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Old 04-14-2019, 11:33 AM   #69 (permalink)
woodstock74
EcoModding Apprentice
 
Join Date: Apr 2012
Location: Charlotte, NC
Posts: 120

TBD - '17 Toyota Corolla LE
90 day: 34.66 mpg (US)
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I've become obsessed with sharpened trailing edges as a means to increase turbulent kinetic energy by sudden flow separation energizing the base area. I've been contemplating sharpening the quarter panel trailing edge on the Dart as it's a large round/bulbous radius as it transitions to the bumper, I've decided on a method, but the realization is that it would be really time consuming and I'd still have to come up with a seamless method for mounting this "patch". So that got me looking elsewhere on the car. My eyes fixed on the trailing edge of the trunk:



It's decidedly thick, about 30 mm on the flat, here it is in cross section:


The trailing edge curves in 3 dimensions, complicating any fabrication. And as I'm wanting to avoid any extensive fabrication as it slows the entire process, I began to brainstorm simple solutions and landed on adhesive weather stripping. Being rubber, it will bend to the shape, it's adhesive backed, so method of mounting is solved (and I can augment with aluminum tape or helicopter tape), and there are a variety of shapes to choose from, and it's relatively cheap. Naturally I'm looking for a 90ish degree angle. However, this turned out to be harder to find than it seemed. I landed upon this shape from McMaster-Carr. Here is what it would look like in place on the hood trailing edge:


All this got me thinking. I've just recently purchase a DLP 3D printer. The beauty of the 3D printer, amongst many other things, is that there is a variety of materials to choose from. One is a rubberized urethane. So I started thinking about designing a bespoke extrusion shape. The only issue I have is that my build box is somewhat limited (155 mm in Z), and to stretch the width of the trunk (about 1300+ mm) would require multiple extrusions stitched together (about 8). So I'd be looking to design an acute angle extrusion, to draw air into the base area, and then add a bit of energy with a sudden separation (sharp TE):

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