ford ranger aero canopy
 

so going to give this whole aero dynamic modification stuff I have a 1996 ford ranger 2wd 2.3l I have not done any aero mods yet i had a bed cover that with that and a slightly larger tire i was getting at most 28 mpg when driving to work and back. So I figured i would give the aero dynamic canopy a shot im not one for math and angles so im just building something i think would help and i think actually looks really good on my truck.

It would look good on your truck, As a idea you could have the boat tailed canopy on a piano hinge near the cab roof so you can tilt it up to ease loading and unloading.
Your little 2 wheel drive 4 banger ranger is a great truck to Mod.

yeah im going to building it out of frame fleece and fiberglass then go from there. I have pics im working on uploading

Yeah this is probably going to sound crazy but im somewhat going to try to cheat the best of both worlds. I Love the truck for its gas mileage and it works really well off road for camping and going out on the logging trails and beaches so the plan is to make plastic covers for under the truck to improve the dynamics under the truck and the canopy but it needs to be taller for my other practical uses off the pavement. so im going to try to improve the dynamics of the truck hope that as long as the flow over and and under the truck is improved the larger tires with allow wheels and new gearing wont be noticed as much. So everyone is probably shaking there heads right now but im trying to keep it at 28-30 mpg with 7 inches (4 inch suspension and 3 inch body) of lift 33x10.5x15 tires and allow wheels and 4.56 gearing will bring me right under my original final drive ratio to counter different weight of tires. later it will get metal removed and fenders hood and bedsides will be replaced with fiberglass ones to really cut down the weight of the truck.

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it will have two windows one on cut out where the particle board is and the other will be on the back over where the third brake light is going to be.

That looks OK.

Do you have any results regarding fuel economy yet ?

no it still has to be fiberglassed and windows inserted

Do the top front corners of the cap stick out further than the top rear corners of the cab? Looks like they may (that increases frontal area, which goes against your drag reduction efforts!)

Is it too late to re-work? If so, I'd suggest adding something rounded to the "front" of those cap corners to smooth the transition.

Yeah they do i need them too for a mounting surface im going to have like a big weather strip that goes from the canopy to the cab to seal the gap. so that should prevent air from slamming into the canopy. Im probably going to do a second canopy that shapes to the bed a lot better and put this one on my other older ranger. its my first go at it so its a trail and error learning experience

I would modify some things here,
1st, that one picture shows the top front corner sticking above the back rear corner of your cab, that really will upset the air flow and almost render a large part of the cap worthless.
2nd, turn those corner supports that run front to back to 45°, this will ease the radius here and really help a lot, particularly in any kid of cross wind.
3rd, you need to raise the back end, your slope is much too aggressive. I understand that you think you want as small of a rear area, and therefore a smaller "Low pressure" zone behind your truck. But it does not work that way. You need to follow the "Aero Template" to achieve the best result.

Here's a pic of yer type of truck with the template.
http://i47.tinypic.com/160r4fb.jpg

4th, see if you cant put in some sort of support that bends the front to back top corners into a arching shape. Going straight from roof to top cap without a eased transition will really mess things up.

I know you've put a lot of work and thought into this already, and getting out to actually build something is awesome! Seriously good workmanship so far. But, you are making several errors that are going to really limit your results. Just a hunch, but your current design is only 30% of what is achievable. Will you see results? Yes. But if you make the 4 changes I suggest, I think you'll be in the 80% or better potential.

I have "photoshoped" some things onto your picture to illustrate what I mean here.

http://i47.tinypic.com/358qujc.jpg

I really think if you're going to take the time to fiberglass this, you'd want it to be as good as possible. Also my suggestion #3 gives you a lot more usable space under the cap and improves the mpg result ta boot.

I think i can manage to work onthose things before glassing it up. the first one isnt really going to happen i need to corner edges because there iare going to be led lights that are giong to be stuffed in between the canopy and the cab. but there is going to be a weather strip removign the gap.


