Investigating exhaust aided diffusers

[DaveW]

vonk: I can accept your argument, but would be happier if it explained the observable performance advantage enjoyed by the RB over the rest of the field through high speed (power on) turns.

[vonk]

vonk: I can accept your argument, but would be happier if it explained the observable performance advantage enjoyed by the RB over the rest of the field through high speed (power on) turns.

DaveW: I believe the reason for RB’s superior performance is the sum total effect of meticulous optimization of every feature. For instance, notice the different cut of the trailing edge of the outboard separators compared to the inboard separators of the exhaust segments. Notice how the bottom edges of the separators curl outboard. Look how the (blue) trailing edges of the side plates curl inboard. If RBR have the sensitivity for such detail, they are probably equally careful with the wing, as well as everything else. I can’t believe that their superiority is due to just one feature.

[ringo]

I think the exhaust opens into the upper deck of the diffuser. Remember the lower one is basically maximized dimensionally by regulations.
The upper part being much steeper would benefit better from energizing from the exhaust.
One of the problems i think the team engineers had to deal when designing the DDD is the steepness and the separation associated with it. Mclaren pushed theirs to the limit and had to use flow vis to ensure the flow was as expected.
The RB DDD it's seemingly small size and it's shape, could be due to the aid from the exhaust. It's probably packing more punch than the others in terms of performance, and may have a bigger internal area.

[DaveW]

DaveW: I believe the reason for RB’s superior performance is the sum total effect of meticulous optimization of every feature.

I'm sure you are correct about meticulous optimization, but I'm equally sure that RB is not unique in that respect.

You might like to think about this.

[Belatti]

...

RBR's clear performance advantage (assuming it has an aero source) implies that they have found a way of lowering the average ride height, thus increasing the effective expansion ratio of the diffuser...

At the beggining of the season everyone was mentioning the fact that the red bull could change its height. Couldnt be proved.

I would like to see a dimentional comparison of several F1 cars ride heights at high speed and standing still, because the Red Bull seems not that low to me, at least when its standing still (It can be the sidepod shape and the black tray after them, I dont know).

What if they simply use a lower than others or even variable ride rate tuned with its corresponding damping and calculated in such a way the suspension compression optimizes the effective expansion ratio of the diffuser?

Can that be achieved? Dave you tell us you are the suspension expert!

And what about the hot air canon shoting low density air just below the rear wing? That is way more clever than the stupid grill Ferrari has...

[Belatti]

The wet wheel diameter is aprox 670mm. That give me and aprox ride height of 85mm. Isnt that too much?

[Belatti]

This motion pic gives me about the same 85mm with the 660 slick tyre

[xpensive]

Nice picture that last one, is that the exhaust we can see on the side there, just ahead of the rear wheel, under the pull-rod?

[vonk]

I'm sure you are correct about meticulous optimization, but I'm equally sure that RB is not unique in that respect.

You might like to think about this.

I guess I left out the most important part of RBR’s meticulous optimization: Adrian Newey.

Thanks for the pointer to the Coanda Effect. I can see how people are thinking about it in connection with blown wings, but can you imagine it as an exhaust blown device?

[DaveW]

What if they simply use a lower than others or even variable ride rate tuned with its corresponding damping and calculated in such a way the suspension compression optimizes the effective expansion ratio of the diffuser?

Can that be achieved? Dave you tell us you are the suspension expert!

Mmm. An over-used word, expert. Somebody who knows a little more than some about much less than most? OK, that might fit. Anyway, the answer to your question is yes. Rising rate springs (or spring/bump rubber combinations) coupled with rebound-biased damping will lower the "running" ride height of a vehicle. The strategy has been used in many aero-dominated series (most famously NASCAR) that have to overcome a minimum static ride height rule.

I guess I left out the most important part of RBR’s meticulous optimization: Adrian Newey.

Adrian is (I think) the most experienced active designer in F1 by a margin. He has probably been responsible for more successful F1 vehicles than any other current designer, but he has also been responsible for an F1 vehicle that made the test track, but not the start grid. His love, & expertise, is aerodynamics & he has a history of trying to harness the engine exhaust (a huge source of energy) to improve the aerodynamic performance of his vehicles. He would probably be quite flattered to hear that he has the reputation for fathering designs that are just reliable enough (in a good year, his detractors might add).

I admire Adrian. He is meticulous about optimization, particularly aerodynamic optimization, to an extent that he will compromise other aspects of a design. But I admire him most for his lateral thinking & his fearless pursuit of radical solutions. That is, I think, the primary reason he has been successful & is also the reason he has made the occasional monumental bloomer. Colin Chapman was fond of saying "when you find yourself in a queue of traffic, you are driving in the wrong direction" - a profound observation that Adrian would agree with, I think.

My conclusion: if you want to understand a Newey vehicle, start with what is different. It is likely to be that way for a reason...

[marcush.]

it surely is not reality when stating Neweay is the only one so long in the business..but we have to realise he was from day one supposed to be the hot ticket but I´m sure he is not easy to handle over time as a team.
It seems at RedBull he found a niche for himself and with this RBR 5,6 line of cars he has shown again he still is on top of his game ,which is a big contrast to the likes of Murray or Barnard ..their designs someday stopped to push the boundaries in the right direction and so could not be class of the field anymore.Not Newey the guy is driven by something..

[autogyro]

This motion pic gives me about the same 85mm with the 660 slick tyre

It is Belatti but only if the car had push rod suspension and a conventionaly mounted disc calliper. It has pull rods and bottom mounted callipers that give an interesting force reaction through the hub geometry.
The ride hight shown will change under acceleration and under braking, due to the wider and far better control over squat and dive. The whole floor presents a wedge to the airflow under braking but levels out under power.
This is why the DF range available is more useful in faster corners and more compromised and sudden in slower ones.
IMO of course, what would I know about aero!!

[shamikaze]

I have always failed to understand why the brake-callipers are mounted the way they are on most F1 cars.

Last year, BrawnGP had them on the bottom of the brake-disc as well, and this year they seem to have repositioned them back. It was actually one of "the" things I looked for during the presentations of the cars in the winter.

I would think the benefist would be 3-fold:
* Lower overall CoG + lower CoG of unsprung-mass, which counts extra + centrifugal forces being placed lower to the group which I could image would aid in grip levels.
* Better aerodynamic placement for cooling purposes

GReetz,

S.

[vonk]

I think the exhaust opens into the upper deck of the diffuser. Remember the lower one is basically maximized dimensionally by regulations.
The upper part being much steeper would benefit better from energizing from the exhaust.
One of the problems i think the team engineers had to deal when designing the DDD is the steepness and the separation associated with it. Mclaren pushed theirs to the limit and had to use flow vis to ensure the flow was as expected.
The RB DDD it's seemingly small size and it's shape, could be due to the aid from the exhaust. It's probably packing more punch than the others in terms of performance, and may have a bigger internal area.

Is there any place I could find a cross section of a DDD?

My assumption that the exhaust goes into the lower deck derived from this picture:

[BreezyRacer]

Is there any place I could find a cross section of the DDD?

My assumption that the exhaust goes into the lower deck derived from this picture:

Yes, just check the program guide for Turkey which has complete specs along a Solidworks CAD file