planetf1.com

All aero dynamics we see in F1 (or indeed all motorised sports afaik) implicitly include having as smooth a surface as possible.

In a way it makes sense, wind tunnels demonstrate the lower drag without question.

However, there are many factors to consider in what is the overall most effective package.

I tend to look at nature as my inspiration how we can improve the physical aspect of the sport and see a lot of solutions not considered in aero development.
Fish aren't smooth, feathers and the layering are not as smooth as an F1 car either...

Again, as far as I know; I haven't delved into it, just notice that I have never seen any experiments on this front either.

If I look at other sports, I do see such ideas being implemented, i.e. in speed skating where they not only used strips for a few years but have tried out 'shark skin' suits etc.
I know a golf ball travels further due to it's dents because of rotation, but is this a field worth exploring or not?

_________________
"Too often we take for granted what our collective dream tells us is possible or impossible, acceptable or unacceptable."
The Four Insights by Alberto Villoldo

My understanding is that a turbulent boundary layer produces less viscous drag than a laminar one (the velocity profile of a turbulent boundary layer is higher on average), which is beneficial for the cases you have cited i.e. a golf ball, a fish etc. In those cases reducing drag is the priority. However an F1 car is different as the priority is not to minimise drag but to maximise downforce via the effective operation of the various aero devices on the car. For an aerofoil to work most efficiently it requires a laminar boundary layer (hence the reduction in aero grip when in the 'dirty air' behind another car) so the car's surfaces must be as smooth as possible to keep the flow laminar.

(I am not an aerodynamicist anyone feel free to correct me - I may have written a load of rubbish there)

I think Ferrari tried painting the underside of their front wing with Shark skin paint earlier this season...

Didn't hear much more about it though...

Let's get the golf ball and it's dimples out of the way. The dimples are there to disturb the airflow, move the air in such a way that it actually creates lift, and that is what carries the gold ball. It has nothing in common with a Formula One car, dimples create a lot of drag.



Rule one, anything that sticks out in the airflow creates drag, if you are going to have anything sticking out, it had better be for a very good reason.

In a racing car you want to have downforce and as little drag as possible. Drag is generated by many things, from tire resistance to wheel bearings, to aero drag, which increases as speed go up.

http://en.wikipedia.org/wiki/Drag_%28physics%29


Smooth is good, it offers low drag.

I realise smoothness decreases drag, I mentioned in my opening post.

I realise also that bits sticking out, create drag.

If I look at an F1 car, the surface hardly resembles a rain drop, therefore the statement that there's obviously more to aero than just creating low drag.

I merely wondered why this has apparently never been explored, I got the most essential basics prior to creating the thread but thanks anyway.

Back to nature again, I can see that water is not the same as air, but surely apart from density/viscosity of the material you're traveling through, the principles don't change so my question still stands. Why not explore into ie shark skin paint?

_________________
"Too often we take for granted what our collective dream tells us is possible or impossible, acceptable or unacceptable."
The Four Insights by Alberto Villoldo

Being totally stupid, if dimples create drag is it not worth trying a dimpled surface at somewhere like Monaco, where downforce is everything regardless of drag?

Otherwise I can see why dimples are ruled out, but I was wondering if it might work on a high-downforce layout like that.

_________________
Organiser of the single most low-tech Robot Wars tournament in history, PM for details!

Downforce seems to be the main issue battling drag for total aero-efficiency.

Why would dimples not be more effective (and estheticaly more appealing) than all the wings and bits sticking out here and there?

_________________
"Too often we take for granted what our collective dream tells us is possible or impossible, acceptable or unacceptable."
The Four Insights by Alberto Villoldo

You are looking at this from the wrong direction. The smooth surface is the definitive as far as drag reduction goes for most applications. Shark skin suits solve a particular problem well, to be flexible, wearable and give low drag resistance in one direction. You would be far better applying an F1 surface to any of these bodies but the practicalities render that impossible. So you end with a practical compromise because you are fitting a low drag surface to a living entity. This is not what F1 can learn from nature, it's about what nature does in trying to emulate F1.

The golf ball is a different issue. the dimples are simply to prevent aerodynamic stall, causing the ball to just drop out of the air after reduced distances. F1 solves this problem far more efficiently by profile without having to add to the drag resistance by roughening the surface.

