Sharkfin Design

[Ian P.]

The best explanation so far is "Stability Under Braking".
Any discussions on rudders and cornering stability don't make much sense since the angle of attack of the fin is so low. No effective angle and no effective lift for what would be a symetrical air-foil.
The braking stability will come with the management of the turbulence generated at the engine air intake when the driver takes his foot off the throttle. It is a quick calculation to estimate the difference in air velocity around the engine cover between wide open and closed throttle. It's HUGH.
My guess is that the combination of the shark-fin and the small wings on the top of the air box serve to stabilize the flow and reduce the buffetting onto the rear wing under braking.
For the same reason that teams stopped running the exhaust pipes through the diffusers, the exhaust flow did increase downforce but there was a stability issue with throttle variation.
McLaren dropped the Viking Horns which likely did the same thing as the Fin. Even BMW tried this and they did have braking issues last year. Kubica admitted that the loss of "engine braking" didn't bother them as much as other teams because they weren't taking full advantage for the taction control (ABS) capability under the 07 rules.
Will be interesting to see if other teams adopt this or if it is just a Testing Thing. Of course, it increases sponsor space, always a valuable feature.

[mini696]

If the sharkfin had any advantage, Ferrari would be using it. If Ferrari does not have it, most likely it doesn't work.

Not if it doesn't work with Feraris aerp package.

If Ferrari are so smart why doesnt every team have an aero package that at least looks the same as theirs?

[mini696]

It acts like a keel/centerboard on yachts too. It will help stop the car sliding sideways through a corner and therefore improving tyre wear.

Really? So you're saying that half a square meter or so of surface area in air (a fluid), is making that much of a difference up against the friction between tire and road, and the low pressure of downforce?

No.

In a turn, no matter how tight, the pressure difference between the side of the car inside the turn VS the side on the outside of the turn is negligible. No real air resistance. The "sail" effect on perpendicular airflow is negligible, even at the speeds these cars see.

Any effect is a good effect even if it is only 1/100th of a second.

[The FOZ]

It acts like a keel/centerboard on yachts too. It will help stop the car sliding sideways through a corner and therefore improving tyre wear.

Really? So you're saying that half a square meter or so of surface area in air (a fluid), is making that much of a difference up against the friction between tire and road, and the low pressure of downforce?

No.

In a turn, no matter how tight, the pressure difference between the side of the car inside the turn VS the side on the outside of the turn is negligible. No real air resistance. The "sail" effect on perpendicular airflow is negligible, even at the speeds these cars see.

Any effect is a good effect even if it is only 1/100th of a second.

I'm curious as to how exactly you can remove all other variables to actually verify a 1/100th effect. Even over 70 laps...nobody says "Gee, that fin sure made the difference!"...because there's no way of attributing .7 over 70 laps to one single factor. Dragstrip...maybe. Formula 1, I don't think so.

I'm more interested in the big picture of how all the parts work together. Which is why I stand by my belief that the sail will smooth airflow as it approaches the rear wing area.

[Conceptual]

It seems to me that it is just a bit backwards in my opinion.

The cutout in the back would split the laminar flow over and under the wing, would it not? And the air leaving the top part in the back, would be a vortex, right?

I thought that passing MORE air under the wing and between the endplates would create more downforce than directing most of it over the rear wing. Maybe that would be true if the wing was flat?

I dunno, but I'm sure that Bernie is a big advocate for this design, simply because of the Ad space that has become available.

chris

[fastback33]

I think i may be able to explain this. You see the dorsal fin sort of acts in the smae way a surf board can. In that, with the little fishtail you can turn in the water much faster and more stable then a surf board without the fishtail on it.

Ala

Conventional board:

Fish Board:

EDIT: note, the bevels on the side of fishtailed board. All for a similar effect.

[ginsu]

I'm curious as to how exactly you can remove all other variables to actually verify a 1/100th effect. Even over 70 laps...nobody says "Gee, that fin sure made the difference!"...because there's no way of attributing .7 over 70 laps to one single factor.

