary layer detachment by keeping the flow of air turbulent at lower pressure.
Send private message  Rate this post
jjcote
3 thumbs up
3 thumbs up


Joined: 01 Dec 2007
Posts: 3218
Location: Lunenburg, MA, USA

PostPosted: Fri Apr 13, 2012 3:15 am    Post subject: Reply with quote #2   
Yeah, maybe. It's also possible that the dimples are there in an attempt to keep the customer from remaining attached to his money, and were designed by somebody in the style and advertising department.
_________________
H4 + various skills (only foot-launch so far)
WW UltraSport 147, WW Falcon2 170, PacAir Vision Mark IV 17
My HG wiki profile and my flying blog
Send private message Blog  Rate this post
Mavi Gogun
1 thumbs up
1 thumbs up


Joined: 26 Jun 2009
Posts: 978
Location: Istanbul (not Constantinople)

PostPosted: Fri Apr 13, 2012 3:21 am    Post subject: Reply with quote #3   
Ya- they can't sucker me into paying for what I can do to myself with a razor and hammer.
Send private message  Rate this post
CHassan
3 thumbs up
3 thumbs up


Joined: 27 Jul 2006
Posts: 4598
Location: Ohio

PostPosted: Fri Apr 13, 2012 3:27 am    Post subject: Reply with quote #4   
Golf ball dimples work great on golf balls. I guess. I have never hit a smooth golf ball. Not that you can compare any of my hits side by side and expect even a slight bit of consistency.


I'm sure that ram air intake is quite aerodynamic too.

_________________
Airborne Climax 14 (C1)
WW U2
H3
AT, FL,ST, RLF, TUR.

There is an art, it says, or rather, a knack to flying. The knack lies in learning how to throw yourself at the ground and miss. … Clearly, it is this second part, the missing, which presents the difficulties. ~~~Douglas Adams
Send private message Blog  Rate this post
Mavi Gogun
1 thumbs up
1 thumbs up


Joined: 26 Jun 2009
Posts: 978
Location: Istanbul (not Constantinople)

PostPosted: Fri Apr 13, 2012 3:38 am    Post subject: Reply with quote #5   
CHassan wrote:
I'm sure that ram air intake is quite aerodynamic too.


The air intake assures that the wearer's head stays fully inflated and maintains shape at speed.
Send private message  Rating: 1 thumb up
old newbie
3 thumbs up
3 thumbs up


Joined: 02 Dec 2008
Posts: 822

PostPosted: Fri Apr 13, 2012 6:09 am    Post subject: Reply with quote #6   
Somehow that hole in the forehead is just screaming fence post, branch, sniper target.

Steve
Send private message  Rate this post
Bondy
3 thumbs up
3 thumbs up


Joined: 02 Apr 2009
Posts: 425
Location: Perth WA

PostPosted: Fri Apr 13, 2012 6:14 am    Post subject: Reply with quote #7   
I tried one of these helmets but when i use my #1 driver it still slices . Razz
Thought it would have worked better fully dimpled with a more diagonal pattern.

_________________
You only live twice

Sonic 190, Sting 154, Combat 2 14, Explorer, Mosquito NRG and a Falcon 3 195
Send private message  Rate this post
Scorl
3 thumbs up
3 thumbs up


Joined: 11 Oct 2011
Posts: 104
Location: Dayton, OH

PostPosted: Fri Apr 13, 2012 6:24 am    Post subject: Reply with quote #8   
jjcote wrote:
...were designed by somebody in the style and advertising department.


Style? Not likely.

_________________
My learning experience: http://mypathtopilot.blogspot.com
My Youtube Channel: http://www.youtube.com/user/Scorl?feature=mhee
Send private message Blog  Rate this post
Bobfly
3 thumbs up
3 thumbs up


Joined: 13 Nov 2009
Posts: 3722
Location: San Diego, Ca.

PostPosted: Fri Apr 13, 2012 8:32 am    Post subject: Reply with quote #9   
Mythbusters covered a car with 2-3 inches of clay and then dimpled it. The result was reduced drag and a significant increase in gas mileage despite the weight of all that clay. Dimples work and airflow turbulators work too. Don't know how effective it would all be at hg airspeeds but for xc competitions, anything that stretches glide and reduces drag is a benefit. Looks odd but then, so do I. Laughing
_________________
Freedom 170 FR
Send private message  Rate this post
Mavi Gogun
1 thumbs up
1 thumbs up


Joined: 26 Jun 2009
Posts: 978
Location: Istanbul (not Constantinople)

PostPosted: Fri Apr 13, 2012 9:16 am    Post subject: Reply with quote #10   
That was the first episode of Mythbusters I watched- just 'cuz of possible HG applicability.

Bobfly wrote:
Mythbusters covered a car with 2-3 inches of clay and then dimpled it. The result was *snip*


-not at all conclusive, given their method (2 cars, different circumstances). They didn't just run a single car on a test track, they took them on the road and drove around, and the differences in economy was way to close for any error margin- they didn't even empirically establish a pre-test base line for the modified car.

Mythbusters is entrainment- not science.
Send private message  Rate this post
Vrezh
2 thumbs up
2 thumbs up


Joined: 19 Nov 2006
Posts: 367
Location: Los Angeles

PostPosted: Fri Apr 13, 2012 9:58 am    Post subject: Reply with quote #11   
Good find, Mavi.

They don't mention any sort of aerodynamic engineering or wind tunnel studies.