Dimples on a golf ball are a specific response to the specific problem. The ball is spinning, and it's desirable to generate lift to increase distance. The ball is round, you can't control that. But you can control the spin (at least, for a decent golfer) and thus you just pepper the entire ball with dimples. There's a close analogy in baseballs, with the stitching or any foreign substance, you can alter the aero properties and get the ball to change direction more than expected. That's why in the major leagues the pitcher is watched like a hawk to make sure he doesn't leave spit on it, or cut the ball.

In a racing car, the aero management is not generalized as in a golf ball, so traditional and classic methods can be applied. There has been countless studies concerning wings, end plates, gurney flaps, all well know for their properties, advantages and disadvantages. Sharkskin has advantages and disadvantages. It can reduce drag, but only on a clean and well prepared surface. For the Olympic swimmer, the suits were carefully prepared and cleaned before each race. In Formula one, after just a few laps, marbles and debris start to accumulate, and what may have been an advantage at the start quickly becomes a serious disadvantage later on.



If anyone has closely examined a race car after a race you realize it's accumulated quite a lot of dirt and debris. This is a real-world problem you have to anticipate, and realize that what looks beautiful in theory may not work so well when in real life. If anyone has closely watched Ferrari during their pit stops, they have two people clean the gaps between the front wing slots, just to clean out those close gaps.

Cool, that's the answer I was hoping for, especially the last bit seals it nicely.

Thank you.

_________________
"Too often we take for granted what our collective dream tells us is possible or impossible, acceptable or unacceptable."
The Four Insights by Alberto Villoldo

Several years ago (maybe 12-15 IIRC), the Americas cup yacht race was won by an American boat which had its keel coated in a "sharkskin" plastic laminate. This was a particulr peeve for the Brtish guys who invented it, but the American parent company had declared it off-limits for discussion with the British team.

There have also been several aircraft coated with the stuff, including an F15 and an Austrian Airlines jet. The results were impressive, giving lower drag and also less weight than using paint. For commercial use the cost didn't outweight the benefit but I understand it got wider military use because they have money to burn.

In principle it would have wide application in F1 cars, but they would have to go way back near square one and do the aerodynamic design around it being in place. And as Blinky says, it wouldn't respond well to contamination, so across the duration of a race a "conventional" solution would probably hold sway.

Mabazza has got it completely wrong - the sharkskin is a natural low drag solution whereas a completely smooth surface is comparatively high drag.

Some experimental aircraft design (gliders and high-end military) have used a "blown" surface with lots of tiny airholes to make the surface less draggy by helping to separate the airflow. This would be terrific on a car but once again, contamination would ruin it.

While we are at it, the dimples have nothing to do with aerodynamic "stall" and a ball won't just drop, it wil follow a parabola just like Newton predicted. There are multiple theories about how the dimples work but one of the most common is that they simply help keep the airflow detatched from the ball and therefore reduce parasitic drag, allowing it to execute a shallower parabola. Spin is a complication which causes slice or hooking but even if you shoot it out of a cannon, unspun, a dimpled ball will travel further than a smooth ball. Good golfers generate spin in a direction which effectively produces a component of "upward hook", but it is still travelling a parabola during flight.

_________________
Me Like - Button, Hamilton, Webber, Rosberg
Over rated, over paid - Räikkönen, Alonso, Vettel. Schumacher
Disappointing - Massa, Kobayashi
I may be wrong about - Alonso

Excellent post, thank you.

I reckoned nature would have better idea of aerodynamics than 'we' do.

How could (look at sharks) hundreds of millions of years of evolution be 'outsmarted' by a few decades of technology?
Mabbaza's remark on nature trying to emulate F1 is ludicrous.

_________________
"Too often we take for granted what our collective dream tells us is possible or impossible, acceptable or unacceptable."
The Four Insights by Alberto Villoldo

I thought this for a long time but then I saw a Mythbusters episode about fuel efficiency. They used a dirty car, a clean car, and a car with a clay surface molded to the exact shape of the car, but with golf ball-style dimples all over it. A stupid myth to test, obviously, as OF COURSE a clean car will have better MPG than a dirty car, but the interesting bit was when the car with the dimples had the best MPG of the three. How does that happen if the design creates drag? Maybe they messed up?

