Partial Tonneau cover on pickup (plus cab extension - cab wing)

[bennelson]

Hey folks,

I just built a PARTIAL tonneau for my pickup truck.

It covers the back two-thirds of the truck. The idea is that if air is hitting the tailgate, it's coming in towards the back.

There should be a lower pressure area right behind the cab, where the bed isn't covered - so air really shouldn't be pushing in there.

I can also still use the front part of the bed to just throw stuff in there, or have a tool box, or something that would stick up a little too far to be under cover.

Here are some photos.






I will let you know how my next tank of gas turns out.

[MetroMPG]

A partial tonneau is known to work. In combination with an add-on that tapers the roof & sides of the cab for a short distance back, you can get almost the same benefit of a full aeroshell.

[Concrete]

Darin,

do you have any seed material / pictures for the combo taper concept
like Ben I am trying to keep my truck bed useful and am interested in this concept
but all I have found is this:

[Concrete]

Ben,

The bed cover I want to know about it this one!

YouTube - Aeromod test 1

stumbled across this on youtube but could not find it here

you and I seem to be the only guys out there posting s10 aero study videos on youtube - I can't imagine it is not more popular

did the soft aero shell work?

[MetroMPG]

Concrete - I'm hoping Phil will see this thread and comment on the cab add-on & partial tonneau specifics. I know he's mentioned it before. If I were you I'd have a look through his pickup truck photo album - there may be a pic.

But essentially, imagine his aero shell, but extending only about 2 feet back from the cab, and you've got the idea.

[bennelson]

Yep, that's me in that video.

My experiment with the construction plastic wedge from the cab to the bed seemed to indicate that it did improve fuel economy. However, if you simply stretch plastic like that, without an internal framework, it ends up concave. Straight or convex would be better.

Also, the plastic still flops around a bit. A rigid material works better than a flexible one.

[aerohead]

Originally Posted by Concrete

Darin,

do you have any seed material / pictures for the combo taper concept
like Ben I am trying to keep my truck bed useful and am interested in this concept
but all I have found is this:

The 1/2 tonneau was good for 5% mpg on the T-100,D-100,Chevy Silverado,'93 Toyota truck,and a F-150 4 by 4.With a "blister" which is like the back portion of the aeroshell mounted atop the 1/2-tonneau,mpg was 8% better on the T-100.If you combine it with the first 20-24-inches of the aeroshell(Ford Motor Co. calls this a "sail panel"),you can pick up a combined 18% mpg improvement,and still have easy access to your gear or cargo.

You can use anything for the 1/2 tonneau.John Gilkison built the cab-wing extension out of 3/4" plywood skeleton and side panels,with 1/4-inch plexiglass windows rabbited down into the plywood flush.The top was skinned with coated Masonite,glued and screwed to the framework.The side panels angled in at 7-degrees on ours,and the top came down at a 12-degree angle.The thing was pretty primitive,but the air liked it alot,and we basically achieved the mpg numbers Ford claimed for the combo.The aeroshell was built to verify Ford's claims,and I've stuck with it as it provides all weather protection and a theft deterent.Since I incorporated plan curvature into mine,I picked up a little additional drag reduction,and a 13% mpg overall improvement on the highway with the single modification.I have yet to see anything from SEMA which is worth the money,so unfortunately your forced to build your own.

[Concrete]

10-13% is significant
I'm almost sure I have seen pictures of your truck mods but I cannot find them now
(looked very curved like a boat upside down on the top of bed??)

I bought a smooth bed cap before I knew any better
A cab Kamm back / sail would allow me to redeem myself

just finished work on wheel covers and was thinking skirts next...
but 13%... I may get distracted and work the cab next
depends on my fab skills and frustration level
(pounded my head on some A-B-A tonight - but I won in the end)

aerohead,
what do you think about sizing/shaping cab "sail" to streamlines (long string) at highway speeds?
Also, is there similar savings with a tail gate "sail"?

[Concrete]

I found bed cover pics - it was Phil Knox with the boat on his truck
sorry about the mix up

would love to see picture of your truck
but let me start with a sketch from Phil's

are we talking about something like the portion I highlighted yellow
but will the same basic curves as Phil's full cap as shown?

[MetroMPG]

Concrete - that's exactly the area.

As Phil said:

The side panels angled in at 7-degrees on ours,and the top came down at a 12-degree angle.The thing was pretty primitive,but the air liked it alot,and we basically achieved the mpg numbers Ford claimed for the combo.