EcoModder.com

EcoModder.com (https://ecomodder.com/forum/)
-   Aerodynamics (https://ecomodder.com/forum/aerodynamics.html)
-   -   '03 Tacoma Prerunner (https://ecomodder.com/forum/showthread.php/03-tacoma-prerunner-6342.html)

mobilerik 12-08-2008 12:36 PM

'03 Tacoma Prerunner - Aerodynamix
 
Ok, so here's a preview of last night's mods:

http://rik.akashian.googlepages.com/wheelcovers.jpg

Current Aero-Mod Inventory:
  • Half-Tonneau Cover
  • Belly Screen
  • Smooth Wheel Covers
  • Rear Wheel Skirts
  • Top and Bottom Grille Blocks

Best Numbers: I calculated my actual best commute, scaling my uncalibrated ScanGauge numbers, at about 29mpg, based on my very consistent and rising commute mpgs from last week. The actual fillup was 27.7mpg. EPA is 18.

Next Adventures: I removed last week's roof vortex generators (DIY AirTab type) temporarily. And forgot to put them back on. I also meant to fold back the passenger-side mirror this morning. For my next mod, I'm thinking to use my remaining strip of coroplast to make a temporary mini-Kammback-spoiler for the roof, and I'll cut VGs into that. I'll also be making dams for the front wheel wells - since the Prerunner comes lifted, there's a lot of space above the front wheels.

I'll post more pix as I go along. As for science... sorry, for now "I want my mpgs", and if I nerd out too much, I'll never finish my mods. But eventually I'd love to do some coastdowns.

For this week, please join me in cheering on my wheel mods. If can I relearn to drive with my way-off ScanGauge recalibration (ugh!), I oughta be able to fill up at 30mpg this week.

Other data for those interested:
2003 Tacoma Prerunner
Double Cab, Short Bed
2.7L 3RZ-FE 4-cylinder automatic

Suggestions needed:
I'll need clever and easy ideas for accessing the tire valves. I'll explain more when I post pix of the wheel covers, which are of the DIY pizza pan variety, secured for now with zip-ties. I'm thinking I may buy valve extenders so they can be permanently accessible. The alternative, of course, seems to be to cut a sizable hole in each of the covers.

For more... please see my Trip Log.

FastPlastic 12-08-2008 01:06 PM

Look like your off to a great start:thumbup: Keep up the good work!

Sulfuric 12-08-2008 03:59 PM

That's one of the best looking cars that have any mods to them.
You get to drive around a cool looking pickup and still get almost 30mpg, that's awesome.

My car gets 10mpg over your car but my mods don't look as pro as yours do(yet :D )

mobilerik 12-08-2008 04:49 PM

Quote:

That's one of the best looking cars that have any mods to them.
Wow, quite a compliment! Maybe I'll keep to my low-resolution cellphone pix for all my mods. :)

It does look fairly cool from a distance, though... but I still haven't gotten used to smooth wheels. There's something so "un-truck-like" about that to me. And racing wheels on a lifted truck that's going 45 in the slow lane... Just who do I think I am anyway??

The demand is growing in my mind for that "Research Vehicle" placard.

rav 12-08-2008 06:43 PM

Did the air tabs help? Nice mods so far, All the best!!

MetroMPG 12-08-2008 07:02 PM

I'm betting the air tabs made no discernable difference.

Great mods!

I'd definitely work on that coroplast taper to the roof & side of the cab. You can't go wrong with a 10 degree taper (sides & top) if you just want to slap something together.

DifferentPointofView 12-08-2008 07:40 PM

its so good looking cause everything matches, and is smooth. the wheel caps match the cars paint while delivering a 2 tone look with the black on the wheels, and the rear wheel cover is black like the fender flares, and smoothly goes from front to back of fender, so it looks as though its supposed to be there. Nice work. :thumbup:

mobilerik 12-08-2008 09:24 PM

Holy crap!!!
 
My SG recalibration was so far off, I felt I had to fill up to get some sense of normalcy back in my monitoring system. Check out my first post-wheel-mod gas receipt:

http://rik.akashian.googlepages.com/gas33mpg.png

And here I thought I had a crappy day! Since the SG was so far off -- about 8mpg too low -- I couldn't hit any of my marks, and gave way more gas than I should have, just to keep my speed up. It was terribly confusing. About halfway through the return trip, I figured out that I need to aim about 5-6mpg lower than usual, based on my previous marks, and just as I got it into my head that I was going to beat 30, I ran into an uphill pile-up! I was totally baffled when the gas pump shut off when it did, and it took me quite a few startled seconds to recognize the easy "divide by 2.0 gal" calculation.