_________________
"No, there is no terrible way to win. There is only winning."
Jean-Pierre Sarti

Dimples DON'T create drag. If they did, golf balls would be smooth. They promote separation of the airflow and as I said, reduce parasitic drag. This is sometimes called "skin friction" drag. Basically, if the surface is very smooth, the airflow stays attached to it for too long and causes high drag behind the point where it detatches.

Some aircraft wing designs use devices to deliberately separte the airflow at a point beyond that where it has done its job. So-called "turbulator strips" are an example. I don't doubt that F1 cars employ a similar approach at some places on the bodywork.

Like I said, there are several different explanations of why dimples work and it is a bit like "how can bumble bees fly". The reality is probably a combination of all the common explanations added together rather than just one of them being absolutely right.

For a simple surface, whether smoothness or some variation of roughness will give the lowest drag depends on a lot of things like the geometry and the topography of the surface. Golf balls are a simple geometry, F1 cars are much, much more complex.

In general terms, you would want part of an F1 car to be smooth rather than covered in lumpy, bumpy rubber grime (hence the reason why they clean them so meticulously). But there are other areas where the sharkskin approach would give benefits, if only it didn't provide such a wonderful sticking place for all the airborn corruption that the car drives through over a two hour race.

As another example of how things can change during the course of a race (or flight), you can even get devices that wind out along aircraft wings to scrape off the bugs that you would pick up during flight - these prevent a very marked deterioration in performance in the height of summer.

_________________
Me Like - Button, Hamilton, Webber, Rosberg
Over rated, over paid - Räikkönen, Alonso, Vettel. Schumacher
Disappointing - Massa, Kobayashi
I may be wrong about - Alonso

Chunky has 1) the best explanation I have yet seen and was going to post similar, and 2) the best sig. I even agree with the drivers.

Just to add - the skin friction of water is SIGNIFICANTLY higher than air, as you might expect because it is more viscous. That is why a lot of the practical applications of disrupting it have been in marine use. The most radical is probably the Russian Shkval torpedo, which uses hypercavitation along its surface to delaminate the flow entirely. When the Russians introduced these torpedos, their speed (200kt+ underwater!) did not seem possible to the Americans at first...

Hello. Just thought I would clarify this explanation as I see some misconceptions here. (I have a Masters Degree in Aerodynamics).

There are two components to drag (skin friction and pressure drag). Skin friction is, as the name implies, drag created by friction between the surface of the material and the air molecules. Having a smooth surface reduces the skin friction drag.

Pressure drag is related to the fact that when objects travel through the air, they leave a region of low pressure air behind them. High pressure in front + low pressure behind means that there is a net force acting and this is what we call pressure drag.



The reason why dimples are used on golf balls is because they promote transition of the boundary layer from laminar to turbulent. The boundary layer is the region of air close to the surface where the velocity of the air particle changes from zero (at the surface itself) to the free stream velocity (the velocity of the free air travelling past the golf ball). A laminar boundary layer separates easily (top). The turbulent boundary layer does not separate as easily (bottom). This delayed separation leads to a thinner wake, which reduces the area of low pressure and hence the pressure drag. This reduction is greater than the gain in skin friction drag for the golf ball case, and therefore you have a net reduction in drag.

For F1, dimples are not used because given the high Reynolds number of the flow around the car (the Reynolds number is a ratio between inertial and viscous forces) the boundary layer will naturally transition to becoming turbulent almost immediately (the flow around a golf ball on the other hand has low Reynolds numbers and thus dimples are used to "force" the transition). Furthermore, the flow of an F1 car is significantly more complicated and designs will make use of 3D flow structures like vortices to work the air which can greatly affect the tendency of boundary layers to separate.

On aircraft, you never want the airflow to separate from the wing at any point (that is stall). Vortex generators (turbulator strips) are used for two reasons:

1. To re-energize the boundary layer (to prevent stall). It does this because the formed vortex (which is like swirling air), will draw in high energy air from the free-stream which then increases the overall energy of the boundary layer, thus preventing it from separating.
2. Sometimes used on swept wings to prevent spanwise flow (i.e. migration of air from the root to the tip), this is also in order to prevent stall (swept wing designs can suffer from some unrecoverable stall states if "fences" are not used).

Hope this helps

It does indeed, thank you very much.

One question though, if you don't mind, to double-check I'm up to speed.

