McLaren MP4-28 Mercedes

[Pup]

Gary Anderson's take on the new MP4-28 FW and other problems.

http://img341.imageshack.us/img341/4236/macabcn.jpg
via AutoSport

Well, he's still beating that same horse, and I'm pretty sure it's still dead. On the other hand, he's managed to evolve his front wing theory from "Needz Mor!" into something that at least seems plausible, and I can appreciate that. Who knows, perhaps he's on to something after all - at least he's given us a decent argument as to why McLaren want to use a simpler wing, which is more than any of us have managed.

[Pup]

The issue with this exhaust ramp thing isn't whether it would help or hurt, because none of us can really know. This sort of thing comes up all too often, and the proper response, as always, is "Tell us why." I mean, just popping in and saying "Winning Car Has X: We Don't Have X: Therefore We Need X" just doesn't do much beyond fill up space on the page. At worst, it's bad logic. At best, it simply does nothing to further our understanding of the problem. So give us an argument as to why X might help, and it saves having to deal with another page full of "Does Too" and "Does Not". I can only roll my eyes so much before they start to hurt.

Someone, back at the beginning of testing, mentioned that the ramped cars do better on corner exit, and the unramped do better on entry. Maybe it was the other way around. Regardless, there was a valid argument at the time as to why - perhaps someone else remembers this? I think it was from an engineer interview.

One could also argue that a ramped exhaust would be better at placing the exhaust where you want, reliably - which seems to be part of McLaren's problem, so I do think the idea is worth discussing. Intelligently.

[ringo]

Why do we always assume equality with aerodynamic solutions?
The ramped exhuast is better. I've given my opinion in the exhuast thread in the aero section.
In summary there are less variables at play which results with it working optimally in a wider range of speeds.
It's more intricate a solution, but if done right is the better choice.
Think of a water park slide. Imagine a slide that carries you down into the pool. The other dumps you off 20ft above the pool.
Both are designed to land you on a tube, a target. The one that carries you down into the pools doesn't need much tuning or tweaking.
The one that dumps you off into the air needs to be tweaked to ensure you hit the target.
What happens if a gust of wind blows by. Or what if you went down the slide with a higher speed which one will be more likely to be thrown off target?
The ramp IMO simply has more control and is affected by less variables. It's harder to designed because of the flow around the car to be considered, but redbull and lotus have done a good job with that.

I'm not saying all this to say that mclaren's problem is the exhuast, i'm just saying changing solutions could be a positive step as well.
Right now their chassis is a mystery within an enigma. At least the mid fielders can blame it on their budget. haha.

[Pup]

I wonder if it's a question of theoretical vs practical optimization. The ramp may have begun life simply as a way to get the system working when you're playing catch up and don't have the time to work out and test the optimal design. But the interesting thing is how RB and the others so quickly caught up with McLaren last year (arguably leaving them in their dust mid-season). Perhaps they found that the ramped solution, while not optimal on paper, was actually able to produce more consistent results and therefore a better solution out in the wild. Meanwhile, McLaren - as they are wont to do - stuck with the theoretically better approach. There's bound to be some sort of killer vortex being produced by the McLaren method.

I admit that, from the armchair aerodynamicists view, the ramped solution seems the more reliable solution.

Or, perhaps I should just go catch up on those exhaust threads.

[wesley123]

Why do we always assume equality with aerodynamic solutions?

No one does that.

The ramped exhuast is better. I've given my opinion in the exhuast thread in the aero section.

And so is the McLaren/Ferrari style, on other points.

In summary there are less variables at play which results with it working optimally in a wider range of speeds.
It's more intricate a solution, but if done right is the better choice.
Think of a water park slide. Imagine a slide that carries you down into the pool. The other dumps you off 20ft above the pool.
Both are designed to land you on a tube, a target. The one that carries you down into the pools doesn't need much tuning or tweaking.
The one that dumps you off into the air needs to be tweaked to ensure you hit the target.
What happens if a gust of wind blows by. Or what if you went down the slide with a higher speed which one will be more likely to be thrown off target?
The ramp IMO simply has more control and is affected by less variables. It's harder to designed because of the flow around the car to be considered, but redbull and lotus have done a good job with that.

The exhaust gasses isnt everything, You also have the coke bottle for example. While I agree that the Ramped exhaust does a better job on getting the exhaust plume where it needs to be a downside is the air around the sidepod. The guys running the ramped sidepod are limited to a 5cm high tunnel. That gives significantly less area around the sidepods to get in between the gearbox and rear wheel.

I'm not saying all this to say that mclaren's problem is the exhuast, i'm just saying changing solutions could be a positive step as well.

If it was the case last year I'd agree, by the time McLaren now have a functional ramped sidepod(and not to mention a good working one) the season is pretty much over so it would be lost anyways. Also the coanda exhausts are of no use next year when the Exhausts have to be relocated further back and inwards.

[henra]

The redbull design would help them. It would help all cars not using the design. It's simply a better solution.
F1 cars are quite modular.

I'm not so sure it would help them without further modifications.
The Ramp/Tunnel solution makes me feel that it is not particularly well suited to an agressive High Nose design.
Those are normally rather optimised for maximum flow around the sidepods and unobstructed coke bottle similar to Ferrai (and Merc to some extent).
The Ramp / Tunnel solution isn't really favouring a strong undercut flow around the sides as this would lead to slow flow / high pressure in front of the tyres increasing cross flow over the ramp, which would disturb the ramp flow to the diffuser.
The tunnel can only take a quite limited mass flow due to the diameter and length of the tubing.
So I'm not sure copy/paste is a good idea in all cases with the Ramp/Tunnel solution. That said, I tend to think that the max On- Throttle downforce effect of an optimised Ramp/Tunnel solution could be superior to the Bulge/Coke Bottle Solution. The Trade- Off should be drag and Off- Throttle Downforce. (RB mitigates the latter with a very clean flow to the diffuser over the sidepods).
The On- throttle downforce advantage trumps Off- Throttle downforce a bit insofar as it improves traction out of the turns. This gives a benefit over the whole subsequent straight as well, whereas Off- Throttle downforce only helps during the first part of the turn itself.

[trinidefender]

One thing makes me think that the ramp/tunnel solution may work better on the mp4-28.The updated side pods seem to be designed to have more flow over the top rather than around the sides (which is what other teams seem to be going for). As a result the tunnel will not have to deal with as much airflow as say on the Red Bull. While having the apparent (what seems to be) advantage of a more accurate exhaust flow.

However this will not happen, at least not this season. As doing all the math and testing on a ramp/tunnel combination will take far to long and will not come out any time this season, assuming they have not been working on it in secret for a while.

[ringo]

The redbull design would help them. It would help all cars not using the design. It's simply a better solution.
F1 cars are quite modular.

I'm not so sure it would help them without further modifications.
The Ramp/Tunnel solution makes me feel that it is not particularly well suited to an agressive High Nose design.
Those are normally rather optimised for maximum flow around the sidepods and unobstructed coke bottle similar to Ferrai (and Merc to some extent).
The Ramp / Tunnel solution isn't really favouring a strong undercut flow around the sides as this would lead to slow flow / high pressure in front of the tyres increasing cross flow over the ramp, which would disturb the ramp flow to the diffuser.
The tunnel can only take a quite limited mass flow due to the diameter and length of the tubing.
So I'm not sure copy/paste is a good idea in all cases with the Ramp/Tunnel solution. That said, I tend to think that the max On- Throttle downforce effect of an optimised Ramp/Tunnel solution could be superior to the Bulge/Coke Bottle Solution. The Trade- Off should be drag and Off- Throttle Downforce. (RB mitigates the latter with a very clean flow to the diffuser over the sidepods).
The On- throttle downforce advantage trumps Off- Throttle downforce a bit insofar as it improves traction out of the turns. This gives a benefit over the whole subsequent straight as well, whereas Off- Throttle downforce only helps during the first part of the turn itself.

One thing i've never heard mentioned from any article is the total flow going around the gearbox. I'm quite annoyed by this "coke bottle" talk. It's very simplistic a view. The flow is three dimensional. The flow going around the gearbox first and foremost is most critical to the beam wing, bewteen tyre and end plate and the top of the diffuser. That area the ramp exhuast is using, isn't the majority of the flow going to the rear of the car, neither is it the quality flow.
The mclaren solution is in fact just as much an obstruction. It obstructs the mid height. The redbull solution is in the best area, closer to where the slowest, lowest quality flow is, which is near the ground. It obstructs where the flow quality is at it's poorest. It's not obstructing the higher heights where beam wing flow and diffuser gurney flow is critical.