So can we say, "Way to go, wheel mods!!" :thumbup:

Of course, such a short tank is bound to have a large error. So we'll see how the rest of the week goes. Maybe I can get another mod in tonight. ;)

Sulfuric 12-08-2008 09:32 PM

33 mpg is simply amazing in pretty much any pickup, high five.
If you could pick a number in mpg, how much do you think you scangauge helps?

I don't have an SG, I think my car is too old, and I still manage to pull about 50% over EPA.
I give myself a pat on the back every fillup.

taco 12-08-2008 10:24 PM

flat landers!!!!!


very nice 3rz ftw!

trebuchet03 12-08-2008 10:45 PM

That's a super small fill..... 33mpg is great, but wait for some better data on your next two complete fills ;)

Mods look good though :)

mobilerik 12-08-2008 11:21 PM

Quote:

That's a super small fill..... 33mpg is great, but wait for some better data on your next two complete fills
NOOOOOOOOOOOOOOOOOOO!!!! :-)


I'm cheering on my wheel mods, see. They just scored a touchdown, and whether the ref made a bad call... is completely beside the point. The scoreboard says 33mpg. GO WHEEL MODS!! Woooooooooo!

Besides, two fills is two or three mods away, so the science experiment is doomed from the start. Now it's just pure sport. Feel the adrenaline. I think I can beat 30 this week. Dig??? :thumbup:

mobilerik 12-09-2008 11:21 AM

My New Bonnet
 
Last night my truck got a new bonnet to go with the skirts.


http://rik.akashian.googlepages.com/bonnet.jpg

Hmm... I think I should restate that, b/c I think my truck is a dude.
"Last night my new truck got a new bandana to go with his kilts."


I don't love this design, but I thought it was a clever use of an extra 4x1 foot strip of coroplast.

Construction was easy. Using a template from a piece of poster board, I cut it and had it ready within 20 minutes.


http://rik.akashian.googlepages.com/bonnet-const1.png


Then I decided to get fancy and screwed it up, causing me to spend another hour fixing it with ugly tape.

Here's how it's applied. The tab attaches to the back of the truck.

http://rik.akashian.googlepages.com/...nstruction.png

I stuck it to the truck with double-sided duck tape. Good stuff.

Since I didn't bother to pre-bend the coroplast, it was tough to get the tab to hold, so I wound up layering a pile of aluminum tape.

http://rik.akashian.googlepages.com/bonnetprofile.jpg

The drive:

I got to my car this morning to find that the tab on one side had detached. Because it was cold and dewey, there was no way I was going to get it to stick, so I left it dangling. Otherwise it was solid, and it made the entire 34 mile drive.

My ScanGauge is calibrated a lot closer now, and marks are easier to hit. Not my old marks, mind you, but marks nonetheless. I think it's still calibrated low, but it's close enough not to be maddening. If it's not still really low, then I'm worried that my engine is starting to lose efficiency now that it's well out of its stock sweet-zone. I'm not sure that's a good diagnosis of my experience though... I'll have to meditate on that.

My nicest discovery ... I can Pulse-and-Glide now! Not everywhere, of course, but at least on some moderate downgrades where my previous choice was limited to DWL at 65mpg. And I was totally able to coast all the way down a few long hills. I noticed the same after the wheel mods yesterday, but now it's even better.

I don't like the look right now though, so I'll be in a hurry to upgrade to a full "fastback". I'll probably procrastinate today by folding paper designs of the folds and cutouts I'll need.

mobilerik 12-09-2008 03:24 PM

Quote:

Originally Posted by MetroMPG (Post 77305)
I'm betting the air tabs made no discernable difference.

Great mods!

