Mercedes AMG F1 W05

[Just_a_fan]

I would expect that the mountings aren't far from a line running through the usual centre of pressure...

Maybe. I just don't understand how the wing can tilt forward under load. That seems counterintuitive to me. Then again, I've been wrong before...

It's quite simple really - design the wing so that the centre of pressure (the point through which the downforce acts) is in front of the mounting points and the wing will want to rotate nose down. Design it so that the centre of pressure is behind the mounting points and the wing will want to rotate nose up.

The front wings are complex and it's likely that the centre section wants to rotate nose down (because the teams seem to get the centre section to develop downforce even though it's supposed to be neutral); the outer sections likely want to rotate nose up. Tuning the resultant force to give your overall desired result will be key.

[bhall]

So you think the wing might twist under load, ie the center section pitches forward while the flaps pitch back? I can easily understand a desire for the latter, but not so much the former, which, I suppose, means I don't understand the reason for designing a wing with such complexity.

Any action that results from aero loading will become more and more pronounced as airspeed increases. Therefore, if any section of a wing is designed to increase downforce under loading, that section will produce peak downforce/drag at the end of straights, areas where downforce/drag is an enemy rather than a friend.

The idea then should be to reduce downforce/drag, which is why it makes total sense to me to design a wing that pitches back to reduce its AoA under loading. Not only would that progressively decrease induced drag, it's conceivable that a reoriented endplate could direct air flow to the vortex that forms on the outside of the tire's contact patch in order to break it up, further reducing drag - sorta like a blown hub.


That last bit is probably a touch pie in the sky, but it's fun to speculate.

[...]

Does the above look like a change in layup to anyone else? Could it be what allows the pylon to flex?

Yes. But no, I don't believe so. I think that is simply an attachment to the pylon for aerodynamic purposes, which can be changed without altering the nose, which would force a new crash test. Does anyone have a video of the pylons / wing / nose flexing? Would be very helpful to see how they handle this.

I was actually referring to the seam in the carbon fiber, not the metal bit. It looks like two different weaves joined together. And, yeah, some video footage would be fantastic.

[e30ernest]

Could be nothing, but what are those gaps on the metal bits for? Usually they'd minimize the occurrence of such gaps to keep airflow smooth would they?

[CBeck113]

I was actually referring to the seam in the carbon fiber, not the metal bit. It looks like two different weaves joined together. And, yeah, some video footage would be fantastic.

http://i.imgur.com/Hxas48l.jpg

Me too - I think that, since they combined the nose and pylons, have attached the aero bits on the back, basically outside the speced nose, so they can make changes if necessary without rerunning the crash test. If they were one piece and they saw that a profile change would help, then they'd have to go through the entire process again. This way they can make any changes they want without the FIA getting involved.

[Just_a_fan]

So you think the wing might twist under load, ie the center section pitches forward while the flaps pitch back? I can easily understand a desire for the latter, but not so much the former, which, I suppose, means I don't understand the reason for designing a wing with such complexity.

No, I'm not saying they're doing that, I'm just explaining how it might be done. It was Ringo (I think) who suggested it was actually doing odd things.

[bhall]

CBeck, JaF, I apologize. It appears I'm without the ability to fully comprehend what I read today.

"Oh, yeah? How's that different from any other day?"

[flynfrog]

The highlighted area just looks like a ply drop in the laminate. Maybe where the structure part ends and the aero fairing begins

[ringo]

I would expect that the mountings aren't far from a line running through the usual centre of pressure...

Maybe. I just don't understand how the wing can tilt forward under load. That seems counterintuitive to me. Then again, I've been wrong before...

Regardless of their precise role, the mounting points haven't changed from the launch version, only the nose itself. So, whatever they're doing, they've been doing it from the beginning.

http://i.imgur.com/uMtFxNx.jpg

I imagine the new, shorter nose allows for more mass flow under the chassis, and it removes a blockage encountered when the car is in yaw. It could also reduce the tendency of the neutral center section to produce lift.

http://i.imgur.com/A05Ja9T.jpg

Does the above look like a change in layup to anyone else? Could it be what allows the pylon to flex?

