Mclaren Mercedes MP4-25

[Darknight]

Hmmm if we assume that the channel to the back wing is the lower of the two on the intake, then can the driver block it with his helmet?

[bonjon1979]

You are.

Consider that you could theoretically stall the wing with some well-directed air, and that it'd be useful at speed.

Consider that there are times when you'd certainly not want this to happen either.

How does the system change between the two?

If this is potentially how it works, this is where it's potentially sinister... go on!

Is it possible to have a valve which opens when air traveling through the duct reaches a certain speed?

[Richard]

The potential of the duct feeding into the rear wings was disussed a couple of weeks ago, around page 40
viewtopic.php?f=12&t=7495&hilit=duct&start=585

We'd also spotted a thin slit in the rear face of the wing that could be used to bleed air out of the duct. You can clearly see this in the flow vis pic, note how the two element wing appears to have 3 elements when teh flow vis gets to work ...



Then on page 41, Ringo came up with this summary...

The fin putting air on the wing wont be of much help. The air wont be a better quality of the free stream air. Stalling is also not desirable at any rate, the wing would behave like a bluff body only creating drag.
The air through the heat exchangers is not steady either and it loses most of the KE hitting into the grating of the exchangers.

What could work however, is if air was injected behind the wing, between the wing elments though a duct in the fin. This air would have to be at a higher pressure than that on the low pressure side of the wing. Introducing high pressure behind the wing would reduce the pressure difference between the sides of the wing, reducing drag and reducing lift. This only works if the enthalpy gained by the air going through the heat exchangers can restore most of the pressure and energy lost.
For it to work the injected pressure has to be higher than that behind the wing. the closer it is to free stream pressure the better. With equal pressure on both sides, ideally the wing would behave as if it was not there, no drag and no down-force.

Something like this:


The curved lines are the wing, red lines hot air, blue low pressure and free stream.
The drawing is a not dimensionally accurate, but you all should get the idea.

This reduction in drag and down-force thing is only desirable on the straights, when a DF reduction wont hurt.

[Fil]

Consider that you could theoretically stall the wing with some well-directed air, and that it'd be useful at speed.

Consider that there are times when you'd certainly not want this to happen either.

How does the system change between the two?

If this is potentially how it works, this is where it's potentially sinister... go on!

Is it possible to have a valve which opens when air traveling through the duct reaches a certain speed?

The contention being.. if something is actively switching this effect on & off, is this counted as a moveable aerodynamic device...?



SZ you're a marvel with your knowledge.. =D> why you don't post more often i don't quite know!

[Richard]

The contention being.. if something is actively switching this effect on & off, is this counted as a moveable aerodynamic device...?

It would be classed as engine cooling, just like the wheel covers were classed as brake cooling ducts.

Since it is a device for engine cooling you could legitimately open it when the engine is worked hard at high revs, and close it for low revs. Which happens to coincide with corners (high downforce) and straights (low downforce).

[Fil]

The contention being.. if something is actively switching this effect on & off, is this counted as a moveable aerodynamic device...?

It would be classed as engine cooling, just like the wheel covers were classed as brake cooling ducts.

Since it is a device for engine cooling you could legitimately open it when the engine is worked hard at high revs, and close it for low revs. Which happens to coincide with corners (high downforce) and straights (low downforce).

Hmm.. high revs are used in each gear, even in mid-speed & slower corners.

You'd hardly want a stalled rear wing through Copse or Maggotts, Eau Rouge or even turns 11 & 12 in Melbourne!

It'd be very difficult to excuse as engine cooling i think.

[zeeeeeeebra]

First post. And i bring you a new gizmo on Jenson's McLaren

[bonjon1979]

Perhaps it works differently when the cars in yaw?

[Darknight]

Adding to the inlet being blocked by the helmet, could it be that Brawn/Merc were hinting to this this when they were saying Rosberg "dropped 1.5cm" during the day. If Mclaren can control this drop and rise then cant they get the drivers helmet to block an inlet at will?

Can the drink button be used to pump fluid out from under the driver to lower him and opposite to raise him?

[SZ]

Richard, i only see two elements on the rear wing and a pretty normal coagulation of flow vis material where the upper rear wing begins to stall. is this what you're referring to? That third split isn't going to be terribly sensitive to much at all in the context of BL reenergisation, I see what you mean but it's very small.

It would make less sense to put it up high as there's a CG penalty inherent and side radiators cool just fine, it'd constitute some extreme liberties with the rules, more so than other less questionable legal mods (*cough* mass damper) ever could.

The key question is surely whether it's an active or passive system, no?

zeeeeeeebra, that's just a pitot-static rake (note the holes on the side of the tubes). Dynamic and total pressure, not sure if they're both on the traversing rake. Same thing essentially as the other just a bank of them as the area is too small to bother going through with a traverse. I'd bet there a vortex or three going around the front wheel, probably developed off the front endplate, that's ending up under the car in that region that they're tracking the progress of. If its a problem that same vortex would probably end up as stalled flow in diffuser flow vis and/or underfloor pressure taps, and this is working from the back of the car forwards. If not, they might be noting a difference in where that flow feature ends up, and are working out the difference.

[Crabbia]

Adding to the inlet being blocked by the helmet, could it be that Brawn/Merc were hinting to this this when they were saying Rosberg "dropped 1.5cm" during the day. If Mclaren can control this drop and rise then cant they get the drivers helmet to block an inlet at will?

Can the drink button be used to pump fluid out from under the driver to lower him and opposite to raise him?

Ohh my... SZ created a monster with his seamingly socratic line of questioning...

[SZ]

Actually, on second thoughts is that rake pitot-static? I can only see one pressure tube out of the rake per position, unless the static channel is mounted on a common manifold.

Darknight... I hope not!

[thestig84]

Thoughts? Just simply because its still coldish at Jerez!?

[horse]

Actually, on second thoughts is that rake pitot-static? I can only see one pressure tube out of the rake per position, unless the static channel is mounted on a common manifold.

Perhaps they use the sensors mounted at the top of the car for static pressure?

EDIT: God, Jenson still looks really high in the car! And whatever that extra channel does, McLaren don't seem to want it doing it any more...

[astracrazy]

Thoughts? Just simply because its still coldish at Jerez!?

Whats with the air box?