Thanks! The DIY AirTabs... hard to say what if any difference they made. When I first installed them, there was a lot of noise, but no real difference in how the car handled. At least as far as I could differentiate from the belly screen that I was fiddling with at the same time. Now, I did see a consistent 1 mpg boost when I cut them down from 2.5 inches to .75 inches and better handling. But again, I was finishing and repairing the belly screen at the same time. You could say "I want to believe" that they should work on my truck. The vacuum suck when I shift to N downhill is hugely frustrating, and it would be great to minimize that. Maybe they need to see a wing. It's a fact that my short bed doesn't allow a shallow 12 degree angle -- it's more like 20. Soon I'm thinking I might experiment with a whale tail. But first I'll see if managing the angle of the roof and sides can accommodate the short 5-foot bed.

Quote:

I'd definitely work on that coroplast taper to the roof & side of the cab. You can't go wrong with a 10 degree taper (sides & top) if you just want to slap something together.
Yeah, "slap" definitely describes this last mod. It's not even a bonnet -- more like a kerchief. Ideally, if I wanted to stick with this mod, I think I need to make it look like a manly backwards baseball cap.

I'm having trouble imagining how to apply the sides-taper to a fastback attachment, that I assume would affix to the bed rails, when my bed is wider than the cab. Is there a model somewhere for this? Or maybe the idea is a gradual taper as it rises towards the top...

mobilerik 12-09-2008 03:49 PM

Quote:

Originally Posted by Sulfuric (Post 77343)
33 mpg is simply amazing in pretty much any pickup, high five.
If you could pick a number in mpg, how much do you think you scangauge helps?

Well, yesterday it didn't help me the slightest bit, LOL. But generally I've been saying it's worth to me about 6mpg, or 20% of my mpg. Of course I could've learned a lot of it, and did learn a lot of it, without the ScanGauge. But I totally depend on DWL, and with the automatic, I often just have a hard time figuring out what gear I'm in, especially coming out of neutral coast. It's so much easier for me to watch the mpgs. If I'm cruising at 48 but eating fuel, I know I need to get my overdrive back. And knowing whether I'm trolling around town at 10mph getting 30mpg vs. 5mpg is priceless.

mobilerik 12-09-2008 08:47 PM

Quote:

Originally Posted by taco (Post 77351)
flat landers!!!!!


very nice 3rz ftw!

ROTFL!! :)

Dude, I'm from WV myself. Northern. ;) And I'm so impressed you get 27mpg in a 4x4. Nice!

mobilerik 12-11-2008 12:38 PM

"Fastback"-style Cab Kamm: Check!
 
"Fastback"-style Cab Kamm: Check!


Here's what I "slapped on" last night:

http://rik.akashian.googlepages.com/fastback2.jpg


The Build:

Funny thing is... I stopped at Lowe's after work to pick up some clear plastic and supplies to make the side fairings. But by the time I got home, I decided it was too complicated to bust it all out in one night, so I decided to put it off.

But I thought "Why don't I try this with some of the screen left over from the belly screen?" It took me all of 15 minutes to cut the screen and prep it. But when I got back to the car... too short. (Measure twice, cut once, stupid!) And that was the last of my screen.

The experience was good, though. When I realized how small those fairings really are (about 17x12", tapering to 5"), I noticed I had a couple small pieces of coroplast left over from the wheel project that were exactly the right size! :D

I quickly cut 'em to size, and cut a few smaller pieces to use as joints - to attach the fairings to the bed rail and to the top fairing. Again I used Double-Sided Duck Brand Tape. If you haven't tried it, I really recommend it. It not only sticks solidly to the car, but it also peels right back off. It's gummy, so I think it's helped by simple vacuum action.

http://rik.akashian.googlepages.com/fastback1.jpg

Geometry:

It's hard to tell from the photos what kinds of angles are involved. Honestly, I didn't measure, but tried to eyeball a taper that would allow around an average of 10-12 degrees. The sides start at the bottom flush with the inside edge of the bed rail and twist to meet the top at around 15 degrees.

The top likes to bulge upwards in the middle, so the angle is near flat, but rapidly starts to curve downwards towards the sides approaching 20 degrees. Note that the tailgate of my short 5 ft. bed is about 20 degrees south of the top of the cab. I'd like to reinforce the middle of the top so that it bulges less and keeps a more consistent downward angle across the top that will keep it from "splitting" the air over the bed.

Visibility:

A short note -- I was very concerned that the visibility around my blind spot would disappear, and that's why I was prioritizing clear plastic or screen for the side fairings. But now that they're on -- not only are they not in the way... I can barely even see them, because they are hidden behind the C-pillars. How about that! :thumbup:

Questions, anyone? Comments from experts?

