Binky the Civic Build Thread

[aerohead]

Originally Posted by JacobLeSann

Thanks again, I'll drop him a message maybe. Elaborate on this flying buttress idea, if you can, as I can't quite picture it right. It sounds interesting.

I'll check out that template generator when I get home from work. Looks like a good starting point for designing the future body shape. Waiting until I'm done my velomobile is a good idea, as it'll introduce me to careful body work and structure design, which will help a ton with future work on the car.

Ferrari, Lamborghini, Lotus, and Porsche have used them.
From a side elevation view, the rear of the greenhouse looks perfectly streamlined: slope, contour, tumblehome, upper edge radii, and boat-tailing.
However, when viewed from above, you see that it's an open space between these buttresses. And often because there's a mid-engine or rear engine layout and the void allows for combustion air, cooling, and typically a vertical backlight for rear vision.
Today's Porsche 918 Spyder would be a recent incarnation of this technology.

[freebeard]

Originally, I was going to tuft-rest some Masito model cars in front of an electric fan...

Your friend likely use the term 'Reynolds number'.That's why air can be substituted with water. See ecomodder.com: Automotive Aerodynamics (video series).

The poster went on to working for Lucid Air designing the air intake plenum.

As to the box cavity, I think of it as an annular Gurney Flap, if you get my drift. Things get all counterintuitive. That Nissan pickup has an half-tonneau. It works better than a full tonneau on a pickup, I think it's because the whole cab becomes a Gurney flap/wickerbill

Gurney flap
The Gurney Flap is a small tab projecting from the trailing edge of a wing. Typically it is set at a right angle to the pressure side surface of the airfoil, and projects 1% to 2% of the wing chord.

I pointed to the ECOfamily Civic as a cautionary tale. Cardboard is temporary. Any construction that includes wood is temporary. Coroplast is temporary. Metal and plastic are strongest together as a composite. Polymetal, MaxMetal or Alumapanel are your friends. Build quality affects the public's perception.

kach22i — the buccopharyngeal cavity of fishes is less germane than Shauberger. DDG:

Viktor Schauberger: The Inexhaustible Power of Water
https://www.facts-are-facts.com/arti...power-of-water
The trout and salmon that swam in the mountain streams were another source of fascination for Viktor Schauberger. How on earth did they manage to stay stationary in the water, even in a mountain torrent in full spate? How could they escape, fast as grea*sed lightning, against the current, instead of letting themselves be swept away by it?

Originally Posted by aerohead

Ferrari, Lamborghini, Lotus, and Porsche have used them.
From a side elevation view, the rear of the greenhouse looks perfectly streamlined: slope, contour, tumblehome, upper edge radii, and boat-tailing.
However, when viewed from above, you see that it's an open space between these buttresses.

Unless they are ventilated, I'd call them sail panels. And include my favorite El Camino, the third generation.

[kach22i]

Small world, if you have 10 minutes.

https://youtu.be/J8j61XTBSVQ

[aerohead]

The original box cavity is related to Continuum Dynamics and testing done by NASA at the Ames Research Center, Palo Alto, California, under an SBA grant from DARPA. Designed for an 18-wheel tractor trailer van.
The Audi structure would qualify as a box-cavity also.
What Mercedes-Benz and Julian Edgar did is more a 'hollow' FKFS 'Kamm' extension, or 'elongation' in Hucho-Speak.
Basically, the box-cavity's panels are inset from the exterior perimeter at the attachment point, to such a degree that the point they project to falls along the imaginary line of W.A. Mair's boat-tail profile, top, sides, and bottom.
Flow separation occurs at the trailing edge of the vehicle, then reattachment right at the end of the panels, capturing four, locked-vortex, stagnation bubbles of circulating air, over which the outer flow will skim across, almost as if they were a solid boat-tailed surface, separating at the 'new', smaller cross-section.
You must pay for the vorticity, however, the pressure regain, and reduced wake size, conspire to increase base pressure and lower pressure drag, just as Julian describes.
They're light compared to a authentic boat-tail, much easier to fabricate, with less material, and with much of the good. Today's 'Trailer-Tail' is a deployable, hybrid version of the technology, more like a boat-tail, but also hollow, unlike any of the FKFS tails of the 1930s.

[kach22i]

What Mercedes-Benz and Julian Edgar did is more a 'hollow' FKFS 'Kamm' extension, or 'elongation' in Hucho-Speak.

Another example of that.

https://www.carthrottle.com/post/amp...-is-slippiest/

[aerohead]

Volkswagen's smart with the XL1. They're using every millimeter of aft-body for pressure regain.
Unlike many of their other products, wasting the most valuable real estate on the whole vehicle.

[freebeard]

They're light compared to a authentic boat-tail, much easier to fabricate, with less material, and with much of the good.

That the value.

Somewhere there is the graphic that shows stepped and angled box sides. The stepped sides would trap larger pocket vortexes. I used to think air could follow a short 45° chamfer, but VW used a 90° corner and steps in the inside (the tail light).

[aerohead]

Originally Posted by freebeard

That the value.

Somewhere there is the graphic that shows stepped and angled box sides. The stepped sides would trap larger pocket vortexes. I used to think air could follow a short 45° chamfer, but VW used a 90° corner and steps in the inside (the tail light).

We'd need the graphic.

[freebeard]

Gonna make me work? I didn't find the one I was thinking of, but this was squirreled away on Imgur:



It suggests an angle of 70-80°. That could be clear [Fresnel lens] over the tail lights, a common hurdle. And it supports my chamfer hypothesis.

edit:
How about an infinity mirror box cavity?


https://www.motortrend.com/news/10-w...a-show-builds/

The wheel has an half-silvered front face; if it were clear, the tunnel would go to infinity ...or, beyond the license plate.

[JacobLeSann]

Interesting replies, thanks for all the support, diagrams, and explanation.
I’ve decided I’ll cut things short and focus on the simplest mods, or rather the ones that matter most for this weather and my time: A full undertray, a grille block setup, and some modified “poor man’s moon discs” OEM covers.

On that, I’ve figured the upper grille isn’t really that important, so I’ve cut a coroplast cover that I’ll rivet to it’s face. It’s flush with the grille insert, so there’s some gaps between it and the hood and such, but it looks cleaner than having coroplast edges overhanging.

Any good links for an adjustable lower grille block? If things are too complicated, I’ll just make a cheap partial block until the season ends, but a setup I can adjust mechanically from the cabin would be great. Then again, part of me wonders if a block could actually create more drag due to the lower grille being inset deep into the bumper. Granted, it would help a ton keeping snow from blasting into the radiator.

Sorry for stoking the fires of a new project idea lol, but I’m wanting to cut it short so I can put all my time into the velo project. Once that’s done, I’ll come back and tackle the bigger stuff.