McLaren MP4-26 2011 – Fan Tail (Octopus) Exhaust

[silversurf3r]

Hi guys. Scarbs just posted this link on Twitter to his blog. It's an analysis of the exhaust that never was! From a recent interview on TFL with Paddy Lowe.
http://scarbsf1.wordpress.com/2012/05/3 ... s-exhaust/

Interesting reading anyway. Check it out.

[raymondu999]

I wonder how that system would've performed in the wet - it would heat up the track right ahead of the rear wheels. Traction would've been mega - and on the flipside, they would have to have a much higher crossover condition. (ie they'd have to wait for it to be wetter before they wet to wets - because their rears would be facing drier conditions than the other rears. Mind you - probably there would be a bit of understeer involved then too, as the fronts receive more water than the rears.

[hardingfv32]

Scrabs just posted a summary of this system.

There are a couple of states benefits: Feed flow to the diffuser and seal off the tire squirt.

Question: Why is exhaust feeding of the diffuser good while the flow around the tire (tire squirt) feeding the diffuser bad?

Brian

[bhall]

Because tire squirt is unstable.

[Crucial_Xtreme]

Scrabs just posted a summary of this system.

There are a couple of states benefits: Feed flow to the diffuser and seal off the tire squirt.

Question: Why is exhaust feeding of the diffuser good while the flow around the tire (tire squirt) feeding the diffuser bad?

Brian

Because "tyre squirt" is lateral air flow into the diffuser, this slows the flow through the diffuser which in turn robs the car of downforce.

[aussiegman]

As above, I think the issue would be the perpendicular direction of flow breaking up the surrounding air stream(s) and the resulting turbulence rather than any perceived instability of the air flow.

The fan tail seems to provide exhaust flow that can be more easily re-directed by the flow already present under the floor due to the angle at which it is directed and placement of the vent as opposed to the flow entering from tyre squirt which causes flow disruptions and turbulence.

Also, IMHO the exhaust flow could also be considered unstable to a certain degree as RPM changes within the boundaries of the engine operating range.

[Shrieker]

I asked the very same question about the 2011 Renault R31 (whether their exhaust blowing downwards would aid rear grip in the wet) and a fellow member did a quick calculation; the heat would be nowhere near enough to aid rear grip in the wet. The blowing effect is a different matter however. Still, I think even the blowing effect would not achieve much. Another quick calculation might prove so.

[raymondu999]

I wonder how that system would've performed in the wet - it would heat up the track right ahead of the rear wheels. Traction would've been mega - and on the flipside, they would have to have a much higher crossover condition. (ie they'd have to wait for it to be wetter before they wet to wets - because their rears would be facing drier conditions than the other rears. Mind you - probably there would be a bit of understeer involved then too, as the fronts receive more water than the rears.

[bhall]

Also, IMHO the exhaust flow could also be considered unstable to a certain degree as RPM changes within the boundaries of the engine operating range.

I don't think you're alone with that opinion. I think a few teams have discovered that the effects of the exhaust on the diffuser are, in fact, unstable and can be detrimental to performance (see: F2012, RB8). It's a whole new ballgame now that off-throttle blowing is heavily restricted and teams no longer have carte blanche to locate their exhausts for max effect.

The variables now are almost as numerous as those related to tire squirt, which itself changes depending on the wheels' rotational speed, orientation and shape, as well as the car's ground/air speed and proximity to other objects. Someone needs to come up with the exhaust equivalent of a wheel fairing.

@Ray, I don't know that the exhaust's effects on the temperature of the track would be noticeable at all.

[PlatinumZealot]

Already had this exact same topic months ago:

Mclaren Mp4-26 "Fan tail" Exhaust

viewtopic.php?f=6&t=11850

I don't mean to brag, but I was the first to decipher what the exhaust was, back in February 2011. Scarbsy didn't give me a shout out on the Flying lap though.. hahaha