Mclaren Mercedes MP4-25

[Spencifer_Murphy]

SZ, is there anyway that any flow coming from a possbile duct in the sharkfin could (even allowing for the pipe losses) be used to activly try and break up the boundary layer, kinda like the dimples in a golf ball?

Also, is it possible that, the duct itself could in fact be a converging duct, raising the static pressure and the mass flow rate of the air in order to counteract the pipe losses when it eventually vents out of the fin to the underside of the wing?

Just a thought, it could be total tosh lol.

[meves]

I've zoomed in a little, but it hasn't helped me!

[bonjon1979]

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...

They certainly seem to be wanting less air going through there.

[CMSMJ1]

In cold conditions restricting the flow through that cooling duct is a better solution than taping the radiator. it may be as simple as that..

It is to cool the components that they moved from the sidepods when they had to make room for the fuel tank so perhaps the components are not as hot as they expected at this time of year.

Related to this....unless someone shows some pictures of the ducting, flappery or mumbo jumbo involved then it is wild speculation.

As a long time F1 fan and geek for technical ideas (hence my presence on here) the snowball effect of these stalling wing/dead zone/driver activated flap by raising and lowering using hydraulics!! (I mean seriously, WTF?) it worries me. You guys are clever enough that you don't need to follow an idea like sheep.

If this was called BS several pages ago it would hav died...as it is it has a trolling life of it's own.

I am a black and white kind of person - it is or it is not.

Things that might be don't class as "it is"

bit of a rant, sorry..but it was building up in me!

Anyway, as you were...

[meves]

I've zoomed in a little, but it hasn't helped me!

Thanks to Scarbs for some real infromation!

They've closed off the oil cooler inlet in the roll hoop

Also they've changed the cooling at the rear

McLaren: they are also playing with the cooling outlets, note the openings on the engine cover

[Richard]

Related to this....unless someone shows some pictures of the ducting, flappery or mumbo jumbo involved then it is wild speculation.

...

You guys are clever enough

There is something very odd about the way it retains its volume, especially when you see Merc with their incy wincy tiny airbox, with a fin to make up the required height dimensions. So why do McL have the bulk in theirs? Maybe it is just a bit of slipstream styling, but you'd think they want it with least bodywork volume to maximise air volume hitting the the wing?

Anyway, you are correct, it is a pure flight of fancy. What I like is that people on here are clever enough to have discussions about a hypothetical concept that could stall a wing on a fast straight. That would be really cool wouldn't it?

[thestig84]

Thanks to Scarbs for some real infromation!

Before you get too loved up with Scarbs...Think he may also have some duff information

McLaren: they are also playing with the cooling outlets, note the openings on the engine cover

Looks the same as Valencia test to me. Only thing I can spot is they have lost the small vents below the head protection, not engine cover

[SZ]

SZ, is there anyway that any flow coming from a possbile duct in the sharkfin could (even allowing for the pipe losses) be used to activly try and break up the boundary layer, kinda like the dimples in a golf ball?

Also, is it possible that, the duct itself could in fact be a converging duct, raising the static pressure and the mass flow rate of the air in order to counteract the pipe losses when it eventually vents out of the fin to the underside of the wing?

Just a thought, it could be total tosh lol.

First idea more feasible.

meeves, I'd trust anyone getting information out of a factory as a member of the press about as far as I could throw them, and my pitching arm is weak.

CMSMJ1 - easy tiger. I'd bet the same process goes on at any other team looking at some new innovation in the sport, though they don't call it 'trolling'. Particularly when you've got an outlet in front of something that usually, explicitly is designed to have another sort of flow field around it.

There's only one way we'll know for sure though - wait for Ferrari to whinge to the FIA about it!

horse, up top it's probably a full P-S system but in that particular region, particularly if flow is swirling, you'd have a hard time picking which direction is truly static. As you correctly state you could just reference it to a common port, or maybe they've got all holes open and are looking at total pressure.

[astracrazy]

Thanks to Scarbs for some real infromation!

