I should do something with the mini Sprint-T

I have been neglecting the model version of the Sprint-T in favor of trying to fix the handling problems inherent in the design of the TGS2. I mean I know I should be doing something on it, but the inspiration has been lacking compared to the TGS2 and posting in the blog.

After it quit raining Sunday evening I went for my walk and picked up a bag of cereal. Yes I’m cheap and buy the bag cereal. It’s slightly cheaper per ounce than the box, we just don’t always have the $ to pay for a bag. I also get PopTarts in the big box except when the sales on the small box makes them cheaper per breakfast. Why cold cereal and PopTarts for a grown man’s breakfast? Simple, those are relatively non-lethal to prepare when I’m pre-caffeine. Cognitive functions generally don’t kick in until the second half of the cup, and it’s much safer to have things that don’t require the use of the stove or anything more complex than pushing the lifter down on the toaster. Even the measuring out of the various ingredients of my cup of coffee have become mostly autonomous. I can’t quite do them in my sleep yet, but I’m close. It’s when things change like switching from milk and sugar to pre-sweetened creamers that stuff gets messed up. More than once I took a swig of what was supposed to be coffee and got a slug of liquid candy instead. And for some reason that stuff just seemed to get sweeter and sweeter during the day. A few hours after pouring my coffee in I felt like pouring it out.

Speaking of my walk, it was so humid after all that rain I could have almost gone for a swim instead. It was 71°F with a 70° dew-point. UGH! sticky! At least it wasn’t hot to go with that sticky.

I would do more writing but my neck and shoulder are starting to bother me and make it hard to type.

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Weather doesn’t stop to enquire about your plans before happening

Well, plans were to wrap my workout around getting my toes done down the street, but the weather has other ideas. There has been a line of thundershowers going over since shortly after noon, when I got to sleep about 0600 after putting the previous blog post to bed about 0430. That post took extra long because I would write a little bit, go crawl around in the bucket body for a while, run some numbers on the calculator, crawl around the body again, run some more numbers on the calculator, write a bit, rinse and repeat. I spent about 3 times as much time with a tape measure inside the body as I did sitting at the keyboard. And I still need to get my toes done, the nails are getting a bit on the long side, while it is still raining with occasional lightning and thunder over Casa de El Poeta preventing my walk.

On the TGS2, the mind kept going after the post was put to bed. I considered saddle tanks as well as wrap-around tanks with luggage space on top of the tank. I genuinely think the best option would be putting the Jaz Products 892-032-01 32 gallon bare cell on edge so that it would be 17″ tall, 14″ wide, and 33″ across, behind the seat and using the space beside the seat for carrying things. Unfortunately nobody I have contacted sells them, so I might have to get it directly from Jaz, which makes the price a mystery. But it is possible to interpolate a price by comparing the costs of bare cells that I can get to the costs with cap and fittings for the same size cell, then applying that difference to the 32 gallon cell with cap and fittings. I think I’m looking at $143 plus shipping. Compared to a custom tank that’s cheap. I would still need to fabricate a firewall and fuel filler, but that would be true for any tank inside the bucket body. Jaz even makes a fuel gauge sending unit to fit this configuration.

On the bike-riding front, I’m still not riding. I do the PT that is supposed to make my neck more flexible but all it seems to be doing is keeping me from getting any worse. It doesn’t hurt to hold my head back or turn to the right, it just doesn’t go back or to the right. And I’m still getting the pain and tingling in my neck and shoulder, especially after I do my exercises. It’s almost like they never took Chris Christie off of my neck, except I have a little more range of motion especially tilting my head back. I still notice it there, and the improvement without a useless lump of fat on my neck. Every few days I check the tires on the bikes to see if they need pumping and once in a while I pump them up.

And now I think I’ll have dessert and a big cup of covefefe (CO-vay-Fay-fay). If Trump can make up words, I can make up the pronunciations.

Still thinking about that dang car

I had another thought about the Thunderbolt Grease Slapper 2 to get better balance and more consistent handling. Instead of putting the gas tank in the front, move the driver forward and put the tank sorta in the middle, between the engine and the driver. This would do two things that could be beneficial to the performance of the car: 1) Put more weight on the front end by moving my fat ass closer to the front and 2) Put most of the weight that changes while the car is driven in the middle where it won’t drastically alter the weight balance of the car as it changes.

