Several months ago I mentioned the top speed of Kimini is about 130mph due to its small tires and the rev limit of the engine. Because of its brick-like shape, aero drag limits it to nearly the same speed, about 140mph. That's fine because it'll be used mostly below that speed anyway. I thought it might be useful to post the equation to show how that value was arrived at.
Wheel horsepower absorbed by drag = Cd * A * V^3 / 146,600
where Cd = drag coefficient, A = frontal area in sq .ft., and V is speed in mph.
Because of modifications Kimini will have about 170hp at the wheel. I know the Cd of a stock Mini is 0.50(!) but because the Kimini body has been smoothed out, it's about 0.45. Frontal area is 20sq.ft. Rearranging the equation and solving for top speed gives:
((170 * 146,600) / (0.45 * 20)) ^ 1/3 = 140mph
Interestingly at 120mph it takes "only" 106hp to push the air out of the way. In order to go that extra 20mph consumes the other 64hp! At 130mph where I run out of engine rpm, 135hp is used up in aero drag, leaving only 35hp for further acceleration. If I were to raise the rev limit and increase horsepower to, say, 200whp, how fast could I go?
((200 * 146,600) / (0.45 * 20)) ^ 1/3 = 148mph
All that engine work and expense gained me only 8mph!!! So much for top speed. Of course the car will accelerate faster below that point but it shows the futility in looking for big top speed gains with engine mods!
First picture is a typical box received from McMaster with their usual two cubic feet of air thrown in for good measure. You think they use their shipping department as an income source?
Started on the fire extinguisher mount. Just yesterday I saw a VW Golf, top down, useless wing on the back, and a fire extinguisher at the top center of the roll-hoop. I guess you have to do that to be cool, wanting to look fast at the expense of actually making the car faster. But what is "looking fast" exactly, like a real race car? They don't put extinguishers up there... whatever. Guess that's the price of car fashion (yeah I have an attitude about this.) I'd rather enhance performance wherever possible by keeping the CG low, that means on the floor in front of the seat. Unfortunately I didn't get didn't get further then cutting the tube you see it sitting on. The extinguisher mount I purchased was the wrong size and of course no other mounts fit either. So then I thought fine, I'll make my own, all I need are a couple over-center mounting clamps. No one had those either. Fine, go on to something else.
Third shot is where the front stabilizer bar may go, represented by the round tube in the center of the photo. This is one of two place it can go, the other being up above the rocker-arms; I haven't decided between the two. The location shown here keeps the CG low, but it's also further forward, increasing the moment-of-inertia. Have to think about it more. I'm unsure if I even need bars but since it's unknown I better assume the worst. At this point in the day I'd accomplished exactly nothing, grrrr.
So I finishing the right side vent inlet. Not visible is a blocking plate for the brake duct inlet that can be removed if brake cooling is needed later. The left side will be next. Like I've said before, I'll consider the chassis done when I don't have to drill any more holes or weld on any more brackets. Not there yet but it's getting closer.
Odds-and-ends. There are some completely outrageous karts people have been building lately, taking a 125-cc cart chassis and putting, oh, "different" drivetrains in them. First is a guy who put a GSX-R 1100cc sportbike drivetrain in a kart. And another guy went even further and put a, get this, 100hp gas turboshaft engine in a kart. Check them out on my Video page. Boy do they look like fun!
A co-worker is completely rebuilding his Porsche 914 and used a rotisserie. Excellent idea and I'm going to do the same. Once my chassis is done there's still a lot of welding to finish, top, sides, bottom. Accessing it all is going to be a pain, rolling the chassis around this way and that. With the rotisserie it'll just revolve. Better yet when it goes off to the powder-coaters, I can wheel it into and out of the truck (saving my back and the delivery charges,) plus the guys there sandblasting and painting it will be mighty appreciative. I believe I have enough left-over steel to make one so it doesn't cost anything.
And finally I learned about a cool "lipstick" camera that can be put just about anywhere on the car while the digi-cam stays safely in a padded box. Viosport makes an "AdventureCam II" that would be really sweet.
Got an e-mail from a fellow stationed in Serbia who said my website helps keep him sane. That really struck a nerve with me, how most of us go along each day, not thinking about some of the very tough and dangerous places people are right now. I don't know what he's doing over there but it's probably not very pleasant. It made me realize several things: how fortunate I am to be able to do this, how my "problems" aren't very important, and how I don't have to worry about suicide bombers... I really appreciated the note, that in some small way I'm providing a thread back to the real world, where a "big problem" is figuring out where the next silly bracket goes...
Talked to a buddy who worked on the Nissan GTP car. He feels based on Kimini's weight and power I don't need brake ducts. That's okay, at least there's a spot for them just in case. What's nice about not making them now is it saves a ton of time - a big item off the to-do list. If you're wondering what's left to do before painting the chassis, here are the tasks in no particular order:
It's really not a very long list... the end is in sight!Camera mount. While not needed for driving, it's nice to record the event! Fire extinguisher mount. Since it'll be in a very visible place it should have clean looking mounts (put in before paint.) Jacking points. Not decided yet, but would be nice not having to put the jack under the very low car, should be in before paint. Ventilation fan mounts. Not a big deal but should be done now. Toe alignment mounts. Extremely helpful for quickly checking wheel alignment. Put in before paint? Sure. Front electrical connector. When removing the nose, need to easily disconnect the electrical (same goes for the back cover too...) Move fuel filter mount. Needs to be done before next test drive due to leak. Reinforce suspension link mounts. Box in mounts so they don't collapse in a minor collision. Sway bar mounts. Whether or not I have bars I should have the mounts available. Tow hooks. Will probably need them! Need to go somewhere, before paint.
Worked on the right-side brake duct and vent inlet which are in the same area, and boom, the day was gone with seemingly little accomplished. I'm trying to finish up things that require drilling the chassis. Once that's done... well, that'll be a big day, I can start disassembling the car for paint. Unfortunately there's a bunch of dull boring stuff still on the list. Of course things aren't helped along by me making things "artistically" which takes longer. For example I realized I can make the brake ducts out of carbon, that would be sweet... but it'll take longer and cost more.
If I seem a little down it's because the remaining tasks are a bunch of nit-picky small things. Regardless of size, everything takes time, the difference being when big stuff is done progress is obvious. With the little stuff, weeks go by with the car looking virtually unchanged.
Added an entry to the video page of a very impressive model airplane, although "model" doesn't do it justice. A fellow in England built a replica B-52 bomber and he sure did, with a 28ft wingspan. The tail is 5-6 feet tall! For engines, he could have done a lot of reasonable things, but no, he decided to make it absolutely authentic, using eight real micro-turbines (which last time I checked were $3000 each.) Sadly it was the last flight; it was suspected pilot error, getting left and right mixed up as the plane turned back, caused the sad ending. Even in the video it's not easy to tell which way it's headed. It's easy to believe that error because I've done the same thing, thankfully with a much less expensive plane... Make sure you have the sound on. Model B-52's last flight.
