Study: Optimal Design of an Ecofriendly Pickup Truck Overhang and Roof to Reduce the Drag Coefficient

[Logic]

Originally Posted by vteco

Just found this interesting read:

https://www.mdpi.com/2076-3417/14/11/4667

downloading the pdf shows the illustrations better.

Nice to see linked science.

[Piotrsko]

Antifreeze is toxic to anything that uses a liver for blood cleansing

[aerohead]

I would want to mention that any quanta generated by this specific, 'simplistic', 'primitive', 'prismatic' shape, would be limited solely to this model, just as with the Ahmed, modified Ahmed, and Windsor CFD models.

[vteco]

Trends are interesting, though.

[Logic]

Originally Posted by vteco

Trends are interesting, though.

Ye; science seems to mean nothing around here. (peer reviewed (before you can) publish, or not)
Seems reading and comprehension isn't big on people's list of 'wanna do's.

When all pickup trucks use this design and it's 'not science' anymore you'll be safer mentioning here.
(Most strange in a forum all about 'every eco advantage' not yet on your vehicle)

Careful you don't end playing 'the accused' in an online Judge Judy show!

[vteco]

I've been treated well here, not worried.

Science is inquiry and postulation, not certainty. It's never claimed to be.

I think the study is interesting, but not a literal prescription.

[vteco]

For me the interesting take-away from that study is that, with regard to the cabin top, a long exit angle and a short entry angle, with a strong bias for location of maximum thickness at about 30% aft of the front of the cabin top approximately mirrors the configuration of conventional airfoils.

As a guess, their model would show improvements, if instead of the simple prismatic shape, they tried a smoothed foil of about the same proportions with thickness at about 30% of chord.

I think, the incidence probably would be critical to shaping the flow over the tailgate in a real truck, and that would probably vary for different trucks, with the heights of the cabin-top, and the tailgate, and the distance between them.

Also, of course if there was a partial or full tonneau.

Lots of variables, no definite statements... this is the postulation part. No certainties.

[aerohead]

Originally Posted by vteco

For me the interesting take-away from that study is that, with regard to the cabin top, a long exit angle and a short entry angle, with a strong bias for location of maximum thickness at about 30% aft of the front of the cabin top approximately mirrors the configuration of conventional airfoils.

As a guess, their model would show improvements, if instead of the simple prismatic shape, they tried a smoothed foil of about the same proportions with thickness at about 30% of chord.

I think, the incidence probably would be critical to shaping the flow over the tailgate in a real truck, and that would probably vary for different trucks, with the heights of the cabin-top, and the tailgate, and the distance between them.

Also, of course if there was a partial or full tonneau.

Lots of variables, no definite statements... this is the postulation part. No certainties.

1) 30% is close to the recommended ' 1/3rd-'chord'' of ' ichtyoid / fusiform ' bodies ( penguin, raptors, dolphin, shark, embryos, seal, tuna, etc.)
2) Dr. Hucho's pick for low drag was a streamline body of revolution, with a fineness ratio of length / width = 2.5:1, @ Cd 0.04.
3) When you examine this shape in mirror image ground reflection ( The 'road' bifurcates the 'teardrop' longitudinally ) leaving streamline 'half-bodies' both, 'above' and 'below' ground. You'll see that the 'forebody/aft-body demarcation occurs at one-third body length from the nose.
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If you parked the pickup next to a shallow pool of placid water and stood back, behind the pool, you'd see the 'phantom' truck 'under the ground. And technically, lowest drag would occur when the 'mirror-image' satisfied the 2.5:1 ratio.
Any shorter, and more drag.
Any longer, and more drag.

[vteco]

Yes aerohead, agreed.

I'm interested in the incidence part of the roof design and how that will work out with the bed/tailgate aero.

The incidence of a new top would be the angle from horizontal of the leading to trailing edge chord. This should be interesting. I'm already thinking of how to make that adjustable.

I know I could instead use a trailing edge tab, but I'd like to see what happens via the foil incidence itself.

[kach22i]

The interesting part of using a roof wing in my experience has been the reduction of lift when used in conjunction with a tonneau bed cover and rear spoiler.

Post #5
https://ecomodder.com/forum/showthre...1-a-19525.html

Table 4.2.1 presents the overall effect of using rear roof garnish. It shows that by attaching Rear Roof Garnish to the baseline truck model, aerodynamic drag coefficient Cd was reduced by about 2.4%;
however, the lift coefficient Cl was increased by about 33%

From the above, you can expect to feel lift with a downward sloped wing. However my wing is just a level flat plane that allows for a clean release of air on the trailing edge that squats it's self down firmly on the cover about 2/3rds of the way back and just before the rear tailgate spoiler.

Something you can feel by the seat of your pants, no question about it.