Rear Spoiler on Pick Up Truck - Experiment

[kach22i]

Rear Spoiler on Pick Up Truck - Experiment
A continuation of the fooling around in aerodynamics which started with the chin spoiler, this phase may upset Dan Gurney (Gurney Flap inventor), so I apologize now.

Status:
It was on for two or three weeks, I have since cut it down to half the height.

Inspiration:
NASCAR Craftsman Truck Series (I've never seen one in person).

Pros:
Incredible down force, not just at the rear, over the whole truck. Driving in a heavy rain at highway speeds was as calming as it could be.

Highway steering used to float with the typical power steering hypersensity, no more - this truck tracks true and straight, the effects of which can be felt at speeds as little as 30 mph.

I laughed at side winds, bring it on!

You could see though the spoiler, good for backing up and headlights from cars following to close were automatically dimmed.

I could still use the tailgate, in fact I helped a friend move, several trips and four other people not familiar with it somehow did nor break it off.

Cons:
You could feel the drag, like towing a boat without the front wheels getting iffy.

The faster you went, the more you could feel the down pressure build, like a giant child pressing his toy car down too hard.

Gas mileage was hurt, I don't know exactly how much because my driving routine was interrupted too many times and I installed a tonneau cover which is alleged to net a fuel savings of 3% to 9%.

I looked and felt like a red neck speed racer boy, I did get a guilty kick out of it most of the time though.

Pictures:
http://s184.photobucket.com/albums/x295/kach22i/S10%204x4%20Pick%20Up/?start=0

[kach22i]

More Pictures:

It opens - a test before the struts were put in.


Common tools for working with the tinted acrylic, composite blades and sand paper.

[kach22i]

More and more pictures.

[kach22i]

PHASE III.....the cut down.

I marked the cut line with a magic marker, and plugged the lower strut holes with rubber automotive plugs/fasteners.




Cut down and trimmed.




The play with the removable cotter pins for tailgate use (moderate pressure).



Fooling with a spare aluminum channel, rethinking the piano hinge which is already rusting.

[kach22i]

Video of play:
http://s184.photobucket.com/albums/x295/kach22i/S10%204x4%20Pick%20Up/?action=view&current=IMGP8441.flv

The "play" is when at highway speeds; just a slight fluttering, mild and not rapid at all. The angle is settled down to about 45 degrees.

The pressure center is now mostly at the aft spar, the taller spoiler had it placed second bay in (huge vortex). I have less downward pressure (and less drag) and is biased over the rear.


Steering is still good, not jumpy and does not feel like it's locked in 4WD like before with the tall spoiler.

[kach22i]

The bed spoilers on new trucks extend the horizontal plane, not doing much at all even when most beds are covered these days.

I think this works better because in snowy conditions we might see fewer pick up trucks ending up in the ditch.


The pins pull out so that the spoiler lays flat for loading, plastic sleeves with depth were glued in.


Angle of max. "play" I think goes on at speed.


NOTE:
I will post gas mileage in a few weeks when I'm driving more highway like I used to.

[lendaddy]

Oh my

You're fearless George, on that a commend you.

[Heel n Toe]

More photos, please... one taken from below with you lying on your back under the truck, and the other taken from the roof of your house.

[jyl]

I like the spoiler. What is next? I'm thinking belly pan and side skirts?

[lendaddy]

Obviously a rear diffuser....

[jyl]

Then a month of litigation with himself.

[Rick V]

Hey You got a Hemi in that thing?

[Dottore]

Drive that baby strait to the Patent Office.

[kach22i]

A question someone asked over at carnuts.us:
How did you decide what angle to use?

I Googled as many racing truck images as I could, spent hours researching it, very few articles on it.

I guessed, and copied what I thought I saw.

Ended up 52 degrees for the big rear spoiler even though it looks almost 90.

I have not taken my adjustable triangle to the short one, but decided early on to let it ease back to near 45 degrees; as that's what I saw many car deck lid fiberglass spoilers doing going all back to the cars in the late 1960's.

Some of the dirt track cars with massive roof spoilers have it set at 45 degrees with a tiny 3/8" vertical Gurney flap on to pf it.

Later on I can always bend an aluminum "L" to 45 and set it on my acrylic 45 for 90 lip.

[kach22i]

Originally Posted by lendaddy

Oh my

You're fearless George, on that a commend you.

You want to see fearless? There is this guy I know (recently - has a 356 Speedster now) who when he was 15 years old purchased a Corvair, cut the roof off, and cut three feet out of the wheelbase.

Thread with picture here:
http://carnuts.us/forum/viewtopic.php?f=6&t=2085&p=29038&hilit=corvair#p29038

[Brillo]

Originally Posted by kach22i

You want to see fearless? There is this guy I know (recently - has a 356 Speedster now) who when he was 15 years old purchased a Corvair, cut the roof off, and cut three feet out of the wheelbase.

Thread with picture here:
http://carnuts.us/forum/viewtopic.php?f=6&t=2085&p=29038&hilit=corvair#p29038

Isn't he the same Barry that has posted on Pelican documenting his car trailer build and now his boat trailer?
Any interest in my boat trailer project?

[kach22i]

Originally Posted by Brillo

Isn't he the same Barry that has posted on Pelican documenting his car trailer build and now his boat trailer?
Any interest in my boat trailer project?

Yes, the same.

[ckissick]

Does anyone have a patent on that? If not, get one. Your device doesn't look bad or blingy at all.

Pickup trucks are just too light in the rear; I never liked the way the light rear felt. Of course, my rear-engine Tristar doesn't have that problem.

[74-911]

Re: the rusting piano hinge. Go to West Marine or other boating supply house and get stainless steel piano hinge.

[DUK]

65 degree is the rule. (nascar 2009)

BTW- anything under 40 degrees usually causes lift.