Normally I don't like posting someone's misfortune and grief as "entertainment." But it's such an impressive plane, no one got hurt, and hopefully some or all of the turbines were salvageable. Interestingly there was a crash of a real B-52 that went down in a similar manner. Once a B-52 banks more then 60deg or so the bank can't be recovered and they spiral in. I read this was because they (and the model) don't have ailerons, which is pretty surprising...
Found a couple of nifty (free) utility programs. One in particular is useful to me, printing out a pattern when two round tubes have to be welded together. Enter the sizes and angle and presto, instant pattern. Even if you have a tubing notcher this program is useful. You can find it and a couple others here.
Been doing a bit of karting lately, hoping it'll give me some idea of what I'm getting myself into with the Kimini. The newer tracks are inside large buildings and some actually use electric karts. Yup, motors, batteries, and electronics have finally reached the point where the electric karts are just as fast as gas, and quick. These aren't like the old lawnmower-engine-powered karts - many times faster, quiet too.
Next is the radiator exhaust ducting. Long ago I'd decided it'll run up and out the top of the hood. Why? Since the bottom of the car will be smooth and flat from front to back, no hot air can be dumped out the bottom. And while exiting the hot air out behind the front wheels is really slick, there just isn't room.
Another issue is the placement of the exit duct on the hood. Because the Mini hood is so short, and because there's a high pressure bubble at the base of the windshield, it means the duct has to be fairly far forward, toward the leading edge of the hood where there's low pressure. To better aid air exiting the hood, a flap will extend up a few inches at the leading edge of the exit port.
The downside of all this is, while it may be functional it sure isn't pretty. There are things I could do to make it look better, but it'll cut down airflow. I'm going to leaving it open and do some track events to see how it works as-is. Assuming it works I can perform a "hood beautification program," covering it with mesh, louvers, whatever, and see how it affects cooling. In the last pictures you can see a gap between the ducting and the hood. That's for 1/4" rubber to keep the two from wearing on each other.
Well I'm done for now, seven straight days of building and I'm actually looking forward to going back to my "day job."
Finished the radiator inlet ducting. First shot shows the from-from-simple cardboard pattern for one side, one reason why little stuff takes so long. Second shot is to assure you I don't have nice high-dollar machines to do my work. Nope, when something needs bending, out comes the I-beam, clamps, and rubber mallet. Third shot is the upper duct cover in place. It was made removable so I can get the radiator out (the fan would interfere otherwise;) the rivets are placed on top to be easily drilled out if needed. I was going to use Rivnuts so the cover is held on with screws, but decided it wasn't likely I'd be removing the radiator often (famous last words.)
Last shot shows it all done. The open areas to the left and right of the radiator ducting are future inlets for brake cooling.
Worked a bit on the radiator ducting then headed to the airport to get a ride in my brother's plane, an RV-8A. I added a video of the flight on the Video page
Temporarily installed the front Dzus fasteners to see how it all fit up... it'll do.
With the last main cross tube in place work proceeded with the radiator ducting, installing a small hoop around the front grill opening to locate it. This way the nose will come off with nothing but the lights attached to it. Of course as I was making the hoop I realized the stainless grill should be mounted to it instead of to the nose itself... like I already built... nuts.
Third shot is the first radiator ducting panel in place. It also serves as the curved entry to the front diffuser. And the last shot, well, it's what keeps everything moving! No, it's not blurry because I'm drunk, only too lazy to manually set the aperture so it would keep everything in focus...
Oh, a company want's to buy my domain name! I've grown kind of attached to it though, it's unique and easy to remember, coming from the mix of my wife's name Kim and "Mini." What would I change it to that would be as simple and easy to remember?
The front bottom nose mounts are done; I need to order more Dzus fasteners. I got in a discussion about how bright it was to put the bumper tube inside the shell. Guess we'll see... looking back a few years from now it'll seem all too obvious. It was also pointed out that having a bumper stronger then the chassis is asking for trouble. I'll drill holes in the support tubes to make sure the bumper collapses first.
Today the Blood Goddess of Construction was appeased, twice. First time was when crouching down using the de-burring tool. Everything was fine until it broke, driving the remainder into my leg, "We've got a bleeder." Later I was cleaning up using the vacuum (what could happen?) I pushed the hose under the car, knifing myself nicely on a sharp, rusty, tube end, "That'll leave a mark." In fact you can see the offender in the picture, it's the pointy tube on the left holding up the shell - bitch. Hydrogen Peroxide and Iodine are my friends. Oh, and I found several Guinness draughts help too...
Took the week off; pushing ahead with the bumper tube inside the nose. Since it butts up against the nose the idea is the force of hitting cones will be transmitted to the chassis rather then deflecting the shell... much.
First shot shows where the tube will go, viewed from inside the nose. Second shot is after it was bent to fit; while I don't use the press often, but it's extremely handy sometimes. Center shot shows there isn't much room for the brake ducting; it'll need to be rectangular here to get the needed cross-sectional area. Next shot shows a minimum of about 3/4" clearance between the tire and bumper tube. Last shot, hours later, the bumper is tacked in position. The support tubes had to be placed so both the radiator and brake ducting won't interfere. My concern now is that the force of hitting something will transfer to the area of the chassis which is narrowed to allow the front a-arms to pass below. My fear is that it'll buckle. I may cut off the aluminum panel in that area, welding in a more robust steel panel.
Still very hot but the Accusump mount is done... tacked, but done. There's going to be a lot of finish welding before the chassis is painted...
Today I started thinking about how to finish the nose. While I took care of the back edge already I had left the front undone, thinking the nose would hinge but I've changed my mind. Then there's the issue of hitting cones at the autocross (not that I ever will...) How do I protect the carbon from cracking? A bumper would work but I like the clean look without. I may instead put a bar just inside the nose for the same purpose, also serving to mount the Dzus fasteners. The trouble is, cones are flexible, bending very nicely around a bumper and still smacking the body work. Two bumper tubes? Ugg... I need to think about it some more. On top of that the nose is too flexible right now, needing reinforcing core and another layer of carbon. That can happen after it's mounted since the Dzus fasteners can't reach through a thick panel very well without the chance of crushing it.
Very very warm weather, 111 deg F says the thermometer so it called for doing something "light." The to-do list included the gas-filler plate; that could be fun. It was placed in the only practical spot, at the base of the windshield at driver's right. As I was picking up the bag of included hardware I thought it would be really cool to use stainless Allen flathead screws with Nylok nuts. And that exactly what was included... good to see the right hardware accompanying such a nice filler.
The blue cylinder is an Accusump, a pressurized oil reservoir supplementing the oil supply if the oil pump sucks air during cornering. At $200, it's a poor man's dry-sump, which is about $3500, more then what I paid for the drivetrain! Between the Accusump and a baffled pan I hope to avoid oil starvation.