I'd really like to know if this "Fastback" style would be better converted to the downward "chopped" style Kamm-back, with the side fairings smaller at the bottom than the top. It's obvious to me that the V where the top and sides meet won't do, but beyond that, what shape should I be going for overall?

By the way, if anyone is counting, I believe this is my 5th ecomod this week.
1) Wheel covers, 2) Rear wheel skirts, 3) Passenger mirror foldback, 4) Top cab fairing, 5) Side Cab Fairing. With two more days to fillup, what's your bet on this week's numbers? :)

FastPlastic 12-11-2008 01:01 PM

That looks awesome!!! :thumbup: Who knew aero mods could look so beautiful (crying a little inside).

Can you still see the 3rd brake light?

mobilerik 12-11-2008 03:15 PM

Yeah, the brake light peeks under just fine. But that's a good reminder for when I try to lower the angle a little.

MetroMPG 12-11-2008 03:43 PM

Cool. I really like the way the mods are looking on your truck. Business like for sure.

My first comment: make it bigger! :)

As for shape to follow, look at Bondo's or Phil's truck and follow those lines. The fact that you're chopping yours off before the tailgate doesn't matter. If you can round the "shoulders" (the transition between the "sides" and "top" of the extension), it'll help.

mobilerik 12-11-2008 04:39 PM

Quote:

Originally Posted by MetroMPG (Post 77919)
As for shape to follow, look at Bondo's or Phil's truck and follow those lines. The fact that you're chopping yours off before the tailgate doesn't matter. If you can round the "shoulders" (the transition between the "sides" and "top" of the extension), it'll help.

Thanks, Darin. I understand that I'm going for a teardrop, no prob. My question concerns how to chop it off for best effect. Right now, it's cut off with a rather ragged shape. I would rather, for aero as well as aesthetics, have it be a straight cut all the way around. The question is... along what plane should I chop it? Most Kammbacks seem to chop at a downward-tilted angle, which makes sense at the very back of the vehicle. (Does it? I guess it does...) But off the cab in the middle of the wake, is there any reason to chop it vertically? Does it matter?

I'm asking, b/c "bigger" was exactly my intent. I only did this version because it was quick and involved scraps, and I'm impatient. And I never intended to attach sides to this -- it was just an impulse when I realized how easy it was. So I want to know for the next project if there's a reason to chop it vertically, or tilted back like yours, or forward like a "fastback fairing".

Ultimately, I'll have a topper. But in the meantime I have a few intermediary ideas I want to try that will still allow the bed to be open.

Quote:

Originally Posted by MetroMPG (Post 77919)
If you can round the "shoulders" (the transition between the "sides" and "top" of the extension), it'll help.

It's hard to tell in the previous pix, but the corners actually are pretty well rounded. See this one:

http://rik.akashian.googlepages.com/fastback3.png

I actually consulted your thread a lot, and I remember you saying that you wish you rounded the corners more.


I'm hoping this thread may inspire some other truckers. This mod was SOOO easy. Way easier than the wheel skirts.

All it involves are about 6 sq. ft. of coroplast scraps and double-sided Duck tape.
It's perfectly reasonable to have it all done in one evening.

aerohead 12-11-2008 05:23 PM

where/how
 
Forgive me for butting in but I wanted to toss out something that might help you answer your own question. Aero isn't that mysterious. Your truck is submerged in air,and as you advance forward,you displace a volume of air equal to your frontal area,times your distance.Air has mass(so momentum and inertia are involved) and air is viscous(so there's friction when you move through it).---------------

With the Tacoma,your trick is to allow the air to recover to the position it occupied before you came along with the minimum amount of separated flow. Once the air has reached the point of maximum cross-sectional area ( about where your head is, outside around the cab),you have converted atmospheric pressure into kinetic energy. The whole point of streamlining,is to provide a ramp which is gentle enough,such that the air can rebound(like a spring),without leaving the surface of the aftbody of the truck. Any reduction in the cross-sectional area of the truck without flow separation will produce a like reduction in drag. If you can reduce the wake of the truck 10% without separation,then you reduce your drag by 10%. If you imagine the imaginary teardrop tail,extending rearwards behind your cab,divided into 10-sections,each section with 10% less area (turbulence-free),the further back you go,the less drag you have,losing 10% for each "section." And you chop it off where ever you choose.That's all there is to the Kamm-back! Kamm and others did recommend that you chop it off when the (clean) cross-sectional area is reduced to 50% of frontal area. -------------

