McLaren active wing

[albertobdq]

In my opinion it's a huge movement, with a bigger impact on aerodynamics than some guys may think. Do you remember the test at Montmelo with pitot sonds over the air intake?

I wrote something about that and the vortex effect some time ago, now I'm wondering if this device helps to sustain the vortex at any speed.

[glypo]

Lift or Downforce, it's exactly the same thing. Just depends whether you label Z negative or positive. I'm used to dealing with aircraft aerodynamics, not race car, so I'm sorry if I use the words interchangeably.

It's not really the chord that's of concern. It's more the alpha (angle of attack/incidence), when you have a movable or sprung section, under high speed load it will move back. This reduces alpha, reduces lift and thus when you resolve the vector you get less induced drag. It doesn't even need to be sprung or pivoted really, if it's flexible enough it will twist by it's own accord along the spanwise axis. This has the same effect. But this is all related to the actual wing sections, this is what Ferrari got into trouble about last season in one of the races. It's not related to guide control like the part in discussion.

It is these issues that the FIA have a problem with regarding movable aerodynamics. As I said early on, and also mentioned by other people, nothing is solid on a race car. Everything flexes under load, so it's just up to the FIA to determine whether a team is doing enough to ensure their aerodynamics are rigid. They have a set of deformation against load rules. If it was against the rules the FIA would easily pick it up.

Alberto - seriously what rules are you reading? Certainly not the FIA ones. There is nothing in the FIA rules about laminar or turbulent flow. Anyway I strongly disagree. The guide when moving with elastics like that will create a vortex flow. This itself will probably create more drag and turbulent flow than if it was solid. The guide is more likely to better place air into the engine intakes, move the air around the driveshaft and linkages better etc.

The type of drag you are talking about is profile drag, not induced drag. The purpose of moveable aerodynamics as I said above it to reduce induced drag. Induced drag is where the force created by the wing is taken perpendicular to the alpha angle, which isn't straight down the Z axis, as there needs to be a given alpha to generate force. Therefore when you resolve the vector you get your lift but also an induced drag component, the induced drag. This section of the front wing isn't producing a lift force by the looks of it, therefore it moving won't affect induced drag, as there isn't any induced drag to start with, only profile drag.

Having this device move in airflow gives no advantage that I can see compared to being rigid. Therefore it's not breaking any rules whatsoever pro diving its movement is in the FIA tolerances, and we can't exactly measure movement off the youtube video. And once again, who knows if it's even being used, the video was from a test session was it not? It might not ever be used at a race.

So summarise my points:

- It's not a traditional device that would be moved during aerodynamics (normally wing sections)
- The movement is aero-elastic rather than hinged or pivoted
- I can not see any advantages of it moving rather than being solid
- It doesn't appear to break any FIA rules

Without seeing any test data, or looking at the real thing or a tunnel model it's impossible to tell exactly. And everyone else would be the same. So who knows really.

And oops, I just realised how much I typed.

[albertobdq]

Hi man, I was thinking about Bernoulli principle and Reynolds numbers. Maybe that "trick" helps them ith this principles.

Vortex in cars with some kind of ground effect, is used to reduce presure below the car extracting air from beneath and enveloping the top of the car increasing pressure there. Some time ago they have some difficulties to mantain the vortex trough all the car lenght, now it seems they've successed.

When I look to nowadays F1 cars, with all the ventings and openings on their top surface I only can think about this. In the past exhaust were placed so they blow just on the diffusor tunels so they accelerate the air exiting the car and then increase ground effect. Today it seems they're using a different strategy, I'm not able to onder about anything but vortex effect.

[glypo]

Okay. Well as interesting as it is that you thought about Reynolds number and Bernoulli.... I'm not exactly sure how either of these relate to this part on the car.

Any kind of in ground effect aerodynamics in F1 is totally against the FIA rules. Anyway you have to consider any body that creates lift sheds a wake. In this case the lift is downwards, so the wake is shed moving with the freestream flow and upwards. And flow going over this part therefore will be affected by this wake, and move upwards, not down under the body.

[rich_cree]

Nice video

[albertobdq]

Ground effect is not banned, just limited from the shape, dimensions and ride height of the bottom of the car allowed by the rules, wich is not the same. Obviously far from what "wing cars" get, but still some thousands newtons of downforce.