The passenger seat was taken down from the rafters (around 130 deg up there) to aid in placing the Accusump. The plan was to put it behind the passenger seat to keep it out of the way and close to the engine, but it was a really tight fit. Installing it wouldn't be hard but accessing it later would be a real pain. It was packed in there so tight I decided it wasn't going to work, so instead it was moved to just in front of the seat. Yes it takes about two more feet of hose but makes it easy to get to and moves a fairly substantial CG forward as well.
So what the heck is that last picture? It's a dragon fruit and my wife's pretty excited our first one has ripened (with help no doubt from the heat.) They originated from the rain forest, growing up in the trees like an orchid, yet the plant itself resembles a cactus. It has a really nice flavor and I think the fruit will get a lot of attention from commercial growers. Don't be surprised if you see them in the store one day.
Added a couple of links to the Video page. Dzus fasteners didn't show up :( Oh well, lots of other stuff to do.
Watched the five episodes of "American Hotrod" when they built the "Alumitub." It was very, very, cool; watching these experts in their field, how they did things, what tools they used, and how long it took them. It was especially insightful seeing the little techniques they used, of making paper patterns for example (and not using plans because they weren't given any!) Being insecure myself, it made me feel better seeing I've been using some of the same techniques without knowing it. At least I haven't been doing everything the wrong way...
Someone once told me an anecdote I thought I'd pass on; I think of it from time to time when building the car. It's of a guy who's at the harbor, we'll call him "Bob", watching a fisherman, who we'll call"Tom", unloading fish from his boat.
Bob: I see you caught a lot of fish today.I like that story. To me it means you can make yourself happy with what you have if you choose to. If I waited until I had "everything" before building the car, it would never happen. The project keeps me happy and I'm very thankful I've had the chance to do this at all!
Tom: Yup.
Bob: You know, you could take more people fishing.
Tom: Yeah, then what?
Bob: Well, you could make more money and buy a bigger boat.
Tom: Then what?
Bob: So you can take out more people.
Tom: Then what?
Bob: Then you can make more money.
Tom: Then what?
Bob: So you can retire.
Tom: Then what?
Bob: So you can do anything you want.
Tom: But... I am.
September already! I went down my list of things-to-do and found there aren't that many items left before it's drivable. Ordered rubber stripping from McMaster to cushion the engine cover. Not that it'll be installed now but it's needed to correctly size the Dzus fastener lengths.
Alas how quickly the legend crumbles regarding the movie "Rendezvous". I'll let a reader (thanks Thimo) tell you what he found:
"Just read your diary entry about Rendezvous. Not too long ago the Dutch car magazine AutoVisie did some research on Rendezvous and found out the following (quoted from a thread in FerrariChat:) It is true the average and max speed is not that impressive, but it took them 16.5 minute, in a Chrysler Crossfire in the middle of the night, twice the time. The car used in the original movie is a Renault Alpine Berlinetta, driver NOT Lelouch himself but Jean-Louis Schlesser (later F1 testdriver) and the car on the soundtrack was a 66-67 330P, probably taped on owner Pierre Bardinon's personal track, although they are not sure about that last thing. Thought you'd like to know... :-)"Well that bites. I was a bit suspicious of the sound myself, but when it echoed as the car drove under a bridge I thought it was real. In hindsite the odd thing about the sound is its lack of everything else; if it were in the car other sounds should have been noticable. Where the car sounds like it's going 175mph, it appears to have an overtaking speed on weenie pedestrian cars of only 20mph or so. Oh well, it's still fun... guess I just feel a bit tricked!
Ordered engine cover Dzus fasteners.
Just watched the 10-minute French movie "Rendezvous". While I disapprove of street racing it's hard not to be impressed, to say the least. The film-maker put a camera on his Ferrari then drove as fast as possible through Paris early one morning, and I mean fast. No dialog, no special effects, no nothing, just the wonderful sound of the Ferrari. It's amazing no accidents occurred, due as much to luck as driving skill since it was on public streets. The movie is available on DVD in the states from:Chasecam. $30 for a 10 minute movie is pretty nuts, but it's a fair bet you'll watch it many, many times, sharing it with friends.
Received mail noting I seem to enjoy writing as much as building the car. Could be, it's nice to record thoughts, to be read years later with a mixture of amusement and nostalgia no doubt. It's easy to write for 15 minutes - but impossible to work on the car for such a short time. That's why these two activities can coexist without intruding upon each other. I need several hours to get into the project and once that happens, interrupting me can be very unpleasant, as my dear wife can attest!
Finally(!) finished the lower-rear Dzus mounts - what a pain. They're not quite done since I still have to buy and install the fasteners themselves, but that's easy. Like I said, this part of the project, well, it sucked... right up there with the doors. Anyway, first shot shows the brackets themselves, which took several hours to make. This is a reminder to anyone building a car - tons of time gets sunk into boring little brackets, they consume far more time then the big fun stuff too. These are stainless for the same reason the mounting bar to which they'll attach is - to prevent rust when rock impacts knock off the paint. Second shot shows once again using the laser to get them places symmetrically. Third shot shows them finally in place, a very time consuming process mocking them up in just the right position. Last shot shows it's worth taking the time to carefully align everything. The hole in the bracket and the shell could not be drilled at the same time, but it paid off measuring carefully.
Received a note from a guy asking when he'd see me at the track - that made me smile. I refuse to have schedules... but I'll go out on a limb and say it'll be on the road (with a primered shell) by the end of the year. There, I said it! I've also decided the first track event will be a mid-week testing session at either Willow Springs or Buttonwillow; much cheaper then the weekend events, they're more frequent, and there's less traffic. This is all because I'm going to need a ton of track time to establish handling and will need time to fiddle around with tire pressure, camber, caster, shock settings, and roll bars (if I have them.) If I go to a "real" event, I'm supposed to be driving the car, not developing it and wasting expensive track time. No, the real track events (time-trials in my book,) will come after it's sorted.
As an aside, I gave a builder a hard time back when he said his car project would be done a year from its start. I asked why would he set himself up for disappointment, wasn't his project supposed to be fun? I said his deadline would only serve to frustrate, annoy, and disappoint him, yet it's a self-imposed disappointment! He then turned around and lectured me about not having a schedule, saying that he's a manager at his day job and that schedules are important. Okay I thought, I'll keep an eye on his project and crazy schedule. I admit a bit of amusement that he's now 67% past his self-imposed time budget. Must be real disappointing... Geez, this stuff is supposed to be fun, not a job. Reminds me of a quote I heard, "I like deadlines, especially the whooshing sound they make as they sail by." (And no, I'm not a manager...)
Discovered that the BBC show Top Gear has an on-line video library of all the cool stuff they've driven. Make sure you have a broadband connection!
Webstats indicate there are still many people coming here via the old website. Please bookmark this new site as I'll soon be cleaning out the old one.
Found a good write up on figuring corner weights on the Grassroots Motorsports site, something I'll be needing to deal with later this year, I hope.
I want to give a big thanks to Peter for helping me clean up these pages and showing me how to use CSS. Thanks again!
