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Old 08-11-2016, 08:42 AM   #131 (permalink)
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Quote:
Originally Posted by freebeard View Post
The rise in the beltline suggests a downward rolling vortex below the edge, but it also suggests downforce. The rear has a sharp, 'tearing edge'. The pyramidal roof is logical for the single occupant.
A little sidebar discussion is what I asked for, so here it goes.

The vortex you mention is the one I have concern over.

Tandem two seat occupancy FYI.

Big flat planes with sharp edges no matter what angle they are pitched at are red flags in my opinion.

Example-1:
Vortex breakdown as an aerodynamic control | TRACE

Quote:
Depending on the exact shape of the vehicle, low-pressure structures can appear at the rear end of the car when the incoming air flow encounters geometric singularities (abrupt change of angle, deflectors, etc.). All these low-pressure structures form a drag force and are responsible of an increase of power consumption.
Example-2
BLAT? - F1technical.net

Quote:
This is how air behaves on a delta wing
So yes I agree, high degree of downforce (or would it be UPLIFT ?), but only because of incredible energy sucking vortexes along the top side edges. A gentle round edge is better along the side edge because it equalizes the top and side pressures so vortexes are slower to form or will not form at all, ideally that is.

This vehicle is an excellent example because it challenges our initial impressions. It looks real aerodynamic, but the air behaves differently I suspect.

The saying I once read online between car guys discussing a curvy Porsche verses an angular Lamborghini went something like this; they both look nice, but which car would you rather hand wash and wax?

The P-car or the Lambo, who's contours would be friendlier to your wrists?

Is the air not twisting like your wrist to follow the form?

Which shape is less strenuous to follow your hand over?

The blessed shape of the holy curve from the Church of Aerodynamics.

Another look at this creation, then look back up at those CFL images.

United Nude Lo Res Concept Car - Boston Commons High Tech Network



United Nude Lo Res Concept Car | HiConsumption



United Nude Lo Res Concept Car | HiConsumption


If you go to the black car links, the shape was derived from a Lambo, a computer blunted it down to it's most primitive angles. Less simple forms were built prior to this one which look more like the familiar super-car. This version is the ultimate abstraction.

Sidebar to the sidebar, I found this neat little paper while looking for images to support my argument. Perhaps a worth looking at if you have some time.

Downforce without wings
https://lucky13racing.wordpress.com/
Quote:
Flow cannot be divided, what happens in one-part affects what happens in another. Therefore, a front spoiler will affect a rear diffuser and vice versa.

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Last edited by kach22i; 08-11-2016 at 09:00 AM..
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Old 08-11-2016, 02:19 PM   #132 (permalink)
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I remember now about the derivation of the shape.

I've had similar thoughts about facet-izing Thee Template. I've failed to have a 1/3 scale model and the gas money to take it to the Darko Wind tunnel on 20160909 with aerohead; but what I wanted to do was make versions like a Matryoshka doll, with the compound curve outside and the more faceted versions inside.



The 1-frequency version of this would be a pyramid, much like the United Nude example except the points would be fore-and aft instead of on the corners.

I agree the side edges are the problem; but one subdivision would make all the difference. They were there and pushed beyond that as an intellectual exercise. Put Lambo scale wheels under it and see what happens.

Edit: The Downforce Without Wings article is pretty good. Thanks.
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Old 08-11-2016, 03:34 PM   #133 (permalink)
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Quote:
Originally Posted by freebeard View Post
I've had similar thoughts about facet-izing Thee Template..
Yes, your geodesic dome-like car designs are similar in concept.

Here is a visual explanation for what they were doing.

Original vehicle:
Car Picker - white lamborghini Countach


Series transformation:
http://alexlloyd19.tumblr.com/post/1...hould-not-make

Quote:
Above are some of the steps taken to ruin one of the automotive world’s most iconic designs. There’s a reason pixel count has become a big deal, and generally we want more of them. United Nude disagrees
EDIT-1

Another image:
Degenerative Design - The Atlantic

Quote:
The project began two years ago with a wine glass (below) and they moved on to test it on various other objects such as a chair, motorcycle, and Lamborghini Countach (also below). United Nude plans on releasing software that will let users "benefit from more automated and semi-automated design" with the help of INUS Technology, which makes 3D scanning software Rapidform.
There is also a woman's shoe in the link above.

Getting back on topic, the transitions between planes where pressures may be different is where vortexes may form. One quote from "Downforce without wings" said you cannot "divide the air", if this were true, why then the wing chimes on the SR-71, F-16, F-18 and other jets?

Perhaps you can divide/slice the air at certain transitional planes if you treat the termination points in turn or due course.

Two of the three jet aircraft listed all avail themselves to wing tip rockets or wing tip fuel tanks. The SR-71 on the other hand has massive air intakes for the jet engines which is one heck of a termination in it's self, a mid-way not wing-tip solution for vortex prevention.
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1977 Porsche 911s Targa
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Chin Spoiler:
http://forums.pelicanparts.com/off-t...effective.html

Rear Spoiler Pick Up Truck
http://forums.pelicanparts.com/off-t...xperiment.html

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http://ecomodder.com/forum/showthrea...1-a-19525.html

Last edited by kach22i; 08-11-2016 at 03:50 PM..
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Old 08-11-2016, 04:13 PM   #134 (permalink)
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Maybe this will explain my thoughts better.

Aerodynamics by George Kachadoorian | Photobucket


I suppose a fourth concept inspired by the SR-71 could be generated, but it look ridiculous.