I can turn 45 degrees shouldnt bee to big an issue.
Do they areally need to be so much in a curver for the aero might be a bit of pain to get the wood to arch like that.


number 4 how tall would you say that i would need to make the back end of the canopy? Its 3.5 inches on the low the center is 7 inches so like 12inches?

You gotta understand that tripping up the air, particularly on the corners, is a dangerous thing to do since this is the area where vortices can and will form. And I mean huge, energy robbing, 18" diameter spinning tornadoes that require large amounts of energy to sustain. That 2" front top corner aero toe stub you have now could render the aero cap benefits useless. You might as well just make a traditional cap and take advantage of all the dry storage room. This is also why you want to ease the edges, sudden pressure changes start air spinning. I know, a vortex was the last thing you figured you'd need to be aware of avoiding, but they'll hose you over quick.

http://i49.tinypic.com/r09s91.jpg

Yes, you need the curvey, it isn't the "Curvey" that makes it aero, it is the lack of an abrupt angle change that makes it good. You want the air to ease its way down from the center of your cab, and an abrupt change will not give you the same benefit. You could actually raise the whole back, without curves, to 10 inches and still get a good result and have more room.
To bend the board, get a piece of 1/4 inch plywood and make it in 3 layers, it will be bomb proof. Or you could cut slits in your solid lumber to get it to bend easier. It looks like you're using 1x4's for those corners, putting notches every 2 inches would do it I'd think at about 1/4 to 3/8 inches deep, and you won't lose much strength there.
Like this.
http://i48.tinypic.com/zui92x.jpg

And I'd think 8 inches across most of the back is where you need to be. The back plate I illustrated is the shape you want to shoot for. You did a good job on your back plate! It's just not quite tall enough to be optimal.

If you need the front plate to be in the shape it is, then make it smaller so it tucks in behind the cab everywhere, this is a very critical area, things sticking up here, or too quick of a transition like you have now, will negatively affect the results in way greater proportion to their size. You'd be better off having it 2 inches lower across the whole top rather than 2 inches taller in the corners. If you put the wood in at the 45° angle, this should get it below the cab line.

Oh, and filling the gap between the cab and cap is not a big aero concern, you could leave a 2 inch space their all day and it would be insignificant, maybe a 2% difference in the improvement you get, so instead of going from 28 MPG to 32.2 MPG from you'd get 32.12 MPG.

Your current design might get you from 28 to 30 MPG where if you make the changes I'm talking about, you'll get to 31.5 or better MPG.

I'm not guessing here, what I tell you is based on a few years of contemplation over this.

Here is a paper upon which much of what I'm saying is based. Pay attention to pages 85, and 89-90. Real numbers, real results.

Drag Reduction of a Pickup using Add-On Devices

I will see about making the changes tonight

looks great. i would raise it up a little bit in the center where there arn't any supports.

ha ha my fiberglass work is pretty awesome once im done with it i wouldnt even need the wood frame let alone additional supports. I have to look at making the modifictions to the frame then fiberglass the shell then cut and insert windows

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ok so new updated canopy with more swoops and curves and whooshes and slants and a whole lot more of a pain in the a$$ to construct ha ha. Let me know what you think about set up number two.

Hi, MoToRNecK. You're making great progress on a solid path to a slipperier AND more cargocious truck. I look forward to v1 completion and test results. Rock on!

I wouldn't be surprised if it serves well enough that you never get around to building that second version up your sleeve. ;)

Looks much better than V1 great job!

Daaaaaaaaaaaaaaaaaaaaaaaaaaaaaaayum DOG!!!! If you fiberglass that, you'll have an amazing aerocap.

The drop in lift coefficient was very noticeable when I had the aerocap on my full size 2000 GMC, the truck felt like it had tail feathers keeping it going straight down the road in winter driving. In slippery conditions at highway speeds, without the cap there were some white knuckle moments here and there, particularly when passing a truck. When I had the aerocap installed, the truck never stepped out even a tiny bit ever.

You NAILED the Template!!! This should minimize the CD achievable with an aerocap!!
http://i48.tinypic.com/2ikefex.jpg

Bigger Version of Pic Above

I analyzed the overall angle at about 8° with a final departure angle at 12° So your CL should be at a minimum, at highway speeds, your truck will feel much more planted, and be quieter too.