Finished the left-side Dzus mounts then finally turned attention to the rear mounts. Truthfully this is the least fun part of the project; lots of time and little to show for it, yet if I don't take the time it'll look bad and be a pain later. And yes I brought this upon myself by insisting the engine cover be removable. But that's what I want so I'm willing to deal with the irritation now rather then later, every time I want to get at the motor and can't reach something. Of course it may all end up looking bad and be a pain anyway, but at least I gave it a good try.
The rear fasteners will be attached to brackets on the curved tube which looks something like a bumper (I hope not!) It's getting kind of busy back here with all the tubes but it'll get the job done and be easy to work on. In the last shot you may be able to see two small tabs on the curved tube. They support the back edge of the shell until the Dzus fasteners are done. There'll be a few more tubes to stiffen up the area but that's about it. I'll probably also need some tubes strengthening the upper corners of the cover, above the window, especially if I later add a lip or wing.
Regarding the discussion from yesterday, I was reminded (thanks Dennis) that there's a whole lot more to it then just power-to-weight. Aerodynamics, tire size, CG height, wheelbase, and so on. Any of these can throw the advantage to one car despite its weight.
Kimini 2.2 is in print! Published as "Internet Hot Rod of the Month" in Grassroots Motorsports, a magazine catering to the hard-core autocrosser and amateur road-racer. So off I went to the bookstore and alas, the latest issue isn't out yet :(
Had an on-line discussion about the performance of some upcoming super-cars, specifically the Shelby GR-1, receiving a terse reply about my negative comment regarding its 3900lb weight. The remark was, "It doesn't have to weigh less than 4k pounds to be fast. Ever hear of power to weight ratio?" So I asked if they think two cars with identical power-to-weight ratio should get the same lap times, regardless of weight. Who thinks a 4000lb car will do as well as a 2000lb car at the track? The post shows the drag racing mind-set, that it's all about horsepower. Sure, in a straight line they'd be roughly even, but "sports cars" are supposed to go around corners too. That's how these new cars are presented, as streetable "road racers" not drag racers; there's no way such heavy cars will corner well.
I completed the clean up of this page - you're looking at it - shrunk by 85% and it looks exactly the same!! Absolutely amazing... cheap memory and hard-drive prices have caused our programming tools to become lazy. The only difference you should notice is it'll load much faster and resizing works. The fat files bugged the heck out of me, having such crappy blotted code sucking up bandwidth.... it was a poor representation of my work, car-related or otherwise.... Let me know of any link problems.
Been wrestling with the HTML on this page. If and when I get it cleaned up (it's a real mess) I'll switch to it. As neat as this page appears, there's a lot of hidden crap that's driving me nuts. Someone said "why bother, leave it alone." If I get tired enough of trying to fix it I may just leave it alone. FWIW, in my work to clean up this page, it's gone from 338Kbytes down to 70Kbytes. The difference in file size is absolute crap code that's just tagging along! Grrrr.
Found a cool site of someone who put not one, but two sport-bike engines in a Lotus Super-7-esque car, nice for 3.1 sec 0-60 times, 300hp Super-7
Worked on the right side Dzus plates for the engine cover. My reasoning is that if I install the rear mounts first, the sides may not align very well, best to work my way back. The mount at the bottom of the picture holds the leading edges of the wheel well. Because of the way the shell is constrained, this point only needs one simple tube to steady it. The mount above it though, the one with the Cleco in it, was in a goofy place where I couldn't just run one tube out to meet it. Between that and it being under some stress, it required three tubes.
Received a funny note for a reader suggesting the way to avoid "arm-chair quarterbacks" is to remove my e-mail address from my website!
I'm getting fed up with Mozilla. While I can't complain too much (it is free) the phrase "you get what you pay for" comes to mind. Trying out DreamWeaver, I went in and viewed the HTML source, the actual code formatting this webpage, finding 131 errors, plus tons of goofball code. I ripped out some of it just to see what would happen... nothing. That's right, removing huge chunks of code makes no difference. Unfortunately because I cut-and-paste sections to save time and be efficient, it's been piling up errors upon errors. What's odd is that the page looks okay in Mozilla and IE6.0, yet if I open it with DreamWeaver things look different, text colors for example. If I make no changes at all and just save it, it get saved with the different look. Grrr. I'm getting close to just using HTML directly.
Had an on-line discussion about fuel tank placement. The point came up that I should have put the tank at the CG of the car, behind the seats. That way whether the tank is full or empty won't affect the CG of the car, giving consistent handling. With it toward the front, the CG of the car will depend on how full it is, causing the handling to be different depending on fuel load. Another point of placing it behind the seats is decreased moment-of-inertia allowing faster cornering. So why didn't I put it there?
There isn't much room back there so the tank couldn't hold much, and it's darn near the exhaust header. As an experiment I went back to my Excel program that calculates CG and weight distribution based on the location of many major components. Where the tank is now, having it full or nearly empty moves the CG only 0.8", which isn't very much. A plus too is that it moves the CG about an inch farther forward then if it were behind the seats and right now weight distribution varies between 42/58 and 41/59 front/rear. With it at the back it'll always be 40/60.
So the argument that I'm going to have understeer doesn't seem correct. That is, the CG will always be further forward, toward a perfect 50/50, then with it behind the seats. What small issue I will have is the CG moving slightly depending on load, but at 0.8" I feel it'll be okay. So did I make the right decision? Heck I don't know; everyone thinks because I'm building this thing I must know everything! If I were doing it over again yeah I would certainly consider moving the passenger seat forward and put it behind it. Doing so could very well require a custom fuel bladder meaning higher cost and complexity. The whole point of using an off-the-shelf cell was so I could get on with things without having to design yet another component, and be able to simply order a standard part if this one gets damaged. Moving it to the back though would get it out of the front area freeing up that space... though for what I don't know.
Regarding the emerging "what I should have done" comments, I guess I just have to get used to it!
Measured and cut the vent above the diffuser. The idea is that air coming up through the undertray around the suspension arms, and in around the wheels, needs a way out in a hurry. Since it'll be moving rearward the thought is that the top of the diffuser may act a bit like a wing, forcing air upward, so it needs a way out. The vent is being cut out now to help determine the mounting points for the Dzus fasteners. If I just put them anywhere I risk having to rework the whole mess if the vent was put in later. Another reason for the vent is engine compartment cooling; even at rest... heck, particularly at rest, the engine compartment will get really warm. With a rear opening down low, and future vents high up, it should provide sufficient air circulation. First shot is finding where horizontal is (with the laser level) for the cut line. Second shot is a top view looking down, right behind the engine. The curved tube is being fixtured in place and will later have the Dzus mounting plates attached to it. Last shot is the new vent area which will later be covered by stainless screen. The space below the horizontal tube will remain open since it is the diffuser area.
Regarding the Lexan windows, I'm going to use glass in the doors and windshield, and Lexan everywhere else...
