DDDs in 2010

[Richard]

I started this as reply in a McL thread, but realised the topic is much more general than just one car, hence a new thread.

We saw most teams struggle to get their DDDs working on this years cars, so how will that feature evolve over this winter?

Some have suggested triple deck diffusers but my perspective is that we have two decks only because the rules require a surface at a set level. Also the loophole requires the supply to the upper part to come from a different source. AFAIK the split doesn't give a performance advantage in itself compared to a single diffuser of the same volume. The split could conceivably make them less efficient?

I can see that a third deck might be required if the teams tap into a third source for the air supply. Spatial reasons might require a separate deck to route the flow around an obstruction, ie suspension, drive train, crash structure etc.

Other factors will limit the development of the DDD. they need to be solved before the diffuser can significantly bigger. Brawn commented about the use of the DDD being more than just the diffuser - sorry ciro no ref, but is was a BBC interview at the track when McL jumped in performance.

Firstly, the DDD is an air exit route, so it needs a balanced air supply route. Then you can't change the under car air flow without having to rebalance the over car (and side) airflow. This results in a significant extra aero downforce on the rear which must surely mean you need to rearrange the other down and lateral forces to keep things in balance. That all requires the mechanical grip to be rebalanced, so that changes the suspension geometry and drive characteristics.

So it is not about who has the biggest or most decked diffuser, but who is able to incorporate in it in the most imaginative way.

[ISLAMATRON]

diffusers are much more effiecient at creating downforce(with less drag) than wings so they will make the diffusers as big as possible and produce as much DF as possible and balance it all out with taking out rear wing.

The air inlet for the secondary difusser(s) come from the verticle plane between the reference and step planes and that extends the length of the sidepods(which will probably be longer next year), so they have adequate area for air inlet.

[Giblet]

Moved my post from the Macca thread as well.


When the DDD first showed up, I asked on this forum how long people thought it would take before a team shows up with a TDD.

I was told that "The diffuser is just one area, it's not some magic device..."(sic) or "There is no way they will allow that loophole to be open next year" and lets not forget "You can't just slap an extra level of a diffuser on, it needs to be integrated in the initial design of the car to be effective...".

The response was overwhelmingly negative.

Looks like we all underestimated the impact this one area of the car would have, even eclipsing KERS as the must have piece of kit.

I foresee tighter integration of the diffuser into the rear wing, and I also predict a surprise in that area.

[compo]

[horse]

ive read on here a lot about how brawn ivented the double diffuser along with toyota and williams so i thought id clear it up

the DD was thought of by a designer at super aguri so obviusely all the designers there new about it and when they went bust some went to brawn some to toyota and some to williams thats why these 3 teams had it developed before the others had even heard of it

This article would slightly contradict you, saying that

... while it seems that Williams came up with the idea themselves.

[RacingManiac]

I was under the impression that DDD was used because of the reduction in diffuser size in the new rule that made diffuser less effective, such that the loop hole allows them to regain the lost volume. So regardless how many level you use, your goal is the same that you can provide as good as a underbody air exit for the car as possible. It wasn't that much of an issue before 2009.

[BreezyRacer]

The double diffuser was the natural outgrowth of the way the rules were written, and I would suspect that since it was the overtaking working group that came up with the wording, someone already had some designs on a double diffuser concept. That was really one sloppily worded rule. Just the part about "in plan view" there must be no openings visible .. I mean really .. who in motorsports design wouldn't read that and think .. hum, that's some interesting wording. how can I use that?

And reportedly RB asked for a clarification on it last year in the design stage. That was their fault .. they asked about it, rather than working within the wording of the rules.

You don't have to be a genius to figure it out. I think a lot of the evolution of the DD package was to take advantage of moving the downforce (low pressure area) further forward in the chassis. To that end, transmissions, et al had to be repackaged, which takes some time to do. Brawn went into the deal with a very streamlined tranny case, so from the start they were way ahead of the game.

[wesley123]

I am having alot of ideas of creating a huge diffuser, as the height isnt resticted in front of the diffusers end you can create an huge second deck, what my idea was is to create a aprtly third deck being driven by underbody and exhaust air. If im correct you want a fast flow speed as possible to gain an as low as possible air pressure under the car, so speeding up the air is a must and allowing the diffuser to move up more air is also important, how more air the diffuser can hold, the lower the pressure can be, my idea was to aloow the hot air to merge with underbody flow but the a bit further in the diffuser it turns into a TDD and the air is split up. By this you can get 'rid' of the underbody flow and also the hot airflow, as last named will speed up either sop the air will be sucked out of the car, enhancing cooling possibly reducing the need of cooling holes, resulting in smaller sidepods, wich will be a must next year.

Also placing the lower element of the rear wing lower on the car can enhance the diffusers flow.

I am making a car myself(it is actually done, but i didnt implement these ideas, it is actually pretty basic, but im trying to get it revolutionary)

[BreezyRacer]

I am having alot of ideas of creating a huge diffuser, as the height isnt resticted in front of the diffusers end you can create an huge second deck, what my idea was is to create a aprtly third deck being driven by underbody and exhaust air. If im correct you want a fast flow speed as possible to gain an as low as possible air pressure under the car, so speeding up the air is a must and allowing the diffuser to move up more air is also important, how more air the diffuser can hold, the lower the pressure can be, my idea was to aloow the hot air to merge with underbody flow but the a bit further in the diffuser it turns into a TDD and the air is split up. By this you can get 'rid' of the underbody flow and also the hot airflow, as last named will speed up either sop the air will be sucked out of the car, enhancing cooling possibly reducing the need of cooling holes, resulting in smaller sidepods, wich will be a must next year.

