Del Sol, Underbelly Pan

[Otto]

Yes, white reflects infa-red and ultra-violet as well as light energy in the visible spectra better than black, so would be cooler if you left it in the direct sunlight, etc..

Zip ties seem an excellent idea. If you need local reinforcement of the Coroplast, simply insert a short length of wood dowel of the right thickness into the Coro flutes and tie the Zip around that. (Distributes the load while reinforcing the plastic.)

[miket]

Otto what is the emissivity of white plastic?

[Otto]

BTW, Jedi, you're doing a fine job of this project. Coupla thoughts:

1. To smooth air over that gap for the exhaust pipe, why not consider aluminum window screen, held tight? Lets heat out, alu. screen is a superb heat conductor, so dissipates hot spots.

2. Control arms move up and down, and make drag hanging in the breeze. Since Coroplast is flexible, would it work to tie panels of it to the control arms, that move up and down with the control arms? Such panels could be fixed at their forward (upwind) positions, and their trailing edges be tied to the control arms. Perhaps elastic ties could be used, to stretch a bit as the control arm/Coro fairing move up and down. This would make almost all of the car's underbelly smooth and flat. Properly done, Coro gaps could act as engine heat vents, drawing hot air out of the engine bay by Bernoulli effect, for less cooling drag.

[Otto]

Originally Posted by miket

Otto what is the emissivity of white plastic?

Dunno, but white is less emissive and less absorptive than black, but much more reflective, so stays cooler in sun. On a sunny day, put your hand on the roofs of various colored cars, and feel that white is coolest. White stays in a narrower temperature range than black, for less thermal stress. That's why German sailplanes are required, by law, to be white--materials last longer with less solar or UV degradation.

Maybe, driving across Death Valley in July in your car with white belly pan, the white would reflect more heat energy back to the road, helping keep your car cooler, getting an extra 1/1,000 mpg since the AC does not need to work quite so hard. That's a stretch, I know. Sorry.

I like white for belly pans because if stuff drips off, say, a radiator hose or oil pan, the drips are easier to see on white. Also, crawling under the car or looking down into the engine bay it is typically too dark to see very well, and white would reflect light better so I can see better. That's just me, though. Overall, probably a chocolate vs. vanilla debate.

When I do my old Ford van belly pan, it will be whatever color politician's sign I can most easily "borrow."

[jedi_sol]

Originally Posted by Otto

BTW, Jedi, you're doing a fine job of this project. Coupla thoughts:

1. To smooth air over that gap for the exhaust pipe, why not consider aluminum window screen, held tight? Lets heat out, alu. screen is a superb heat conductor, so dissipates hot spots.

2. Control arms move up and down, and make drag hanging in the breeze. Since Coroplast is flexible, would it work to tie panels of it to the control arms, that move up and down with the control arms? Such panels could be fixed at their forward (upwind) positions, and their trailing edges be tied to the control arms. Perhaps elastic ties could be used, to stretch a bit as the control arm/Coro fairing move up and down. This would make almost all of the car's underbelly smooth and flat. Properly done, Coro gaps could act as engine heat vents, drawing hot air out of the engine bay by Bernoulli effect, for less cooling drag.

Aluminum meshing would be an excellent idea, there is another user on here with a 2002 Infinit Q45 that is doing the same thing.

In terms of the control arm panels, I am picturing something like this in my head?



I was googling "alumalite," yes it says its very strong, light, and durable, however, the nice thing about coroplast is that its very flexible (and strong, light, and durable). Plus the pricing for a 4'x8'x 0.5" (thick) alumalite sheet is $545 The same size coroplast only costs $20ish.

As another user on this forum said, people always mess around with different build materials on here, but in the end, they all end up using coroplast because its light, flexible, waterproof, durable, and CHEAP.

[miket]

well alumalite is $88 for 1/4 inch and $126 for 1/2 at my local place, you'r getting ripped off. Alumalite is used for permanent signs. It doesn't break down in the sun and get brittle, it has a smooth enamel finish and is stronger.

I pay $15 for 4mm coroplast which comes in all the colors of the rainbow and $33 for 10mm only in white.

[3-Wheeler]

Originally Posted by miket

White reflect sunlight better but does white coroplast reflect infrared better than black??

I think black might last longer in UV which isnt an issue below the car. If you wanted a material that last longer and looks better than coroplast buy alumalite. Alot of people make splitters and sometimes undertrays for their expensive sports cars out of that.

Otto is correct.

A reflective surface, such as shiny aluminum or a mirror for that matter is better at reflecting heat away from the coroplast.

White would be the next color of choice, even for keeping the sun's UV from degrading the material over time.

The worst color is black, which has the most absorption of visible light and/or UV.

Jim.

[Otto]

Originally Posted by jedi_sol

Aluminum meshing would be an excellent idea, there is another user on here with a 2002 Infinit Q45 that is doing the same thing.

In terms of the control arm panels, I am picturing something like this in my head?



I was googling "alumalite," yes it says its very strong, light, and durable, however, the nice thing about coroplast is that its very flexible (and strong, light, and durable). Plus the pricing for a 4'x8'x 0.5" (thick) alumalite sheet is $545 The same size coroplast only costs $20ish.

As another user on this forum said, people always mess around with different build materials on here, but in the end, they all end up using coroplast because its light, flexible, waterproof, durable, and CHEAP.

My budget includes Coroplast, especially right after the next election in November. Those politicians must be good for something. Once I get the free stuff properly sized and installed, may replace it as needed with some nice new white stuff.

Yes, the Coro under the control arm is the idea. If the wind catches it and it rips off, it's so light that it probably would not cause damage to car, tires, or another vehicle.

This may be a stretch, given the difficulty of gluing anything to Coroplast, but has anybody tried using adhesive-backed Velcro on Coroplast?

[euromodder]

Originally Posted by Otto

Zip ties seem an excellent idea. If you need local reinforcement of the Coroplast, simply insert a short length of wood dowel of the right thickness into the Coro flutes and tie the Zip around that. (Distributes the load while reinforcing the plastic.)

Good idea !
A thin metal rod (or even thick wire) would easily fit into the thinnest coroplast.

[miket]

Originally Posted by 3-Wheeler

Otto is correct.

A reflective surface, such as shiny aluminum or a mirror for that matter is better at reflecting heat away from the coroplast.

White would be the next color of choice, even for keeping the sun's UV from degrading the material over time.

The worst color is black, which has the most absorption of visible light and/or UV.

Jim.

Okay but is coroplast of any visible color reflective to infrared heat? there isn't that much sunlight or uv below the vehicle to worry about.