It's called a windtunnel. You see they build models of the cars and then they put it in a windtunnel and measure the forces generated by the wind on the model. In that way they can verify the effect of a certain part. They use these force measurements to obtain a coefficient of drag, or downforce figure. Once they have that number they use it to predict a change in lap time. You see, more downforce reduces the lap time, and less drag also reduces the lap time.

That's why they say, this front wing helps us gain 2 tenths a lap. Not that complicated, dude.

[The FOZ]

I'm curious as to how exactly you can remove all other variables to actually verify a 1/100th effect. Even over 70 laps...nobody says "Gee, that fin sure made the difference!"...because there's no way of attributing .7 over 70 laps to one single factor.

It's called a windtunnel. You see they build models of the cars and then they put it in a windtunnel and measure the forces generated by the wind on the model. In that way they can verify the effect of a certain part. They use these force measurements to obtain a coefficient of drag, or downforce figure. Once they have that number they use it to predict a change in lap time. You see, more downforce reduces the lap time, and less drag also reduces the lap time.

That's why they say, this front wing helps us gain 2 tenths a lap. Not that complicated, dude.

Thank you for making my point for me.

Yes, a wind tunnel can measure large improvements in terms of downforce, drag, etc. But the dynamic nature of a Formula 1 pretty much guarantees that plenty of the conditions found in the track cannot be predicted in the wind tunnel. Momentum? G forces? Centrifugal forces? Nope. 1/100th improvements in lap time simply cannot be predicted using the tunnel. 2 tenths? Sure. 1/100th? Nope.

Take, for example, the theories of how the fin will work in a turn. How will a wind tunnel address and evaluate that condition? Will the fin make things better in turns? Worse? There is no way of knowing that with a wind tunnel.

[Conceptual]

I'm curious as to how exactly you can remove all other variables to actually verify a 1/100th effect. Even over 70 laps...nobody says "Gee, that fin sure made the difference!"...because there's no way of attributing .7 over 70 laps to one single factor.

It's called a windtunnel. You see they build models of the cars and then they put it in a windtunnel and measure the forces generated by the wind on the model. In that way they can verify the effect of a certain part. They use these force measurements to obtain a coefficient of drag, or downforce figure. Once they have that number they use it to predict a change in lap time. You see, more downforce reduces the lap time, and less drag also reduces the lap time.

That's why they say, this front wing helps us gain 2 tenths a lap. Not that complicated, dude.

Thank you for making my point for me.

Yes, a wind tunnel can measure large improvements in terms of downforce, drag, etc. But the dynamic nature of a Formula 1 pretty much guarantees that plenty of the conditions found in the track cannot be predicted in the wind tunnel. Momentum? G forces? Centrifugal forces? Nope. 1/100th improvements in lap time simply cannot be predicted using the tunnel. 2 tenths? Sure. 1/100th? Nope.

Take, for example, the theories of how the fin will work in a turn. How will a wind tunnel address and evaluate that condition? Will the fin make things better in turns? Worse? There is no way of knowing that with a wind tunnel.

Are you saying that it is impossible to have the car on a spinning platform in the tunnel?

What you are saying would only be true if the nose of the model is by some mystical force aligned with the tunnel. For some reason tho, I believe that the engineers can vector it at any angle that they choose for their testing purposes.

Chris

[teecof1fan]

Obviously we are just using a made up number with the 1/100th of a second gained per lap, but for the sake of the discussion I'll go along with that. I think what the FOZ is getting at is that although they can measure these tiny details in the wind tunnel and predict the car's theoretical performance, nothing is gauranteed once you get out on track ( .7 of a second after 70 laps is a great way of saying it btw FOZ). Getting stuck in traffic could cost you .7 per lap, a bad lock-up could cost you .7 in a single corner; as he said there are so many variables.

I'm not denying the exactness of the aero and tech sciences. In fact, one of my favorite F1 moments was Jerez 97, where Villeneuve, Frentzen, and Schumacher all qualified with the exact same time: 1:21.072! Incredible stuff, and it probably won't ever happen again. (you can find a great video of it online with the brilliant Murray Walker handling the comments)

So, what we should really find out is how much Renault and RB really do expect to gain from their fins. If they think it's good for a tenth a lap (through aero or better stability or however) then this discussion would be completely different.
Anyway that's just my take. Now bring on the Friday practice!