Doing this does create its own set of challenges. First is I will have to create some kind of metal enclosure between the gas tank or fuel cell (explosion-resistant gas tank, not the kind that you spray fuel and air in one side and get electricity out the other) and the driver’s seat, second is I will have to create some kind of enclosure in front of the firewall because I’m going to stick my legs through the one molded into the body. This brings the secondary question of seating position, sprint go kart or stretched out?

or

If I go with legs together and just leave enough room for the steering between my feet (like in the front-engine Sprint-T) I don’t need to make a big hole in the factory firewall and have additional support for the steering column. If I go with the sprint go kart seating position most of the firewall will need to “go away” and I’ll need to add structure to support the cowl and the steering column, but I will be able to sit several inches closer to the front axle reducing my arm and moment and moving the CG closer to the front. Not to mention all that structure will add weight right behind the front axle helping move the CG forward. And there we get the major drawback to the go kart driving position, added weight. The car is already almost 100 pounds over the initial target weight, and adding more structure will not help that situation in the slightest. So to maximize straight-line performance I think the legs together position. And I just fell outta my chair while typing again, so I’m going to bed now.

Don’t take any wooden nickels while I nap.

Working on the look of the front of the car

I have been looking for smaller headlights for the Mid-Bucket (aka Thunderbolt Grease Slapper 2) because the standard 7″ round headlights make the poor car look like it has a bad case of the Girly-Eyed Measles . A standard T grill and radiator look normal with the 7″ headlights, probably because the stock model T had 10″ headlights. But for some reason they are just too big when I put them on the TGS2. I would like to be able to just install a single high-low LED projector unit in a bullet housing but they don’t seem to be available as single units, and I lack the tools needed to spin a sheet into a bullet housing.

Getting smaller lights in a configuration that is street legal is not hard, but not cheap either. This is the best bang for the buck I have found so far. Drag Specialties 5 3/4″ LED Headlight Assembly . As you can see compared to a standard 7 inch sealed beam in an aimable housing it’s rather pricey, especially since I can go down to the local autoparts store and buy a sealed beam for under $10 (the previous link was just for the bucket but add $10 for the light and you see what I’m saying).

What’s really annoying is there are 4½” LED spot and fog lights available that look like the larger 5³/₄” lights but are either spot or fog not high/low. The manufacturer even calls them “headlights” in the part description, but they’re not, they’re just driving and fog lights.

Well I have to get up early for another trip to the Lab Rat Keeper in the morning so I’ll end this now.

I am disapoint

My book finally got here yesterday. Hundreds of pages about fuel injection… for other kinds of car than the donor vehicle for the Thunderbolt Grease Slapper 2. For the make of the donor vehicle it had 3 pages, none of which applied to the year my car was made. So basically I spent $9 and a week of waiting for some interesting light reading and a bunch of stuff I already had elsewhere (on my computer).

I think the local library will be getting a donation.

Something I have been looking at very hard lately is the Holley HydraMat fuel pickup and pre-filter for fuel injection systems. What it amounts to is my car will never run out of gas as long as there is gas still in the tank. Also the pre-filter on the donor vehicle is basically a screen to keep large debris out of the pump, while the latest permutation of the HydraMat is a 30 micron filter that is way better than the 100 micron post-filter on the donor vehicle. So in theory I could install a HydraMat and just plumb from the pump directly to the injectors without additional filtration. I won’t of course, because the pump could break down sending junk down the line to the injectors, but I could if all I was concerned about was the gas in the tank. Now there is the competing parameters of maximum size to allow minimum fuel for racing and minimum cost. The cheapest one is the 8″ X 3″ that for this application would mean I could get maximum fuel endurance on the highway between fill ups. If I was running a tiny tank like a 3 gallon this would make sense. Even the 10 gallon tank could use this, but for anything larger than that it doesn’t make sense. For the larger tanks the mat acts as an extended pickup to allow racing with just enough gas for the course, so it has to be large enough to catch most of the fuel slosh. The largest mat that fits the tank I have selected is the 24″ X 15″, and the cheapest that will work is the 15″ cross. How this is good is I can use a large gas tank/fuel cell for getting there, offload almost all the gas to another container when I get to the race and only have enough gas to complete the run in the car while I race, further reducing the racing weight of the car without the bother and expense of multiple tanks/cells and support systems, or finding a place to put them.

