Roof Spoiler on Pick-Up Truck Cab - Phase-1

[aerohead]

Originally Posted by kach22i

From what I've read a 10 or 12 percent downward angle on the "garnish" will net a +20% reduction in drag, but a +30% increase in lift. This is one of the reasons I never angled it down.

I would be interested if your "science" can measure this reported "lift", or at least graphically represent it.

I think for the most part your program underestimates the suction/flow of air though the small air gap between the end of the roof and the beveled leading edge of the wing. I do need to find a way to measure this alleged flow, smoke bomb in a coffee can on the roof?

Texas Tech found that the most beneficial angle depended on whether the truck was long-bed, short-bed,long-wing,short-wing,and degree of bed cover.
It's gonna be hard to do the 'one-size-fits-all.'
'suppose a step-side would have its own peculiar flow.

[DaveVM]

Read through all of this and was wondering if your design might work for the back of trucks with shells on them? Also read about the new design one that has a complex shape that is supposed to work for vans and so forth. (the yellow drawing on pg 1)

As to how to adjust the angle (up or down) I would think using washers between the mounting bracket and roof would work. More washers up front to angle the wing down in back. To measure the angles a dial gauge angle finder would work or a digital protractor, depends on how much you want to spend.

To get it to follow the curve of the roof (left to right) rather than going to the trouble of heating it and trying to get the curve just right, maybe a third support in the center of the roof line. Though that means more holes in the roof.

Keep up the good work. A mpg here and one there soon add up!

Just my three cents.

[kach22i]

Originally Posted by DaveVM

As to how to adjust the angle (up or down) I would think using washers between the mounting bracket and roof would work.............

Keep up the good work. A mpg here and one there soon add up!.

Thanks for the input, the washer thing is super simple, I have toyed with the idea, but like the current "down-force" setting.

Went to the AK-Fest stereo show on Saturday, followed some friends (while going to lunch) who were in a Porsche. I ended up making a three lane change with them at 80 mph to exit the highway. That added bit of down-force allowed me to keep my pants dry.

[DaveVM]

...a three lane change with them at 80 mph to exit...

WOW... in a four wheel drive at that! Dry and clean drawers are always a good thing!

I've got a 93 Olds Bravada (glorified Blazer) one thing I did with it to improve the handling was put on 1.5 inch billet rear wheel spacers. It brought the rear wheels out inline with the fronts. Which in winter would put the tires inline and may help in the snow. Don't know if the second gen 4wd S10's were as bad as the first gens for that. Also dropped the nose with the torsion bar adjustments to the minimum spec. Look for ride height adjustment and is easy to do with a wrench and a ruler/tape measure.

I also have a 97 2wd S10 ext cab 5spd that I have been working on to improve the MPG as well as the handling.

As for the mpg I've put on larger diameter rear tires, (less RPM for the same speed) but you have to be careful as your travelling faster than indicated. Installed smaller mirrors on the doors, though I still have both - like to see what is going on around me. I like your chin spoiler and was thinking along those same lines, though was wondering if you were having any fold under with yours?

Thinking about getting a reprogram for the computer from pcmforless as they can work some magic as well.

The handling, I've put on some of the ZQ8 parts. Really helped. And like you I use my truck like a truck.

[kach22i]

Originally Posted by DaveVM

I like your chin spoiler and was thinking along those same lines, though was wondering if you were having any fold under with yours?

No tuck-in, the arc shape I think helps prevent that, plus the plastic is stiff and secured very well.

Item of note, last winter I had it in 2WD to save gas and went on to a slippery side street where a garbage truck was heading towards me. I touched the gas slightly coming out of he turn, which sent me sliding. Rather than spinning into the garbage truck I nudged a snow drift. This nudge was enough to form a small cut or crack in the plastic valance which the spoiler is attached to.

Over the past year the crack or tear has grown and because this is near where it turns the front left corner there is stress pulling on it at the bend.

I plan on fixing this as soon as it stays warm long enough. My point is, don't go hitting any snow drifts made of frozen ice.

[Varn]

Kachi sez: ...I think for the most part your program underestimates the suction/flow of air though the small air gap between the end of the roof and the beveled leading edge of the wing. I do need to find a way to measure this alleged flow, smoke bomb in a coffee can on the roof?

You might just lay in the bed with a wand that has yarn on it. Have someone drive around. You could move the wand around and see what is happening at various points.

[kach22i]

Originally Posted by Varn

...... yarn

I could tape a bunch of yarn strands of various lengths, drive around and see if any of them get sucked into the gap (from boundary flow).

If all the flow goes over the wing and somehow just manages to dump downward after the wing, all the yarn strands will lay over (or short depending on length) the wing.

If the boundary layer is being sucked into the gap (at a downward angle of perhaps 45 degrees), and then pulling or drawing on the air above it (as theorized), then some of the yarn will end up lying in the gap between the cab and wing.

If someone were to video the truck at speed during a heavy snowfall, I bet some data could be acquired as well.

[Sven7]

You've gotta work on your drifting skills, George!

[kach22i]

Originally Posted by Sven7

You've gotta work on your drifting skills, George!

I once found that I had a broken drop-link on the rear swaybar of my vintage 911 while making a three lane change at 90 mph. I was following a Ferrari F-40, a Lamborghini Countach and a Vector! I had two heavier guys in the car and handling was compromised to say the least. I've had all the drifting I care to have in a single lifetime.

[DaveVM]

...to form a small cut or crack in the plastic valance which the spoiler is attached...

A sheet metal trick may work here in that when a crack forms and you want to stop it. Drill about an 1/8 inch hole just in front of the crack. The crack will reach the hole and usually stops growing from there.

This is a temporary fix kind of thing as the part is still weaker but will last longer till it can be replaced or patched.

It's hard for me to find snow drifts, plowed or otherwise here in Florida, sand on the other hand... though I would gladly have the snow over the hurricanes. Grew up in Pa. so I learned to drive in the white stuff as well.

Going to have to try the roof spoiler though on the back of my shell, may only set it for a few degrees down though, not the eight to twelve I've read about. Though I may try to incorporate winglets to further reduce drag.