After talking to people who've worked on real race cars I'm having second thoughts about Lexan getting scratched during cleaning. Due to the chassis layout the rear windows are going to get very dusty on the inside without inner fenders. Adding an engine cover would be awkward and tricky because of all the tubes, and for what, just to have slightly cleaner windows? Another issue is that some smart guy thought he needed to completely remove the engine cover (I still do.) Having glass at the back and sides would make it heavy and more awkward to remove. It makes sense to have Lexan as the bulkhead window for safety and noise dampening and I can stay with glass in the doors. The rear quarter windows are a bit tougher since "someone" passed the parting line right through them so they should be Lexan. That leaves only the rear window... I have to think about it a bit more. Sometimes a Super-7 type car seems oh-so-much easier.
Found a simple but cool device called the StickyPod, a suction-cupped camera mount for all of us want-to-be film makers. Good for sticking digi-cams to, oh, cars for example ;). I may visit their site later...
Looked into Lexan for all but the windshield. Disappointingly expensive, $300 for a 4'x8' sheet of 3/16" scratch-resistant Lexan MR-10. Unfortunately it seems to be The Stuff to use though I'm looking for an alternative.
Went to Carlsbad raceway in the morning before it got too hot. Perhaps it livened up later, but it was oddly normal for the last day of its existence... and not one single import car except for some old VWs. After a few hours I got bored, wanting to work on the car.
Worked on getting the engine cover to fit... still a puzzle why it didn't. Since the shell used to be one piece it should have fit together perfectly but it wouldn't in one spot. It must have warped when I put the flanges it; so be it, it was trimmed to fit. I spend a lot of time staring at the shell trying to figure out where the fasteners should go and how to mount them. I need to think about it more before starting.
Since the engine cover mounts are being placed it means the cover has to stay on while I access the engine area... time to cut out the rear window. It keeps looking more and more like a car. At the end of the day I also got an impulse to cut out the headlamp and front turn signal holes. Of course that meant I just had to drop in both to see how they looked. Perhaps it's due to the close up picture, but the fender flare sure looks huge doesn't it?
Last shot is from Martyn Walker's website. I think this Mini roadster looks really, really, nice. Very clean. For some dumb reason Mozilla absolutely refused to link to my own full-size picture so I had to point the link to his webpage. Grrr.
Debating if I should give up some build time tomorrow and visit Carlsbad Raceway (as a spectator.) It's our local drag strip that's being shut down after 41 years; very sad to see it go. Apparently our city "planners" (and I use the term lightly) feel we need more homes and industrial parks because we have cheap electricity (no), plentiful water (no), and little traffic (no!) Makes me wonder if they've ever turned down anything. When it takes 35 minutes to drive 17 miles to work (this was before the building started), at some point one wonders if things are really getting "better." We're told we should ration water, yet at the same time 1000 new homes are going up, it makes you wonder about priorities.
We recently visited a local museum where they had an amazing picture of a beautiful valley, a few houses here and there, with large open spaces, and I caught myself saying, "I'd like to live there." The thing is, I do, along with thousands of others thinking the same thing over the last 40 years. It's really sad we humans find a nice place and basically love it to death. There's no sort of moderation or density planning - nope, the more the better.
If only city planners would set a reasonable density of housing. The most recent housing developments here have homes ten feet apart. Yes, 10 feet wall to wall, necessary to keep prices down. Do people enjoy living within 10 feet of neighbors, in a cookie-cutter white stucco, red tile roof home with side windows that will never be opened? The argument is that imposing a density restriction would make homes too expensive. It also means there's enough water, electricity, and few traffic problems. But the city doesn't want to hear that, instead selling its soul to maximize tax revenue. Alright, enough of this.
On a lighter note I ran across an amazing site of a guy who spends lots of time making extremely custom PCs. Click on his Past Projects column for what it takes to create some of his masterpieces.
Received an e-mail from Dave, builder of the Norton Shrike. His own version of "driving delay" came from a fear of success! That if he truly finished his car, that people might want one, so then what? Sell it and start another? Start a kit-car company?
I said I thought I'd more likely suffer from "post-project-depression," loss of focus, sitting around the house feeling sorry for myself. But in actuality, finishing the car simply moves me into the next phase of the project, driving, tuning, and testing. That'll keep me busy for a while ;)
Okay, this topic is done, time to get on with things. I'll be adding engine cover mounts this weekend.<
I received an e-mail from Rob in the U.K.:
"Being in a similar position with my Terrapin I'd like to add a few comments on the subject of 'driving delay.' I've mentally been through this process a few times and I learned from experience it's best to complete the job prior to the first real drive. I think it's all to easy to try to get the car running whilst still at the 90% stage. Problems you then encounter include:
1. Getting bogged down trying to fix issues identified during testing (rather then finishing the car.)
2. I have met many builders who's cars are up and running at the 90% stage and are still at the 90% stage after a long time! ('yes I was going to complete that, but hey it's cosmetic and it's running now!')
Why compromise your build integrity with a deadline?"
Well said.
I've done some soul searching regarding the earlier question, "don't you ever want to drive it?", wondering if I really am putting it off. I voiced this to a friend who's designed and build several cars, so he's in a good position to offer insight. He said each time his latest design nears completion, he finds himself doing the same thing, straying from the shortest path to driving it. He thinks it's the designer's subconscious fear of being wrong, that some aspect of the car is flat out wrong. That it'll be driven and be found to be, well... extremely poor; that it has to come all apart to fix the big design screwu. I think it might also be the fear of getting into something quicker and more powerful then anything I've driven, something unknown, something that can kill me or, worse, others. However I do know that as he described the above, it was as if a big weight had disappeared. Could it be these things? I don't know yet. In any case, awareness is knowledge, and knowing what might be going on inside my head makes it a bit easier to work through...
Along the lines of finishing the chassis, I made up a list of what's left: fire extinguisher mounts, Accusump mounts, windshield wiper mounts, camera mount, gas filler mount, sway bar mounts, interior fan mount, adding extra carbon to the nose, fender vents, dash fabrication, splitting the stainless firewall panel, brake ducts, toe alignment frame mounts, mirror mounts, lights, electrical, body work on the doors, rebuilding the doors, and body work on the shell...
So there you have it. Yes some of these aren't needed to drive it, yet it also means at some later date, no doubt after the chassis is painted, the paint must be ground off to weld on whatever's missing. The body work can wait until later, but as far as the chassis goes, I'd like to at least weld on the mounting brackets for everything. It gives me a much better feeling of having finished something and moved on, rather then going back and redoing stuff over and over... is that the real reason, or is it something else...
Decided to take a breather from the recent big stuff and build something simple, something fun that could be built in one day. While perhaps another unnecessary-for-driving component, I wanted to build the front grill.
First task was the frame, made from 0.375" tubing (simply because it looked about the right size.) The grill is going to take a beating from sand and rocks and I don't want it to rust; paint won't stand up to the abuse hence it's stainless. I don't own a bending jig so I used hand pressure and my knee to form the frame. The grill itself is stainless wire mesh from McMaster, four rows per inch, 0.063 wire. It's thick to both stop a 130mph rock (or bolt) and be easy to weld. One concern was the percent open space of the mesh as it's very easy to pick mesh that cuts off too much airflow; at 67% open space this material will be fine.
