Tag Archives: thinking too much

I’m awake during the day but still thinking

Ordinarily “Still thinking” would have the caveat “Take cover” but not so much today as what I’m thinking about is another A/MOD SCCA car. Basically what I’m thinking about is an LS style engine and a Powerglide transmission smack in the middle of a 72″ wheelbase and offset enough to the right to balance a driver to the left so the total polar moment is as low as possible for good transient handling. The chassis would be a semi-monocoque tub with a tube roll structure and subframes to tie everything together and if I did my sums right I’m looking at a 1000 pound as-raced weight, or about 100 pounds over the minimum. Combine this with the power and torque from the LS architecture V8 and forward progress would basically be limited by available traction, which would be limited by tire compound choice and footprint which would be limited by tire and wheel size, which would be limited by what’s available and unsprung weight considerations. So, basically a beastly quick car that was more limited by human reactions than the laws of physics.

The aluminum block LS engines all weigh within a few pounds of 415 minus the engine driven accessories. When those are stripped to the configuration for running in this car, which is basically water pump and alternator, I need to add those in and we’re looking at 450 for the engine. I have been watching enough videos to know that what I need for this car is a mild cam, a long runner intake manifold, and either tri-y or long tube 4 into 1 headers to get enough low end power that also doesn’t fall off as the RPM rises to redline, which are all included in the 450 pound engine weight. So add in the 76 pounds of Powerglide and you have 526 pounds of powertrain to moment out for left-right balance with the roughly 200 pound driver. Basic math tells us the driver has to be about 2½ times as far to the left as the engine is to the right, add in the widths of the engine and the driver’s legs which have to go to the left of the engine and a little algebra gets us the driver has to go 27.5″ to the left of the engine which is slightly to the left of the left side of the car. Going back and letting the top part of the engine hang a little over the driver’s legs and we get 24″ left offset if the engine sits with the bellhousing on the centerline. Again this places the driver outside of the car. Going to the minimum width of the driver the driver centerline has to be at least 7″ left of the engine minimum width which is 8″ to the left side of the engine so driver is -15 moment arm or -3000 moment to the engine. Solving for x gives us 3000/526 which is 5.7″ right going to the level of precision limit of the driver’s seat mount. The driver sits 9.3″ to the left of center, 15″ left of engine centerline. But doing the moments we get a moment of -1860 for the driver and a moment of 2998 for the engine and transmission which means the driver is not far enough to the left and the engine is too far to the right. But if the driver is 14.991″ to the left of center then the moments are equal which means I set the equation up wrong.

Going back to first principles (526*x)+(200*y) = 0 and also y = x-15 because the driver must be 15″ left of the engine, minimum. So substitution gives us (526*x)+(200*(x-15))=0 gives x=500/121 and y=15-(500/121) making x=4.13″ and y=10.87″, and dividing out gives the exact 2.63 ratio in moment arms. Which means I got the formula right this time. My butt would be just to the left of the bellhousing of the Powerglide, and my legs would be under the left cylinder bank with the exhaust manifold radiating heat over them. Bad for a street car, but for this it would be warm but tolerable. Combining my shoulder width with the offset the narrowest the car could be is 2*(10.87+11.25)=44.24 which means my right arm would be on the right side of the car… And the car would be 44¼” plus the width of the tires wide and 72″ plus the diameter of the tires long, aka tee-niney, aka a V8 powered gokart.

We don’t have any, but happy Pi day to everyone else!

Last week we were more than a little short buying groceries, so we left out the supplies for Pi(e) day, but I highly encourage everyone else to get theirs. [Billy]I like pie![/Billy] Really, Pi(e) day kinda snuck up on us this year. My favorite is cherry, but really there aren’t many things that can be legitimately called pie that I won’t eat, and like. The one exception to that is peach, because during a very bad period of my life that was the only kind of fruit I got, and it kinda leaves a bad taste in my mouth because of that. I associate everything peaches with that bad time, and just generally avoid them.

