Pickup tailgate up or down

[skyl4rk]

YouTube - Pickup boattail wind pattern

Aero pickup bed plus rounded tail

[aerohead]

Originally Posted by extragoode

What exactly is meant by basic redesign? Buy a car?

You have to put the research in context of the state-of-the-art in pickup design at the time the paper was published(1988).You could take a current production truck and aero-mod it to get a 20% drag reduction,or the carmakers could design more aerodynamically efficient production pickups with 20% less drag.
That's the context.

[garys_1k]

Originally Posted by skyl4rk

Aero pickup bed plus rounded tail

Looks like a K-back would do better than the curved back...

[extragoode]

Originally Posted by aerohead

You have to put the research in context of the state-of-the-art in pickup design at the time the paper was published(1988).You could take a current production truck and aero-mod it to get a 20% drag reduction,or the carmakers could design more aerodynamically efficient production pickups with 20% less drag.
That's the context.

So trucks have been redesigned (comparing an '88 tacoma to a '08 tacoma) for the better and it might be a 20% improvement, but are the auto makers still "redesigning" pickups or is the best option now just an aeroshell?

[aerohead]

Originally Posted by garys_1k

Looks like a K-back would do better than the curved back...

The K-back yielded Kamm Cd0.37 on the Mercedes chassis.I prefer Cd0.32.

[aerohead]

Originally Posted by extragoode

So trucks have been redesigned (comparing an '88 tacoma to a '08 tacoma) for the better and it might be a 20% improvement, but are the auto makers still "redesigning" pickups or is the best option now just an aeroshell?

I don't think "Tacoma" existed in 1988.I think Toyota just called their pickup a Truck.A friend has a '93 Toyota,and it's architecture is very similar to the T-100,which is rated by Toyota at Cd0.44.---------------------------GM dropped the Cd on the S-10,from 0.485 to 0.42 in it's last incarnation ( about a 13.5% drop) I don't know what the older Toyota was.------------------------------ I think the spirit of the "re-design" comment,is that for existing technology of the day,and given what was understood about pickup aero,that a new softened model could easily pull off a Cd which was 20% less than models of that day (1988).I did a 74% reduction with the T-100.

[Kevin Cooper]

The answer is simple. Keep your tailgate up. I did a series of wind tunnel tests on full-sized pickups in the 30-ft-wide, 30-ft-high test section of the NRC Low Speed Wind tunnel in Ottawa, Canada to investigate this issue. The results almost always showed that the tailgate up was best. With an 8-ft box, having the tailgate down or off decreased the drag coefficient (CD) by about 0.003 in a CD 0f 0.50. With the shorter boxes found with crew and extended cabs (6 ft & 4.5 ft), the drag coefficient was increased by up to 0.025 when the tailgate was of and a little less with it down. Adding a mesh tailgate instead of a solid one increased the CD by another 0.025, to a total of 0.05 above tailgate up. I would expect that any similarly porous tailgate would also increase drag. Since the gain of 0.003 is extremely small, it would not seem worth doing considering the loss of utility. Putting the tailgate down is a real loser since it is unsafe to following traffic and increases drag.

There you have it: keep your tailgate up.