[ginsu]

Take, for example, the theories of how the fin will work in a turn. How will a wind tunnel address and evaluate that condition? Will the fin make things better in turns? Worse? There is no way of knowing that with a wind tunnel.

Yes, there are always unknowns and the ability to correlate wind tunnel data with on track performance is always a bit risky. But the teams that are successful are somehow able to perform this herculean task and exactly how often does a team put a new aero part on the car and end up performing worse?

Well, it does happen, but I think the 'Walrus Nose' is probably the most recent example and that was like 5 years ago. It seems that the teams have figured a lot of this out, and if they didn't fire/lose their precious engineers then they would be a lot more consistent in this regard.

[teecof1fan]

I know what you mean, ginsu, but I think that these teams who "perform these Herculean tasks" (teams like BMW-Sauber and Ferrari) are producing fundamentally better cars. That is, while Renault adds a fin to the engine cover and a connecter between the sidepod vanes and the bargeboards, BMW (who 'invented' the sidepod-bargeboard connection, and who introduced a toned-down version of the tail fin during Spanish testing) still outperformes the Renault. In other words, the performance of a car is not strictly defined by the aero bits featured on it. Thus, Ferrari and BMW-Sauber are at the top of the tables.


(On a side note) You mentioned Williams introducing the so-called "Walrus-nose" in 2004, but there is a long story behind that:

viewtopic.php?f=6&t=4589&st=0&sk=t&sd=a ... &start=130

To quote myself (I did plenty of research): "Funny, this: When the FW26 Walrus-nose came out, Steve Matchett said in a broadcast that he talked to a few engineers and tech directors about the concept. Ross Brawn told Steve that Ferrari had messed around with the idea a few years before (presumably 2001-2002). So that means Ferrari toyed with it, then Williams used a version of it, and now Ferrari will use the original version 6 years after they first looked at it? Maybe it's because aero is so important now thanks to the engine freeze and SECU and all that other junk"

So, to ginsu, (and assuming you read the above quote):
you specify the FW26 'Walrus nose' as not-working on the FW26, but that exact concept is what is now currently featured on the F2008's nose. Williams debuted a development to that concept and decided that instead of featuring a hole in the nose, it would be better to just cut the nose back (hence the 'Walrus' shape).
But, Ferrari have a different approach to that exact same concept. Instead of drawing the nose back, they kept the same length and simply added the 'hole-in-the-nose.'

I'm sorry that this post is all over the place; I'm a bit loony from a very exhausting day!! I can't wait to relax with some F1 practice from Spain! Cheers!

[Saribro]

For some reason tho, I believe that the engineers can vector it at any angle that they choose for their testing purposes.

There used to be some youtube footage on BMW's tunnel where you could see the car+rolling road rotate to simulate yaw.

[edit]
http://youtube.com/watch?v=Pq4tuT_l36g
at ~3min

[ginsu]

So, to ginsu, (and assuming you read the above quote):
you specify the FW26 'Walrus nose' as not-working on the FW26, but that exact concept is what is now currently featured on the F2008's nose.

Well, I think they actually work a bit differently. From what I remember about the Walrus nose, it did not interact with the flow coming off the front wing because it was high above it. The Ferrari nose cone should enhance the front wing performance, and looks to have very few, if any, detrimental side effects.



Although, I don't really know exactly why the Walrus Nose had such bad effects.

[modbaraban]

So, to ginsu, (and assuming you read the above quote):
you specify the FW26 'Walrus nose' as not-working on the FW26, but that exact concept is what is now currently featured on the F2008's nose. Williams debuted a development to that concept and decided that instead of featuring a hole in the nose, it would be better to just cut the nose back (hence the 'Walrus' shape).
But, Ferrari have a different approach to that exact same concept. Instead of drawing the nose back, they kept the same length and simply added the 'hole-in-the-nose.'

The concept is not quite the same. Have a look at the 'walrus' pic above. The airflow leaving the front wing still goes under the nosecone, in F2008 it goes up the hole