You can cut it anywhere you want and you can calculate your drag reduction as a direct function of the area of the remaining wake. That's all there is to profile drag! But remember,the curvature of your structure cannot exceed the curvature found with the teardrop or separation will occur,and you're right back where you began.Careful examination of your roof will tell you if Toyota gave you a little curvature to begin with,you can take it from there.

mobilerik 12-11-2008 06:06 PM

Wow, that was a really helpful explanation. Thanks! You're perfectly welcome to "butt in" any time. :)

Quote:

Kamm and others did recommend that you chop it off when the (clean) cross-sectional area is reduced to 50% of frontal area.
Hmm... I see the problem, since on a truck, with the bed taking up at least 50% of the area all the way to the back, that pretty much forces a topper and a partial boattail on you.

But I think you've also suggested that you can pair a cab Kamm with a rear tonneau or Kamm extension to provide that continuity. That's probably my next mod. I've been wanting to ask you... My short 5' bed has a pretty sharp angle from the cab to tailgate, on the order of 20+ degrees. How much would I be able to bridge that gap with fancy curvature on the Kamm? I'm figuring I may have to whale-tail it a bit, and I'm wondering how high I might need to build the extension. Thanks again.

lunarhighway 12-12-2008 02:32 AM

i did a quick measurement off the rear windshield/roof angles of some sub 0.29 Cd car profiles and most where somewhere between 15 and 16 degrees. most also had a little vertical spoiler or simple trunklid like structure just before the end of the car.

taco 12-12-2008 07:35 AM

if u noticed gm and ford are using short beds for the xfe models, they add a cover. they claim the bed is short enough that the main air flow dont hit it.. i know the air hits the last foot or so of my 6 foot 3 inch bed.

mobilerik 12-12-2008 11:39 AM

Quote:

Originally Posted by taco (Post 78046)
if u noticed gm and ford are using short beds for the xfe models, they add a cover. they claim the bed is short enough that the main air flow dont hit it.. i know the air hits the last foot or so of my 6 foot 3 inch bed.

Taco: Can you find an article that explains the XFE aerodynamics? It'd be nice to see an airflow diagram of this.

It still seems to me that optimally I would want the reattach the airflow at the back. Maybe with the short bed, I would have a chance for a really short wake if I get the curvature right.

LH: I actually made the half-tonneau sit inside the rails instead of on top, and it sits just below the top of the tailgate, creating a small lip. I think for those cars, the angle from the cab to the top of the lip is generally in the 12 degree range. In my case, it's about 22 degrees. It sure would be amusing to try putting a 6" tall "lip" on my tailgate to see if it helped reattachment. How's that for counterintuitive?

1.5Ldave 12-12-2008 01:04 PM

Might be easy to test this out. Maybe try extending the rear of the vehicle a bit, like they do on the salt flat cars. It wouldnt have to be this dramatic, but it might help by making the bed essentially longer. The lip on the tailgate also sounds like a good idea to combat this issue. Or perhaps both with be called for to be effective on a short bed.

http://z.about.com/d/mustangs/1/0/V/...gen-racer3.jpg

mobilerik 12-12-2008 01:38 PM

Yeah, that's what I was thinking of. The other idea was to continue the curved lines of the roof fairing into a rounded tailgate Kamm and/or spoiler-type tonneau top. I think a rounded arch-style tonneau top, sloping downwards, could look cool and un-spoiler-like enough not to be laughed at. I could make it look like some kind of fancy executive beer cooler. :)

Actually, since I couldn't let a day go by without trying something new, I did stick a tiny flat extension on the back using the only scrap of anything I had lying around. But it looks so stupid the way I did it that I'm embarrassed to post it, and besides, it made no difference in my commute. To mate the air off the cab at 12-13 degrees, it would need to be long... I think my trig told be that it'd need to be 12-24" past the tailgate to have a chance. I think my best choice is to raise it a little , and make up some of the angle with fancy curvature from the cab fairing.

