New Wind Wing - Effective or not? An ongoing question.

[Cliffmeister2000]

That looks pretty good, Dale. I wonder if air getting under the wing might hinder the performance of the wing itself?

[angib]

My apologies if I am trying to teach my grandmother to suck eggs, but do you know about 'coast-down' testing? This would be the obvious way of testing this wing reasonably accurately - things like mpg over a journey have all sorts of other variables (like wind/weather) that are hard to keep constant.

Plus you would get to drive up and down the same bit of road testing out different wing angles until most of the local population comes out to see what's going on.....

This web page even has a method and spreadsheet that enables you to calculate your drag coefficient:
http://www.instructables.com/id/Measure ... -your-car/

However, this does require a manual transmission so that may rule it out.

[cracker39]

Cliff, I would imagine that the air going up over the roof would have more air pressure just above the roof than at the roof level of the cap. There should be very little air going under the wing. The front edges of both the wing and the platform it's attached to are angled a little to further reduce drag a mite.

Andrew, cost down testing is how I tested my first wing while towing the squidget. It wasn't as scientific and as accurate as I would have preferred. But then, I was using my speedometer and a stop watch, not very accurate to the fraction of a second. I drove over the same stretch of road, passing my start point (a road sign) at 55 mph, took my foot off the accelerator, and timed the truck until I passed stop point (a fence post). I did that with the wing off, wing in the center of the cap, and wing at the rear of the truck cap. The first two coast times were about the same and the last one nearly a second less, indicating that there was less drag to slow the truck as it had to be going a little faster at the stop point to do it in less time.

[canned o minimum]

Like most thangs...the journey is PART of the destination and usually the most exciting part since the destination means..it's over !

It beats the snot outta bein in a bar !

[Ageless]

I keep looking at the placement of the wing . . . .perhaps having the mount cantilever, so that the wing actually extends past the rear of the canopy (in the deployed situation) might even create better flow over the trailer. Like the whale-tail spoilers????

[cracker39]

I keep looking at the placement of the wing . . . .perhaps having the mount cantilever, so that the wing actually extends past the rear of the canopy (in the deployed situation) might even create better flow over the trailer. Like the whale-tail spoilers????

Now, that's an idea. How simple and easy can it be.

Whale-tail spoiler...looks like one to me, extends beyond the rear of the cap...yep...ya know, it just might work. As long as it doesn't rain and I have to lower the spoiler to keep the stuff inside the truck bed dry.



But after all the work I put into my wing, I guess I'll use it anyway.

[kennyrayandersen]

My apologies if I am trying to teach my grandmother to suck eggs, but do you know about 'coast-down' testing? This would be the obvious way of testing this wing reasonably accurately - things like mpg over a journey have all sorts of other variables (like wind/weather) that are hard to keep constant.

Plus you would get to drive up and down the same bit of road testing out different wing angles until most of the local population comes out to see what's going on.....

This web page even has a method and spreadsheet that enables you to calculate your drag coefficient:
http://www.instructables.com/id/Measure ... -your-car/

However, this does require a manual transmission so that may rule it out.

Actually, coast down tests aren't so easy to do. I buddy of mine and I did one in college for a project (everyone had to pick something different. We were able to 'show' that the faster the car went the lower the CD was. The professor ribbed us pretty good in class over it, but we thought it best not to 'dry lab' the data.

My opinion is that it will cost you mileage -- for a couple of reasons. The first is that the gap between you two vehicle and the trailer are comparatively large and therefore the turbulence has already started by the time the air behind the tow vehicle gets to the trailer. As it turns out it doesn't take much of a gap to really introduce some serious turbulance.

The air also 'spills' around the vehicle in every direction as Andrew was suggesting; so, you get turbulence from the sides AND the top. Since you are actually kicking the air up even further, my guess is that it creates even more turbulence than if you did nothing. Also, your wedge is open on the sides, so you are essentially making it a flat plate in an air stream as opposed to some type of aerodynamic body.

Another friend and I were doing some research on vehicle aerodynamics and there is a LOT of stuff on trucks and trailers (kind of what you have going on there). Do a little poking around about the trucks and you'll see what I mean. You'll notice that the ones the truckers use are 3-dimensional first off, so they spread the air both around and over the top. The second thing to notice is that they mount those air dams as close to the trailer as possible (see myth-busters drafting episode about how close you have to be). Your trailer will already be in the aerodynamic shadow of your tow vehicle, the problem is making the transition from one body to the other more smooth. I'm thinking you would be better off shortening the tongue and getting the trailer as close to the tow vehicle as possible. Another might be to extend some side fairings and even a top fairings aft to make the tow vehicle body 'closer' to the trailer.

Anyway, check out some truck (tractor) and trailer aerodynamics on the web for some ideas on what can be done to improve the aerodynamics.

[cracker39]

Kenny, there ya go, trying to confuse me with facts after I've made up my mind.

[kennyrayandersen]

Kenny, there ya go, trying to confuse me with facts after I've made up my mind.

Yeah, facts are pretty stubborn little things -- they've gotten in my way on more than one occasion

[Shadow Catcher]

I am looking at Airtabs http://www.airtab.com/main.html
It will be interesting to see if your wind wing works.

You might want to try doing your own wind tunnel test, a source to generate smoke and a high volume blower of some sort.

[cracker39]

For my part, the wing topic is finished for now. The wing is complete except for measuring the needed angle/height and making and installing the supports and that can't be done until the trailer is built. For now, it's suspended in the ceiling of my storage shed for a few month. Maybe I'll find a good place where there's a straight, flat back road little or no traffic to perform "proper" coast down tests after the trailer is built. That is, coasting from 65 or so in neutral down to a complete stop at least twice with and without the wing on the cap. I'll use my cruise control to obtain and maintain the same speed on each run. Luckily, I do have a manual transmission.

Meanwhile, until I sell my older Frontier, I don't have the cash to go full tilt into building as my wife is not happy about me building another trailer, and doesn't want me to use any of our savings on the project and I understand that. As I receive income from my plans sales, I order bits and pieces. I have my three tires and wheels and am ready to order my axle. One or two more sales and I can buy the steel and start building the chassis. I suppose I need to order my fenders too in case i need to weld on fender mounts.

[Mike-n-Britney]

I think it's a great idea - and hey, if you have the skills to try it out, then go for it!

I'm wondering if the wing on the trunk of my GTO is causing excess turbulence - more than would usually be present between a car and trailer. I think on the next trip I'll take the spoiler/wing off and see if it helps.

I have a feeling it will help...

[rowerwet]

you need to add dimples all over the truck and trailer like myth busters did, it did improve their mileage in that episode

[pete42]

we ran test on our homebuilt airplane using tuffs of yarn to see when the wing started to stall don't know how scientific it was but made us feel good that both wings pretty much showed the same pattern.

a wind deflector has to help hurry with build of new trailer I'm waiting to see how much it helps.

pete