How to improve fuel economy with a tonneau cover

[aerohead]

Originally Posted by voyagerX

Sorry for bringing up this old thread. I found a good deal on a tonneau cover for my truck and been reading those threads about design and portion of cover will help on aerodynamics. We need the full cover to protect the stuffs and thinking to add a simple wing if that will help. Any insight? TIA

*For some trucks,a 1/2-tonneau had lower drag than a full tonneau.


*A 1/2-tonneau plus cab-wing had almost as low a drag as an aeroshell.

*A 1/2-tonneau,plus cab-wing,plus half-aeroshell blister has essentially the same drag as an aeroshell.


*Adding a conventional spoiler on top of a full tonneau may have no effect as far as drag goes.The tonneau provides for the captured-vortex,reattached flow and, kills the rear lift.An additional spoiler might provide downforce at the expense of higher drag.We have no data from research on this topic.


*The more you can make your truck like a passenger car,the better off you'll be.This GM-Holden Ute is Cd 0.309.The World's lowest drag production pickup.

[kach22i]

My opinion is that a wing on the tail will do little for down-force unless it is way up in the air flow, and the air flow will not be down at the cover.

If you really want a wing, try a roof wing.

Sven7 posted a PDF a while back which may contain more information.

Also see the link in my signature below.

I did find this old thread:
http://ecomodder.com/forum/showthrea...uck-11520.html

And this:
http://ecomodder.com/forum/showthrea...ics-15640.html

EDIT: Found the posting I was thinking of.
A Practical Guide to Pickup Truck Aeromods
http://ecomodder.com/forum/showthrea...ods-32386.html

From his blog:
http://tylerlinner1.kinja.com/a-prac...=1437153595522

[Hersbird]

Has anybody tried a cab wing that will also angle up into a deflector for a travel trailer? I was thinking a boat on a ladder rack but that's $$$ and we may not always be going to water. Plus the wing could help the non-towing. I think I want a full bedcover anyway to keep stuff dry. The aerocover with the modification of the hard side inserts was the best.

[kach22i]

Originally Posted by Hersbird

Has anybody tried a cab wing that will also angle up into a deflector for a travel trailer?..........

There is a project thread in this forum on something similar, but as I recall it was intended for trailer use, then easy removal from the truck cab.

I did find this example today, it uses the air slots similar to my roof wing design. I guess I'm not so crazy after all.

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[Hersbird]

I was thinking of something similar but bigger and attached to the bed not the cab. So something like this but with a long moveable center piece added.

I thought about the side wings as well as the camper is 8' wide, wider than the truck.

[Vman455]

Originally Posted by aerohead

*Adding a conventional spoiler on top of a full tonneau may have no effect as far as drag goes.The tonneau provides for the captured-vortex,reattached flow and, kills the rear lift.An additional spoiler might provide downforce at the expense of higher drag.We have no data from research on this topic.

The only OEM-designed spoiler on a tonneau that I know of was available on the 2005-06 Ram SRT-10. It differed slightly from the spoiler designed for the open bed:





Dodge claimed 150 lbs of downforce for the initial spoiler; I don't remember ever seeing a quoted figure for the tonneau spoiler. The open-bed spoiler also has a trough on the underside that Dodge claimed reduced drag, but they didn't specify by how much.

[freebeard]

This off-cycle technology is available for purchase to help improve aerodynamic fuel efficiency and gain off-cycle credits.

Their website apparently doesn't define 'off-cycle technology'. Which may or may not be different to 'aftermarket parts'. Despite the marketingdroid-speak they do have some interesting technology in 'adjoint':

Shape optimisation takes the exterior of a car, for example, and shows whether you should push or pull on the surface to improve a given parameter, or set of parameters (drag, downforce, efficiency, balance, etc.). This delivers in a single run what would take many hundreds, or thousands, of CFD runs to deliver using traditional parametric techniques.

[slowmover]

Originally Posted by Hersbird

Has anybody tried a cab wing that will also angle up into a deflector for a travel trailer? I was thinking a boat on a ladder rack but that's $$$ and we may not always be going to water. Plus the wing could help the non-towing. I think I want a full bedcover anyway to keep stuff dry. The aerocover with the modification of the hard side inserts was the best.

How many miles of annual use over a lifespan of? (Is always the problem). Gains are minimal unless annual miles are high for Interstate use.

I'm willing to bet an aeroshell, side skirts and appropriate front air dam are best as most miles for most people are solo.

Ahead of that is mechanicals. Trailers have a list as do trucks. Then the hitch lash up. That's a couple mpg after vehicles are. perfect. (Next to no one dies it).

[aerohead]

Originally Posted by Hersbird

Has anybody tried a cab wing that will also angle up into a deflector for a travel trailer? I was thinking a boat on a ladder rack but that's $$$ and we may not always be going to water. Plus the wing could help the non-towing. I think I want a full bedcover anyway to keep stuff dry. The aerocover with the modification of the hard side inserts was the best.

This was online,but no performance claims were made

Something like this would help while towing,but hurt when not

2nd down from the top on the right would be best

And again,when you weren't towing,it'd tear you a new one!

[aerohead]

Originally Posted by Vman455

The only OEM-designed spoiler on a tonneau that I know of was available on the 2005-06 Ram SRT-10. It differed slightly from the spoiler designed for the open bed:





Dodge claimed 150 lbs of downforce for the initial spoiler; I don't remember ever seeing a quoted figure for the tonneau spoiler. The open-bed spoiler also has a trough on the underside that Dodge claimed reduced drag, but they didn't specify by how much.

Downforce would be bad.The truck is plenty heavy to begin with.
At DARKO,Spirit had around 2,083-lbs on the rear axle at 135-mph.
Just eliminating the separated flow and capturing the locked-vortex over the box will essentially kill all rear lift on a pickup.