Aerodynamic surfaces...

[calibrax]

Here's one to get yer teeth into.

I was thinking about aerodynamics on my way home from work (as you do!) and had a thought - why don't F1 cars use dimpled surfaces to reduce drag, in the same way as dimples are used on a golf ball to reduce drag? I find it hard to believe that I'm the first to think of it, so is there a specific rule banning dimpled surfaces, or is there some aspect of the physics behind it which means it simply wouldn't work?

[Adam43]

Interesting first post calibrax.

Here are a few threads on this subject in the racing technology sub-forum of 10-10ths:
What would you do to your own car to decrease drag?
Dimples are not zits

Amongst some other in this sub forum and some kicking around elsewhere.

[ss_collins]

read the article I wrote on the subject - its on the racecar site. F1 teams have tested it.

Just realised Trikes never sent me that vee pic...

Look at Zipp Speed cycle wheels

[AU N EGL]

Originally Posted by calibrax

Here's one to get yer teeth into.

I was thinking about aerodynamics on my way home from work (as you do!) and had a thought - why don't F1 cars use dimpled surfaces to reduce drag, in the same way as dimples are used on a golf ball to reduce drag? I find it hard to believe that I'm the first to think of it, so is there a specific rule banning dimpled surfaces, or is there some aspect of the physics behind it which means it simply wouldn't work?

Ok when the next hail storm comes your way, leave your race car or your normal car out in that hail storm.

Then let us know how much faster you go with all the dimples....


Oh and Welcome to 10/10ths

[Chris Y]

My car's full of little dents.. Don't think it goes any faster though

[tristancliffe]

Is this why acne riddled teenagers with craters in their skin are usually faster than me?

[Notso Swift]

I would bet my right one on the fact that it has been tested
My guess is that high speed vs low speeds would be the reason it is not done
if the dimples can't trap the air to cause the boundry layer then you are just generating drag.
Even though Bike wheels go fast 40 mph ground speed (less at the rim) is nothing like 120 mph, like wise boat use dimples, but the are also slow.
(Also note not all manufactures use dipples, Zipp are the highest profile maker of TT equipment in the world, but other, well resoured organisations do not see the value in it, like Mavic)

[Locost47]

There are a couple more things to add to this.

Currently F1 cars are developed in low-turbulence tunnels (~0.1%) at 50-60% scale and 50-60m/sec wind speeds. This means they are optimised for Reynolds numbers less than those experienced at normal racing speeds and that there will be no wing or diffuser stalls at anything but the lowest speeds on track, where the aero input to grip is minimal.

One of the reasons the dimple / boundary layer trip approach tends not to work on track is because the ambient wind (in the UK at least) typically has a turbulent intensity of around %5. This means that boundary layers become turbulent a lot sooner than they would in a typical wind tunnel and so these sorts of boundary layer techniques become almost completely redundant.

Somewhat ironically the road car industry is leading the way on this one, with a lot of focus being put on simulating 'realistic' on-road/track aerodynamic conditions in the wind tunnel, as it tends to lead to different optimal solutions than if you develop in a super-smooth low turbulence facility (the aeronautical ideal, but less so for ground vehicles). F1 would benefit a lot from this, particularly with respect to the aerodynamic aspect of the overtaking problem.

[Notso Swift]

Intersting stuff,
Question, do they (both F1 and Road) test with various degrees of yaw as well?

[dasc04]

Yes. They all test at different yaw angles.

[Locost47]

^What he said^

Plus the racing guys will do some steering and roll work too.

There are some people currently working on a kind of lap simulation system, which will drive the wind tunnel model through a virtual lap. This is the next step on from the heave / pitch / yaw / roll / steer maps they do currently in that it will take into account the transient responses (such as those behind 'porpoising'). The measurement and analysis side of this is an absolute nightmare though!

[AU N EGL]

Originally Posted by Notso Swift

Intersting stuff,
Question, do they (both F1 and Road) test with various degrees of yaw as well?

Seven Post shaker rigs. AT least one manufacture has a seven post rig inside a wind tunnel

[ss_collins]

(Also note not all manufactures use dipples, Zipp are the highest profile maker of TT equipment in the world, but other, well resoured organisations do not see the value in it, like Mavic)

er nope its beacuse Zipp holds the patent!!

see here (I know bad form but...)

http://www.racecar-engineering.com/a...-surfaces.html

I also know that Hendrick uses rough surfaces on its CoT's to cut drag.

[Notso Swift]

Ok, but previously HED had a system on their wheels where they had dimples on part of the wheel (edges of low spoke wheels, can't remember if it was trailing or leading) and they abandoned it. Admit it not the rim like Zipp, but the same concept, indeed it should be more significant because the spokes are trying to "break" the air each time, and there are 3 of them
Look at how many track bikes use Zipp wheels... not many, and that is not a sponsorship thing, like it is in the protour.
Don't get me wrong, I use 60mm deep Reynolds Wheels and pay a weight penalty over a shallower section, because aero is more important than weight in overall performance (and with wheels it is reciprocating as well) but personal experiance didn't see Zipp 303's living up to the hype

[ss_collins]

look om the protour - you will see Zipp wheels badged as botrangers or whatever rather a lot.

[Notso Swift]

Agree the badge mean nothing. If you want to know who really uses what look that cyclingnews.com, they review actual protour bikes, and they list riders because the spec can change within the same team, both TT and road, and let you know about the "discrepancies".

Also note that nearly all of the high profile US brands are owned buy about 3 companies

[ubrben]

The most famous example being Lance Armstrong's 1999 "Trek" TT bike that was of course a Litespeed Blade sprayed blue with a Trek sticker :-)

Ben

[AU N EGL]

Originally Posted by ubrben

The most famous example being Lance Armstrong's 1999 "Trek" TT bike that was of course a Litespeed Blade sprayed blue with a Trek sticker :-)

Ben

Of course. Has been for a long time.

The Great Eddie Merckx's bicycles said Peugeot in his early days, then Colnogo. His early Peugeots were built by Masi, and his Colnogos were built by Kessels in Belgium.

Kinda Like ther GT1 an GT2 race cars. PPL think they are converted road going off the show room floor cars, but they aren't. They just LOOK like road going cars.