New front wing design

[kilcoo316]

The picture you have posted is very, very different from the original post. The horizontal and vertical offsets are considerably higher as a percentage of either chords.

The low lift coefficients targeted for aircraft use make biplanes a lot more acceptable than they are in motorsport.

If that were the case, why do several of the top teams already have bi-planed wing arrangements at the front.

Having a closed wing makes it alot more efficient, for instance, an elliptical planform wing (like the spitfire) has a lift distribution efficiency of 1. [In contrast, most tapered wings have an efficiency of around 0.7]

A circular wing planform, has an efficiency factor of 2!

http://www.aerodyn.org/Wings/noplane.html


If you have time, this is worth looking at:

http://aero.stanford.edu/Reports/VKI_nonplanar_Kroo.pdf


This pic illustrates what I mean by closed wing planform:
[img::]http://forums.x-plane.org/uploads/cdm/s ... 76eab0.jpg[/img]

[Carlos]

AeroGT3 - Thanks for the extremely interesting links.

[BreezyRacer]

AeroGT3 - Thanks for the extremely interesting links.

Yes it is! Check out the C wings on page 15-16 of the PDF and compare all that to today's front wing designs. Quite informative!

[MrT]

I ran a model on stacing front wings recently whilst developing the aero package for a single seater. I reached the conclusion that stacked elements probably wouldn't give an advantage to a well positioned flap as, as already mentioned, there will be a degreade of performance unless the vertical spacing is very large. This degregation of performance came from the fact that the upper element increased the flow velocity over the top of the lower element, therefore reducing the downforce provided by the lower element. The downforce produced by the top element, just about offset the loss. A limitation of the model i ran was that i didn;t model the wheel behind, as i was just modelling the concept, but i felt the results were conlusivce enougth for me not to implement this solution. Current teams seem to use very un agressive upper elements, probably to divert aeroflow more than anything else......

<img src="http://www.redmistracing.co.uk/Home___News/cfd5.JPG">

[joseff]

...the upper element increased the flow velocity over the top of the lower element, therefore reducing the downforce provided by the lower element. The downforce produced by the top element, just about offset the loss...

But wouldn't this also reduce trailing vortices and hence reduce drag?

Plus, if you look at the C-wing designs, the winglets are on the low-pressure side, trailing edge. F1 front wings (R26, FW28, etc) have the winglets on the high-pressure side, leading edge. So they work entirely differently I guess.

[kilcoo316]

Plus, if you look at the C-wing designs, the winglets are on the low-pressure side, trailing edge. F1 front wings (R26, FW28, etc) have the winglets on the high-pressure side, leading edge. So they work entirely differently I guess.

By C wing, I assume you mean aircraft wings?


Don't forget, the wingtips have to have a specified ground clearance, which does limit the development of winglets on the downward side of aircraft wingtips.

[joseff]

Check out the C wings on page 15-16 of the PDF and compare all that to today's front wing designs. Quite informative!

I was referring to this comparison between the PDF and F1 wing.

[AeroGT3]

If that were the case, why do several of the top teams already have bi-planed wing arrangements at the front.

They don't. The worst thing you could possible do is throw the suction peak of your second element directly on the highest pressure region of a lower element . . . which is exactly what the original poster's design does.

Having a closed wing makes it alot more efficient, for instance, an elliptical planform wing (like the spitfire) has a lift distribution efficiency of 1. [In contrast, most tapered wings have an efficiency of around 0.7]
A circular wing planform, has an efficiency factor of 2!

That's all good and well, but you sacrifice an enormous amount of downforce with a biplane, especially in ground effect. If teams were all about L/D, they'd do this. But they aren't. True bi-plane wings are fundamentally wrong for motorsport. The application is totally different from aircraft, so stop trying to draw parallels. An aircraft designer would puke if his aircraft had the Cd of an open wheel car, and so would an F1 engineer if his car had the Cl of an aircraft! A good aircraft has an L/D of 16-19 for the entire craft. What's L/D for an F1 car?

This pic illustrates what I mean by closed wing planform:

Again, you are fundamentally missing the basic concepts here. Stop thinking of the pretty visuals like wingtip vortices and start thinking of mathematically tangible pressure coefficients and circulations. I don't care how many vortices the closed wing prevents, nor does anyone give a hoot about span efficiency factors. Downforce is the name of the game. You don't go fast by having a Cd of 0.006 (NACA 0012 . . .), you go fast by having a Cd of 1 but a Cl of -3.

