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Old 01-06-2014, 08:52 PM   #22 (permalink)
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Originally Posted by euromodder View Post
Not just racing trucks, but just about all Euro cabover trucks.

And looking at the different truck models on the MAN website, it looks like they too have gone for blocked grilles
I understand the need for air fences on swept wing fighters, but as jtbo asked, what is the purpose of those on the front of Euro- cab-over tractors?

Originally Posted by RunningStrong View Post
I've noticed the air fences on the front of trucks for a while, but was unsure as to whether they where aerodynamic or sacrificial plastic in case of bumps and scrapes.

Regarding fences in general I think in the vast majority of cases they are a waste of time, certainly when you are not actually using the air for anything and simply trying to maintain a clean flow.

Winglets on plane wings are functional but take 100s if not 1000s of hours in wind tunnels to perfect as they are very specific to each wing design. Earlier "bolt on" designs were of limited benefit economically as the added weight and cost actually gave little economical benefit over fuel savings but did allow airliners to appear more modern. Winglets that are integrated into new design (787 and A380) are far more effective from what I've been told in my studies.

Multiple fences on flat surface are simply increasing frontal area and can possibly cause more turbulence that they prevent. Don't forget you are creating further edges which will lead to further issues at the edge were the two separate air flows meet again.

And then finally there's the side profile, greatly increased but for what real gain?
That question crossed my mind, to a degree. Would there be anything to be gained with air fences running lengthwise? I would think little would change, except at the roof/door edges perhaps.

Which reminds me, air streaking down the sides of the vehicle has a pretty bumpy path, with wheel wells, door handles, window trim and all. Over the roof seems a little better, but that's just from looking. I guess some tuft testing would be in order...

[edit] as I stew on this more, I could see how these curved air fences may serve similar to a recent rear spoiler or Kammback design I saw here last week. It was shaped a bit like some wing flap airfoils, and was said to reduce drag. The page escapes me at the moment though...
Found it!!

Last edited by ECONORAM; 01-06-2014 at 09:31 PM..
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