Front wing

[19000rpmF-2004]

can some one explain me how the two or three element of the front win works. I like to see and understand how the first element work and so on ( secound, third) and where the air it's reflect it.
Thanks.

[coysht]

Basically the first element is of an aerofoil shape (inverted wing). Air passes around this first element, and is forced upwards by the shape of the element.

The second element is then angled more steeply than the first and does the same thing again.

By using several elements you can gain a high angle of attack (how much of an angle the wing is to the airflow hitting it) for the wing as a whole, without causing the wing to stall (when the air separates from the surface of the wing) this allows you to generate more downforce than you could with a single element. 3rd (or more elements) follow on from the same principle.

If i get a chance I'll find/draw a diagram of this.

[JustBringIt]

Originally posted by coysht
By using several elements you can gain a high angle of attack...

I think it would be more correct to say camber.

[fermy]

So we might see wings following the razors: start with 1 element, then go to 5?

[coysht]

Originally posted by JustBringIt
I think it would be more correct to say camber.

Both are valid, although I was trying to not use another phrase that needed its own separate explaination.

fermy
So we might see wings following the razors: start with 1 element, then go to 5?

Unlikely (in the near future anyway). I don't think there is really the space to make an efficient wing with more than 3 at the moment.

But In theory, yes you could.

[JustBringIt]

Originally posted by coysht
Unlikely (in the near future anyway). I don't think there is really the space to make an efficient wing with more than 3 at the moment.

But In theory, yes you could.

Isn't there a rule limiting the number of elements? Or is that just in the rear wing?

[Luca de Montezuma]

Camber and angle of attack are different things (assuming a fixed camber device). Multiple element wings, however, will increase maximum camber and/or angle of attack before the onset of stall. However, the speed regimes will alter. There is an optimum for a given speed. Therein lies the design difficulty/compromise.

Increased numbers of elements isn't necessarily more efficient in terms of lift/drag ratio.

Maximum number of elements (within a given wing envelope) is also limited by structural strength and/or rigidity/flutter requirements. Longitudinal supports to negate those effects will increase interference drag, although low aspect ratio wings may benefit from the restriction to spanwise flow.

[coysht]

Originally posted by JustBringIt
Isn't there a rule limiting the number of elements? Or is that just in the rear wing?

Just the rear I believe.

[JustBringIt]

Originally posted by Luca de Montezuma
Camber and angle of attack are different things (assuming a fixed camber device). Multiple element wings, however, will increase maximum camber and/or angle of attack before the onset of stall. However, the speed regimes will alter. There is an optimum for a given speed. Therein lies the design difficulty/compromise.

Increased numbers of elements isn't necessarily more efficient in terms of lift/drag ratio.

Maximum number of elements (within a given wing envelope) is also limited by structural strength and/or rigidity/flutter requirements. Longitudinal supports to negate those effects will increase interference drag, although low aspect ratio wings may benefit from the restriction to spanwise flow.

The reason I mentioned camber was because having multiple elements at differing angles of attack increases the overall camber of the wing assembly, rather than the angle of attack.

I imagine that its not until you get to a higher angle of attack with one element where it becomes beneficial to add extra elements, i.e. just adding elements doesn't help to make the wing more efficient until you get into a high downforce situation. And since the rear wing is limited in the number of elements allowed, the front wing will not need a lot of downforce and therefore elements because the balance between the front and rear would be totally uneven.

Also its interesting how you mention the spanwise flow. Coysht, this is where I had trouble understanding when you were talking about the vortices. From what I remember, vortices are caused by the spanwise flow going around the ends of the wing tips and F1 cars have endplates and sometimes little fences along the wing to stop this happening. So if the vortices are responsible for downforce, why are they trying to stop them?

[Luca de Montezuma]

The endplates will reduce spanwise flow.

They'll increase the pressure differential between the upper and lower surfaces.

Very importantly, they allow the designer to condense the vortices and control their path as they leave the wing.

[coysht]

Originally posted by JustBringIt
Also its interesting how you mention the spanwise flow. Coysht, this is where I had trouble understanding when you were talking about the vortices. From what I remember, vortices are caused by the spanwise flow going around the ends of the wing tips and F1 cars have endplates and sometimes little fences along the wing to stop this happening. So if the vortices are responsible for downforce, why are they trying to stop them?

I don't remember ever mentioning span wise flow.

Voticies appear in various places and in various directions, not just those you mentioned above.


On the subject of chamber and angle of attack, yes adding elements to the wing will increase the chamber of the wing but it will also change the effective angle of attack of it - so both are true.

[JustBringIt]

Originally posted by coysht
I don't remember ever mentioning span wise flow.

Voticies appear in various places and in various directions, not just those you mentioned above.

No, you didn't mention spanwise flow. It was just what I had in my mind when you were talking about vortices. I hadn't thought about other types of vortices.

At the time, you were talking about vortex shedding devices. Do you remember what sort of vortices you were talking about? Perhaps there are some underneath the wing?

[coysht]

Originally posted by JustBringIt
At the time, you were talking about vortex shedding devices. Do you remember what sort of vortices you were talking about? Perhaps there are some underneath the wing?

Not sure what you mean by type of votex.

[JustBringIt]

Originally posted by coysht
Not sure what you mean by type of votex.

I mean direction and location, i.e. where it comes from.

[coysht]

Originally posted by JustBringIt
I mean direction and location, i.e. where it comes from.

Its quite hard to explain (not sure I entirely get it myself).

My understanding is that you have large vorticies going roung the wing itself, and this accelerates and decelerates the flow of air on the lower and upper surfaces of the aerofoil.

You can also make use of the vorticies to generate downforce by deliberately shedding them and running them along a surface (google "vortex induced lift")

I'll have a look and a think and try and explain it better, but hope that makes sense for a bit.

[Luca de Montezuma]

May I have a go?


An aerofoil shape generates lift by accelerating the air over the top (if it's lifting upwards....of course, an F1 wing acts by pushing downwards, but I'm more accustomed to talking about upeard lifting devices e.g. on aircraft).

As far as the air particles going over the top of the wing are concerned, all they feel is the wing causing them to describe a circle in mid air.

That circle is not a vortex. It's called "circulation" and it's what produces the lift (as well as the drag, of course).

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Vortices are undesirable, in that the energy within them is wasted energy. In other words, it's drag. However, vortices are a necessary evil in some situations (next paragraph deals with that).

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Over some parts of any structure in an airstream, the air will separate from the structure. When it separates it becomes turbulent. Once again, turbulence = wasted energy = drag (and in the case of lifting surfaces = loss of lift)

The separation can be prevented or delayed by energising the air near the structure by just enough to make it "stick" to the surface. This is achieved by adding relatively small "vortex generators" just upstream of the point of separation. They're usually just a row of very short rectangular projections, often arranged at alternating angles to each other.

You see these "vortex generators" on aircraft wings, where they are used to make the airflow "stick" to the wing in areas where airflow separation would not only produce wasteful drag, but would, very importantly, cause a loss of lift.


Hope that helps.