that flows so nice. well done.
I like it.
Well thank you(!) gentlemen, I really appreciate the feedback and compliments. I agree, red on top and semigloss black on the bottom is the way to go.
You will notice that the aluminum back-support could be made taller...significantly increasing downforce but moving more towards a whale-tail so-to-speak (Porsche folks will know what I mean). The overall look would be more in your face along with that increase in downforce.
What becomes a concern is mounting integrity. Given there are only 3 bolts and 4 or so one-way plastic connectors, a design-change to increase downforce will also have to address an increase in mounting integrity.
I'm also making provisions to mount a wickerbill, the idea being to accelerate the localized air just prior to it departing the upper surface right at the upper trailing edge to increase shear. If this were to work properly, it would allow for an increase in downforce with a significantly smaller increase in (parasitic) drag.
looking at the time...I will glass it tomorrow evening...
Last edited by Hemissary; 06-24-2008 at 12:28 AM.
---VIPER--VENOM--RED-- ------------------------Click-- Hemissary--to read complete story at--CarDomain----
After cutting 3 layers of 8oz fiberglass and one layer of tight-weave 4oz e-glass cloth, I mixed up a match of West Systems 104 resin and 205 quick-cure hardener and started wetting out layers.
A 1/2hr prior I sprayed the upper spoiler surface with Freekote mold release, and allowed the solvent to flash off. This particular mold release material is easy to apply and easy to remove from the underside of the finished lay-up. I need this in this case, as I will be adhering that lower surface to the existing OEM spoiler and aluminum back support. I need for the mating surfaces to attach to each other without issue (you may recall - I will use PL Premium urethane adhesive to perform this task).
This shot shows my coffee table serving double-duty, this way(!) I can watch the F1 race I taped on the weekend! Someone had asked...no I am not married, and no I did not spill a single drop or make a mess:
This shot shows the raw materials, the roller and brushes are key to distributing resin evenly. And that small tray that comes with the roller works wonders at keeping exothermic heat build-up down (more on this later):
First of 3 layers of 8oz being layed down:
Here you can see where the resin has not been properly wetted out yet:
A good shot showing the difference between the 3 8oz layers, and the final 4oz tight weave that will reduce the amound to filler required to get that smooth paintable surface. This type of one-off molding process is tedious, as one is working from the inside out as opposed to the outside in with a nice negative mold. However, in order to "get" to that negative mold a "positive part" is required that is perfect in every respect...similar to what I am actually doing. It is a positive part that is used to make a sturdy negative mold that then can produce repeatable/consistent copies.
All three 8oz layers down:
The right side, everything layed down:
Oh ya, do not leave resin standing more than say 1/2" deep. In this cup it sits about 1.5" deep and measures in excess of 80C (almost 180F). As epoxy catalyzes, the exothermic nature of a quick-curing epoxy (the reaction process releases energy in the form of heat) can be dangerous:
Now to let the resin flow out nice and smooth, and allow the structure to properly cure for a day or two before popping it off the substructure with compressed air:
Last edited by Hemissary; 06-24-2008 at 12:18 AM.
"They Were Just Jealous That My Charger Pulled More Kitties Than A Bowl Of Milk"
06 Black Magmum R/T
22" KMC JACKS and FIVE
Hmmm, good timing as I was about to post the results:
Separating the work from the buck was super-easy this time. I'm sold on that Freekote Release Wax I used. Before I removed it though I stuck the entire fixture in a home-made autoclave and baked it for 6hrs at 160F. This raises the glass transition point of the epoxy-impregnated matrix, thereby adding strength, rigidity and surface hardness.
In the pics you will note the work is somewhat translucent, clear epoxy along with ~26oz/4 layers of material does not equal what you would see/feel on a Corvette fender. But given what it is going to be adhered to, this is more than adequate. Once trimmed, fitted (thanks to that Sharpie line I drew along the edge), and secured to the existing OEM spoiler/Aluminum backbone, there will be ample support.
Note that the mating surface of the work is just as smooth as the Ultracote mylar that formed the compound curve in the first place. And no, the Ultracote did not budge after wetting out 4 layers of cloth. In fact, as you can see I could continue to pull more:
Last edited by Hemissary; 06-25-2008 at 10:02 PM.
From another forum, thought folks here might find it interesting:
"Let's see how this unit deals with evacuating that pesky dirt that lays down while cruising. I suspect it will be worse, because I have removed some of the existing turbulation from that stagnent air loitering back there at low speeds (<70KPH). On the other hand, if the air travelling off the upper extreme rear edge is as coherent (defined - as in retains it's high velocity without intermixing with that stagnent air) as I think it will be, it in itself may act as a conveyor belt and evacuate even more stagnent air from behind the vehicle. THis would be a benefit as it reduces drag.
Stagnent air = drag in a big way. Bits of yarn I taped to the rear of the Magnum showed no coherency (they blew in all directions randomly) at less than 70KPH) in free air (going down the highway, straight into the wind, with no other vehicles to inpinge/alter the airflow).
Above 70KPH, things got interesting. The upper 3rd saw some organization straight up (yarn blew straight up toward OEM spoiler), and outwards near the side glass.
The center-lower area of the glass and the upper center area of the hatch...still 100% incoherent (actually all the way to 230KPH - a woman-friend attempting to videotape out the targa-top of a Porsche could not hold the camera steady enough to make out a satisfactory image above that).
What was noteworthy to me and got me thinking more about one of the next (unusual) mods was the lack of organization all the way down to the exhaust tips. This mod entails cutting off the spare tire well and fabricating a functional(!) diffuser, like this: