McLaren MP4-29 Mercedes

[basti313]

Well you were the one trying to discuss the placement of the suspension, which in turn complicates the discussion.

Did I? I only wanted to explain, that Boulier's statement for me has nothing to do with the aero.

The (latest) discussion started from the simple point, that the car is slow because of the butterflies which compromise everything. And this is just wrong for me:
-They could use a cooling solution without looking at the butterflies if it would be more efficient even with the butterflies on as they do not affect the exit of the air aerodynamically and, thus the cooling inside of the car.
-They could use flat wishbones if the downforce/drag ratio produced would not be worth keeping them without compromising anything else but rear downforce.

And now the interpretation, why they used it in China, like it was in China:
-The test without butterflies and the data gives them a good downforce/drag ratio.
-Aiming the cooling on the butterflies gives more advantage by better downforce than disadvantage by aiming the cooling.

What I think they will be doing:
Possibility one:
-They will keep the butterflies as they have a good downforce/drag ratio and do not compromise the suspension too much.
-They will perhaps compromise the coke bottle shape to get the cooling air exits deeper, like RB or Merc do.

Possibility two:
-The butterflies compromise the rear suspension too much. Thus they need a new rear axle, new mounting points...this may only be done in 4 races with new gearboxes...

[Lazy]

I'd say you could get a FW neutral section in there.

[turbof1]

Well you were the one trying to discuss the placement of the suspension, which in turn complicates the discussion.

Did I? I only wanted to explain, that Boulier's statement for me has nothing to do with the aero.

The (latest) discussion started from the simple point, that the car is slow because of the butterflies which compromise everything. And this is just wrong for me:
-They could use a cooling solution without looking at the butterflies if it would be more efficient even with the butterflies on as they do not affect the exit of the air aerodynamically and, thus the cooling inside of the car.
-They could use flat wishbones if the downforce/drag ratio produced would not be worth keeping them without compromising anything else but rear downforce.

And now the interpretation, why they used it in China, like it was in China:
-The test without butterflies and the data gives them a good downforce/drag ratio.
-Aiming the cooling on the butterflies gives more advantage by better downforce than disadvantage by aiming the cooling.

What I think they will be doing:
Possibility one:
-They will keep the butterflies as they have a good downforce/drag ratio and do not compromise the suspension too much.
-They will perhaps compromise the coke bottle shape to get the cooling air exits deeper, like RB or Merc do.

Possibility two:
-The butterflies compromise the rear suspension too much. Thus they need a new rear axle, new mounting points...this may only be done in 4 races with new gearboxes...

For the record, I also believe the suspension works for them; it's not that that I'm having an issue with. I actually agree with everything here. I also agree that at the current car they probably have the most efficient solution.

You know good enough that's not where I disagree .

http://s29.postimg.org/jscd4yviv/mp4_29_above.jpg

I'd say you could get a FW neutral section in there.

Yeah, you could fit the width of it there. But not the length. The picture also gives the impression the suspension bones are the back end of the endplates, which completely isn't: they end on top of the diffuser. Granted, 10cm is too short, but it'll be around 20-25cm.

[basti313]

You know good enough that's not where I disagree .

i made my point clear, so maybe you just do the same not that we run into useless discussions. Because after the answers in the second to last post I really do not see your point anymore.

http://s29.postimg.org/jscd4yviv/mp4_29_above.jpg

I'd say you could get a FW neutral section in there.

Yeah, you could fit the width of it there. But not the length. The picture also gives the impression the suspension bones are the back end of the endplates, which completely isn't: they end on top of the diffuser. Granted, 10cm is too short, but it'll be around 20-25cm.

I made my estimation with the rear wheel. Maybe 3/4 of the wheel diameter is too much, but it is more than half, isn't it?

And the pressure is influenced by the temperature of the air which has been used to cool components. CFD has a very hard time with that.
........
What the hell? Are you trying to compare the front wing, which hits unaffected mainstream air, with the cooling air hitting the butterfly suspension? I think this is the f1sciencefiction you mentioned: mainstream neutral pressure air = hot, high pressure and very turbulent air. In a world where increasing AoA will reduce drag .

I totally agree, that the CFD simulation is not precise because of the hot, turbulent air and that the pressure zone of a front wing in clean air is different.

But why do you think pressure zone is larger than CFD estimates? What is the physical explanation for that?
For me this is total nonsense. If we have turbulence the pressure zones are smaller and this is normally not questioned as cars loose downforce in turbulent air for example.

[turbof1]

But why do you think pressure zone is larger than CFD estimates? What is the physical explanation for that?
For me this is total nonsense. If we have turbulence the pressure zones are smaller and this is normally not questioned as cars loose downforce in turbulent air for example.

That's an assumption you made on your part. I only assume the cfd wouldn't predict it accurately; I can't make assumptions about whether it's higher or lower. Again, CFD has issues with getting close to reality when temperature plays a role.