I did a similar series of studies for my S-10 pick-up truck, including some hollow PVC tube things (full-circle-winglets)...................it's in one of the links in my signature I think.
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1977 Porsche 911s Targa
1998 Chevy S-10 Pick-Up truck
1989 Scat II HP Hovercraft

Chin Spoiler:
http://forums.pelicanparts.com/off-t...effective.html

Rear Spoiler Pick Up Truck
http://forums.pelicanparts.com/off-t...xperiment.html

Roof Wing
http://ecomodder.com/forum/showthrea...1-a-19525.html

Last edited by kach22i; 08-11-2016 at 04:21 PM..
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Old 08-11-2016, 10:11 PM   #135 (permalink)
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In a head on wind I think the vortices will be on the bottom of the "wing" as the top is "frontal surface "=high pressure and the bottom is tapering slowly away in 2 plains causing low pressure
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Old 08-12-2016, 12:22 AM   #136 (permalink)
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Random UnAerodynamic Cars and Trucks

I used to own one of these. I got a flat 21mpg on the straight six for both city and highway. Top speed 65 mph. Plus if you floored a neutral drop, it would pull the front wheels! I had just put nearly $1000 in repairs when the carb fell off on the highway seconds before it went up in flames. Worst POS I have ever owned!!!



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Old 08-12-2016, 01:27 AM   #137 (permalink)
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Originally Posted by ChopStix View Post
I had just put nearly $1000 in repairs when the carb fell off on the highway seconds before it went up in flames.
I've already seen many vehicles in a bad condition, but none having the carburettor falling off on the road. Anyway, did you buy that one at a gov't auction?
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Old 08-12-2016, 02:35 AM   #138 (permalink)
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Originally Posted by cRiPpLe_rOoStEr View Post
I've already seen many vehicles in a bad condition, but none having the carburettor falling off on the road. Anyway, did you buy that one at a gov't auction?
I got it from a friend who likely got it at auction. I also had a mail jeep at a different time. Both these mail trucks that I owned were junk. Constant maintenance and break downs even with less than 60k and 80k total miles on them.
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Old 08-12-2016, 04:02 AM   #139 (permalink)
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kach22i -- I agree with gumby79. The chines (not chimes) are roughly longitudinal and raked.

About the Degenerate Design. It looks like they did it by hand and eye instead of algorithmically. Midway a new points appear in the middle of the windshield and door windows, etc. The final shape is so low poly it could be anything — a pickup truck.

About your Schemes. Once again the vortexes would roll into the underbody. Your solutions all add polygons. If you take the four top faces and raise them, it would chamfer the chine and do more for the problem and only add four vertexes.

ChopStix -- In the background is my father's 1948 Chevy delivery truck. I drove it until I got my first car, the Studebaker. It had double bunks across the back, a kitchenette down the left side and a Buick tube radio bolted to the roof above the engine hood. We drove through drive-ins with the doors slid back.



My mother drove the school bus then and one day it coughed and rolled to a stop because the gas tank had fallen onto the highway.
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Old 08-12-2016, 10:28 AM   #140 (permalink)
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Quote:
Originally Posted by gumby79 View Post
In a head on wind I think the vortices will be on the bottom of the "wing" as the top is "frontal surface "=high pressure and the bottom is tapering slowly away in 2 plains causing low pressure
Quote:
Originally Posted by freebeard View Post
kach22i -- I agree with gumby79. The chines (not chimes) are roughly longitudinal and raked.
Guys, the top of the car is like the top of a wing, except to simplify discussion for a moment forget the underbelly of the car and ground pressure wave. Focus instead on the longer path the air travels going over the top of the roof verses flowing along the sides in straight line and shorter path.

Like with a wing, the car's air rolls/travels laterally from middle to outside edge (look at the "Random Wind Tunnel Images" thread). It does this because of the longer path traveled over the top, the air must move faster than when at the sides, when this happens pressure is lowered as velocity goes up.

The greater pressure air at the side rises up because of the lighter air pressure above being formed by the car's shape.

On an aircraft a wing fence may be used to impede the air drifting across the wing surface. This was a solution I have not yet illustrated, mentioning it for context now.

aircraft secondary flight controls

Quote:
Wing fences are fin-like vertical surfaces attached to the upper surface of the wing, that are used to control the airflow. On swept wing airplanes, they are located about two-thirds of the way out towards the wing tip and prevent the drifting of air toward the tip of the wing at high angles of attack. On straight wing airplanes, they control the airflow in the flap area. In both cases, they give better slow speed handling and stall characteristics.
http://airforces.fr/category/aircraft/x-planes/x-29/


The Vought V-173 "solution" to wing-tip turbulance





TBS C _ _ _ I _ _ _ _ A ?! - Page 6

Quote:
The more swept the wing is the more the airflow changes from flowing straight front to rear to flowing more or less outward, at an angle...
I supposed the question is; is there a slope in the plan view of the Nude Car Project which would add to the air differential pressure problems already discussed?

Anyway, returning to the topic of this thread.

1969 International Harvester Scout
Viewing Auction #300691362125 - 1969 International Harvester Scout 4X4 Pickup Truck with Snow Plow | Keith Martin's Collector Car Price Tracker


I bet this design has never seen a wind tunnel.

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1977 Porsche 911s Targa
1998 Chevy S-10 Pick-Up truck
1989 Scat II HP Hovercraft

Chin Spoiler:
http://forums.pelicanparts.com/off-t...effective.html

Rear Spoiler Pick Up Truck
http://forums.pelicanparts.com/off-t...xperiment.html

Roof Wing
http://ecomodder.com/forum/showthrea...1-a-19525.html

Last edited by kach22i; 08-12-2016 at 02:32 PM..
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