Commercially produced aerodynamic pickup bed cap

[95badbird]

Here is a pic of my truck....but only from the front(you can kinda see the camper in the pic).....I just don't have anymore pics of my truck hosted right now..

[Bicycle Bob]

The rounded back edge causes more drag than a sharp lip, which would help to establish a single large vortex instead of general turbulence in the wake. The slight taper in profile is beneficial, but could be increased considerably without causing flow separation, giving a smaller wake.

The 'roo bars on the front must be costing you a significant percentage, too.

[aerohead]

Originally Posted by 95badbird

Hey everyone.

just joined the site, and wanted to say something.

Note, the pic I'm about to post is not my truck, but I do have the same exact camper on my truck.

What do yall think about it for better aerodynamics?

The top was made by snugtop, and was called the topgun.





I'll get pics of mine later.

95badbird,its a great looking cap.It's a little more daring than conventional caps,with apparent good utility.It doesn't reduce in cross-section area much,so probably not much drag reduction,but better than open bed.

[metromizer]

Back in the late 70's, my friends and I had a band practice at the new bass player's work... which turned out to be a place in San Jose that did short-run fiberglass projects.

They did everything from in-house developed products (race fairing for motorcycles and outhouses I think), others were customer owned boat, odd things I couldn't identify moulds that this company would make small runs on a 'to order' basis. They also stored the customer owned molds. Just an idea...

If you own some quality molds, and don't want to set up a facility to apply gel coat and a chopper gun glass (nasty stuff, who would blame you), talk with several boat hull manufactures, spa manufacturers, race car body part manufactureres in your area about small lot contract production. I encourage you to get your ducks in a row and find an investor to fund 20 caps.

[crexcrex]

Impressive.....................reminds me of the fast back jeep top.........nice work!

[Deisel Dodger 06]

Originally Posted by Snowmann

sooooooo, when you making some for a Dodge?
As a truck owner, I would prolly be willing to pay about $1000 or maybe more for one of those. That thing is sweet!

Just by adjusting some driving habits I have gotten my 95 Dodge Ram 1500 with the 318 to get a combined of 16.0. WOOT!

Bondo,

I saw Snowman's comment and had to add to it that I would like to see some for the dodge's. I have a '06 5.9L Mega Cab, and right now it's a lawn ornament, sort of! Keep us informed of your progress please, I think they look great!

[MetroMPG]

It's hard to tell from that photo, but I'm going to side with Bicycle Bob. The effective angle on the rear 'glass' portion of that cap looks like it may be pretty close to the angles that Hucho shows increase drag by spawning a large trailing vortex on each side.

[95badbird]

Originally Posted by MetroMPG

It's hard to tell from that photo, but I'm going to side with Bicycle Bob. The effective angle on the rear 'glass' portion of that cap looks like it may be pretty close to the angles that Hucho shows increase drag by spawning a large trailing vortex on each side.

hugh??

the cap follows the lines perfectly with the truck.

I still need to get more pics up.

[MetroMPG]

Was referring to the REAR glass. Not the sides.

[95badbird]

so what exactly is causing a vortex?

[aerohead]

Originally Posted by 95badbird

so what exactly is causing a vortex?

As the air moves rearward along the cap,the air atop, and aside the cap are moving at different velocities, and at different pressures,mingling only at the top intersection,and held in place by the positive pressure gradient ahead of,and around the truck.When the air reaches the back,there's no longer any surface left to support the flow,and pressure differential will cause the slower,higher pressure side- flow,to head for the faster,lower pressure top- flow,spiraling into the vortex as the two dissimilar flow fields attempt to mingle and blend.------------------------------------ From Hucho's research at Volkswagen, a backlite angle of 28-degrees produces the most violent vortex,and this kinetic energy of the "spin" cannot be converted back to static pressure,for perhaps hundreds of feet behind the vehicle,where viscous attrition from colliding with surrounding air,finally brings the vortex to rest.I think this is what MetroMPG and Bicycle Bob are referring to.-------------------------------- 28-degrees is big trouble!

[95badbird]

Originally Posted by aerohead

As the air moves rearward along the cap,the air atop, and aside the cap are moving at different velocities, and at different pressures,mingling only at the top intersection,and held in place by the positive pressure gradient ahead of,and around the truck.When the air reaches the back,there's no longer any surface left to support the flow,and pressure differential will cause the slower,higher pressure side- flow,to head for the faster,lower pressure top- flow,spiraling into the vortex as the two dissimilar flow fields attempt to mingle and blend.------------------------------------ From Hucho's research at Volkswagen, a backlite angle of 28-degrees produces the most violent vortex,and this kinetic energy of the "spin" cannot be converted back to static pressure,for perhaps hundreds of feet behind the vehicle,where viscous attrition from colliding with surrounding air,finally brings the vortex to rest.I think this is what MetroMPG and Bicycle Bob are referring to.-------------------------------- 28-degrees is big trouble!

so, is what I have hurting me more than an open bed?
or worse then a tanuea cover?
or a regular camper shell?

I have gone from 13 mpg to 17 just changing my driving habbits.


I'm guessing this vortex is bad.

[aerohead]

You'd have to conduct back-to-back tests,with and without the cap to really isolate it's performance.I can't imagine that it would "hurt" your highway economy.I think the consensus is that its less than ideal,but still way out ahead of nothing.I'd keep it.Shooting from the hip,I'd say its good for 5% mpg gain.

[Big Dave]

A flat tonneau would be better. When used a flat tonneau, it was good for 1.5 MPG over the open bed with tail gate up.

[toyobug]

I stumbled on this thread from another site. I noticed that no one has posted since the 1st of Aug. Where is everyone? Bondo, are you still out there making it happen?

[torr]

I realize that this thread is dead or dying, but I just returned from a trip to Italy. When there, I saw a Nissan Navara pickup truck with a hard bed cap on it that looked unbelievable to the one that bondo made for the F150. It looked like this.




In all, I saw 3 of the pickups and all had the bed cap on it. There is a cap like the one shown that is available through Nissan that cost € 2.614,80!!!!! But there are other makers of the hard caps like the one above that look the same. Do a google images search on Nissan Navara Hard Top and you will see all the suppliers of the cap.

[aktill]

Oh, torr, I wish you hadn't posted that. I have a Frontier that REALLY needs that cap now! I was going to build one over the winter, but have decided to do an electric car instead, and having a pre-fab cap would have been great.

Emailed the mfgr about North American distributors...

[Chris D.]

wow, that thing flows with the truck like crazy!!!! mite be a factory option?

[95badbird]

Originally Posted by Chris D.

wow, that thing flows with the truck like crazy!!!! mite be a factory option?

If I would get off my butt, and take some pics of my setup, you would think mine is a factory piece...

[toyobug]

95badbird- Do you have any recent pics of your set up? other than the one you posted on
7-29-2008.