Possible advantages of Red Bull Racing's matte paint

[J.A.W.]

Mark Webber, who knows Newey well and still has strong links to RedBull, reckons that the only reason that matte finish is on the car is because of performance.

He reckons it had to be approved by Dietrich who didn't like it but approved it anyway.

djos, is that an actual quote of what M.W. said?

& did he offer some proper technical data, or just a bland adjective.. "...performance."?

[SamCrawford]

From what I could tell the Renault is of a similar satin finish

[djos]

Mark Webber, who knows Newey well and still has strong links to RedBull, reckons that the only reason that matte finish is on the car is because of performance.

He reckons it had to be approved by Dietrich who didn't like it but approved it anyway.

djos, is that an actual quote of what M.W. said?

& did he offer some proper technical data, or just a bland adjective.. "...performance."?

That's what Mark said on the local channel 10 telecast. He said he believed it was for drag reduction but he also couldn't say that was 100% the case.

[J.A.W.]

Watching the recent race at Monte Carlo, in the wet/road-grime conditions, it appeared notable ( on TV at least)
that both the Williams Martini pearl gleam & Red Bull bright 'pop' finish schemes shone through, seemingly unimpaired..

[pierrre]

That is rubbish from Tedd as usual.

That paint you see is called "Frozen." It is not really matte finish as some people are saying, but a special clear coat with micro particles in it that traps light that gives that dull gleam effect like a frozen glass.

You might be right. I'm still a bit torn on this subject.
The 'Matte' finish would support a very thin turbulent boundary layer. This is in general inferior to a perfect laminar flow. That said, any imperfection on a high gloss surface (Gap between panels, Carbon weave shining through, etc.) will cause separation. In this case the air doesn't re-attach quickly and the drag will be higher than with a controlled thin turbulent boundary layer. Therefore they could possibly use less filler and/or achieve a little bit less drag. But it is really difficult to judge if in a real car with all its imperfections this would be a net loss or gain.
Having followed RBR's approach in the last years I'm somewhat tempted to believe they are simply trying this.
With the nice additional benefit of a bit of PR (which is also not completely unknown to RBR).

with platinum zealot here, with this argument, the thin turbulent layer as you pointed out would have negative effect on sticking with surfaces. this may result in less effective outer wing, blades or turning vane surfaces in producing vacuum as it needs to stay attached as much as possible for its purpose

[jjn9128]

with platinum zealot here, with this argument, the thin turbulent layer as you pointed out would have negative effect on sticking with surfaces. this may result in less effective outer wing, blades or turning vane surfaces in producing vacuum as it needs to stay attached as much as possible for its purpose

? turbulent boundary layers adhere better to surfaces especially ones with adverse pressure gradients, it's why we use vortex generators to prevent flow separation. Transitional and turbulent flow states are also part of the linear force enhancement region of a lift/alpha curve so turbulence does not adversely impact the negative pressure.

Is there a supposition that the boundary layer on the car is laminar otherwise? The transition Reynolds number on a flat plate is 5e5; even a front wings state of flow is turbulent as Re at 50mi/hr is 1.15e6 - and that's ignoring the effect of adverse pressure gradient in creating a thicker boundary layer.

There will be a slight increase in skin friction from a "rougher" surface, but that's such a small part of the overall drag of an F1 car - the biggest sources being the separated flow behind the wheels, then the induced drag from the wing tips and all the little vortex generators, then the cooling flow.

[Just_a_fan]

Glad you said that. Much better than I was going to post.

[pierrre]

with platinum zealot here, with this argument, the thin turbulent layer as you pointed out would have negative effect on sticking with surfaces. this may result in less effective outer wing, blades or turning vane surfaces in producing vacuum as it needs to stay attached as much as possible for its purpose

? turbulent boundary layers adhere better to surfaces especially ones with adverse pressure gradients, it's why we use vortex generators to prevent flow separation. Transitional and turbulent flow states are also part of the linear force enhancement region of a lift/alpha curve so turbulence does not adversely impact the negative pressure.