And BTW, that boxed wing picture is of a supersonic aircraft. Look up hyperbolic PDE's and you'll find that the two wings will never influence each other as they're most likely outside of the characteristic lines (Mach cone.) Again, you are comparing F1 cars to road going station wagons. Apples to apples, please. A super/hypersonic aircraft has totally different Aero requirements.

Too many people with too little knowledge of the ENGINEERING fundamentals are parading a heightened sense of knowledge that simple doesn't exist.

[AeroGT3]

I ran a model on stacing front wings recently whilst developing the aero package for a single seater. I reached the conclusion that stacked elements probably wouldn't give an advantage to a well positioned flap as, as already mentioned, there will be a degreade of performance unless the vertical spacing is very large. This degregation of performance came from the fact that the upper element increased the flow velocity over the top of the lower element, therefore reducing the downforce provided by the lower element. The downforce produced by the top element, just about offset the loss. A limitation of the model i ran was that i didn;t model the wheel behind, as i was just modelling the concept, but i felt the results were conlusivce enougth for me not to implement this solution. Current teams seem to use very un agressive upper elements, probably to divert aeroflow more than anything else......

<img src="http://www.redmistracing.co.uk/Home___News/cfd5.JPG">

Thank you for providing some sound engineering to this discussion. The second element is used to keep the flow over the first element attached, using the suction peak of the second element's leading edge to force the streamlines to stay attached to the first body longer. But it also plays a significant role in deflecting air over the tire.

If people keep disputing everything that's being said, perhaps I'll run some CFD cases including the rotating wheel to prove my point. But I would hate for it to come to that as my computer is quite slow!

[AeroGT3]

But wouldn't this also reduce trailing vortices and hence reduce drag?

Yes, but at the expense of a ton of downforce! F1 cars are very inefficient because they have to be to generate so much DF at such low (incompressible) speeds.

Plus, if you look at the C-wing designs, the winglets are on the low-pressure side, trailing edge. F1 front wings (R26, FW28, etc) have the winglets on the high-pressure side, leading edge. So they work entirely differently I guess.

They have winglets on the high pressure side because they could hit the ground on the low pressure side, and because they can more effectively influence flow over the tire on the high pressure side.

Sometimes, what is best for Aero, isn't feasible or best for the entire car. Endplates that contact the ground are not ideal!

[kilcoo316]

They don't. The worst thing you could possible do is throw the suction peak of your second element directly on the highest pressure region of a lower element . . . which is exactly what the original poster's design does.

So you could put very little camber on the top wing, use it like a compressor blade* to increase pressure - while this will be cancelled out on the section immediately underneath on the lower wing, downstream it won't.

Again, why did they mount an upper wing on the rear wing element if it doesn't work?

*actually more like a turbine blade, its incompressible flow.

[BTW, the original poster's sketch is just that, a sketch - its not meant to be scaled exactly etc so the chord spacing point (while true if you base everything on that sketch being scaled) is a cop-out]

The application is totally different from aircraft, so stop trying to draw parallels.

What's L/D for an F1 car?

Its not so different. Somethings don't work, and some do.

L/D for an F1 car is around -3.3 [but depends on config obviously]

I don't care how many vortices the closed wing prevents, nor does anyone give a hoot about span efficiency factors. Downforce is the name of the game. You don't go fast by having a Cd of 0.006 (NACA 0012 . . .), you go fast by having a Cd of 1 but a Cl of -3.

Right, if no-one give a damn about span efficiency factors they wouldn't bother with endplates would they? You do realise that for an open wing there is zero lift/downforce produced at the wing tip - an endplate will raise this by a little, a closed section by alot more.

And BTW, that boxed wing picture is of a supersonic aircraft. Apples to apples, please. A super/hypersonic aircraft has totally different Aero requirements.

I know the difference between super and subsonic aerodynamics thanks - that picture was an illustration of what I mean by closed section - doesn't mean I'm gonna try and stick on a front wing with 40 degrees 1/4 chord sweep.

Too many people with too little knowledge of the ENGINEERING fundamentals are parading a heightened sense of knowledge that simple doesn't exist.

You'd be surprised.

[kilcoo316]

If people keep disputing everything that's being said, perhaps I'll run some CFD cases including the rotating wheel to prove my point. But I would hate for it to come to that as my computer is quite slow!

Gimme a mesh in Fluent, and I'll run it for ye. (or even a CAD geometry in Parasolid format - I can mesh it myself)

Size doesn't matter (although try and keep it sensible).