If we have turbulence the pressure zones are smaller and this is normally not questioned as cars loose downforce in turbulent air for example.

Just as a lower velocity means more pressure, which also is never questioned. Air coming out of the cooling is of low velocity. But again this hardly comparable. Turbulent air coming from a car has been in contact again with mainstream air, dropping temperature and decreasing pressure.

i made my point clear, so maybe you just do the same not that we run into useless discussions. Because after the answers in the second to last post I really do not see your point anymore.

My point was there's interaction between the cooling and the butterfly suspension, and one influences the other, with the shape and size of the cooling adapted to the butterfly suspension. That was the original point, but the discussion drifted into smaller, several things. One thing that I hate when somebody cuts up your post like it was a salami. It's tedious to answer that, and everything gets lost into details.

[basti313]

But why do you think pressure zone is larger than CFD estimates? What is the physical explanation for that?
For me this is total nonsense. If we have turbulence the pressure zones are smaller and this is normally not questioned as cars loose downforce in turbulent air for example.

That's an assumption you made on your part.

That's not an assumption. That's physics.

I only assume the cfd wouldn't predict it accurately; I can't make assumptions about whether it's higher or lower. Again, CFD has issues with getting close to reality when temperature plays a role.

So my assumptions that the high pressure zone of the butterflies can not reach the cooling exits are wrong, because CFD may not be precise...sorry...is not precise.

So on which basis can you make assumptions that the high pressure zone reaches the cooling exits?

i made my point clear, so maybe you just do the same not that we run into useless discussions. Because after the answers in the second to last post I really do not see your point anymore.

My point was there's interaction between the cooling and the butterfly suspension, and one influences the other, with the shape and size of the cooling adapted to the butterfly suspension. That was the original point, but the discussion drifted into smaller, several things. One thing that I hate when somebody cuts up your post like it was a salami. It's tedious to answer that, and everything gets lost into details.

Well, not cutting this up gives a completely useless discussion. Just saying "yes it is" or "no it is not" is both wrong for me.
Of course I agree, that the position of the cooling exits may be influenced by the butterflies. Although there are many other points defining that position. But all this blocking of the cooling exits over a 10cm or whatever gap is just physical nonsense to me.

[turbof1]

So on which basis can you make assumptions that the high pressure zone reaches the cooling exits?

You get it wrong here. The problem is that the suspension blocks the transition of the high pressure air coming out of the cooling outlets to lower pressure surrounding air (phsysics 101: airflow goes from high pressure to low pressure). This normally helps in extracting the hot air out of the cooling outlets and makes the whole cooling outlet more efficient. The suspension blocks this, atleast for a part.

[colonelbadger]

Is this the Barcelona MP4-29? I don't see the "turrets" at the back.

[Carmack]

That's a repainted MP4-24...

[Just_a_fan]

Looks more like the MP4-24 to me...

edit: beaten to by Carmack

[JackHammer]

Is this the Barcelona MP4-29? I don't see the "turrets" at the back.

https://pbs.twimg.com/media/BmUnpU8CEAEGecl.jpg:large

No
Looks like the 2009 MP4-24

[heimana]

Is this the Barcelona MP4-29? I don't see the "turrets" at the back.

https://pbs.twimg.com/media/BmUnpU8CEAEGecl.jpg:large

no you can see the exhaust, there is an exhaust on each sides of the car

[hollus]

I see a sizeable high pressure area in front of that turning vane, and we are talking of an "obstacle" that is razor thin and designed to keep the flow attached and as fast as possible. The butterflies are a bit like a triangular prism: if any two sides allow for nice, laminar, attached, more or less unobstructed flow, the third side cannot.

[RagingBullx]

The hot air cooling exits work in tandem with the rear suspension providing air which blocks or at the very least smoothes the higher energy faster moving air from the top surfaces, thus creating a virtual aero surface out of thin air! The hot air alters the effective angle of attack of the suspension arms. IMHO.

[basti313]

It is just simple physics, that turbulences disturb high and low pressure zones and, thus reduce the zones given by CFD for laminar flow.

So on which basis can you make assumptions that the high pressure zone reaches the cooling exits?

You get it wrong here. The problem is that the suspension blocks the transition of the high pressure air coming out of the cooling outlets to lower pressure surrounding air (phsysics 101: airflow goes from high pressure to low pressure). This normally helps in extracting the hot air out of the cooling outlets and makes the whole cooling outlet more efficient. The suspension blocks this, atleast for a part.

No, I am not getting anything wrong here. You are just, I do not know why, switching the pressures. Of course there is a pressure behind the cooling exits and this pressure is lower than the pressure inside of them. But the question still is the same: Is this pressure right behind the cooling exits higher with or without butterflies? And you are, again, not answering that question in any useful way. You could at least try to explain physically why you think the butterfly can overcome a gap of more than 10cm in front of it. You do not even need to explain why you think it is just a high pressure zone and not, as usual a high and a low pressure zone in front of them.