Wood it be a "gut feeling" type of design or what?

I do believe it has merits, though. I would totally try it out (after taping the forehead

hole).

One way to judge the aerodynamic qualities of a helmet is to observe the wind

noise level in flight (something I learned by going trough helmets over the years).
Send private message  Rate this post
kukailimoku
3 thumbs up
3 thumbs up


Joined: 14 Dec 2010
Posts: 591
Location: Oahu, Hawaii

PostPosted: Fri Apr 13, 2012 10:09 am    Post subject: Reply with quote #12   
Seems like the big air scoop located just above the little goatee might negate the dimple's effect....
_________________
Suppose you were an idiot.
And suppose you were a member of congress.
But I repeat myself.
- Mark Twain
Send private message  Rate this post
Bobfly
3 thumbs up
3 thumbs up


Joined: 13 Nov 2009
Posts: 3722
Location: San Diego, Ca.

PostPosted: Fri Apr 13, 2012 10:11 am    Post subject: Reply with quote #13   
kukailimoku wrote:
Seems like the big air scoop located just above the little goatee might negate the dimple's effect....



I think it's for hotheads. Laughing

_________________
Freedom 170 FR
Send private message  Rate this post
dangarlandut1
3 thumbs up
3 thumbs up


Joined: 07 Oct 2009
Posts: 81
Location: Salt Lake City

PostPosted: Fri Apr 13, 2012 10:14 am    Post subject: Golf ball dimples work - on cars, on golf balls - they work! Reply with quote #14   
Golf ball dimples work - on cars, on golf balls - they work!

Just watched a MythBusters TV Episode last night. They tested identical brand smooth and dimpled golf balls with a Pro Driving them, the dimpled went 890 feet and the smooth went 550 or so. "Like hitting a brick", quote the PDGA pro.

Then they made an elaborate Clay covered Automobile, and tested it with and without dimples. With Dimples, 29MPG. Without 26MPG. mosh

FYI: as they always do, Mythbusters DID establish various scientific baselines from sample sets, for the golf ball, for the (only one car used due to slight differences in each car of the same model) car: unmodified, clay-modified, clay-dimpled (with exact dimple clay weight in back seat to keep weight the same).
Send private message  Rate this post
tom emery
3 thumbs up
3 thumbs up


Joined: 24 Sep 2011
Posts: 664
Location: san diego

PostPosted: Fri Apr 13, 2012 11:47 am    Post subject: How Reply with quote #15   
So, how much does it cost?
Send private message  Rate this post
Mavi Gogun
1 thumbs up
1 thumbs up


Joined: 26 Jun 2009
Posts: 978
Location: Istanbul (not Constantinople)

PostPosted: Fri Apr 13, 2012 12:41 pm    Post subject: Reply with quote #16   
I think it's like $250... and irrelevant for me: I require mine to have a dimpled chin guard, too.
Send private message  Rate this post
pipefuser
2 thumbs up
2 thumbs up


Joined: 02 Mar 2010
Posts: 51
Location: Douglasville Ga

PostPosted: Fri Apr 13, 2012 12:52 pm    Post subject: Dimples Reply with quote #17   
My first girlfriend had dimples and she was real fast.
_________________
Shhhh! They're listening.
WW F3
H2 CL FSL AT
PPSEL HP
C182
L19
A&P
Mile High club instructor
Send private message  Rate this post
Avnav8r
3 thumbs up
3 thumbs up


Joined: 06 Jan 2008
Posts: 999
Location: Trenton, Georgia

PostPosted: Fri Apr 13, 2012 3:00 pm    Post subject: Re: Dimples Reply with quote #18   
pipefuser wrote:
My first girlfriend had dimples and she was real fast.


You hope she didn't say the same about you! Embarassed

John Stokes
www.osceolabaldeagle.com

_________________
To err is human. To blame it on someone else, shows management potential.
Send private message  Rate this post
jjcote
3 thumbs up
3 thumbs up


Joined: 01 Dec 2007
Posts: 3218
Location: Lunenburg, MA, USA

PostPosted: Fri Apr 13, 2012 4:54 pm    Post subject: Reply with quote #19   
Dimples definitely work on a golf ball. But there are a number of differences between a golf ball and a helmet (e.g. a helmet doesn't spin), and I wouldn't necessarily think that scaling the dimples proportionally would be the right thing to do. This just strikes me as something that was developed by a simple principle: "Hey, people know that dimples work on golf balls, and helmets are round, so let's make the helmet look like a golf ball, and people will buy them because they'll think it will work the same way".
_________________
H4 + various skills (only foot-launch so far)
WW UltraSport 147, WW Falcon2 170, PacAir Vision Mark IV 17
My HG wiki profile and my flying blog
Send private message Blog  Rate this post
Vrezh
2 thumbs up
2 thumbs up


Joined: 19 Nov 2006
Posts: 367
Location: Los Angeles

PostPosted: Fri Apr 13, 2012 5:06 pm    Post subject: Reply with quote #20   
Dimples work, spinning or not.

Even Atomic went to an extent to make the upper surfaces of

their racing skis sort of "dimpled".
Send private message  Rate this post
Display posts from previous:   
Post new topic   Reply to topic    Hang Gliding Org Forum Index -> Hang gliding general
 
All times are GMT - 8 Hours
Goto page 1, 2, 3  Next
Page 1 of 3


 
Jump to:  


(c) HangGliding.org All rights reserved. Based on PhpBB