I believe that the device over the front wing create some kind on chanel or "air restrictor" for the incomming air going trough the car. If you change the shape or dimensions of this chanel you change pressure/speed of the air over the car, doing this you can turn turbulent flow into laminar and so, reduce drag and/or create downforce. Furthermore, a laminar flow will make easier to achieve a constant vortex.

I'm just wondering...

[glypo]

Turbulent flow can actually reduce drag sometimes. The greater kinetic energy of turbulent air means that it follows boundaries for longer, and this can delay separation. This helps in getting the flow to go around objects laminar may not.

However to make vortices, you just use vortex generators, no need for complex devices like this. And laminar flow in fact makes worse vortices than turbulent, and nearly all vortices are turbulent flow anyway.

[TryHard]

To wade in on this.... that movement isn't being fully generated by the flexing of the bridge wing... it's being generated by the flex in the main plane of the wing.
Watch the video closely, and you'll see the outer lower elements of the wing flexing downwards. As the bridge wing is attached to the endplates, this also drops downwards, closer to the nose (which is the effect seen here). Given that also the span of the wing is also being streched (as the endplate will rotate slightly, rather than moving straight up and down), this exagerates the movement, effectively flattening the centre section.

Now, how is this legal? Simple, the FIA have a test where they place a specified load on the wing endplates, and the wing cannot deflect more than a certain dimension. If it passes the test, then quite simply it's legal. As the bride wing is attached to the endplates, if the lower wing passes, then the bridge wing passes too.

The whole idea of the bridge wings is to use the centre section to guide the flow to the rear wing, by directing the air flow in the best possible direction over the cockpit... whilst the outer sections generate some downforce for minimal drag.
McLarens seems to be the most extreme example (especially given it now uses a slot in the outer section). Renault for example have a strut to hold the centre section in place.

Regards
Ed

[rocketrob]

Originally Posted by albertobdq

Take a look at FIA rules again, then talk. It does not generate downforce? Please, review your aerodymanics notes.

If they truely want something to get in a huff over, then maybe they should look up some old 1960's videos of Chaparell (sp?) and McLaren CanAm cars of that era with their REAL movable/active wings.

[telboy]

Apparently, Mclaren say that this part broke on Hamiltons car just before he hit Alonso on sunday, which was the cause of his sudden increase in speed which made him hit the renault.
Apparently the loss in drag was enough to increase the acceleration.

http://www.formula1.com/news/headlines/2008/4/7615.html

If you look at the lower picture on this page ^^^ you can see that it has broen off of lewis's car.

So it must provide 'some' downforce.

[TryHard]

The thoery it broke just before the impact is quite suspect, as there's a few images from on the first lap that show his wing was already broken...

I'm still personally of the opinion that Alsono had a messy corner, and didn't get good traction out, and it simply caught Lewis out... but that may just be me

Ed

[telboy]

probably, I think they mention 2 seconds before the impact, but of course without video footage we'll never really know.
I'd love to see some incar footage from Alonso's car. So we can hear the sound. 'Cos Mclaren say that the renault telemetry suggest nothing.

Edit: I've just watched the video on the F1 site http://www.formula1.com/gallery/race/2008/789/ (right hand side of screen) You can see that he clouts the upper wing on the first corner into the back of the williams, then half way round the first lap it flies off. So he did a half lap without the upper plain. So I would have thought that if it effected the accel' that much, he would have planted it into the back of Alonso before the incident....unless he wasn't close enough to pick up a slipstream under accel'.

[TryHard]

cool video...
However, watch again, and reduce the time speed. Alonso is well out on the right, accelerating hard on the kerb... Lewis is in the middle of the track, on the racing line...

Wonder who has better traction

And at the speed they are going, the slipstream will be the grand total of naff all...

[telboy]

Either way, Mclaren haven't watched the video obviously. I think his wing broke a LOT more than 2sec's before the impact.

Just watched it again, what is ironic is that its Alonso that he gets into the back of to break the wing in the first place!!
But yes, Lewis does get a lot better line through the corners than Alonso. Alonso runs a little wide meaning that he technically has to turn the 'kink' into an actual corner...slowing his speed. Whereas Lewis just goes flat out through there, with no backing off. Pure racing incident by the looks of it.