11/19/14 Busy few days - mostly machining parts (until compressor died, then we bought a new one, then it died too and mill won't run without air). The good part is that some of the parts take about an hour for each op so while the machine is running I can do other things. Tinker with the bodywork design is one of them. Below are some pix of the latest.
It certainly has evolved from the last post a week ago. Now I can look back at the early renderings and ask 'what was I thinking?!' - of course that's all part of the process and is as I expected. But at the same time it's nowhere near done and there are still quite a few awkward lines, surfaces and angles. As a result I'm in some discussions that could lead to advancing it to a whole other level, as well as lead to additional models. We'll see. What I can say is that I'm quite excited about the possibilities.
In the meantime I've run some initial CFD on the new bodywork, with and without a wing. The most striking aspect is the drag reduction versus the current design - almost half at 100 mph. Not unexpected but gratifying. In real terms it means an increase in top speed from about 165 mph for the current car with no wing (152 with) to over 185 mph for new bodywork, with a stock LS3 engine. As the pictures below show my initial placement of the wing was not ideal so I'm rerunning it with a different setup. At some 16 hours per run, and being disciplined changing only one thing at a time, it's slow going but fortunately I have a computer I can dedicate to doing that and work on other things in the meantime.
The concept of taking the air THROUGH the car rather than around is not new but it works pretty well and over time more seems better. They probably weren't the first but in my mind Audi were notable for it with the LMP R8 (which was really on-top-and-then-through) and progressed to the R10 and then the rather dramatic R15.
For my part, the dp1 started the concept in my designs progressing to the D1 and now I'm looking to take it even further with the rebodied D2.
We'll see where it all ends up. It's a process.
11/22/14 Doing a few more CFD runs, a couple things about the results bothered me. Changes to the wing were not having exactly the results that I would expect. And, the flow through the radiator was not happening. So it was time to check what I was doing. I have a spreadsheet which I designed to convert raw CFD data (forces and torques on individual parts) into numbers I care about - drag, downforce and front/rear balance. It is the balance part of the results that didn't look right. So after some careful checking - sure enough, a typo in one of the equations that converts the sum of torque to front/rear downforce. To take the low-wing configuration as an example, the results went from 22 lb total downforce (177 front, -154 rear) to 119lb total (-15 front, 134 rear). Just a single character in the equation and the results are very different indeed and make much more sense now.
On the radiator issue I discovered a stray surface in the model that was blocking 90% of it (the blockage was obscured by the radiator itself) and the results were exactly as you'd expect to see for that case. Second picture shows problem fixed.
Incidentally the duct geometry was given to me by an experienced aerodynamicist some time ago as a 'rule of thumb', something they figured out by trial and error long before this stuff was available. Looks like it works in CFD (D1, D4 and D2 radiators all use this and they've been shown to work in real life too). Actually nice to see that tools are accurate, as long as the model and the interpretation is.
All of this goes to show that just having the computer spit out a bunch of numbers and colors doesn't guarantee that what you get is correct. Even if you start with a known good and validated setup, as I did, when changes are made human error does creep in occasionally. Frequent reality checks are a good way to catch that - never blindly trust the numbers. If it doesn't look right, chances are it isn't (but don't rule out the possibility that it is in which case it's a learning opportunity). This of course requires knowing roughly what to expect in the first place, what's reasonable and what isn't.
While all this is happening much else is getting done on all fronts. More soon.
11/28/14 With the redesign direction mostly set and in the process of being handed off (more on that soon), I just wanted to post the most recent set of screen captures showing where the D2 is headed. But the fans of the current design need not fear - the current bodywork will remain an available option for those who prefer it and yes the new body will inevitably cost more - progress has its price. The new design will support several versions including a hardtop with doors, an elemental roadster and a 'race' configuration having the added safety of a full rollover structure but foregoing the weight and complication of a windshield and top. Something for everyone :)
The couple promotions we have going are expiring in just over two weeks, so anyone contemplating a D2 for the 2015 driving season, with either current bodywork or new, might want to consider acting sooner rather than later :)
12/2/14 It's now official - Zukun Plan, the same team that created the Sector111 Drakan Spyder design which uses a Palatov chassis, is going to take over the D2 bodywork restyle. They will take the concept that I've started, add their own ideas, further refine it and then detail it out as tooling-ready CAD. It should be a lot of fun! And of course I'm really looking forward to the result. The goal is to have the tooling done and first body produced in spring of 2015. Those who want a new D2 with the updated bodywork in time for summer should be placing their orders now. In the meantime, below are a couple pix of the latest concept evolution and some of the steps that it took to get there. Always makes for an interesting look back :)
Here are the steps along the path:
12/13/14 Another cumulative post, just happens to be on the D2 page but has a bit of everything in it. The day is interesting in that we actually managed to run a trackday in the middle of December at ORP, in beautiful weather no less. Writing the date on the release form at the track I noticed that the numbers were kind of cool, too :) The purpose of the event was to shake down the newly reassembled Pearl, after its refresh and prior to its trip down south. Everything worked well. Just a few minor adjustments need to be made back at the shop
The last picture is of our crew for the day - all FSAE alumni, it so happens, from three different schools.