They've closed off the oil cooler inlet in the roll hoop

Also they've changed the cooling at the rear

McLaren: they are also playing with the cooling outlets, note the openings on the engine cover

yeah i've been playing spot the difference and i see none

[Pup]

OK, am I daft or is SZ describing exactly what we've been talking about for weeks? SZ, no offense, but the whole cryptic "I know and you don't" thing is a bit childish. Just tell us what you think is happening.

If the whole "blown flap" theory is true, then I suspect that the topmost section is ducting through the fin into the wing, where it's then released via what looks like a small slit that runs across the back, near the leading edge.

Some of us were talking about this via PM's - my thinking now is that the flow of air would be continuous, without any sort of control other than the speed of the car. At lower speeds, the airflow acts just like a blown flap would on a plane, allowing a steeper angle for the wing without the boundary layer separating and stalling. But then at high speeds, the effect of the blown flap is overcome and the wing then stalls. The point at which that happens could be adjusted then for each circuit as needed by limiting the maximum flow of air to the wing slots.

Of course, I don't know if physics really works that way, but it sounds good to me.

Checkered sent me these links, which are pretty interesting...

http://en.wikipedia.org/wiki/Blown_flap
http://www.tu-braunschweig.de/Medien-DB ... ngsten.pdf

...and this one, which made me laugh since I'd never have put the two together...

http://www.dyson.com/fans/

So I suspect that it isn't the oil cooler that McLaren are experimenting with today, but rather the flow to the wing.

[tok-tokkie]

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.

This comes from Wiki:Circulation Control Wing which seems to quite the reverse of what is suggested above.

A circulation control wing (CCW) is a form of High-lift device for use on the main wing of an aircraft to increase the lift coefficient. CCW technology has been in the research and development phase for over sixty years, and the early models were called Blown flaps.[1]

The CCW works by increasing the velocity of the airflow over the leading edge and trailing edge of a specially designed aircraft wing using a series of blowing slots that eject high pressure jet air. The wing has a rounded trailing edge to tangentially eject the air through the Coanda effect thus causing lift.[2] The increase in velocity of the airflow over the wing also adds to the lift force through conventional airfoil lift production.[3]
.....
The main purpose of the circulation control wing is to increase the lifting force of an aircraft at times when large lifting forces at slow speeds are required, such as takeoff and landing. Wing flaps and slats are currently used during landing on almost all aircraft and on takeoff by larger jets. While flaps and slats are effective in increasing lift, they do so at a high cost of drag.[3] The benefit of the circulation control wing is that no extra drag is created and the lift coefficient is greatly increased. It is being claimed that such a system could increase the landing coefficient of lift of a Boeing 737 by 150% to 250%, thus reducing approach speeds by 35% to 45% and landing distances by 55% to 75% and that such advances in wing design could allow for dramatic wing size reduction in large, wide body jets.[

Full entry *here*

Of course - on a F1 car the wing is inverted so instead of increased lift they are aiming for increased downforce.

[meves]

yeah i've been playing spot the difference and i see none

It took me a while but I've circled it for you.

[Pup]

Also, I think what we see in this image is that McLaren placed a line of flo-viz just below the blown slat in order to see how effective the flow of air actually is. You can barely make out the top of the slat, but it's clear that there is a gap in the flow-viz where the air from the slat would be blowing, and a heavier line of flo-viz where the boundary layer is separating.

[Tbox]

<ill informed aero ranting>

I seem to remember a bit part of the 'spirit' of the new diffuser rules was to de-couple the diffuser from the rear wing. Previously the flow from the diffuser went upwards at a very acute angle and this meant the rear wing could be much more efficient (and the wake behind the car more turbulent).

Looking at the flow-vis and the height of their double decked diffuser, it kind of looks like McLaren have managed to recouple their wing and diffuser... The air exiting from the oil cooler might help this...

[thestig84]

yeah i've been playing spot the difference and i see none

It took me a while but I've circled it for you.

I spotted that like i said. Its not a engine cover change though.