In speed skating (it's been dismissed since, after reading your post I fully understand why), they used strips like this some 5-10 years ago for some time.


Would that be similar to what you refer to as 'vortex generators' (albeit it on a larger) scale on aircrafts?

_________________
"Too often we take for granted what our collective dream tells us is possible or impossible, acceptable or unacceptable."
The Four Insights by Alberto Villoldo

I would guess so! But really in the case of the human body I think it would make so little difference as the rest of us is so unaerodynamic that you wouldn't notice any change from having it to not

Would an 'aerospike' work on a car?

Could say the exhaust via a turbo be directed forward?

Dont laugh, my knowledge of this is very low, and if you dont ask, you dont know.

Hello.

I don't understand what you mean by aerospike.

You could indeed direct the exhaust forwards, but it wouldn't be of any benefit to the airflow.

As I said above, this is beyond me really, just asking like. But.. As I understand it, which may not be right, the speed of approaching air is not conducive to moving it into a tube for a motor, so it is 'shaped' by a pressure wave. (if this is misunderstood so is the rest) Is this in principle not the same as a 'blunt' nose of a car hitting air?
Could a pressure wave from either the movement of the car, or moving gas produced by the car not 'shape' the approaching air to what is useful to the car?

As I reiterate, I may well have the wrong end of the stick

http://www.roadandtrack.com/racing/motorsports/the-secret-underside-of-a-modern-f1-car

Thought i;d share this here about F1 udnerbodys

Every six months - without fail - the theory that the design of a golf ball should be incorporated in F1 chassis designs pops up on this forum.

_________________

If you look at nascar they have adopted a panel system on the outershell of the car that when its sliding or spining out of control they pop up dependant on direction to slow the car. I would like them to employ moveable aero devices in F1.

we also have to remember there are restrictions in place on an f1 car when it comes to aero development so they are not at maximum aero efficiency.

I might be being stupid here, but I am sure I read that an F1's drag coefficient (Cx) was well over 90, compared to a modern roadcar having about 30... Now, I understand that this is down to the nature of 'downforce', disrupting the airflow to push the car down onto the track surface. But, a lot of people posting on this thread seem to be writing from the perspective that an F1 car is pushing itself through the air and creating as little drag as possible.
Now, to me that seems counter-intuitive if it is the creation of 'drag'.. i.e the disruption of the air to maximise downforce, that is the primary function of the overall design.
It's the design of the car, and using the air as a 'tool', but still trying to balance it (at the 'edge') against the maximum speed.

Yes in design of aircraft wings during WW2 the tradition fixing rivet could take some 10 % of the top speed of the aircraft due to drag. The early development of smooth materials without such drag was demonstrated by the mosquito fighter in the second world war.Much research has taken place in the development of the most efficient aircraft wing coverings. BSC Consulting is aware of research into self molding body panels to increase laminar flows.

This thread topic, the questions and expert explanations are so impressive!
The aero problem in designing a F1 car must be so complex: highest speed on straights but max downforce on corners, and coping with lateral, cross winds,e yaw, etc. The complexity is clear from the many, contorted front wings, small fins, flaps (banned after 2008), louvres, etc.

Would it be correct to say that downforce has long been considered more beneficial than low-drag, top-speed generating shapes, since most of circuit distances are not straight?

An early aero development that seemed brilliant was Frank Costin's 1971 March; his raised, full-width front aerofoil must have been so much more effective that the then-common two lateral ' nose fins'. The general smooth, roundedness of the rest of the March's body reflected Costin's first GP car work, the beautiful Vanwall. Simpler times.

Hope this discussion continues.

_________________
http://grandprixratings.blogspot.com

Would the teams opt for lower levels of downforce (=> drag) next year to be able to cope with the 100kg fuel limit, than they would've otherwise? Which one has a smaller impact on lap times, a leaner mix or smaller wings?

_________________
Räikkönen - Vettel - Bottas
Thank you Nico - You´re the champ!

PF1 Pick 10 Competition 2016: CHAMPION (2 wins, 8 podiums)

Sorry just noticed this and there were too much misinformation that I couldn't sleep.

qczhao had the most accurate explanation.

To summarise:
1. Dimples can help reduce the size if the wake, by causing a turbulent boundary layer
2. It is worthless in f1 as the flow is already turbulent.

now I can sleep.