On the D2 front we bought and test-fitted a production windshield that I would like to use on the restyled bodywork. Finding a suitable glass is really hard - while the D2 is a very wide car overall (80"), the cockpit is actually very narrow. For example, the windshield on our Fiat 500 is about 6" too wide. This one is narrower than that and even though it is still a bit wider than I'd like it should work reasonably well for the 2015 restyle. Eventually we'll tool up our own curved glass but for the moment it's an expense (and time lag) that I would like to avoid. Choice is not final yet but looks promising enough to pursue further.
The last two pictues show the relative alignment of forward rollcage tubes vs the windshield edges from a driver's point of view. Not great but tolerable on existing frames, on future ones we'll probably omit the forward tubes and go with thicker wall main hoops. Actually the forward tubes can be cut out on the existing chassis without any real loss in safety, the car is seriously overbuilt as-is. All part of the evolution.
Those who paid close attention to the most recent set of renderings may recognize that I've already 'prototyped' this windshield with the approximate dimensions as part of the restyle exercise. Next steps are to get it scanned in and see how it might look in the finished product.
And finally on the Stiletto, the splice-in part is out of the mold and ready to be bonded into the bodywork.
We have recently gotten a number of orders in so the target delivery date for any new orders placed now is late spring. The new D2 bodywork should be ready by then as well. We'll have a number of announcements in the next couple of weeks, including our Pikes Peak plan and future products.
12/15/14 Moving right along. Kyle came out to scan the windshield, we should have the CAD file in a couple of days.
The glass is painted white so the scanner can see it. The dots are to help it get the dimensions and curvature.
The upgrades of existing D2s to the new suspension are getting done. We are also updating shifter mechanisms and some electronic bits. Huge learning curve, one that can only come with having a few cars out there and being used.
Stiletto work is moving forward as well. And so is the turbo D4 - more on that separately.
01/11/11 Time flies - I just realized it's been almost a month since the last update. Not for the lack of things happening. Quite the opposite in fact. There are now two concepts for the new bodywork from Zukun Plan. Alongside with my own '3D sketches' we now have a range of options to consider and some feedback as well. Next step is to take the best features of each and combine them in a way that works aesthetically, aerodynamically, functionally and is manufacturable in our target timeframe. Easy, right? :)
One thing I've learned is the importance of reality checks and input from people who understand and care about what we're trying to do. To that end I'm happy to announce our Lead Customer program - it's a way for a few enthusiasts to get directly involved in the process of creating the next couple generations of our cars. The brochure is at the link and has all the details - if you know anyone who might be interested, please forward it.
In the meantime here's a quick peek at the concepts I'm talking about.
Other things: there's more progress on the Stiletto, the turbo D4 motor has been dyno'd at over 350hp and is now back at our shop in the process of being installed. The D4 trailer design is closer to completion and many parts are here already.
More on the D2 side of things, we are now updating our very first prototype D2 frame (which has been serving as a bodywork alignment fixture) to the current spec and beyond. There will be a few experiments involved, including making a version with doors.
The supercharged D2 chassis is coming along as well and we're finalizing the details of our Pikes Peak program for this year. The goal is to run this car in the Open class.
In other words things are moving right along. Even the vinyl cutter is getting some good use :)
03/15/15 Yeah I know another long pause in updates, and yes it's because I'm just too crazy busy to get to it. But today I'm mostly doing machining and there's some time while the mill does its thing. So, where to begin...
I took three different trips recently. The first was to southern California to visit Sector111 and discuss progress on the D2-based Drakan Spyder. We also took the opportunity to make a lot of updates to Alex's D2 (chassis #1). It's pretty crazy how many updates we have come up with since his car was delivered last May, less than a year ago. It took Tristan from 9am to 1am to get everything except the transmission oil cooler kit installed.
The next trip was to the Bay Area, dropping off the D4 with Jonathan and visiting HSE, our dealer/service center there, to update Joe's and Brandon's D2s. This was another full day and I had to do the updates myself since Tristan didn't come along. Fortunately these two cars already had most of the new bits installed (being geographically closer helps, until we fully develop a dealer network). This is all part of our growing up as a company, establishing local support for customers and providing the necessary information, training, etc.
The third trip was to Lancair in Redmond, Oregon. They are building the Drakan bodywork and will most likely build our redesigned D2 panels when those are ready. More on that soon but in the meantime a batch of Drakan chassis are being built at our shop and we brought the first one down for test-fitting the body panels. The Sector111 blog has some details.
The chassis are essentially D2 with a different rollhoop structure and some tabs and panels relocated to accommodate the Drakan bodywork. This makes it efficient since we can use the existing D2 jigging to build them.