FANTASTIC WORK!!! Super proud of you!

yeah thanks for the help with the modifications for it Now i just need to glass it and get some plexi glass. I am looking to do some skid plates underneath i just have to figure out where to get some plastic sheeting to do so. but otherwise i am going to just reinforce the canopy structure with some flat bar in certain places and start wrapping it in the next couple days. i do appreciate the help tremendously I figure if im going to put all the work into making this thing might as well get it right the first time!

oh i did have a couple other questions now that you have seen it re shaped the rear end where the tail meets i have about an inch of wood still sticking up from where the curved edges are can i cut that down to bring it level? or should i leave it? http://farm8.staticflickr.com/7122/7...a9a7510006.jpg
IMG_0595 by MoToRNecK!, on Flickr

Just a suggestion, home depot sells a product called frp , fiber reinforced panel, same stuff they use to skin RV's nowadays - also used on car wash walls, its thin, its light, and if you use a polyurethane foam under (ie greatstuff) it makes for a near bulletproof composite panel...I've had some good results by tacking down the frp using greatstuff to fill with a 3mil poly backing to keep the inside neat...

With a little heat the frp bends relatively nice too (but watch out - too much heat melts it, and its a royal pain to fix the finish after melting)

I'd say anything to make it smoother and easier to work with at this point, cut it off. You can make a straight cut by screwing a board in place and using it as a straight edge guide so you don't even really have to remove it. I was wondering what that was about. If you leave it or cut it, the difference aero wise isn't significant I'd think.

Use it as a mold for your fiberglass skin. That way you can make multiple copies. All your friends are going to want one. :)

I was thinking about working on a mold for it so i could make it lighter and not have all the wood bracing inside it. Non of my friends have small vehicles We are primarly A big truck group my other truck is a 2001 dodge ram 2500 Cummins Turbo Diesel and my buddies all have PowerChokes. I am building this prototype primarly because of if it works well enough i want to build one for my dodge which has an 8 foot bed on it. It gets around 18mpg at 350 horse 900 lbs tq. so im aiming to get 20 mpg with some areo modifications modifications oh yeah and the dodge is on 37 inch humvee tires so its giong to be a challenge but i will do a write up for that one as well!

It's obvious you're comfortable with carpentry; but as you go on, if you frame it up in foam plastic rods and sheets, after it's fiber-glassed you can just melt it out with acetone.

I've been wondering about mudflaps, curled so they can hang at an angle, in front of the tire. Do you require a picture? It might take me a while.

yeah get a picture.

as for doing it with wood is because it makes for a lot more rigid set up for now because this truck is going to be used very hard all my trucks are so for the prototype wood is my thing I will probably build everything based in wood and just create a mold for it late i just dont like plastics lol too easy to mess and more expensive in the long run for me to buy.

This looks great.

If the tires are a concern to you, consider making some removable fiberglass strakes ahead of and behind the tires to reduce the turbulence. You could even mold them with the belly pans if you plan on taking those off when off-roading.

Something like this, but more conservative.
http://t1.gstatic.com/images?q=tbn:A...jIRUUju7YclFzl

what kind of vehicle and take a photo or i can find one myself if you give me make model year

MoToRNecK, your work looks awesome!

thank you

Here's a simple, and I do mean simple, diagram of a spat to cover a lot of tire exposure. A strap metal bracket and rubberized belting and pop rivets:
http://i.imgur.com/Sj28D.jpg

If you want rigid, a bamboo/hemp truss would be as strong as carbon fiber or titanium (according to them) and you can grow your own, man:

How to Build a Bamboo Bicycle

what kind of vehicle are you looking at having it done too? I would look at making it out something more flexible in case you bottom of the car out or unless you know exactly where your maximum up travel is and can make it up to that point or make it flexible so that it can be as close to the ground and just flex if it hits lol. that would be kinda ghetto though. And yeah bamboo and hemp makes me feel like a tree hugging hippy. Im just a broke ass redneck with two many toys and want to get the most out of what i can ;)