Does a traditional square pickup camper shell topper help or hurt drag & mileage?

[aerohead]

Originally Posted by winkosmosis

Wait a minute... So lowering the tailgate does reduce drag, presumably by creating a lengthened surface for flow to reattach to.

After Texas Tech published and reported on there R&D,some big guns were interviewed by Sport Truck Magazine for their big Aero issue.
Some trucks were reported to deviate from the "norm".
One carmaker rep indicated that swinging the tailgate from the TOP actually reduced drag for some pickups.
Up or down can be within 1% and easily lost within the signal-to-noise ratio of some testing.
We probably ought to stick with case-specific investigations of single vehicles.

[Christ]

Originally Posted by aerohead

After Texas Tech published and reported on there R&D,some big guns were interviewed by Sport Truck Magazine for their big Aero issue.
Some trucks were reported to deviate from the "norm".
One carmaker rep indicated that swinging the tailgate from the TOP actually reduced drag for some pickups.
Up or down can be within 1% and easily lost within the signal-to-noise ratio of some testing.
We probably ought to stick with case-specific investigations of single vehicles.

I agree.

I find it difficult to quantify improvements for a specific truck against other trucks without some context, because each model has varying cab height, bed length, etc.

What specifically works for one truck may be totally off for another. The only concrete point is that they all are affected by the same rules, but the workarounds are often different to a degree.

[aerohead]

Originally Posted by Christ

I agree.

I find it difficult to quantify improvements for a specific truck against other trucks without some context, because each model has varying cab height, bed length, etc.

What specifically works for one truck may be totally off for another. The only concrete point is that they all are affected by the same rules, but the workarounds are often different to a degree.

The context issue always looms large.
Something which is also part of the moving battlefield is how pickup box rail height has come up with respect to cab height over the years,just as trunklid height has come up on passenger cars,mirroring the relie've,or reflex-camber of Morelli's banana-car of the 1970s.
I think it's going to change the whole equation.With a tonneau cover,many late model trucks resemble some of the angular coupes and sedans in their maker's stable.

[aerohead]

I dug through the rat's nest looking for square bedcover-related material.
I found two articles which may share some insight and one personal experience to share.
(1) When the all-new Chevy/GMC pickups entered the market around 1987,their Cd had been trimmed from 0.535,to 0.45.
In 1992,the Chevy Suburban K 1500 was reported with Cd 0.39,about 11% drag reduction.It's station wagon style roofline closely mimics a traditional square camper shell.
(2) When the VW Vanagon loses it's roof to become the drop-side pickup truck,it's Cd grows from 0.42,to 0.46 ( about 8.5% difference)and with identical power,the top speed falls from 83 to 78 mph.
(3) When John Gilkison owned the T-100 which I now have,on astronomy camping trips,a LEAR square type fiberglass shell was reported to increase fuel economy by up to 1.2-mpg,a 4.8% mpg improvement,and 8% drag reduction.

[Christ]

Originally Posted by aerohead

The context issue always looms large.
Something which is also part of the moving battlefield is how pickup box rail height has come up with respect to cab height over the years,just as trunklid height has come up on passenger cars,mirroring the relie've,or reflex-camber of Morelli's banana-car of the 1970s.
I think it's going to change the whole equation.With a tonneau cover,many late model trucks resemble some of the angular coupes and sedans in their maker's stable.

I actually took a look at a Honda Ridgeline today.. I never really took notice to the attached bedsides that look to be around 10 degrees or more from the ground plane? I saw it specifically today... was surprised by it, actually.

I also noticed an Avalanche. Not quite so pronounced about it, but definitely appeared to have a slight angle to the "bed" sides..

[winkosmosis]

Originally Posted by Christ

I actually took a look at a Honda Ridgeline today.. I never really took notice to the attached bedsides that look to be around 10 degrees or more from the ground plane? I saw it specifically today... was surprised by it, actually.

I also noticed an Avalanche. Not quite so pronounced about it, but definitely appeared to have a slight angle to the "bed" sides..

I assumed the Ridgeline's bed beltline is like that to reduce the amount of air lowing into the bed

[jamesqf]

Originally Posted by Christ

I actually took a look at a Honda Ridgeline today...

I thought we were discussing pickup trucks? Which those sure aren't. They belong in a separate category all their own - if you can't be honest, and call them oversize sedans with missing trunk lids.

[Christ]

Originally Posted by jamesqf

I thought we were discussing pickup trucks? Which those sure aren't. They belong in a separate category all their own - if you can't be honest, and call them oversize sedans with missing trunk lids.

Unfortunately, most states do not agree, as evidenced by the presence of a "truck" plate on the vehicles in question.

The Escalade EXT and Avalanche are of similar design, but are still regarded as trucks.

I believe the Subaru Baja is also a connected-bed design with a quad cab, but I could be wrong on that one.

[jamesqf]

Sure, some states may think these things are trucks. They also think the Aptera is a motorcycle.

[Christ]

Originally Posted by jamesqf

Sure, some states may think these things are trucks. They also think the Aptera is a motorcycle.

Might have more to do with federal recognition than state, ya think?