05/26/11 The interior is now fleshed out a bit. From here, the process is of refinement and tweaks to curves (sometimes that does require redoing a component significantly just to get a slightly different look).
The interior tub is dimensioned to take either a standard seat or a custom bead seat and will accommodate a very wide range of occupant sizes. We'll probably have some other options there as well (think 'full containment' style setups).
After doing some additional research it looks like we'll be using primarily Porsche G96/96 gearboxes (GT3 fitment). These are available factory remanufactured directly from Porsche dealers for around $13K and are very nice modern 6-speed units that are well matched to the LS3 torque, even if some customers decide to bump horsepower to 600 and beyond.
05/30/11 Part of the Lead Customer program is providing feedback in the final stages of the design. After seeing the latest updates Alex, our customer, had some good points about the styling. The panels in the back were too rounded off, both the tail and the 'humps'. I kind of thought that but it took someone else pointing it out for me to make a change. I definitely think it's for the better (compare to previous version below the current one).
The styling is now more consistent and better integrated overall. I've made some tweaks to the interior to make it work better with the rest of the car too, since it's always visible.
Still more tweaks to go but they will be progressively more subtle. Except the addition of fenders will be rather obvious, I'm working on that next.
06/08/11 Just a few more customer-requested styling tweaks. Also fenders and a transmission guard. There's progress.
Next is the windshield mount frame/rollbar cover, a few more detail tweaks, then a lot of detail mechanical design.
In the meantime the GTS uprights just came back from anodizing, one set will go on this car.
06/30/11 About to do some styling refinement on the nose and tail sections, but in the meantime I figured I'd do a few ray-traced renders of the car as-is. Here they are. Click on each for larger version.
I think the overall shape and architecture of the car are pretty much set but there is a need for better surface development and detail. Look for updates shortly. The chassis tubing will get ordered in the next couple of weeks and some parts are already being made.
08/01/11 The chassis design completion is waiting on the arrival of a built-up Porsche transmission to verify the fit prior to ordering chassis tubes (should be in a week or so). In the meantime I've spent some time thinking about the brakes and decided to upgrade the standard brake package from 11" (same size as was on the Atom) to 12.2". I have a lot of experience with the larger size having run it on the MINI, a 2,600 lb car, where it worked extremely well. Even though target weight for this car is 1,600 lbs (yes, 1,000 lbs lighter than the MINI - puts it in perspective, doesn't it?) the power is more than double so I think it will be a good fit. You can see the rotor size difference in the pictures below.
There will be two parking brake options for those wanting to drive on the street, both utilizing same rotor sizes.
In a recent coversation the subject of names came up. Alex, the lead customer for the dp2, suggested that perhaps a more elegant naming scheme is in order. The current designations are a bit awkward to pronounce and don't work too well in other languages, 4 being a very bad number in Asia on top of that. I have been thinking about it casually for some time having found myself mostly referring to the cars as 'the one', 'the two', 'the proto' and so on. So one possibility is to go with current 'code names' - dp1 - > 'halo' or 'draco' (since 'uno' is a Fiat); dp2-> 'duo'; dp3 - > 'solo'; dp4 - > 'moto' (since 'quattro' is an Audi). Another is to go with a function-based designation with a letter and a number, where 'T' would stand for track, 'S' for street, 'R' for race, 'E' for electric, 'X' for offroad and so on although there are lots of those in the industry and coming up with a unique scheme might take some doing. Yet another, since one of our customer projects is named 'Stiletto' and we'll be building the chassis, is to stay with that theme and go with sword/knife blade names which might be cool. I'm also open to suggestions. It would be good to have a name space from which we could draw for a variety of models. Suggestions we like get a free T-shirt.
08/24/11 A few things have happened so an update is in order. First, we now have a second D2 customer. This closes our lead program for this car (maximum two lead customers per car model). Pete is a very experienced trackday enthusiast and his input and feedback has already been very valuable. One thing I've been working on that was hurried along by customer input is the improved side impact protection. There are now additional cross-body tubes and extra side intrusion protection tubes behind the exoskeletal triangulation. These will not be visible with panels on.
According to SolidWorks the entire frame is 240 lbs which should keep the overall weight on target. The fuel tank is 15.9 gallons which should be good for 2-3 sessions on track before having to refill.
A quick experiment styling-wise is body-colored side panels. Looks pretty good actually.
Alex's gearbox (for chassis number 1) is here and I've verified the fit in CAD.
The tubing kits will be ordered shortly. This is quite exciting and I'm looking forward to seeing the first and the second cars take shape in metal.
09/25/11 Among all the other projects (D1, D4, Stiletto) I've been working quite a bit on the D2. Yes, that means full days on the weekends but that's what it takes. I've gotten a lot of good feedback and input from the two lead customers and consequently there are quite a few changes to the structure and styling. It also helps to come back to it after a couple weeks away - amazing what a fresh look at things can show you.
Anyways, below are some pictures of the new styling direction. It's a work in progress and is not finished yet so yes there will be lights/mirrors/intakes/stuff above the engine. Mostly this iteration is about accommodating structural changes (for example engine/transmission are now 3/4" lower in the chassis) and also about finding a unifying styling theme for the car. I want at least a token family look, more sophisticated surfaces and a design that works packaging-wise and is manufacturable. Here's what I have so far...
These screen shots don't necessarily show the detail all that well but if you look really close you'll see it (clicking on each picture will give you a bigger version). Exhaust routing is the most obvious change of course. After I spend some more time looking at all this I'll do some better renderings. It's getting there though...
9/28/11 Some more changes. The back end is now more aggressive, there is now an engine intake on top and I've made a version with exhaust exiting low.
The intake covers up the top rollcage tubes, feeds the engine and gives the styling a bit more balance and continuity. It should have limited impact on rear visibility - certainly better than an Exige or an Atom! The back still needs some tweaking but it's getting there.
I have to say I personally like top exiting exhaust better, but it's so easy to do either that I'll just give customers the option to do it either way. In fact it can even be switched after the car is built. The picture below shows the packaging of the headers and catalysts that come with GM E-Rod kit, a pair of large stainless mufflers and the tailpipes.
It's easy to see how either top or bottom exit can be made in this setup.
The styling now cries out for some side panels behind the cockpit so I'll work on those shortly. They'll have the added benefit of incorporating scoops to channel cool air through the tight engime compartment.
10/03/11 Well, the styling tweaks are nearing completion. After this round I'm going to let it sit for a while styling-wise and maybe make some minor tweaks later, maybe not. Click on each picture for larger version.
Now, on to building the actual car. Really looking forward to it! :)