What a drag

[phatveedub]

Are you feeling okay?

[syncro2x]

Face it we are driving billboards. A good slippery rig is .28, a westy is nearly double that @.52. My 86 Syncro with tall tires is a real workout when the wind blows and you crack 100km/hr (60mph). Keeps you awake.

[ragnarhairybreeks]

check out the bustle pics here on my blog

http://shufti.wordpress.com/2009/11/10/vanagon-bustle/

vanagon got back


alistair
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'86 7 passenger syncro, converted to westy pop top, project still in progress
'82 westy, diesel converted to gas in '94, now gone...
https://shufti.blog/
Old address still works...
http://shufti.wordpress.com

[DAIZEE]

That was interesting, hard to understand but none the less necessary. I was the shiats at Physics and I have a bad attitude about it.

So bottom line, ? close off luggage racks or
_________________
'09 2.5L Jetta 5 cylinder, 5 spd, super turbo, see thread in H2O Cooled Jetta, etc...
83.5 Vanagon L Riviera Model with 98 1.9L TD AAZ 4 speed Daily Driver 3 out of 4 seasons (sold)
84 Vanagon GL Wolfsburg Westy WBX 4 speed (sold)

[wildenbeast]

[Vanagonner]

To really clean it up, several things would need to be done. A well shaped cap over the luggage should give good flow without as much frontal area as a high top. A rear spoiler (like the one linked to above) would help. A pair of flow separators on the sides could encourage the air to spiral into the vacuum behind, and of course a good air dam would help a lot. With an ultra-low HP rig like mine, these kind of things would really help me. I'm working on the cap.
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Sage
'82 Westy 1.6 D
the mighty n/a

[randywebb]

one could certainly:

1. improve the Cd
2. better manage the airflow re lift, brake cooling, engine cooling, passenger cabin flow, etc.
3. alter the trailing eddies that attach to the rear of the vehicle

BUT

4. there is no way to escape the fact that you are pushing something about the size of a sheet of plywood down the hwy.
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1986 2.1L Westy 2wd Auto Trans.

[floggingmolly]

Driving in Baja recently, with a good (20-30 mph) headwind I could not maintain speed in 4th. In 3rd I could stay around 50-55, but shifting to 4th was a gradual decrease to 40 and dropping. I had a load though, and a kayak on top, so not really fair. But the next day, with no wind, I could ride at 65 in 4th when the day before saw speeds nowhere near that.
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'85 Wolfsburg Weekender

[iiigoiii]

on the original subject of noise - the most significant factors would be of course the direct engine and tire/road noise, but also the resonances driven by the engine, tires and trailing vortices shed from the vehicle at speed.

as a non-perfectly-streamlined body (uh can you say 'vanagon'?) moves through air, the body itself periodically sheds little tornadoes of air off of just about every one of the protruding objects (mirrors, rain gutters, trim, antenna, under-body components, etc.) and angles of the vehicle, not just the flat rear of the body. as was pointed out earlier, the energy of the vortices can increase exponentially with speed.

how often these vortices are shed off of each component causes noise. not only does this frequency vary with the shape and size of each component, but...that which the component is attached to. body parts (especially large metal sheets like door skins) and cavities (like the space inside the door) all have their own characteristic resonant frequencies. there are literally hundreds of panels and cavities which could be actively resonating from trailing vortices or tire, road, and engine vibrations.

it's those resonances that greatly amplify the vibrational noise of the component that is driving it. these resonances seem to 'come and go' non-linearly with speed. that's because as the speed of the vehicle changes, the vortex shedding frequency changes; that frequency occasionally will move through the resonant range of some panel or cavity, making it more or less noticeable.

so what? so, moreso than trying to track down the hundreds of vortex generating components, the hundreds of cavities, and the myriad of ways the vortex energy is transferred from one to the other, the most important things you can do to reduce noise is to dampen the resonance of the panels (hence the many samba threads on noise damping materials) and cavities, change your tires, and reduce direct transmission of noise from the engine.

hope this helps....
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1984 Westfalia Wolfsburg Ed. w/ Subaru EJ22 power

[jerrydog411]

[Orbitald]

[thummmper]

there is a mechanic named john out there that made each vehicle he owned more a.d. [google, aerodynamic] he said the results were significant. speedway hubcaps, panning the belly, fairings for gaps and spoilers made significant gains in mileage. up to 4 mpg. teflon coating the paint works contributed 1/2 mpg alone.
seems like an inflateable bladder for the rear deck would displace the ball of air we all pull along. wouldnt hurt in collisions, either.
Flushing out the windows would help too. the vanagon is more slippery than she looks, but she has a broad side too.

[dhaavers]

[Vanagonner]

[randywebb]

why the bump?

is it for clearance of something underneath?
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1986 2.1L Westy 2wd Auto Trans.

[levi]

jackbombay did something similar, came out looking good.

_________________
One of these days I'm gonna settle down,
but till I do I won't be hangin round.
Going down that long lonesome highway,
gonna see life my way

https://youtu.be/cSrL0BXsO40

[Vanagonner]

The bump is for two things,
1) to provide the most aerodynamic flow for the massive amount of air coming up over the windshield, similar to the new hybrid busses running in Denver. They have that shape for a good reason, I believe. There is a lot of attention given to aerodynamic details on them

and 2) making some room to store stuff under the cap and use the luggage space.

I would love to hear opinions and "best guesses" from pilots and engineers (and others) as to the efficiency of a curve like that vs jackbombay's flattop, which I think is also an admirable design.
p.s.- note that the trailing edge of my cap kicks up a tad, to help get wind and water over the leading edge of the tent seal.
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Sage
'82 Westy 1.6 D
the mighty n/a

[levi]

Since you're asking for guesses, here's mine about the hump on the bus.
If you look at that photo of the bus, you'll see that without the hump it has a sharp edge, which creates turbulence, so the hump eliminates that.
Jackbombay's already has a smooth transition, so doesn't benefit from a hump.
Just my guess.
_________________
One of these days I'm gonna settle down,
but till I do I won't be hangin round.
Going down that long lonesome highway,
gonna see life my way

https://youtu.be/cSrL0BXsO40

[randywebb]

fluid flow is a lot more complicated than just scaling something from a large bus to your van, beside the shape differences, but have fun

reason 2 is a good one
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1986 2.1L Westy 2wd Auto Trans.

[Vanagonner]

Yeah, it's probably a balancing act between making a rounded transition vs. increasing the profile of the vehicle. I can probably make it less dramatic and still have it work well. I just want it really round up there, like a hightop. And randywebb, I'd love to hear your ideas about it, complicated though it be.
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Sage
'82 Westy 1.6 D
the mighty n/a