News: Renault ecomods a tractor/trailer ... fuel consumption down 13%

[MetroMPG]

Along the lines of what Walmart is hoping to do with its truck fleet, manufacturer Renault recently gave a presentation on a truck it has modified to reduce fuel consumption by 13% through a combination of aero & drivetrain mods:

• increased leading edge radii
• boat-tailing panels on trailer
• slight arch on trailer roof
• trailer wheel skirts & side diffusers
• tightened/smoothed cab/trailer gap
• latest Michelin tires
• video cameras in place of large mirrors
• revised back axle ratio
• engine re-mapping to deliver a bit more torque lower down the rev range
• semi-synthetic engine oil

The "Big Lorry Blog" has a detailed piece about the truck, with lots of photos:

Renault Optifuel Lab offers 13% diesel fuel savings...Biglorryblog tells you all about the slippery Gallic streamliner! - BigLorryBlog

[Frank Lee]

Looks cool.

I've seen that sort of trailing edge extension before, in Hucho's book. Still don't know why it helps but apparently it does.

[MetroMPG]

I think it's more than just an extension - there's some plan & profile taper as well. It's subtle, but you can sort of see it in this pic (look @ the upper left corner & compare to trailer roof line) :



Of course, they haven't solved the problem of opening the doors fully...

[MetroMPG]

Renault must have an ecomodding division:

Article: ecomodding a vanilla Renault production sedan... efficiency up 19%

[Frank Lee]

Wouldn't that be a fun place to work?

If I recall correctly, the one in Hucho's book didn't really taper in.

[MetroMPG]

I recall seeing "straight" extensions, but they were inset from the trailer top/sides, so there's an "effective" taper between the end of the trailer and the tip of the extensions.

[aerohead]

Originally Posted by MetroMPG

I think it's more than just an extension - there's some plan & profile taper as well. It's subtle, but you can sort of see it in this pic (look @ the upper left corner & compare to trailer roof line) :



Of course, they haven't solved the problem of opening the doors fully...

On the 1978 Renault V.I.R.A.G.E.S. the boat-tail planes came in at a 5-degree angle.They ran 16-inch panel and got Cd 0.308.Their drag table for the boat-tail shows that a 32-inch tail gets the drag to Cd 0.29.Not too shabby for a "10-wheeler".

[some_other_dave]

Originally Posted by MetroMPG

Of course, they haven't solved the problem of opening the doors fully...

The extension is split in the middle at the top. So each half follows the door. Looks like each door can open out just a little over 180 degrees. So while it can't flip the door all the way forward along the side of the trailer and hook it there, it can at least open as wide as the interior of the trailer. Sounds good enough to me.

-soD

[cfg83]

soD -

Here it is open, but it's hard to tell if it is open "all the way" :



CarloSW2

[MetroMPG]

Only problem with that is if you're in a warehouse lot where normally you would open the doors flat against the side of the trailer, then reverse to the dock in a narrow slot between other trucks.

Not insurmountable, but making them flat folding would add complexity.