One advantage to modding a truck is that, if it's designed cleverly enough, I think a tailgate Kamm could fool people into thinking it's some sort of towing apparatus. :)

DifferentPointofView 12-12-2008 02:03 PM

^
lol :D
*man examining truck*

well folks it looks like some sort of towing apperatus.

*akashic returns to truck with grocieries*
HEy HEY! get away from my truck!

MetroMPG 12-12-2008 06:29 PM

akashic - did you see the teardrop photoshop templates I did in my Kammback thread? If you fit your truck into that shape, with the highest point of the cab at the highest point in the teardrop, you'll be able to see the "ideal" curvature from the tail end of the roof, aft.

I think you're right in that the end point of the ideal curve is going to be higher up than the top of the tailgate.

Here's the image:

http://ecomodder.com/imgs/ideal-teardrop-comparo.jpg

mobilerik 12-12-2008 07:16 PM

Sweet! Yeah, I was looking for that, but I couldn't remember who posted it. Suppose you could post a template of the ideal curve for me to play with?

mobilerik 12-13-2008 03:32 AM

Woohoo!!! 30mpg is mine
 
Woohoo!!! I made it !!!! The 30mpg barrier is broken. :D


http://rik.akashian.googlepages.com/Picture5.png

Whew, that was close!


For the record, since last Friday's fillup of 27.7mpg, the improvement is 8.3%.

That's the effect of 5 mods completed this week:
  • Smooth Wheel Covers (Sunday)
  • Rear Wheel Skirts (Sunday)
  • Passenger Mirror Foldback (Tuesday)
  • Cab Roof Fairing (Wednesday)
  • Cab Side Fairings (Thursday)

All together at the same time, they're probably worth about 10% total, or 2% each, which agrees with the findings of others who have done similar mods.


Next up -- Whatever I can get to from this list:
  • Better Cab Kamm
  • Tonneau Extension
  • Front Wheel Well Dams
  • Front Wheel Skirts
  • Passenger Mirror Delete

Along with these clean-up projects to complete or improve what I already have...

  • Wheel Cover Air Valve Access
  • A Real Grille Block instead of this stupid cellophane wrap
  • Make Wheel Skirts More Easily Removable
  • Add Paint to the Belly Screen - Necessary, I don't know

and research projects...
  • Sketch My Truck's Ideal Teardrop Curve
  • Locate a Coastdown Hill and Cruising Test Strip


We need more emoticons on this board. I want the ones that dance around excitedly. Woohoo!!!

aerohead 12-13-2008 02:04 PM

ideal curve
 
Quote:

Originally Posted by akashic (Post 78123)
Sweet! Yeah, I was looking for that, but I couldn't remember who posted it. Suppose you could post a template of the ideal curve for me to play with?

akashic,the dark area in the template is the ideal curve.If you have a good side shot of the tacoma,scale it to just fit under the curve,where the highest point of the cab intersects the max height of the pattern.The curve dropping away and to the rear represents the ideal path,without separation,that the air will follow.-------------------------- For your shortbed,and 60-inches of bed length,I took the tangent of 10-degrees(probably a slope you wouldn't want to exceed for the short-bed),and it shows that at the tailgate,your cover shouldn't be any lower than 10-1/2 inches lower than the height of your roof.You could make up the difference with a rear spoiler laid back at a shallow angle no more than a 30-degrees which would intersect the line of the template.If you tilt it more upright,it will begin to dig back into drag.
The template will give you the better form,but at 10-degrees slope,you shouldn't get in too much trouble.P.S.,you almost have to do a rear spoiler because of the short bed!Happy fabricating!

mobilerik 12-14-2008 01:17 AM

Thanks! Here's the fit:

http://rik.akashian.googlepages.com/Wake.png

http://rik.akashian.googlepages.com/WakeCloseup.png

Wow, that's a lot of height to make up! I almost want to just stick a vertical board there to see what will happen. Or better yet, a couple of boxes. But I'm in a hurry, so I'll just make an arch-shaped spoiler.

When I make the arch, do you think I need to leave the tunnel clear, or do you think it might benefit to block it to encourage the stationary vortex, so the air knows to go above and around?

mobilerik 12-15-2008 12:08 PM

"Ton o' Aero" (Aerodynamic Tonneau Topper)
 

Preview of my next mod: The most visually striking yet!