Also placing the lower element of the rear wing lower on the car can enhance the diffusers flow.

I am making a car myself(it is actually done, but i didnt implement these ideas, it is actually pretty basic, but im trying to get it revolutionary)

Wesley
You have to understand, that first, turbulence is your enemy. Just a little turbulence destroys your downforce, so introducing airflow from a cooling system is likely to destroy your downforce. Your cooling air will be flowing at a different speed than the airflow around it, creating the turbulence. second, a diffuser is merely a way of using the wake behind a vehicle to pull/speed up airflow under the car, thus creating the low pressure area.

The diffuser doesn't care whether it's a double, single, or triple design. It's all about using the wake area behind the car. F1 cars have gigantic wakes due to the rear wings, thus the diffuser designs in F1 can be more radical without incurring turbulence. Now if you have those double and triple element rear wings, then by all means copy what the F1 guys are doing. However, if you don't, be very gentle with your diffuser design because, again, a little turbulence is all it takes to destroy what you're trying to build.

[Richard]

The diffuser doesn't care whether it's a double, single, or triple design. It's all about using the wake area behind the car. F1 cars have gigantic wakes due to the rear wings, thus the diffuser designs in F1 can be more radical without incurring turbulence.

Does the higher rear wing give more space for the diffuser and a bigger wake than the previous lower wings?

So the OWG raising the height of the rear wing set it up perfectly for bigger diffusers? Is there spatial/aero scope to make the diffusers even bigger?

[BreezyRacer]

The diffuser doesn't care whether it's a double, single, or triple design. It's all about using the wake area behind the car. F1 cars have gigantic wakes due to the rear wings, thus the diffuser designs in F1 can be more radical without incurring turbulence.

Does the higher rear wing give more space for the diffuser and a bigger wake than the previous lower wings?

So the OWG raising the height of the rear wing set it up perfectly for bigger diffusers? Is there spatial/aero scope to make the diffusers even bigger?

Richard
I would imagine that the OWG raised the rear wing to try to separate the upper wing wake from the lower wing and diffuser wake, thus reducing the wake to make passing more possible. IMO, all the work the OWG did was wiped out by the DD diffuser "clarification". OTOH, RB would have totally trashed everyone in the field had the FIA banned the DD diffuser. It simply wouldn't have been a contest.

The DD diffusers, as they developed over the year, became more like tunnels than diffusers. Check out this very rare glimpse of the McLaren undertray/diffuser here ..

This is clearest example I've seen as to what the DD diffusers have evolved into. Notice how far forward in the chassis the diffuser/tunnel starts now that DD diffusers were legalized. In the past diffusers pretty much started at the axle center line area. Look at it now. Also you can imagine the sharp inlet edges on the floor, and if they didn't have all that low pressure wake behind the car this design would certainly be too turbulent to use. But as it is, the wake behind an F1 car is strong enough to keep the airflow uniform thru the entry of the tunnels of the DD diffuser. As an aside, notice the radiused tops on the McLaren tunnels. It's done in an effort to build a vortex in the tunnel.

[Richard]

Thanks Breezy, I've been searching for that pic for the last half hour! It is a real gem and I can't imagine the McL designers team were pleased to see their secret paraded for all to see.

I agree about the OWG comment, it seems the monster diffusers have filled the spatial gap created by moving the upper wing. Could the DDD work/fit with the old lower wings?

I guess the main thrust of the 2010 DDD development will be to open up that inlet to the tubes? Repackaged mechanicals to allow bigger tubes. Bigger tubes means bigger inlets, which means longer slot, which means moving the inlet and tubes forward. Possibly full width of that step ... not sure where the transmission would go!

Some have mentioned a full length slot but I'm not sure that would be right. They would need something more sculpted and directed to get the airflow working?

[BreezyRacer]

Yeah, that is one sweet pic! It's so telling. IMO, they will continue to work on packaging to get the tunnel inlets as far forward as needed. You can really see now how the whole DD diffuser changes everything. I mentioned before that I expect sidepods to be further forward in the chassis. That's not just for packaging. The further forward you move the sidepods the further forward you can move the low pressure area of the undertray. It wouldn't totally surprise me to see maybe a little tilt of the engines to allow the tunnels to begin sooner .. I don't know exactly where the maximum payoffs will be. But one thing is evident. These 2009 cars are somewhat compromised when it comes to optimal DD diffuser design. BTW, I don't think the whole full length slot idea would work. You're encouraging the airflow to change direction too much IMO. Remember turbulence is the enemy.

Of course next year the real fight will be to control car balance at min and max fuel levels. Moving the aero balance towards the center of mass will do a lot to help this.

BTW, The DD diffuser setup would work even better with the old wing setup because the wake was even stronger and lower on those cars.

[dp35]

Lots of great info in this thread, vey well illustrated by that McL floor pic.

I find it so irritating that the OWG's work resulted in massive car changes & costs to the teams, and much less visually appealing wings (they are NOT growing on me) - only to all be undone by their overlooking of this one detail. The result was a total failure to improve passing in F1. But if the FIA were to declare DDD's illegal for 2010, the OWG's work would not have been wasted. Instead it is.

Next - narrower front tires to reduce front grip, one year after the OWG mandated the snowplow front wings to increase front grip. I hope there's some logic in all of this that I'm missing.

[timbo]

It is a real gem and I can't imagine the McL designers team were pleased to see their secret paraded for all to see.

Why? Floor-défilé is a mandatory practice this year