alluminum bellypan construction advice wanted
 

i'm contemplating a bellypan for my next car (coming soon). the upper side has great aerodynamics, the underside is well laid out but otherwise the usual mess.

the stock Cd is somewhere between 0.29 and 0.28 as the car already has more than half it's grill area blocked of from the factory.

i'm thinking about useing sheet alluminum for the undertray. the car should last for quite some years to come so i'd like to device something durable.

it's a long term project however. so for now i'll have some fun planning things and than see what can and can't be done while i establish a baseline FE.

first of all i'd like to have a look at some aluminum sheet to see how i could use it.
how much should i expect to pay for a sheet aluminum? and what are the best places to look?

i'm also looking at the best way to attach something under my car. there's a subframe under the engine that could be handy, but how much would these rails move in relation to eachother while the car's driveing? what should i look out for in terms of vibrations etc? i'm condiddering useing two U frames that clamp to a side of the subframe and rivet or screw the plate to that. good or bad idea?

weight is an important factor as i don't want to loose my high speed gains in acceleration.

first of all i'd like to see if what i have in mind is technically possible and affordabel and make an estimation of how much weight that would ad.

Hmmm I was thinking these had stock plastic tray mouldings under the engine bay.

nope
it's an opel vectra A, it did spawn the calibra coupe with a 0.26 Cd wich did have a stock belly pan (interesting the cd was only for the 8 valve versions wich had their upper grill blocked) most calibras had a 0.29 cd...i wonder if they retained the fairing. i vagualy recall my dad and other mechanics not really likeing that feature of the car, for obvious resons... i'll ask if he recals some speciffics about the construction of that thing.

i've been looking all over the place for a view of a calibra underside or at least the plate but i can't find it, people are not in a habit of takeing pictures of their cars underside, even when it would be more interesting than average. googling for calibras will usually get you horribly mutated things with spoilers and sideskirts that scream drag all over the place. i wonder however how similar the two cars where and if a calibra baseplate could be addapted to a vectra.

I think vinyl siding aluminum coil is a good compromise of strength vs price. a 24" X 50' roll cost around $75. The downside is you'll need some type of frame to support it. I used old patio doors as my frame. I screwed them to car with self tapping screws. I'll be converting some of my pan to sheet fiberglass to reduce noise this spring.

https://cgi.ebay.com/White-Aluminum-C...QQcmdZViewItem