Mclaren Mercedes MP4-25

[Pup]

Hi all Mclaren fans !

This is my first post. I was following this forum since the start of the 2010 testings. I am following F1 since 1989. Some explanation I found for blown flaps :

http://www.aerolab.com/Display_Pages/Flow_Vis.html

At the bottom of the page there is an example of not blown/blown pair of wings, and visible airflow around them. It's clearly visible that a blowned wing has a great advantage in retaining the flow much longer around the wing.
Hope I helped. I think too, that it has to be something special with this Mclaren rear wing.

Very nice find. The suction example is pretty interesting, too.

[joseff]

Thanks, kalinka.

Interesting indeed. So, both blowing and sucking would pretty much achieve the same effect. Why bother with a long duct and deal with the extra drag?

[SLC]

The slot in the flap of the McLaren top rear wing (and the shark fin - roll hoop duct) is there to stall the rear wing at high speed. This decreases the car's overall drag by a couple of percent and will increase the straight line top speed by around 10-20kph.

Rumour is that it is a semi-active system controlled by the driver - something to do with the driver's knee covering a hole in a pipe in the cockpit which, in some way or another, acts as a pressure switch.

[PNSD]

where did you hear/read that?!

[marcush.]

wouldn´t a exhaust driven slot (as a suction pump) not be a lot more effective?

[CMSMJ1]

You guys are all mad.

Anyone want to buy some Snake Oil? It will do whatever you want it to....

In this world of proof...can anyone show us sceptics some?

[SLC]

wouldn´t a exhaust driven slot (as a suction pump) not be a lot more effective?

Using exhaust for anything aero related is dangerous because:

A). It is hot - 400-500K
B). The effect would be completely throttle dependent.

[Pup]

You guys are all mad.

Anyone want to buy some Snake Oil? It will do whatever you want it to....

In this world of proof...can anyone show us sceptics some?

Welcome to the world of ideas.

[Poleman]

The slot in the flap of the McLaren top rear wing (and the shark fin - roll hoop duct) is there to stall the rear wing at high speed. This decreases the car's overall drag by a couple of percent and will increase the straight line top speed by around 10-20kph.

Rumour is that it is a semi-active system controlled by the driver - something to do with the driver's knee covering a hole in a pipe in the cockpit which, in some way or another, acts as a pressure switch.

Lets say we agree to the first assumption about stalling the wing at high speeds...However that driver-knee-piping scenario is quite not possible and unorthodox...

1.I dont see a "working" or compact solution of air transfering to the rear wing through the cockpit considering the limited almost zero space around it...

2.That would require one hell of a piping-vent system which it would be far too long and complex that the actual "gain" would be nothing more but plain loss.Also the hypothetical cockpit vent system would require an opening in the front of the car which i doubt it would be effective.That Mclaren scoop on top of the nose seem too small for that purpose and i think is more like a sensor than an actual air vent.

[Pup]

The slot in the flap of the McLaren top rear wing (and the shark fin - roll hoop duct) is there to stall the rear wing at high speed. This decreases the car's overall drag by a couple of percent and will increase the straight line top speed by around 10-20kph.

That's pretty much been the working theory.

Rumour is that it is a semi-active system controlled by the driver - something to do with the driver's knee covering a hole in a pipe in the cockpit which, in some way or another, acts as a pressure switch.

That, on the other hand, would be highly illegal, though possible, I suppose. I think it's much more likely to work passively.

[segedunum]

The slot in the flap of the McLaren top rear wing (and the shark fin - roll hoop duct) is there to stall the rear wing at high speed. This decreases the car's overall drag by a couple of percent and will increase the straight line top speed by around 10-20kph.

I think that seems to be the established idea now. It should give them a nice advantage in that department, until other teams work out how to copy it that is.

Rumour is that it is a semi-active system controlled by the driver - something to do with the driver's knee covering a hole in a pipe in the cockpit which, in some way or another, acts as a pressure switch.

I doubt it. Anything other than a passive system just wouldn't be legal. Even then, that's possibly a movable aerodynamic device as well, passive or not. That's why I cannot see there being anything more complicated or a smoking gun somewhere to what McLaren might be up to. Anything as complex as what has been described at various points in the depths of this thread would need to be completely passive, and to make some of the wild and wacky ideas work anywhere near reliably enough you would need an actively controlled system.

[PlatinumZealot]

REEEEEWWWIIIIIINDD!!!

The slot in the flap of the McLaren top rear wing (and the shark fin - roll hoop duct) is there to stall the rear wing at high speed. This decreases the car's overall drag by a couple of percent and will increase the straight line top speed by around 10-20kph.

Rumour is that it is a semi-active system controlled by the driver - something to do with the driver's knee covering a hole in a pipe in the cockpit which, in some way or another, acts as a pressure switch.

Where did you hear that (and how did you get those numbers)? Another site that copied from this site or another totally different source?

[PlatinumZealot]

My take on the blown slot.. is that it is not made to shoot high velocity air to keep flow attachment because:

1. It seems so close to the second slot. I don't know if the effect is going to help at that point.
2. It's soo small..
3. You can see that the green paint is collecting near the gap.
4. The air speed coming out of this slot is going to be MUCH slower than what it was when it entered the shark fin; just imagine the undulations and turns it has to go over before it reaches the wing.

I think this is a device to reduce drag by increasing the pressure behind the wing.

[Fil]

SLC's first sentence makes sense. Wings are horrendously inefficient for downforce due to inherent drag levels associated.
So logic would say McLaren would be aiming to reduce rear wing drag.. and leave the bulk of the downforce creation to efficient tools like the diffuser.

As for the cockpit method of manipulating the rear wing.. it sounds extremely crude.. surely there's plenty of controlled airflow under the engine cover they could use - excusing its active manipulation for the means of cooling some component.

[Giblet]

That would in fact explain why they were trying different sized holes in the top split of the airbox, and even tried covering it up.

So THE BOSS and THE BUTTON will get hickies on their knees at high speed manipulating suction?