It made it about 20 miles in the rain today before I watched the reinforcement fall off. It definitely needs better reinforcement all around to cope with freeway speeds. It's made of two layers of coroplast, with steel strapping. Unfortunately I only glued them on, but it doesn't matter, since it clearly needs more stability anyway. I'm going to try a layer of hardboard under it.

Because of the rain, I definitely won't be setting any records this week. My morning commute said 26 mpg, with a much more accurate calibration. So not much help for testing aero performance.

The angle is 10 degrees and is set slightly shallow of the ideal curve from the roofline. The arch passes 10 inches above the tailgate at the highest point. Rear visibility is minimally impacted, because the perspective of the rearview mirror is similar to the roofline. I'll post pix later when there is decent lighting. It does happen annoyingly that what little rear vision it does impact, it slightly obscures cars following at the proper highway following-distance. But I it doesn't completely hide them, and I can confirm by adjusting my glance a tad.

Once I get this thing stabilized, I also have the templates ready for clear "Kab-Kamm" which I hope to have ready this week, provided a few moments of dryness for the adhesives to stick.

http://rik.akashian.googlepages.com/spoiler2.png

aerohead 12-15-2008 02:28 PM

clear or block
 
Quote:

Originally Posted by akashic (Post 78350)
Thanks! Here's the fit:

http://rik.akashian.googlepages.com/Wake.png

http://rik.akashian.googlepages.com/WakeCloseup.png

Wow, that's a lot of height to make up! I almost want to just stick a vertical board there to see what will happen. Or better yet, a couple of boxes. But I'm in a hurry, so I'll just make an arch-shaped spoiler.

When I make the arch, do you think I need to leave the tunnel clear, or do you think it might benefit to block it to encourage the stationary vortex, so the air knows to go above and around?

I would begin with a clear block at the rear.The "box" should not behave as a parachute,as it is not in the free-stream.Closed like this,it will force the surrounding air to go around,and my intuition tells me that it will behave like the Gilkison"dog-house" or my "blister",both of which added mpg to Tacoma and the T-100.

mobilerik 12-15-2008 05:00 PM

Damn, this is getting expensive, especially for a prototype. Now I need a 5'x1' sheet of plexi, just so that I can cut half of it off in a non-standard shape. :eek: Oh well...

Hey, is there any particular reason why the block would be more preferable at the rear of the spoiler tunnel than at the front? What if it was blocked in the front with some sort of curvy "ramp" to further entice the air over and around the spoiler?

aerohead 12-15-2008 05:29 PM

expensive plex
 
Quote:

Originally Posted by akashic (Post 78584)
Damn, this is getting expensive, especially for a prototype. Now I need a 5'x1' sheet of plexi, just so that I can cut half of it off in a non-standard shape. :eek: Oh well...

Hey, is there any particular reason why the block would be more preferable at the rear of the spoiler tunnel than at the front? What if it was blocked in the front with some sort of curvy "ramp" to further entice the air over and around the spoiler?

akashic,at some fabric stores,they carry a very heavy, clear sheet vinyl,which when stretched tight and stapled down, is almost as clear as glass,virtually weightless and a fraction of cost of rigid plex.It's probably tough enough to get you through testing to see if a more permanent and "expensive" mod is justified.
Just a thought.

lunarhighway 12-16-2008 02:18 AM

what if you where to raise the sides of the bed untill they are t the right height and than add a horizontal spoiler on top? shouldn't block vision to much, wouldn't really look like it was a spoiler

Christ 12-16-2008 09:12 PM

Continued banter from other thread -

Yeah, exactly like that. LOL

I was talking about the full shell though. Seems like it's just easier to make the whole thing, rather than worrying about compound air effects caused by the open area between spoilers. - To me, anyway. I could be wrong, it's happened before.

But, it seems like you've got the right idea, so I'll shut up now :P

Oh, on your wheel fairings (kilts): If your flares are ABS, You can get a spare set that will allow you to build the fairings from ABS, and you can actually "weld" them together with Acetone. (ABS melts to a putty in acetone, and will bond to other ABS as the Acetone evap's)

This might make it appear cleaner, and will leave a smoother wheel area for you to look at. Just a thought, you might not even care.

Good work so far, though, keep it up! Always nice to see someone working on a beast of burden!


All times are GMT -4. The time now is 04:27 PM.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com