I don't think we have any substantial evidence to say how either solution works in a corner. What is most obvious is that one has less variables to account for. So i can't speak to any on or offthrottle effects. What is certain is that if there is a headwind, the mclaren solution will overheat the tyres as the exhuast flow will land further back. I can only speak to the relative speeds between car, wind and exhaust.

edit: to add to the "coke bottle" (hate that word! ) flow thing, redbull's sidepods and lotus have a certain design feature i'm still yet to divulge, but there is a stronger downwash on these side pods. Bring flow from upwards down over the diffuser. So as i said, think in three dimensions, don't assume all flow is coming from the flanks of the car.

[henra]

edit: to add to the "coke bottle" (hate that word! ) flow thing, redbull's sidepods and lotus have a certain design feature i'm still yet to divulge, but there is a stronger downwash on these side pods. Bring flow from upwards down over the diffuser. So as i said, think in three dimensions, don't assume all flow is coming from the flanks of the car.

That is exactly the point I have been trying to make a couple of times. Please read back if you didn't notice it, seems I dind't get my theory across...
The RB philosophy with their relatively low nose seems to be directed at getting more air over the sidepods of the car to the diffuser over the whole width.
While Ferrari with a very high nose and rather high bulge and open coke bottle (there it is again ) seems to try to get the air mostly around the sides to get the flow towards the diffuser. They seem to use the slopeback on their sidepods more to get the exhaust down to the diffuser. close to the gear box both flows should re- merge.

McLaren has a more highish nose trapping lots of air underneath. That is why I don't think the ramp/tunnel will work 'Out of the Box'.

[turbof1]

edit: to add to the "coke bottle" (hate that word! ) flow thing, redbull's sidepods and lotus have a certain design feature i'm still yet to divulge, but there is a stronger downwash on these side pods. Bring flow from upwards down over the diffuser. So as i said, think in three dimensions, don't assume all flow is coming from the flanks of the car.

That is exactly the point I have been trying to make a couple of times. Please read back if you didn't notice it, seems I dind't get my theory across...
The RB philosophy with their relatively low nose seems to be directed at getting more air over the sidepods of the car to the diffuser over the whole width.
While Ferrari with a very high nose and rather high bulge and open coke bottle (there it is again ) seems to try to get the air mostly around the sides to get the flow towards the diffuser. They seem to use the slopeback on their sidepods more to get the exhaust down to the diffuser. close to the gear box both flows should re- merge.

McLaren has a more highish nose trapping lots of air underneath. That is why I don't think the ramp/tunnel will work 'Out of the Box'.

Yet Torro Rosso has a nose comparable to the level Ferrari has, they brought an exhaust ramp to Barcelona, and that worked beautifully for them.

It could work out too for McLaren, but only after they are able to keep the DF level consistent. Bolting it on now will never bring any benefit. I highly doubt they will go for it anyway. If they can't fix the car within a few races, they will drop this year. If they can, it'll be highly unlikely to will change concepts which have no use next year.

[raymondu999]

Someone, back at the beginning of testing, mentioned that the ramped cars do better on corner exit, and the unramped do better on entry. Maybe it was the other way around. Regardless, there was a valid argument at the time as to why - perhaps someone else remembers this? I think it was from an engineer interview.

Ooh! Pick me! Pick me!

Thread: http://www.f1technical.net/forum/viewto ... =6&t=14500

An excerpt from the latest edition of Autosport magazine. It's Tim Goss talking about exhausts:

“For 2012 we did look at what Red Bull eventually ran,” says Goss. “We termed it the ‘slopey top deck’ but we found significant negatives to it. It was difficult to feed the diffuser ramp and starter hole, so we then looked at the tunnel arrangement to help with that but we found greater benefit using our extreme undercut to drive the diffuser and starter hole. It’s two different approaches to the same thing.”

I think what's important should be to not fall into the category trap of "Tim Goss tested both solutions, and he found the semi-coanda better than the ramp/tunnel, so that must be better." The exhaust, especially being something that far downstream in the car, would probably be very dependent on the car's sidepod, front wing and diffuser philosophies. Perhaps this coanda bulge design doesn't work as well on the Red Bull's sidepods, for example.