All wing profiles producing lift have a pitching moment. Depending on the shape the moments have different magnitudes and sometimes even directions. The pitching is about the centre of pressure.
Most wings tend to twist, hence they must be designed to resist torsion. This wings are no different, and they can tend to rotate backwards or even forwards, it just depends on how they are designed.

[PhillipM]

I cannot see how you would expect a wing such as that to provide a pitching moment and direction that would make it ever twist forwards around the axis of the front wing pylon mounts.

[bhall]

All wing profiles producing lift have a pitching moment. Depending on the shape the moments have different magnitudes and sometimes even directions. The pitching is about the centre of pressure.
Most wings tend to twist, hence they must be designed to resist torsion. This wings are no different, and they can tend to rotate backwards or even forwards, it just depends on how they are designed.

Yes, I understand that much. Like PhillipM above, and others previously, I just don't see how the wing will pitch forward. To do so, it would seem the center of pressure would somehow have to be located in front of the wing in order to overcome the forces acting on the trailing edge. I also don't see why such movement would be desirable anyway, because it would tend to progressively increase downforce (drag) at speeds in which downforce (drag) is a hindrance instead of helpful.

[Tommy Cookers]

I cannot see how you would expect a wing such as that to provide a pitching moment and direction that would make it ever twist forwards around the axis of the front wing pylon mounts.

a conventional wing twists mainly by the distribution of its structure's reaction to the lift, ie the concept of(equivalent) 'shear centre'
this will outweigh any benefit from a favourable PM position
ie the net twist will always be in the direction of increasing the AoA (typically this is counterintuitive and inconvenient)

though if the wing is made of an anisotropic material such as CRC inconvenient twist can be eliminated

and our case is of course complicated by unconventionalities of mounting and wing plan shape

(yes, I wish that I hadn't started this post)

[___]

though if the wing is made of an anisotropic material such as CRC inconvenient twist can be eliminated

No need to rely on anisotropy necessarily - the the wings are hollow so some well-placed stiffeners might be enough. But of course anisotropy helps and I'm sure the designers use it to its full advantage.

[bhall]

I see it now. And I should have remembered that most downforce is produced at the leading edge of the wing, because it was once one of my prime arguments in favor of inwash endplates that maximize the space available for the leading edge.

If the center of pressure is in front of the mounting points (red dots below), the wing will indeed pitch forward. Moreover, if the pitching moment is strong enough, the CP can even be in front of the wing altogether.

So, I stand corrected.


Williams FW31

I guess the question is now, why is this action desirable? Or is it just a consequence of something else?

[___]

Moreover, if the pitching moment is strong enough, the CP can even be in front of the wing altogether.

In theory for an arbitrary body that's true, but remember that downforce being the goal, the pressure on almost every little bit of the wing acts downwards so acts on a line that passes the same side of the leading edge as all the others. To achieve a pitching moment big enough that the CoP lies forward of the wing there needs to be some region where the pressure acts in the opposite direction to the resultant force on the whole wing acting through the CoP. In this case that means some rearward part of the wing generating lift, which I'm quite sure is a sign something's gone horribly wrong!

[Owen.C93]

I see it now. And I should have remembered that most downforce is produced at the leading edge of the wing, because it was once one of my prime arguments in favor of inwash endplates that maximize the space available for the leading edge.

If the center of pressure is in front of the mounting points (red dots below), the wing will indeed pitch forward. Moreover, if the pitching moment is strong enough, the CP can even be in front of the wing altogether.

So, I stand corrected.

http://i.imgur.com/qQeS0kk.png
Williams FW31

I guess the question is now, why is this action desirable? Or is it just a consequence of something else?

I'm just going to be a nuisance and refer to the old McLaren flexing front wing that reduced it's angle of attack at high speed for less drag/aero balance.
http://i.imgur.com/7Uj8XqX.jpg
http://i.imgur.com/cYL3qem.jpg