Next step was to clamp the mesh to the frame to measure for cutting, done on the band saw. Then, a lot of careful welding of every single wire. There were two tips passed on to me for making this. On is to clamp the wire to an aluminum block to suck away the heat so as each wire is welded, it doesn't melt back too far. The other tip was to curve the screen outward toward the front. That makes it both stronger in impact and also so trash like leaves or paper will drop off when the car slows down. If it were flat or concave it would just plug up the grill. It'll mount with tabs to the carbon lip surrounding the opening.
It took six hours to build but it was a nice size project for today. The last shot shows it in place... looking very functional. It'll do!
Just found out my brother flew his home-built plane, an RV-8A, from SoCal, to Palm Springs, to Jackson Hole, WY, and on to the annual Oshkosh fly-in. Then to Kansas City, then Texas, and he'll be home tomorrow. That's pretty cool; I hope to do something similar, but on four wheels.
The conclusion on the Rust Bullet testing: It's a really good coating, doesn't run, hard to chip (I really had to whack it), minimum surface prep needed, brush marks make it look very amateurish, it really needs to be sprayed on. So... either I do an "urban paint booth," lining the garage with plastic, or take the can of paint and the chassis to a paint shop, "how much to just spray it?"
Tried the Rust Bullet coating on some scrap tubing. The stuff is metallic-gray in appearance with emphasis on metallic, it looks like real metal. The good news is it's thick enough there's no problem with runs. The bad news is brush strokes are very visible, at least when applied with a cheap brush. I could spray most of the chassis but that has its own problems. The stuff smells nasty, I won't subject the neighborhood to a poison gas cloud, and painting it in the garage means making a paint booth with fans and filter screens, and wearing a real mask, one that covers the entire face. That's because this stuff cures by moisture in the air. I don't want it curing in my eyes...
Regardless how it's sprayed on, the problem is the same, how to guarantee even coverage on all the tubes on all sides. As said before, it's one reason why powder-coating is popular. The catch is, I've heard powder-coating chips easily; my brother had trouble with some of his aircraft parts. Ironically when I went to the powder-coater to ask about this, I walked in on an unhappy customer asking why his dune-buggy chassis chipped so easily...
Anyway I'll test the pieces tomorrow to see how the coating stands up to abuse ;)
There'll be several brackets near the tires no doubt taking direct hits from sand, pebbles, and rocks. Having them rust is not cool so they'll be stainless steel, picked up today.
Ordered stainless wire mesh from McMaster for the front grill. A buddy at work shared his tips, learned from building the front grill for Nissan's GTP car no less. Is a grill really needed before I drive it... no, until a stone punctures the radiator. I'll also need screen for vents at the back of the car but it's too early to know what's needed. Ordered a small can of the Rust Bullet coating. I'll paint a few sample tubes to see how the stuff goes on, if brushing will work or if it has to be sprayed, then beat on it to see how it holds up.
I was asked, "Do you ever get the urge to just drive it a bit?" The context was that I'm avoiding doing so by finding unimportant things to do, like working on hinges. Yet if I push to drive it now the chassis must be painted first, and many tabs and brackets have yet to be attached. Painting it now also means within weeks I'll be grinding it off to put these brackets on. Is this a problem? While technically no, psychologically I feel like I'm doing the work twice, of being inefficient, of not really being done with something before moving on to the next. The point is well taken though, that I can deal with non-critical stuff afterwards; hinges shouldn't be holding up driving it. An item like the carbon dash, while great fun to make, also isn't needed for driving. Of course the dash (and hinges, gas struts, sway-bar mounts, fire extinguisher mounts, etc) will attach to brackets that don't exist yet, hence my reluctance. Of course no matter what, I will be grinding off paint so I should decide how to deal with it. Which brings me to a controversial point...
I feel this argues for using a brush-on chassis paint. Yes, I know, "the horror!" Yet there are benefits: Much cheaper then powdercoat, no need for sand-blasting (and getting sand inside tubes through rivet holes), I can control the process, it doesn't chip, and perhaps most importantly, it's easy to repair. There is new paint on the market that isn't really paint at all, but a tough, tenacious coating. Rust Bullet is a good example, used on Steve Graber's car and he's completely sold on the stuff.
Speaking of paint, I was wondering what color to paint the suspension bits. They have to be painted anyway so a little color would be nice, perhaps light blue to go with the gray chassis.
Found another good composite source,U.S. Composites caters to the hardcore composite user, supplying fabrics, glues, mold components, etc.
Been reading "The Elements of Style" by Strunk and White, to improve my writing style...
Trimmed the carbon covering the foam areas and sat the engine cover in place. It fit well except for one spot, which is a puzzle to me. There's no reason why it shouldn't fit perfect since it was all one piece originally... so before trimming anything I better mess with it some more. There's a chance it warped when I put the flanges on, though the way it's interfering it doesn't seem like it.
Oh, I've begun thinking about hinges again. It's a bit of a nuisance fitting the cover on and I see it's going to be all too easy to bump the painted surfaces together. Hinges would avoid that... we'll see. On a related item, I found that gas shocks (for holding up hatch-backs,) work differently depending if they're hot or cold. If I use them at the back, in the engine compartment, it could be interesting how well they'd work depending if the car is hot or cold. I wonder if there's an equivalent part that doesn't use high pressure gas, but rather an old fashioned spring and oil.
Layed up the nose patch first thing so it could be pulled later the same day. While that was curing I dug out some of the foam core material at the left and right rear edges of the passenger compartment and covered the vulnerable areas with a layer of carbon; the same was done to the mating faces on the engine cover. The foam was never intended to be exposed, that was a consequence of where I placed the engine cover parting line. It remains to be seen how much grief I've brought upon myself by putting it where I did, but I can already tell it'll be extremely functional, allowing full access to the entire drivetrain.
Later in the afternoon it was time to see how the hood patch turned out so out it came. It was my first mold and frankly it didn't turn out very well but it could have been a lot worse! While it'll need body work to fix, a fair amount of it will be cut out, covering my goofs. Yes, that's right, most of the nose patch will be removed. That's because the radiator exhaust air will come up through the hood in this area, but since it has its own unique shape there wasn't much choice about covering the hole... patching the entire hole was easier then trying to figure out where it was needed and where it wasn't. (Notice in the lower shots the hood patch is offset. That's due to the mold maker intending to install a KAD drivetrain which was offset to the right.) In any case, the hood patch isn't any worse then the rest of the shell. That's a whole 'nother story; I don't look forward to 100 hours or so of sanding and filling, unless I want to pay someone else... but being a cheapskate prevents this ;) I couldn't help but take the last shot, of all three major shell pieces being worked on at the same time...
Continuing on the "nose job." At left is the carbon nose sitting upside down in part of the front nose section mold, the giant abyss is what has to be filled and at 4-6" deep it's not trivial. Second shot is the fiberglass mold insert, trimmed and ready to be glued in with epoxy/micro. ("Micro" refers to micro-balloons, microscopic glass spheres, used to lighten the epoxy mix and make it thicker.) Next shot, weighed down with whatever was around, waiting for the epoxy/micro to set up. At right you can see all my dirty laundry, where many wrinkles/voids had to be filled, in addition to filling the edge all around. Mental note to self, wrinkles are bad... don't let that happen again...
