Commercially produced aerodynamic pickup bed cap

[bluetwo]

I'm guessing "slantback" might be out of the question. I saw this snugtop version a few months ago and these are just a few examples of what came up when I Googled it. I have a crappy internet connection and some of the other links wouldn't come up.

The way these guys are doing it I don't think the areo benefits are as good and sadly I've only seen this particular thing for the Hummer 3 which isn't even close to being smooth in the first place.

Snugtop - Custom Fiberglass Manufacturing, Truck Cap & Tonneau Top Covers, Camper Shells Tops, Customized Truck Toppers, Pick Up Truck Canopy

SNUGTOP SLANT BACK BED COVER / 2009 HUMMER H3T

First Look - H3T Slantback Shell - Pirate4x4.Com Bulletin Board

[Christ]

I'm pretty sure it needs a trip spoiler to actually help anything.

[Frank Lee]

Several sources say it doesn't.

[Christ]

Originally Posted by Frank Lee

Several sources say it doesn't.

Doesn't.... need a trip spoiler? Doesn't help aero?

I'm sure it doesn't actually need a trip spoiler, but I'm sure also that it would help more than just the cap alone. See how the back is rounded off toward the tailgate? I'm almost positive that's going to cause some measure of screwed up flow over the backend of the taper.

[Frank Lee]

LEER- Fuel Savings

[winkosmosis]

Originally Posted by Frank Lee

LEER- Fuel Savings

I like how they completely made up those airflow lines

[Frank Lee]

They all do that.

There was a designer who put some of them on his latest and greatest. Of course I had to mock it by drawing a cube with the sweetest airflow lines going over it.

Still, Leer says they've done a significant amount of actual wind tunnel testing. Their figures seem sensible.

[Christ]

Yeah, but that only covers tonneau covers. Like I said, I'm not saying that this tapered cap won't do something better than an open bed, but I'm also not saying it's going to be the best option available retail... a simple $3 piece of rubber trim mounted at like 45* to the tapered plane as a trip spoiler is what I'm suggesting, a la 70's gas crisis Pinto.

No telling which product(s) they've tested, and nothing scientific about that page except that they claim to have done scientific testing. I don't doubt they have, LEER is a pretty reputable company. I just still (intuitively, of course) think that they didn't "go all the way" on this design.

[aerohead]

Originally Posted by winkosmosis

I like how they completely made up those airflow lines

the airflow lines are actually pretty accurate.What they don't show,is the enormous vortex underneath that costs you up to 16% higher drag than another cap I know of.

[bluetwo]

Originally Posted by aerohead

the airflow lines are actually pretty accurate.What they don't show,is the enormous vortex underneath that costs you up to 16% higher drag than another cap I know of.

Is the vortex under, as in right behind the tailgate?

I'm curious about something maybe some of you can help with too... my tailgate can open about half-way, basically at about a 50 degree angle, so what would that do for airflow? Would there still be a cushion of air, though less than if the tailgate was all the way up, that sent most of the over-the-truck air to flow fairly well?