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Old 10-04-2013, 06:56 PM   #1 (permalink)
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base drag visualization

here is an image which suggests what a boat tail would be all about
in the second image we see how the Schlor cars aft-body is improving things
in the 3rd image,VW's 1-liter car has attached flow all the way to its tail end
4th image is SolarWorld GT slipping along at Cd 0.14
5th image is base-drag free 2013 CUER
6th image is Dave Cloud's base-drag free 2004 'Dolphin'
7th image is Paul Jaray's 1922 'pumpkin seed',Cd 0.09
8th image is from Porsche
9th image M.A.N. intercity bus
10th image
11th image 'wake-be-gone!'
12th
13th (wear a respirator)
14th ouch!
15th image:a CFD look at things
16th semi-trailer wake CFD
17th image:simplified wake management
18th: SST's boat tail
19th:more current research with Ahmed et al model
20th:K-form BMW,1938-(aesthetic compromised truncation)
21st:a proper K-form truncation(Cd 0.186 vs 0.23 for Kamm's best)
22ndartial wake visualization of semi
23rd: van wake CFD
24th: '1980 NASA Van' with wheel skirts and more proper boat tail
25th:she's very unhappy about her base pressure
26th: incinerating the wake ( look for the kit at all Pep Boys)
Another CFD
From long ago

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Last edited by aerohead; 11-11-2013 at 07:36 PM.. Reason: add 27th image
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Old 10-04-2013, 09:36 PM   #2 (permalink)
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That V-dub looks slick! - and I'm not just talking about the airflow!

The dust after the RV seems to mimic what snow does to a car while driving after sitting overnight.
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Old 10-05-2013, 02:58 PM   #3 (permalink)
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V-dub

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Originally Posted by jeff88 View Post
That V-dub looks slick! - and I'm not just talking about the airflow!

The dust after the RV seems to mimic what snow does to a car while driving after sitting overnight.
And oddly enough,the Schlorwagen shares an identical Cd 0.186 as with VW's current XL1.
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Old 10-05-2013, 03:32 PM   #4 (permalink)
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Aerohead, on the XL1, do you think the bottom of the rear end is angled up too steeply? It seems the angle goes up too much, too fast and it will make the air collide with itself.
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Old 10-05-2013, 04:00 PM   #5 (permalink)
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Aerohead, on the XL1, do you think the bottom of the rear end is angled up too steeply? It seems the angle goes up too much, too fast and it will make the air collide with itself.
It looks like Wolfsburg spent a great deal of attention with the under-body.
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Old 10-07-2013, 09:32 PM   #6 (permalink)
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Here is an hot-link wrapped in URL tags
http://www.shining-wit.net/rick/buggy/overview/dust.jpg
Here is the same hot-link wrapped in IMG tags

I can't figure out links to videos.
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Old 10-08-2013, 06:59 PM   #7 (permalink)
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hot link

Thanks freebeard for the hot link! It's way better than having to click on things.
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Old 10-09-2013, 05:55 AM   #8 (permalink)
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'Hot-link', at least as I use it refers to offering the URL of an image on an external website, rather than an album under your control. It's quick but it's trusting the external site to not remove or change that linked object. I thought I had a bookmark to a good defense of the practice, but it doesn't 'fall to hand'. Until I find it here's a page where you can see people argue whether it's better to steal and repost the picture or just steal the bandwidth.

You can see the result if you experiment in the Preview window. You don't have to post it. Here's the same URL wrapped in Quote, Hyperlink and the Image tags.

http://ecomodder.com/forum/attachmen...p;d=1261602367



On-topic: Notice the way there's a solid stream of dust carried over the top of the front tire from the rear, then blown back along a nice template curve?

Last edited by freebeard; 10-09-2013 at 06:02 AM..
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Old 10-09-2013, 04:34 PM   #9 (permalink)
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stream of dust

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Originally Posted by freebeard View Post
'Hot-link', at least as I use it refers to offering the URL of an image on an external website, rather than an album under your control. It's quick but it's trusting the external site to not remove or change that linked object. I thought I had a bookmark to a good defense of the practice, but it doesn't 'fall to hand'. Until I find it here's a page where you can see people argue whether it's better to steal and repost the picture or just steal the bandwidth.

You can see the result if you experiment in the Preview window. You don't have to post it. Here's the same URL wrapped in Quote, Hyperlink and the Image tags.



http://ecomodder.com/forum/attachmen...p;d=1261602367



On-topic: Notice the way there's a solid stream of dust carried over the top of the front tire from the rear, then blown back along a nice template curve?
Yes,the dust becomes a template for a pontoon fender which would help clean that area up.
Mercedes-Benz tested cars both ways and discovered that enveloping the wheels inside the saloon body,while increasing the frontal area,nevertheless,lowered the overall drag.
GM did this with their OLDS AEROTECH LSR March Indycar chassis in 1987.
The streamliners (enclosed wheels) always get higher speeds than the lakesters (exposed wheels) for a given horsepower.Better mpg too!
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Old 10-09-2013, 10:27 PM   #10 (permalink)
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That's why they have classes.

Accepting the limitation is what makes it art. What I'm thinking of is a belly tank with the VW boxer cylinders and heads sticking out of the nose like a light-plane with no propellor, front wheel drive like the XR-3, long axles with tall, narrow, rock-hard front tires for traction, a reclining cockpit like an F1 car, and the two rear wheels in tandem, (like the Speed Demon has in front). If you could get any traction, it would go real good.

If the rear wheels need to be open, it could be done similar to the Junker G.38 landing gear.

_____

Edit [20131012]: Like this

This is not well developed, yet; the proportions of the tires to the body are eyeballed, etc. But the idea basically is to have the same cross-sectional area as a P-38 tank (36" dia), but since I don't like the idea of a circular cross-section so close to the ground, it's more triangular, like a shark or ME-262.

The flat-4 boxer is in the front with exposed cylinder heads and a corrugated dry-sump tank for an external radiator. There is zero internal ducting.

The front tires are on 33" wheels with open spokes, but with a V-shaped rim like bicycles use. This is to improve cross-wind performance. The VW transaxle would be inverted to put the axle centerline above the crankshaft centerline (this saves needing to flip the ring gear). The rears are on an independent truck that is torsionally sprung.

I roughed in a Golden Submarine-style turret but I suspect that forward vision would be video on a head-mounted display. Driver is to the rear so they can tell when they're driving sideways.


Last edited by freebeard; 10-12-2013 at 09:35 PM.. Reason: dry- not wet-sump. Duh!
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