Thanks to Mike of the local Mini club for loaning me a Mk 1 Mini hood. I needed it to modify the mold so I can patch the huge hole in the hood that the mold builder installed. First shot is the loaner hood and the second is the splash mold curing. To be honest it didn't go very well, at one point it looked like the epoxy was setting up too fast but I pressed on. Separating the splash mold went very well, no doubt due to the mold release wax and PVA (which I had no clue about until recently!) Last shot is the result which came out okay though it should have a couple more layers. Anyway what you see here is not the actual patch for the hood, but rather the patch for the mold.
About the SL65 Mercedes below, I was told that in fact the brakes will last a good long time because they're composite. Could be, but when Gordon Murray was designing the McLaren F1, they couldn't get composite brakes to work (they were using carbon and they didn't work when cold.) To be fair I don't know what the Mercedes uses.) In any case, at 4500lbs and 600hp, the brakes are going to take a severe beating at the track, though I doubt owners are likely to take the car to the track anyway... kind of like SUV owners never going off-road.
Saw a cool paint scheme on a Mercedes so I went to their website; while there I noticed their new top-of-the-line coupe, the SL65 AMG. Oh my, 604hp and get this, 738ft-lb of torque between 2000-3000rpm, all for only $180,000. I found one spec very interesting... the poor thing weighs 4500lbs, more then triple the Kimini, and with coincidentally triple the power - both have about the same power-to-weight ratio. It would be an honor to run Kimini against an SL-65 at the track; I wonder how long the SL's brakes would last. Did I mention I very much enjoy beating expensive cars? Of course I need to finish Kimini first...
Removed the passenger compartment shell from the mold and put it back on the chassis. Marked the edge of the flanges onto the metal and removed the shell. Punched rivet holes. Placed shell back on chassis, ready to finish drill rivet holes through the composite. Round and round we go... I think my wife's getting annoyed how many times I keep moving the shell, putting it on the chassis, in the mold, out of the mold, or moving it from one to the other, over and over. Unfortunately it's the only want to do things.
Added another cool car video link... a high quality video of a Lancia that's also on another video I was hosting. I decided there's no reason for me have 60% of my bandwidth sucked up on that video alone. I put a link to the place selling the tape and you can watch the video from there.
Someone sent me a link to this place, eMachineShop. Here's the idea, you provide CAD software for designing mechanical parts... and give it away for free. People use it, discovering it even calculates what stuff costs to make. And here's the cool part. After you design your gear, bracket, bearing cup, a-arm, or whatever, you send the file to them with payment, and magically, the CNC-generated parts show up soon after. The trick is (I think) they're the only place that can read the files! Very, very, crafty business plan that!
Completed the flanges (whoo-hoo!) along the top and side of the shell. I took a few pictures but none came out very well; the carbon reflects the light making it hard to even see that there's a flange there. I'll try again tomorrow from a different angle.
A long day but much accomplished, psychologically at least. The passenger compartment shell was put back on the chassis and fastened down with Clecos. This was to use the chassis and shell as the fixture for the vertical flanges. While the flanges could have been made completely in the mold, doing it this way is faster and more accurate. Once the shell was in place, paper patterns were made of the necessary shapes then cut from cured carbon sheet. These strips then had a profile that exactly followed the inside surface of the shell, and sit flush against the steel flanges made earlier. Once in place and clamped, the steel flanges hold the carbon strips exactly where they need to go, and a small amount of epoxy/flox mix was used to tack them in place. Once cured the shell will be removed, placed back into the mold, where epoxy and reinforcing will finish this portion of the shell.
Recall the purpose of doing all this is to completely seal the passenger compartment... from everything, dust, dirt, and especially the engine. Keeping out the heat, exhaust fumes, and noise will go a long way to making it a more enjoyable car to drive. Just because it'll be quick doesn't mean it has to be uncomfortable.
In the morning reinforced the sides of the engine cover, shown in the first shot. By afternoon it had cured enough (thanks to our hot weather) to add rubber stripping and tape - same as along the top edge of the cover, and lay up the overlapping flange.
I'm unsure how to deal with the large open foam section you can see in some of the pictures. The best thing is to lay up a cover for the foam faces to seal them and strengthen the area... but the two faces shouldn't touch either. So... another rubber pad is in order but it gets a bit tricky trying to provide just the right backspacing so the rubber doesn't hold the engine cover out of alignment...
You may have noticed I've been working on the car just about every day. When working on composite, often there's 1-2 hours of work followed by 24 hours for curing, so working on it a little each day works out well. If I did this in my usual Sunday afternoon schedule, either it would be really slow going or I'd have to find something else to work on while it cures. Since the chassis is waiting for the flange to be finished, I really need get this done before moving on.
Pulled the passenger compartment portion of the shell out of the mold. It was a little tougher then expected to remove, I had to work at it, slowly peeling the flange away from the tape. It looks pretty good though I won't know for sure until I reunite them on the chassis. The second shot has the rubber strip placed where it'll eventually live and the small step is for the mating flange. All in all, for a first go at composite work, it turned out pretty good... I'm happy.
The flat portion of the top flange is done, coming out pretty well. I was reminded what happens when a bit too much epoxy is mixed at one time. It happens often enough to people that there's even a term for it, about the pot "going off." As it starts to cure it gets warm... and when it gets warm, it starts to cure faster... and the hotter it gets, the faster it goes. The cup got so hot I couldn't hold it and the contents started steaming! "Ohhhh yeah...", okay, small batches...
Below shows the work just starting, putting "flox" (powdered cotton) mixed with epoxy into the junction of the two shell halves. Onto that went three layers of glass, then peel-ply. (peel-ply leaves a rough surface so future layers can be added.) I learned quickly peel-ply doesn't bend well, hence the air bubbles. Sandpaper will deal with that. I don't have any "in process" shots because things happened quickly once I started laying up the glass. If I stop I risk the epoxy getting too thick.
Version 1.7 of Mozilla is buggy... this table won't dynamically resize so you're stuck with keeping the window large. I can enable it, but it just disables itself. That's the problem with open source code... many bugs.
Cleaned up the mating edge on the passenger compartment portion of the shell and put it in the mold. I then noticed at one edge of the engine cover the carbon layers weren't bonded together, looking kind of like a partly opened book. So out came the epoxy and about 12 C-clamps... it's not a big deal but it looked like crap. Since this is being done outside I started losing daylight so quit for the day. Laying in the flange is a decent size operation, one needing a lot of time to set up and execute quickly before the epoxy sets up. I need to get everything all ready to go before starting.