[MrT]

I think the problem here is not whether stacked wings work, they do given the correct spacing...... However i have to disagree that in my opinion if you look at current f1 wings they are not biplane arrangements, they just have a non aggressive element above to control the air flow. However they will produce downforce although i belive this not to be their primary function... I could be wrong, but based on my fluid mechanics knoledge and the CFD models this is what i belive to be true. Sauber utilised a full biplane element last year in testing but ditched and never used because it was discovered that there was minimal advantage......

http://www.formula1.com/insight/technic ... 7/168.html

[AeroGT3]

So you could put very little camber on the top wing, use it like a compressor blade* to increase pressure - while this will be canceled out on the section immediately underneath on the lower wing, downstream it won't.

What happens downstream doesn't produce lift or drag. The box wing isn't a benefit unless the two wings are spaced far apart in the vertical direction. That kind of spacing is prohibited by the rules.

Again, why did they mount an upper wing on the rear wing element if it doesn't work?

They mount upper elements because they are mostly used in flap configurations, not the bi-plane configuration that's being discussed.

[BTW, the original poster's sketch is just that, a sketch - its not meant to be scaled exactly etc so the chord spacing point (while true if you base everything on that sketch being scaled) is a cop-out] [/qoute]

No, it isn't, but the sketch is clearly a box wing design that requires the wings to be nearly stacked on top of each other.

Its not so different. Somethings don't work, and some do.

L/D for an F1 car is around -3.3 [but depends on config obviously]

They are TOTALLY different. The THEORY is the same, but the form that the applications of that theory take are massively different.

Right, if no-one give a damn about span efficiency factors they wouldn't bother with endplates would they? You do realize that for an open wing there is zero lift/downforce produced at the wing tip - an endplate will raise this by a little, a closed section by alot more.

People use endplates because they don't negatively effect the pressure distribution over the upper surface of the first element. A boxed wing does. This is why endplates are ubiquitous and box wings are almost always throw out after testing. (See the sauber post below)

I know the difference between super and subsonic aerodynamics thanks - that picture was an illustration of what I mean by closed section - doesn't mean I'm gonna try and stick on a front wing with 40 degrees 1/4 chord sweep.

Well, then thanks for posting a picture of a closed wing, even though the original post IS one.

You'd be surprised.

I'd love to be, but I'm not. A bi-plane hurts performance by mixing high/low pressure regions more than it helps by marginally increasing the span efficiency factors.

[kilcoo316]

What happens downstream doesn't produce lift or drag. The box wing isn't a benefit unless the two wings are spaced far apart in the vertical direction. That kind of spacing is prohibited by the rules.

It will if the local static/dynamic pressure is influencing another surface (e.g. some of the first, and all of the second flap on the lower plane)

They mount upper elements because they are mostly used in flap configurations, not the bi-plane configuration that's being discussed.

I'm not talking about muli-element flap configurations, I'm talking about mounting a small element directly above the main plane of the wing.

No, it isn't, but the sketch is clearly a box wing design that requires the wings to be nearly stacked on top of each other.

Like the current Renault, Ferrari & Williams front wings.

They are TOTALLY different. The THEORY is the same, but the form that the applications of that theory take are massively different.

Its true that F1 cars operate in mostly a highly turbulent flow regime, whereas aircraft operate in mostly clean air, without the presence of a ground plane. However, aside from the diffuser, downforce is generated in essentially the same way as lift on an aircraft - a horsehoe vortex system consising of 1 bound and 2 lift dependant vortices.

Working the airflow around the wheels and body work as efficiently as possible is another element to it.

People use endplates because they don't negatively effect the pressure distribution over the upper surface of the first element. A boxed wing does. This is why endplates are ubiquitous and box wings are almost always throw out after testing. (See the sauber post below)

Right, those same biplane arrangements renault and ferrari ran with all of last year?

Well, then thanks for posting a picture of a closed wing, even though the original post IS one.

That may be clear to you, me and some others, but maybe not to everyone else in here.

I'd love to be, but I'm not. A bi-plane hurts performance by mixing high/low pressure regions more than it helps by marginally increasing the span efficiency factors.

That flies in the face of the teams actually using the things!


I do accept that biplanes can be a negative influence on each other dependant on chord spacing etc. However, I do not accept there is no place for them with careful design - if it were true they were useless they would not be seen on any cars - never mind the 2 cars that finished 1st and 2nd in last years WCC.