Is there a supposition that the boundary layer on the car is laminar otherwise? The transition Reynolds number on a flat plate is 5e5; even a front wings state of flow is turbulent as Re at 50mi/hr is 1.15e6 - and that's ignoring the effect of adverse pressure gradient in creating a thicker boundary layer.

There will be a slight increase in skin friction from a "rougher" surface, but that's such a small part of the overall drag of an F1 car - the biggest sources being the separated flow behind the wheels, then the induced drag from the wing tips and all the little vortex generators, then the cooling flow.

could be mistaken but think there is a big difference between vortex generators, rough surfaces and between vortex and general turbulence. when air flow detaches it creates turbulence. vortex generators are blades that are designed to try and avoid vertical airflow and instead design an intended turbulent starting with side forces

rough surface in general would have shapes that encourages airflow to go vertical as well probably one of the reason why you point out drag..in general would be shaped with more symmetry than vortex generators.

ferrari rear wing looks to have rough surface on top but smooth below. right click on the picture and select open image in new tab for higher resolution



what would be interesting though are those shark skin surfaces, definitely an area to be explored

[strad]

ferrari rear wing looks to have rough surface on top but smooth below.

I don't know to me it looks like the way the light strikes the surfaces.

[jjn9128]

Bottoms of wings are both critical surfaces and generally not visible to viewers so are left uncovered - both a weight and boundary layer consideration - they don't want to add a potential trip. Wings are worked particularly hard compared to bodywork (peak pressure coefficients in excess of -3/-4 vs maybe -1 peak around the body but more like -0.2 on average) so are near the separation point or are partially separating anyway, transitioning earlier will start the separation process sooner which could cause some balance issues.

There's also the issue of stone chips, if you add paint or other coverings then the chip gets bigger and can cause issues, but then we're talking 2/3 orders of magnitude bigger than any surface finish effects. See that the wrap/sticker starts a little downstream of the stagnation point.

[pierrre]

was reading on iced wing build up. it's earliest stage which has a surface like sandpaper effecting wing stall speed increased by ten to twenty knots from loss of lift, however, this build up is mostly on the front opening shape of a wing



those reynolds numbers blinded me for a moment. on red bull, they've got the whole car on what looks like a rough surface finish even on areas that is not beneficiary where it will only amount to drag like the front nose, wing element and blade angle that build up pressure such as the approaching angle of the bargeboards

we could speculate that having low drag surface in areas to influence, clean and speed up airflow towards more important aero areas would be the aim yet it does not look to be the case. they've got the whole car matt. so platinumzealot may have a point that the paint is smooth after all. and on cars like the m-amg, they've got the whole car all glossy and don't seem surface critical. in fact, none of them seem to be surface critical

[Just_a_fan]

If RedBull's surface finish choice caused a net reduction in performance (more drag or less downforce for example) then it wouldn't be on the car.

Ergo, it's performance neutral (my guess) or beneficial.

[jjn9128]

On icing, skin friction is a muuuuch higher proportion of total drag in aircraft than F1. I mean look at the camber of an F1 wing vs an aircraft even in takeoff/landing. Aircraft don't have big bluff cylinders rotating in the airstream at all times. Also it is again many orders of magnitude rougher than any different surface finish on an F1 car - more in the order of stone chips as I mentioned.

[Just_a_fan]

Ice on aircraft wings adds drag (bad), reduces lift (bad) and increases overall weight (bad as it compounds the loss of lift). At just under a kilo per square metre, the weight of ice soon adds up - on a light aircraft e.g. Cessna 172, a 1mm layer of ice over the wing (16m^2) could be c.2% of the weight of the aircraft.

[PlatinumZealot]

Interesting information, JAF.

I bet the Red Bull Matte paint is smooth to the touch. They don't want it to be rough, or else tyre debris will stick to it and cause problems. The satin look is just the optical properties of the paint, I suspect. The main advantage I would say of this paint, is that it is lighter than full gloss?