Started assembling the mold. It's kind of hard to explain what's going on... the first shot shows the upside-down engine cover sitting loosely in the mold which itself hasn't been fully bolted together yet. The tape is the surface on which the flange from the adjoining shell section to the front will rest on. Since there will be a rubber strip between the shell halves when assembled, compressed by the Dzus fasteners, it must be in place here, now, so the flange halves have the correct offset. It's hidden by the tape...
Alas,, fame is such a fleeting thing. A reader broke it to me, that website "hits" people talk about (including me,) is very misleading. In server-speak it means "file access." It means that a single webpage with text will cause one hit when opened and a webpage with text and one picture will cause two hits... and so on. This page has, what, 80 thumbnails or so? Yup, every time someone clicks on this page link it punches up about 80 hits. The real number I should look at is "visitor count," not hits. Oh well, it doesn't change anything, just brings me back down to earth...
Again reviewed the tape, "Moldless, Low Drag Wheel Pants," by The Arnold Company, which shows how to make composite one-off assemblies without a mold. Watching it again reacquainted me with the proper sequence of steps of how to lay up the main flange. I've found when I first start on a new technique I get all excited... a very bad thing. It guarantees I'll do something wrong somewhere, causing all sorts of bad language and loud noises to come from the garage. It's a good thing I took notes too because sure enough I would have forgotten a couple steps.I also realized I don't need to waste time making a fence to lay up the flange against in the mold. Since it's a simple flat flange I can make up some flat composite strip assemblies first, off the car, then clamp them to the steel mating flange on the cage and tack them to the shell with a bit of epoxy. After that sets up, remove the shell from the car, put it in back in the mold, then fully lay up the flange. It'll save a bunch of time and guarantees perfect alignment.
I also cranked the picture resolution back up to 1024 x 768. You're welcome.
Began the next chapter in Kimini's construction, the composite work. I've had a little experience with composites, asked lots of questions, and read many books, but at some point I had to dive in - so here we go. While I'll still (probably) hire some composite expert buddies, my present plan is to do as much as I can myself to cut costs.
First shot is the existing roof "sandwich," (the roof being upside down in all these shots.) Second shot is during removal of the core, stripping it back to only the outer surface. What's I'm doing is making the flange that the Dzus fasteners will mount to. The core has to be removed because the Dzus fasteners aren't long enough to reach all the way through, and even if they did they'd crush the core when tightened.
Third shot is the entire upper roof flange, sanded and ready for reinforcing. While a composite sandwich is extremely stiff, removing all but the outer skin results in a very flexible flange... no good. Out came the fiberglass cloth and two additional layers were added with generous overlap of the flange, core, and surrounding surface for strength. (It's hard to see in the last shot because fiberglass essentially becomes transparent when wet through with epoxy.) I'll wait for it to cure to see if it's stiff enough... if not I'll add another layer or two. While I do have carbon cloth I didn't feel it was needed here... not sure about the logic of that decision though...
One other tidbit, with the new website I finally have access to real data regarding web traffic. On the previous site I was amazing there was 130 hits per day. Now I have the real numbers... nearly 10,000 hits per day! I'm dumbfounded - I had no idea there were that many people that had an interest in this goofy project. Seeing that huge number makes me feel that... what, that I have a responsibility to finish this and get it on the road. It's like performing on a dark stage knowing there are 1000's in the audience watching, even if I can't see you. I'll try to not let you guys down... I want it done too.
I've also all but made up my mind on colors; chassis color will be navy gray and the shell metallic gray. Which metallic gray isn't decided yet but BMW's is really nice... ironically the same gray available on the new Mini...
I'm now in possession of all the mold sections, all 10 of them! The plan is to place the shell back into the mold to hold it while I work on the flange and fence along the engine cover cut-line. Future mold modifications will be fender vents, but first things first.
Picked up, "Competition Car Downforce," by McBeath. I'm only part way through, but it's a "must have" when building or modifying a car. The author has a knack for explaining things so that even I can understand - you don't have to be an engineer to benefit from it. It's different enough from my other favorite aerodynamics book, "Race Car Aerodynamics" by Katz, that both should be purchased.
Dennis of dpcars.net did some rough aero calculations for the Kimini. The windshield will be loaded at roughly 100lbs at 130mph. The car as a whole, using a frontal cross-section of 20 sq. ft, 0.45 Cd, gives a drag of around 370lbs at 130mph. Working back further it means I need around 150hp at 130mph simply to push the air out of the way! This is a very good example of why aerodynamics is so important. Let's assume (probably in a wishful way) that because I upgraded the intake and exhaust, have no A/C or power steering, and run an aluminum flywheel, that I might have about 210hp at the crank. That means at 130mph I have only 60hp left over for acceleration. But, since the wheels and tires are so small (compared to a Prelude,) I can't go faster then about 130mph anyway due to the rev-limiter. So while I'll be trounced by Z06's at the end of the straight, I hope to be a real irritation everywhere else. And isn't that the whole idea, to beat more expensive car s...
Finished the upper windshield brace. Why is the brace so far forward of the main cage tube? Good question... I should have extended the cage further forward before having the tubes turn downward... what I was thinking. The down-tubes do look reasonably placed though, as shown in the July 4 photo. It's not a big deal, but something I'd do different next time.
Quit early to clean up, the grit underfoot had become tiresome, always reminding me how messy it was. There's something about working in a clean shop that's just so much more pleasant.
Also rolled the car out to take some hi-res shots with and without the shell. They're being sent to a magazine to hopefully appear in a "Hot rod of the month" blurb. I don't want to mention names so I don't jinx things!
The time is near to jumping into the composite work, putting the shell back into the mold to modify it. However since I haven't picked up the mold yet I went around in circles, overswhelmed by all the stuff still to do, with seemingly nothing I could actually work on today. I also couldn't do the rear Dzus mounts because I didn't have the right size tubing for the brackets. To not waste a workday I made the upper windshield brace - I don't trust the shell to handle the expected air pressure on the windshield. The mounts are for the obligatory windshield hold-down clips (already along the bottom edge.) The horizontal bar will be bonded along the edge of the windshield cutout to really make sure everything stays put. There will a couple more tubes then shown here; this shot was right after tacking it. The windshield cutout still isn't finish-cut which is why so much of it is visible.I'm not sure how to actually mount the windshield glass. The obvious way is to use 3M windshield adhesive but I worry how to get the sure-to-be-broken-someday windshield back out. I fear the force needed to remove it from the adhesive will damage the composite. I suppose I could count on the hold-down clips to do their job and use some less nasty adhesive, something like RTV for weatherproofing. It's not a big deal but still something to think about.
Made the leap and bought my own domain, www.kimini.com ("I'm a somebody!") While my previous host Cox gives customers 60MB of "free" webspace, it's broken into 10MB chucks for each of the six e-mail addresses they issue per account. It was becoming a drag pushing stuff around to meet their 10MB size limit, with pages getting scattered and hard to find. With it all in one place, (I'm now hosting the videos too,) I'll do a much better job maintaining it all. Ironically when I went to my Cox-based webpage to add that one last diary entry pointing to this new site, it said I had overfilled my account (again.) Enough of that silliness.