_________________
Pathfinder

The things is, anything that makes the air move around (in turbulence or swirls or anything else) requires energy. The end result is that all turbulence robs the engine, which isn't using that power for straight speed.

The second thing, and this is where conflicts arise, is that sometimes turbulence is necessary. One example is the interior of the engine intake for the Williams, treated to be similar to the scales on a swordfish. This non-slick treatment induces vortices, which mix the air and the end result is that when the air finally reaches the engine, it is homogenious.

I think you're mixing your drinks a bit Blinky and what you are saying isn't logical. Because:

Although we were all taught at school that laminar flow is better than turbulent flow, this was usually the case of a fluid constained within a pipe. An F1 car, in comparison, is in an unconstrainded environment (an open system). The fact is that the very act of punching a hole in the air creates both drag and turbulence and it's simply a matter of ensuring that the turbulence is shed in the lowest drag configuration possible.

If creating turbulence robbed power per se, then high efficiency aircraft wings wouldn't use turbulator strips and for that matter, F1 cars wouldn't use Gurney flaps

The scales of a swordfish are not designed to create turbulence, they are designed to reduce drag. Just like shark skin does. Nature doesn't do turbulence, or at least evolution doesn't. By the way, only juvenile swordfish have scales, the adults don't. Hence their debated eligibility as kosher food.

I can't understand your Williams air intake example, because air is already as homogenous as it can possibly be. One of the only ways to make it less homogenous is to add loads of energy to squeeze it through a fractionating sieve, the way that they get liquid oxygen and liquid nitrogen.

F1 engines are now direct injection (engine reg. 5.10.2) and injection upstram of the inlet valve is forbidden so there can be no possibility of your non-slick treatment encouraging fuel/air homogenisation. Maybe you are talking about temperature homogenisagtion or perhaps moving a bit of extra air by detaching the static boundary layer at the surface of the intake? If it's the latter then I'm guessing that the only place this is relevant is in the big air intake behind the driver's head.

Afterthought - I wonder if air separation is forbidden by F1 rules? If they were able to use free energy to fractionate air (lets say from front wheel energy recovery instead of braking) then they could mix fuel and either pure oxygen or even (if the regs allow it) liquid oxygen directly. No need for turbos to compress all that useless nitrogen that makes up 80% of air! Mr Newey - you heard it here first and I claim my £1M prize.

p.p.s - The engine power would be greater as well, because there would be no energy lost heating useless nitrogen. In a former life I had a lot of dealings with oxygen/fuel fired industrial furnaces instead of just burning gas in air. Despite the added cost of liquid oxygen, the total energy balance was reduced and it was cost effective.

p.p.p.s It would also be a zero NOx system, so they could get rid of the stupid fuel limit for "environmental credentials" and let us get back to proper hairy chested racing

.

_________________
Me Like - Button, Hamilton, Webber, Rosberg
Over rated, over paid - Räikkönen, Alonso, Vettel. Schumacher
Disappointing - Massa, Kobayashi
I may be wrong about - Alonso

I know its a few years old, but I've just read this thread and have to say that I love the info. Regarding the grime that accumulates on a car during the race, have they ever tried non stick coatings such as Teflon or ?? on cars to reduce adhesion of rubber dirt etc?

Correlation does not imply causation.

With a golf ball the air is moving fast. With a smooth ball air quickly detaches as it rounds the ball. Once detached there is negative pressure in the turbulent tail of air behind the ball. That negative pressure is pulling against the back of the ball, slowing it down (drag).

With a dimpled golf ball the boundary layer is thicker which allows the air to stay attached to the ball longer and farther around the radius of the ball. This means that when the air does detach from the ball there is a smaller area at the back of the ball for the turbulent negative pressure air to pull against.

Dimples do cause drag. The reason a golf ball goes farther with dimples is because the drag that the dimples create on the front and sides of the ball is outweighed by the reduction of drag at the back of the ball. This is a unique solution that applies to a sphere, not a racecar.

In racecars they build aerodynamically efficient profiles. A bullnose in front separates the air and quickly attaches it to the surface while a taper to a point in the rear merges the airstreams together with a minimum of drag producing turbulence. You will see these shapes in the wings, struts, camera pods, sidepod inlets, spine of the engine cover, and even in the shrouds around the round half-shafts that drive the wheels.