• Welcome to the Two Wheeled Texans community! Feel free to hang out and lurk as long as you like. However, we would like to encourage you to register so that you can join the community and use the numerous features on the site. After registering, don't forget to post up an introduction!

Helmet Aerodynamics

poser

0
Joined
Mar 25, 2007
Messages
12,044
Reaction score
336
Location
COS
First Name
jason
Last Name
bohac
I was watching Myth Busters last night (I love that show), and they were testing the myth that a dirty car gets better milage than a clean, because the uneven surface gives it a "golf ball" effect and creats less drag (the clean car got better milage).

They took it a step further, testing a smooth and dimpled golf ball, and then even further and gave a car a dimpled exterior like a golf ball.

During their test, they tested the wind drag of both smooth and dimpled golf ball, and a a smooth and dimpled model car.

The dimpled ball and model car had less drag, and during a hitting test the dimpled ball went 30% +/- further than the smooth.

In the final full scale test - dimpled car vs smooth car - the dimpled car had an 11% increase in milage.

What does that have to do with helmets?
Well if a uniform dimpled exterior has less drag, wouldn't it stand to reason that a dimpled helmet would cause less rider fatuige, and provide a quiter ride?

It's be something worth trying
 
Don't just talk about it. Give it a try. Buy yourself a few dozen golf balls and peel the covers off and glue them to your helmet. That should give you a good idea of whether it works or not. Go with the logo balls. It would make for a little better design.
 
I don't know if it'd give a quieter ride. Part of the reason the dimples work is the little pockets of air in the dimples circulate allowing the other airflow to travel over them. Kind of like the MythBusters test of open tailgate or closed tailgate. Put some packing peanuts in the bed of your truck and you'll be able to see the effect. You get a swirling motion in the bed and the air flows over truck and over that pocket of air. You'll probably still have most of the peanuts when you get there. I've yet to be able to successfully empty the bed of my truck of leaves and other garbage just by driving.

Back on subject, I'd wonder if all those little swirling bits of air might cause more noise instead of less. As far as rider fatigue, I don't know how much of it is played by fighting against the air. Only long trip I have done was on a sportbike and the fatigue in my neck was from keeping my helmet up in that awkward position you need to keep on a sportbike.

BTW, I watched that episode too last night. I'd actually caught part of it when they first aired it but missed the end. I was a little disappointed that they tested the dimples as scale for the size of the vehicle. I wonder if they'd get a similar effect by using the same size dimples as are actually on a golf ball.
 
You do know that Schuberth did this with one if the BMW helmets right? I think it was the System II. I had a System and a System III. Apparently it either didn't work or just wasn't a big hit, since the dimples disappeared on the System III.
 
You do know that Schuberth did this with one if the BMW helmets right? I think it was the System II. I had a System and a System III. Apparently it either didn't work or just wasn't a big hit, since the dimples disappeared on the System III.

I did not know that.
I wonder if the looks turned people off enough that the minimal benifits weren't worth it. Not to mention I'm shure production cost was more, and graphics would be difficult if not near impossible
 
Though I'm not an aero guy, I'd wager the benefits were small to non-existent. The flow around a helmet is typically turbulent. If you have any kind of windshield or fairing, air is moved over and around your head. Even a naked bike will push air up and over the rider to some extent because of the forks and headlight.

I know my head never gets as much wind resistance as sticking my hand straight out the side when riding. Look up some of the drag coefficients for bikes, they're pretty dirty relatively speaking.
 
The problem with this is that if you had that type of helmet and were riding with it at speeds, your head and neck would extend forward so much, (trying to go faster that your m/c due to less drag,) that it would break your neck.
But, truthfully the thought is great. Keep eating your brain food.
 
I vote we use Poser's helmet as a test! Maybe if we soak the helmet in boiling water, then use a ball-peen hammer to make the dimples it will work.

Poser, would you like your head in the helmet or out of it when we make the dimples? :lol2:
 
I'm with RedPill on this one, and I think I live far enough away so as not to have to fear retributation! :-P:rofl::rider:
 
I'm not sure about the dimple effect, but I do know that some helmets perform far better than others in the "wind tunnel" that is my bike.
:nono: HJC CL-15 < HJC AC-11 < Shoei TZ-R < Shoei RF1000 < Shoei X-11 :clap:
 
I vote we use Poser's helmet as a test! Maybe if we soak the helmet in boiling water, then use a ball-peen hammer to make the dimples it will work.

Poser, would you like your head in the helmet or out of it when we make the dimples? :lol2:

You stole my idea!

Mike
 
Great minds run together, Mike. . . . . Then there's us.
 
I vote we use Poser's helmet as a test! Maybe if we soak the helmet in boiling water, then use a ball-peen hammer to make the dimples it will work.

Poser, would you like your head in the helmet or out of it when we make the dimples? :lol2:

Or when it's boiled. :rofl:
 
While dimpled or no dimple is a good question, I have noticed that my Rossi replica AGV with "contours" seems to be a bit quieter than my helmets with out such contours. I have two helmets with the more traditional "smooth" exterior, and two with some type of contour. Both of the helmets with contours seem to limit noise better than those without. So here are the helmets: Arai and Scorpion are both with a "smooth" exterior and small vents. AGV and Shoei both have some type of contour, with the AGV having the most surface area with contours and large vent channels.
 
The problem with this is that if you had that type of helmet and were riding with it at speeds, your head and neck would extend forward so much, (trying to go faster that your m/c due to less drag,) that it would break your neck.
But, truthfully the thought is great. Keep eating your brain food.

Maybe if you ran into a telephone pole. Otherwise no one is breaking anything from dimples alone.

I get way less noise on my dual sports with zero shields than the Ninja 250 with zero bubble whatever shield. That shield just introduces super turbulent air around my face. It's so much noisier than my direct air flow zero screen dual sports. This is with a Scorpion exo-400.
 
You could always try a cycling time-trial helmet.....

Louis_Garneau_Superleggera-798-75.jpg
 
Back
Top