The weather is temporarily wonderful, mid-70s F but a bit breezy. The trees haven’t started shedding pollen yet, so I can still breathe sorta. The dust is a little bad and sometimes stops things up for a few minutes. It’s nice to see the sun again after about a week of cloudy to mostly cloudy skies. If I had a car waiting to get an engine pulled this would be the perfect weather to do it.

I have also been doing some more walking practice, disguised as “pacing” which is something I do when I’m thinking, pacing, I pace back and forth when I’m trying to pull an idea together. I’m trying to overcome the effects of spending too much time behind the computer by remodeling my stride to reduce the natural limp caused by the short leg. The limp causes me to burn up too much energy when I walk, leading to losing my balance and falling down. That is generally considered as “bad”. Or “not good”, if it isn’t actually considered “bad”.

Excuse me, speaking of “bad”, but there is a bad cat on my lap demanding attention from me. Back in a few.

Now to resume, I pace when I think and I’m not thinking at a keyboard. This is something that started back when my age was in single digits, so I don’t think I can break the habit any time soon, and even when I’m behind a keyboard I sometimes have to get up and pace to get my thoughts together on a subject. About the only thing that can keep me from pacing is a case of COL (Cat On Lap). Then the cat gets rubbed on while I think, something they can’t stand for less than 20 minutes.😸 But thinking, I do lots of thinking while I walk, putting things to the back of my mind and letting them run as background processes (yes, I’m a programmer from long ago, I learned how back when Fortran and Basic were still bleeding edge). Eventually an answer spits itself out, but I might be in another county by the time it happens. And the walking practice (remember walking practice?) helps make sure I don’t fall down while I’m pacing. I think of this as rehab, that I’m doing because I lost a lot of muscle mass behind the computer after the hip began keeping me off the bike. Well I have to build up endurance again so I can get around like I used to.

My soundtrack while I’m writing this is from my YTM app and it’s algorithm has decided I want a mix of electroswing, real ’30s, ’40s, and ’50s swing (mostly Duke Ellington and Benny Goodman) and classic rock, with some New Country. And nearly every song is something I either clicked “like” on or from an artist I had clicked “like” on, or “similar” to something I had liked. I like the old stuff from when I was a kid and before because I respect my music history.

Now go eat some pie.

Well I have good news and bad news

The good news is there is nothing wrong with my new computer. The bad news is I need to get a new Wi-Fi router. I checked the FCC compliance sticker and it has a 2010 date, which is equivalent to late paleolithic in computer years. So now I get to talk to Frontier FiOS about getting a new router.

In other new computer news I spent $20 + tax on a 128 GB USB flash drive, loaded all my books and pictures from the Chromebook on it, and still had 114 GB free space on the drive. Seeing how I have about 100 GB in graphic novels alone, that’s some heavy-duty data compression there. This was a discounted unit originally priced at $80 and is over 1000 times the size of the hard drive of the computer I was using at Y2K that cost about $2000 for the original buyer, a 486DX2 with 640KB RAM and 100MB storage. For you young’uns that was an engineering workstation at the bleeding edge of technology when they bought it, and still pretty cutting edge when I bought it. Now I have a phone with more RAM than the computer had storage and a faster processor and a higher resolution screen, that I picked up for $28 when I upgraded to a new line. And that I use mainly for playing Solitaire these days since I upgraded to a better phone last year when I started having issues updating the OS because it lacked storage and wouldn’t move the files to the SD card I bought to give the damn thing some breathing room. I moved the card to the new phone where the OS finally recognized the card was for things like pictures and porn video files.

On other things, I’m still working on that steering box mount for the Sprint-T and increasing the triangulation in the front end. Basically by running another light tube (0.060 wall) from the upper corners of the front roll hoop to the center of the front diaphragm, making a Warren truss of that face for more torsional rigidity, to go with the Warren truss of the front diaphragm, and the modified Warren truss of the bottom face and the side faces together. Never. Stop. Thinking.

