Prototyping Vanagon Aero Wing

[Pingora]

Many of you may have run across this article detailing a design for a spoiler/wing that was designed by some PHD students using computational fluid dynamic models. I was intrigued, but couldn't find any examples of actual test articles built, or any pictures or details of one actually being built.

Being an Aeronautical Engineer (but not having access to that kind of high end modelling program, and also not specializing in programming) I liked the idea, and figured I'd test it out as best I could.

I tried to contact the originators of the design to get better data for sizing it, and learn which parameters were most important, but no luck. So I just started trying to size it from the vague picture and go from there.

I'll be posting some photos here of progress, and then test results. My hope is that it will at least help crosswind handling, and maybe also show some noticeable increase in MPG. The design makes sense to me, and I doubt it can hurt the aerodynamics anyway.

I will be covering it with heat shrink Dacron and then coating with epoxy. This makes it easy to prototype and change if needed.

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1990 Vanagon Carat
2002 Suby 2.5 Mizu Bokusa
17" wheels, 26.5" diameter tires

[dobryan]

Looks like a fun project! Let us know how it goes.
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Dave O
'87 Westy w/ 2002 Subaru EJ25 and Peloquin TBD

"To travel hopefully is a better thing than to arrive." Robert Louis Stevenson

MD>Canada>AK>WA>OR>CA>AZ>UT>WY>SD
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https://www.thesamba.com/vw/forum/viewtopic.php?t=746794

[MarkWard]

Looking forward to seeing what you come up with. I have noticed on the last few road trips that some 18 wheelers are running a similar idea to help the air flow leave the trailer. I recall a vanagon that had a similar setup a few years ago.

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[danfromsyr]

heres a vanagon aero tail
http://www.vanagonhacks.com/2014/07/the-aerodynamics-of-the-vanagon/

http://ecomodder.com/forum/showthread.php/roof-spoiler-pick-up-truck-cab-phase-1-a-19525-10.html

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[Pingora]

Yes I had seen that design on the big rigs, and it does work as simple as it is.

I had also seen that Vanagon tail. I bet it did have some effect, but my goal is to achieve similar if not better benefits, but with a simpler and better design that is less obtrusive, looks better, and is easy to take off.

My plan is to have bent metal tabs that are fitted with rubber gasketing that then simply gets compressed when you close the hatch, so easy on, easy off.

There are more weird angles than you would think on the rear of a vanagon, it has been interesting getting the wing to match up to the shape. It also has a slight downward curvature (high part in the middle) to match the roofline.

I'm playing with the idea of tapering the side parts all the way down the back, or reducing them.
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1990 Vanagon Carat
2002 Suby 2.5 Mizu Bokusa
17" wheels, 26.5" diameter tires

[Abscate]

There is no way that is street legal unless you make it clear do that lights etc can be seen
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.ssS!

[Pingora]

There are no lights up there for it to cover. I think it will make more sense when I post closer to finished pics. The side pieces just hold it in place and add a bit of a taper in for the sides. And for the driver it will only block maybe the top 1/4 of the window view.
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1990 Vanagon Carat
2002 Suby 2.5 Mizu Bokusa
17" wheels, 26.5" diameter tires

[MarkWard]

The campers have the top of rear window blocked with a cross cabinet. Would not worry about visibility. I think the comment about rear lights was related to the Vanagon with the tail posted above, not your design. Best of luck.
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[Pingora]

You are right, I think they just looked at the most recent post and thought the picture was mine.

Yea, I'm not worried about visibility. Though I did consider at one point a transparent covering. You can get it in model aircraft strength, but I decided I wanted it to be much tougher, so went with Dacron.

If I find an iteration that works really well I may eventually carve a foam core version and coat with fiberglass and resin for a nicer smooth surface.
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1990 Vanagon Carat
2002 Suby 2.5 Mizu Bokusa
17" wheels, 26.5" diameter tires

[T3 Pilot]

Following this thread with interest in the name of improved fuel mileage, and secondly looking to further the discussion about airflow around and under the Van.

I noticed rear air vent scoops in your image showing the test fitting of the foil frame. Here is a link to a Samba thread discussing air flow and pressure around and inside the vent inlets in the D pillar:

https://www.thesamba.com/vw/forum/viewtopic.php?t=...mp;start=0

Good luck with the experiment.....
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1988 Vanagon

The most important part in every vehicle is the nut behind the wheel......

[Steve M.]

[campism]

Garden edging. It's available in widths to about 8" with a bead on one side for mounting. Can be reinforced from behind with metal brackets, if necessary.
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'87 Westy in Wolfram Grey Metallic

[Pingora]

The main aerfoil almost ready for Dacron covering. Here you can kind of see the curvature to match the roofline.

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1990 Vanagon Carat
2002 Suby 2.5 Mizu Bokusa
17" wheels, 26.5" diameter tires

[tmart]

Fellow aero engineer here, in school my team actually looked into reduction of drag in trucks (briefly, we ended up working on something else) and came across these: http://www.airtab.com.

The idea is that the negative pressure is reduced at the back end of the truck/trailer/vanagon by initiating turbulent flow. I never looked into the numbers or anything but could be something to consider.

Nice because they don't block the rear window at all, but not as fun of a project...

[Pingora]

Yes I have looked into the airtabs as well. I haven't been able to find any proof that they have worked well on something like the Vanagon, but it would be pretty easy to try.

I think the idea with this wing concept is that by leaving a space between the leading edge and the van top, and by making the airfoil thick in the middle you really make use of the low pressure in the back and draw air down where you want it and direct it down and low much more than an ordinary spoiler would. Maybe energizing it in the correct aft direction instead of all willy nilly tripping off the blunt back.
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1990 Vanagon Carat
2002 Suby 2.5 Mizu Bokusa
17" wheels, 26.5" diameter tires

[Merian]

something this crazy will need a spoiler on the front and some elements to block crosswise flow on the rear tail (i.e. sideways eddy movement)



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[Pingora]

There's no reason to need a spoiler on the front. Front end mods could help as well, but the majority of drag on a shape such as this comes from the blunt back end and the huge wake that it drags behind it (in fluid flow analyses you can see a wake at least twice the length of a semi-truck being dragged behind the truck).

I left those side panels on to guide some of the side flow, and mentioned I may try continuing/tapering them in all the way to the bottom. That part wouldn't be hard to add.

Nothing too crazy about it. I actually saw a Lexus SUV parked near me that had a very simplified and smaller version of this on it. I'll take a pic if I see it again. From the design you could tell it wasn't there to look cool, so they definitely put some thought into the function of it.
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1990 Vanagon Carat
2002 Suby 2.5 Mizu Bokusa
17" wheels, 26.5" diameter tires

[Red Beard]

[Merian]

[danfromsyr]

Yes in the 88-91 models with plastic cladding..

and for the sake to make it easier to reference I'll post this image here.
http://www.vanagonhacks.com/site/wp-content/uploads/vanagon-wind-tunnel.jpg

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