Partial Tonneau cover on pickup (plus cab extension - cab wing)

[aerohead]

Yeah Concrete,that's the idea.If you combine that with the half-tonneau,your looking at an 18% drag reduction,and 9% mpg better at 55-mph.

[aerohead]

P.S.,put some Plexiglas or Lexan on the passenger side if you can.When you're backing out of a parallel parking space,the extra visibility can help keep you from being T-boned!

[Concrete]

would love to see picture of your truck

Aerohead,
I'm a little slow... but I will get there eventually
found the "girly man" post yesterday ....

Thanks for all the pics and data
I'm reading thru the "Library" of aero data on the forum slowly
but as I work my way around the truck

Thanks again,

[aerohead]

you bet!!!!!!!! That's what we're here for.

[Kevin Cooper]

A partial tonneau cover, having about 60% of the length of the box, attached at the tailgate and running forward gives the largest drag reduction. Even greater than a full tonneau. This was shown some years ago by GM and was the subject of a patent. Since then, I showed the same behaviour in a full-scale wind tunnel test reported in SAE 2004-01-1146 entitled "Pickup Truck Aerodynamics – Keep Your Tailgate Up".

[aerohead]

Originally Posted by Kevin Cooper

A partial tonneau cover, having about 60% of the length of the box, attached at the tailgate and running forward gives the largest drag reduction. Even greater than a full tonneau. This was shown some years ago by GM and was the subject of a patent. Since then, I showed the same behaviour in a full-scale wind tunnel test reported in SAE 2004-01-1146 entitled "Pickup Truck Aerodynamics – Keep Your Tailgate Up".

Kevin,I wish your paper was available at dealer showrooms! The automakers have been installing faux spoilers on tailgates for a few years now,in hopes that it will promote"tailgate-up" driving.Unfortunately,many truck owners apparently do not "get it",and continue to drive with the gate "down," clinging to intuitive concepts about how the air "must" behave.Some remove the gate altogether,thinking the combined :weight-savings and drag reduction" will save them fuel.Hope you sleep okay knowing what you know.It drives me nuts!

[Kevin Cooper]

Its good to see partial tonneaus being tried. Keep you tailgates up!

Kevin Cooper

[cmroseberry]

Originally Posted by Concrete

Darin,

do you have any seed material / pictures for the combo taper concept
like Ben I am trying to keep my truck bed useful and am interested in this concept
but all I have found is this:

Hey, that is a graph that includes some of my handywork. I was a member of the TTU undergrad team that did the wind tunnel test on the cab extension - partial bed cover combination. Tim Maxwell and Walt Oler are still at Tech and probably have photos of prototype devices installed on pickups.
I have a story about that particular wind tunnel test: I was against trying that combination because I did not think it looked advantageous on CFD simulations. This was an early version of FLUENT - the pickup contour basically looked like lego blocks. I thought I could read the tea leaves just by looking at the plots of the velocity vectors to see how big the eddy was that filled the bed region. I was very naive about the limitations of CFD in regards to getting accurate results for separated flows (at least in those days). Fortunately, one of the other guys on the team found an 1/8" thick piece of wood, and quickly cut it into the right shape to go over the last third or fourth of the bed of the 1/5 scale model. My reaction was 'oh what the hell, go ahead and tape it on, it will only take about five minutes'.

[Christ]

Originally Posted by cmroseberry

My reaction was 'oh what the hell, go ahead and tape it on, it will only take about five minutes'.

You'd be amazed how many times that phrase has been the precursor to a major discovery in something.

[aerohead]

Originally Posted by cmroseberry

Hey, that is a graph that includes some of my handywork. I was a member of the TTU undergrad team that did the wind tunnel test on the cab extension - partial bed cover combination. Tim Maxwell and Walt Oler are still at Tech and probably have photos of prototype devices installed on pickups.
I have a story about that particular wind tunnel test: I was against trying that combination because I did not think it looked advantageous on CFD simulations. This was an early version of FLUENT - the pickup contour basically looked like lego blocks. I thought I could read the tea leaves just by looking at the plots of the velocity vectors to see how big the eddy was that filled the bed region. I was very naive about the limitations of CFD in regards to getting accurate results for separated flows (at least in those days). Fortunately, one of the other guys on the team found an 1/8" thick piece of wood, and quickly cut it into the right shape to go over the last third or fourth of the bed of the 1/5 scale model. My reaction was 'oh what the hell, go ahead and tape it on, it will only take about five minutes'.

That's funny! What a small world! Tim and Pat Nixon gave me a copy of the paper based on your classes research that they presented at SAE in 1988.I think Dr.Maxwell and Pat made the Dallas Truck Show,trying to educate truck owners.Never saw anyone run the mods.What a shame!---------- I'll have to personally thank you for the "aeroshell" depicted in the paper,as I've enjoyed them for a decade now!------ You the man!!!! Thanks for all that,Phil.