Speaking of chassis, we are making revisions to the D2 design as well (and some of them can be seen above). Since the bodywork is being redesigned, we're taking the opportunity to revise the frame along with it. On the list - multiple-height shoulder harness locations, altered side-intrusion bracing (also in preparation for full doors with lower step-over height down the line), a new front rollbar structure to better work with the new windshield, and so on. As a test we took the very first proto chassis which has been serving as a body-fitting jig for the first dozen cars, and applied the changes. As a final step we'll actually cut the upper frame rails and see how much things move, if at all. Might even measure the stiffness before and after while we're at it.
Other items in no particular order. There is now a custom car cover for the D2 made by Covercraft. A bit pricey but the fabric is fully weather resistant and rolls up into a tidy bundle that fits beside the passenger seat. Really shows how wide the car actually is, and the challenge of doing a full body.
We are making some carbon fiber fenders for the Drakan cars. After a couple wet layup test parts didn't produce the desired finish Mark is now dialing in a resin infusion process. Looks promising.
The machining of parts for Drakan and D2 builds is on its way - this weekend I'm doing the uprights. I learn a bit more about machining every day. Last time I ran these parts was only a few short months ago but with what I've learned since I was able to cut almost 20 minutes of run time off each part. When doing 32 of them that matters. Still, at about 45 minutes spread across 6 different setups it takes a little over 3 days to crank them all out.
We got the lasered wing rib blanks in, they will go in the machine shortly after I finish the uprights and a couple other higher-priority parts. Then we'll build some wings. It's more efficient to laser the raw outline (the rough edge is also better for bonding) and just machine the internal pockets afterwards. This is a similar process to what we're using for D1/D4 sprockets that are also in the pipe - lasered, lathed and waiting for the mill ops before heading off for heat treat.
The D2 restyle is also progressing, albeit slower than I'd like. We are starting some CFD verification on the basic design, some adjustment/refinement will follow and then I'll post some pictures. The goal is to get a new body on the supercharged D2 we're running at Pikes Peak this year, but time is getting pretty tight. We'll see. Oh, and more on that whole adventure soon. The build is well underway.
In the process of designing and refining things I always try to see how others have done it. A recent visit by a McLaren P1 to our shop provided one opportunity. The local intro of LaFerrari was another.
All these things definitely influence what I do. I can honestly say that I have no interest in owning one of these hypercars (even in a fictional world where I could afford one), but they do provide inspiration. Mostly in details - hinges, grilles, panel fits, etc., although the P1 influence goes further than that and will be visible in the new D2. I do understand why these cars are what they are, but for me they're just too complex, too electronic, too big and heavy. On the track I prefer cars that are minimalist, honest, direct and to the point. Just the engine, the driver and an efficient chassis to intimately connect both to the pavement. That's why I design them that way. On the street my priorities have changed over time and I am generally happy with the Fiat these days. It does the job without being boring and that's sufficient for the kind of driving I do now. But that's not to say I don't enjoy an occasional good-weather blast in a D2 :)
Anyway, I think that's enough for now (well, there's a bunch more on D4, D1 and Stiletto but that's for other posts whenever I get the opportunity). Like I said, it's been busy.
04/07/15 Now with over 50 trackdays on it the demo is getting some updates and maintenance. The car has held up remarkably well overall, especially considering how hard it gets driven. There will be more updates soon but this one is just an interesting item that came up as part of prep for testing this Friday. We've installed the drysump on the car and were checking over a number of other things which led to discovering considerable play in the balljoints. These are not very old, and we've seen a similar issue develop on other cars as well a bit sooner than I'd like. Rather than just say 'they all do that' we decided to dig a bit deeper. The lower balljoint is the one that bears most of the load in the D2 suspension.
So we pulled out the worn parts and ordered a number of balljoints of the other brands we've used so far, then cut them apart. All turned out to be similar on the inside - the ball rides on a plastic liner that can cold-flow under heavy pressure (worn parts showed clear signs of this). There are only slight dimensional differences from one brand to another. The plastic liner definitely explains the rapid wear.
After some research, I found that MOOG claims to make their parts better. They also happen to be double the price of most of the other brands and I was curious to see whether there's any substance to the claims. So we got a couple and cut one apart.
Sure enough, the difference is dramatic! It is indeed a proper load-bearing balljoint, with metal bearings and belleville washer to maintain preload. Good to see truth in advertising (and to find a solution to the problem!). From now on the MOOG part is the only one approved for our cars.
Learn something every day.
04/15/15 Some progress on the brake upgrade. Finally figured out the fixturing for brake hats (see Pikes Peak blog), now it's time to fit them. All appears well. Testing in the next couple days on street, then next weekend at the track.
The new rotor is only slightly bigger in diameter (12.9" vs 12.2") and weighs within a half pound of the old one. One major difference is that there are 12 bolts instead of 8 and they are on a much larger pattern diameter. This should make the hat last longer. I've also switched from floating to fixed hat (using locking helicoils). The floating setup does start to make considerable noise once it's worn a bit. The second picture below is somewhat amusing - the new D2 rotor vs D1 wheel.
After we test the new rotors, next is a cooling update that Tristan has been working on, and after that a test of bigger calipers. We're doing it one step at a time so that we can see the effectiveness of each item separately.
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