Happy Father’s Day, I’m changing the TGS2 design again

I woke up in the middle of the night thinking again, because I had to use the bathroom. While I was sitting I started thinking of how I was going to make the splitters, because they had to be somewhat thin and fairly strong because the aero loads would get rather high at highway speeds and faster, and because people would probably stand on them getting in and out of the car. Then I had a flash from the past back when I was building ultralights (lightweight single-seat airplanes that don’t require a pilot’s license under Civil Aviation Code Part 103) and I sat in on a composite construction clinic. During the clinic we watched a video on making a solid core wing with fiberglass skins using vacuum bagging after wet lay up. I realize that the preceding sentence read like Star Trek technobabble for most of you, so I will explain by describing how I’m going to make the splitters and how that changes the way the rest of the car will go together.

First of all, the core. I’m going to make the splitters and the floor of the car as a single piece, using blue styrofoam insulation board, from the nose to the start of the diffuser at the rear. This is our solid core. Now I could get all high-tech and use carbon fiber to remove every last gram possible, but that would be both expensive and overkill. I will make use of different layers of material for different purposes in the lamination, but the most exotic will be the Kevlar under my butt and the gas tank. Now the layers outside in from the ground up. First will be some light fiberglass mat that will basically be there as a sanding layer and to prevent “print through” from the woven layers. Next will be three layers of fiberglass cloth oriented in different directions to make the splitter stiff no matter how it’s loaded from people standing on it. Then the core of insulation board, then another three layers of ‘glass like on the bottom and the ‘glass mat. Then under the driver and gas tank compartments 9 layers of Kevlar oriented like the ‘glass cloth in the previous layers. The purpose of the Kevlar is to protect my butt and other parts from road debris like what broke the engine on my last car. It goes on top of the mat because the Kevlar is inside the car and it is easier to lay up that way and the mat is damned cheap so I can just run it all the way across without leaving any gaps.

Now the “wet lay up”. This means I mix up batches of very slow curing resin and completely saturate the various layers with the resin before laying them on the core using things like paintbrushes and rollers to make sure every fiber is covered in resin before it goes on the core. The reason slow curing resin is used for this process is applying the many layers is time consuming and exacting, because there can be no gaps or wrinkles in the lay up. Now why wet lay up is simply cost, buying cloth and resin separately is much cheaper than buying pre-preg which is the cloth and resin all-in-one but not yet cured, because it is made below the kick-off temperature of the resin and shipped frozen to prevent the resin from curing until the cloth is molded to the desired shape.

Now “vacuum bagging”. As the name implies there is a bag involved that has the air removed from it after the part is placed inside. Now between the bag and the part are 2 more layers of materials that just keep the bag from sticking to the part. First is what is called the “bleeder layer” that just exists as a path for the air to escape from around the part so atmospheric pressure can squeeze against the part and the layers and get everything really close together. Next is the “peel ply” that goes next to the part and gives the excess resin a place to go and is the real reason for vacuum bagging a wet lay up. The process squeezes excess resin out of the layers which then goes into the peel ply where it is wicked away from the part. Resin is the heaviest part of a composite part, my 47 pound bucket body probably has less than 20 pounds of glass fibers and the rest is resin, in fact from looking at the actual body I would say it is closer to 15 pounds of fibers and the rest resin. So leaving just enough resin to hold the fibers makes a major difference in weight. You can see graphically how much resin is squeezed out by weighing the peel ply and bleeder after unbagging the part. The outside of the bag is polyethylene sheet like what is used as a drop cloth for painting.

And there you have my major objection to vacuum bagging, the amount of waste left after the process. The bag, the bleeder, and the peel ply are all garbage after the part comes out of the bag. The only thing in the process that is reusable is the fitting between the bag and the vacuum pump, and that vacuum pump. In my case I will be using a shop vac so I will be getting sub-optimal results compared to using a real vacuum pump, but I will be getting a flatter, smoother surface by leaving the part to cure on the garage floor. And then throwing away a full garbage can worth of bag and bleeder and peel plies.

Now the real thunder, I can use this process to make an entire monocoque frame and only have the roll cage made from tubing. And in the process reduce the weight of the frame by half over welded tubing.