The following is an excerpt from Mark Hughes' MPH column in the 28 February edition of Autosport:

Ross Brawn, who said: “Maybe their exhaust solution [regarding rear-bodywork design] was based on the idea that there would be more leeway with the mapping. [The Renault-engined] Red Bull’s and Lotus’s solution is problematic off-throttle, because in off-throttle mode there is less blowing from the exhaust and therefore less downforce contribution by the exhaust, which means that one has to rely more on the Coke bottle [profile of the rear bodywork]. But the Coke bottle on the Red Bull and Lotus is less pronounced because of their ramp behind the tailpipe. Therefore, their solution is inferior at corner entry compared to the solution pioneered by McLaren, and which all the teams except Red Bull and Lotus followed. It’s possible that they wanted to compensate with clever engine mapping.”
The design choice of exhaust layout is essentially whether or not to compromise the extent of the Coke bottle-style cut-in of the rear lower bodywork by partially blocking it with an exhaust-exit ramp that allows you to target the exhaust flow over the downforce- producing components to better effect. You can either have a McLaren-style sharply-defined Coke-bottle section that enhances the speed of the airflow along the flanks and over the brake ducts and diffuser top, but with compromised exhaust-enhanced downforce. Or you can go the Red Bull route and have ideal exhaust positioning at the cost of compromised airflow from the Coke-bottle section. This would be expected to give you superior downforce to the McLaren layout on-throttle but less off-throttle.

An excerpt from the April 2013 edition of Racecar Engineering:

Most teams on the grid have followed McLaren's lead on exhaust design, but Lotus and Red Bull have pursued an alternative layout featuring tunnels under the exhaust exit. Goss argues that this approach is not as good as McLaren's. "We tried it back in 2011," he said. "There are some significant negatives to doing it in that it becomes very difficult to feed the central diffuser ramp and the starter hole, and sure enough we looked at the Red Bull solution. But we found greater benefits using the concept we launched last year, where you have quite an extreme undercut running through that area which is used to drive the diffuser and the starter hole. Fundamentally it's two different approaches to the same issue. The thing is you have to make sure that when the exhaust gases are not flowing, the rear end of the car is still behaving itself."

[Pup]

Well. There you go.

I guess if Brawn says it is so, then it is so.

Which returns us to the question of whether McLaren might be better off adopting the ramps. I mean, if you take Brawn's comments as truth, then you have to wonder why Newey has stuck with his solution. He's not shy to copy others if there's an advantage and he has the resources to do it.

Given that McLaren were working on this for at least a year, according to Goss...

I wonder if it's a question of theoretical vs practical optimization. The ramp may have begun life simply as a way to get the system working when you're playing catch up and don't have the time to work out and test the optimal design. But the interesting thing is how RB and the others so quickly caught up with McLaren last year (arguably leaving them in their dust mid-season). Perhaps they found that the ramped solution, while not optimal on paper, was actually able to produce more consistent results and therefore a better solution out in the wild. Meanwhile, McLaren - as they are wont to do - stuck with the theoretically better approach. There's bound to be some sort of killer vortex being produced by the McLaren method.

Perhaps the difficulty in getting air to the diffuser isn't as bad in practice, or perhaps the advantage of a precise exhaust path is greater?

At this point, I think I'd have to vote 'yes' on the ramps - there's a point where you've got to cut your losses and get on with a solution that works, even if it isn't optimal.

[SiLo]

I thought it was inferior because when the car is in Yaw, one side of the sidepod is deprived of air moving around the coke bottle, but the Mclaren solution somewhats counteracts this with the amount of air moving through that area. The Red Bull version becomes a lot more choked, multiplied when off throttle.

[bonjon1979]

Well. There you go.

I guess if Brawn says it is so, then it is so.

Which returns us to the question of whether McLaren might be better off adopting the ramps. I mean, if you take Brawn's comments as truth, then you have to wonder why Newey has stuck with his solution. He's not shy to copy others if there's an advantage and he has the resources to do it.

Given that McLaren were working on this for at least a year, according to Goss...

I wonder if it's a question of theoretical vs practical optimization. The ramp may have begun life simply as a way to get the system working when you're playing catch up and don't have the time to work out and test the optimal design. But the interesting thing is how RB and the others so quickly caught up with McLaren last year (arguably leaving them in their dust mid-season). Perhaps they found that the ramped solution, while not optimal on paper, was actually able to produce more consistent results and therefore a better solution out in the wild. Meanwhile, McLaren - as they are wont to do - stuck with the theoretically better approach. There's bound to be some sort of killer vortex being produced by the McLaren method.

Perhaps the difficulty in getting air to the diffuser isn't as bad in practice, or perhaps the advantage of a precise exhaust path is greater?

At this point, I think I'd have to vote 'yes' on the ramps - there's a point where you've got to cut your losses and get on with a solution that works, even if it isn't optimal.

i suspect it has something to do with the engine and the way exhaust gases are produced. Williams went the ramp route having switched to Renault engines. didn't work out too well for them but there's definitely a pattern there.

[stefan_]

Monaco 2013 - Wednesday (22.05.2013)



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