On other parts I just found out the smallest adult-length seat I can buy is gonna be too big for my backside. I think I mentioned a long time ago I did some width measurements to see about buying a streamlined shell for the Stratus and basically the only way I would fit would be removing an arm or two to make my shoulders narrower. Well I also measured my butt width, and to fit the 14.5″ wide seat on my build list I’m going to have to fill ³/₄” on either side of my butt with firm foam of some kind. I think maybe the seat insert kit will fill the gap? It may have to because smaller seats are pricy and will still need the insert kit for things like back support. Although it would be nice to not have to buy the insert kit, the fact that selling the car will become necessary at some time means a removable insert to fit me can be removed for a prospective buyer to see if he or she fits. Otherwise a new seat at $300-500 for a home-built car could be a deal-breaker. I know the seat I had in my last car was too tight for most people but gave me a lot of wiggle room on long trips.

And it’s getting late and I still need to take my walk so I’ll see you later dudes.

A minor breakthrough

Still thinking about making the TGS2 lighter and simpler to build and I had a minor revelation. If I lower the 3″ tube until it is on the axle centerline that will reduce the bending moment enough to not need any bracing other than what is provided by the double-shear spring mounts (that’s a plate on either side of the coilover heim with the mounting bolt going through both plates) welded to the top. That unloads the top radius rod on the 4 link allowing for higher loads from restraining the brake rotation etc.

Someone asked me IRL how I know there is going to be so much weight in the back of the car. That one is simple: The engine and trans combined weigh 620 pounds with the CG about 10″ in front of the rear axle centerline on a car with a 100″ wheelbase that will weigh about 1600 pounds. I’ll let you do the math yourself, after I set the equation up for you. The arm for the drivetrain is 90″ and the weight is 620. The arm for the rest of the car is going to be 40″ if we are incredibly lucky, probably real close to 50″ split the difference and call it 45″ and the weight is 980. Moment is weight times arm. Add the moments together and divide by weight. That is the total arm of the car, between 63 and 65.5 and since we used the front axle as zero datum and we have a 100″ wheelbase that makes the rear percentage equal to the momentarm, I.E. between 63 and 65.5 percent. I learned this one when I was taught weights and balances for flying. Yes, I used to be a pilot before the wreck. Sioux this one was for you 😀 Math IRL for your students. Oh and the reason I don’t know the exact arm for the rest of the car is there are a bunch of parts I don’t know the exact weight for nor where they will go on the car when it’s finished. So I had to use a SWAG for the arm of the car without engine.

Excuse me I zoned out for a moment listening to an old piece from the ’70s on YTM; Mike Oldfield’s “Tubular Bells (Pt.I)”. They had just gotten to a part of the piece I call “The Procession of the Instruments” that starts about 17:00 into the piece, and continues to the end of Side One of the LP. This was one of my first experiences listening to polyrhythmic music, which my mind finds very relaxing. Anyway, Mike says the name of the instrument and they bring it up in the right channel then mix it over to the center front then over to the left and back but still up enough to hear if you focus on the sound. I didn’t know this at the time but polyrhythmic music has a calming effect on people with ADHD and PTSD. At the time there wasn’t any such thing as PTSD by that name, it was “Shell Shock” and didn’t happen to kids (that they knew), but I had been diagnosed with “something” tied to my high IQ, that we now know as ADHD. Anywho, when I listen to polyrhythmic music I zone a bit and get real calm.

Back to the car, I’m really feeling torn between totally enclosing the roof and windows and saving weight. Putting a roof and windows on it will make the car look more complete, but will need A/C in the summer. Or I could figure out some other way to keep dew and rain off the instruments and save about 50 pounds, most of it off the back of the car, by leaving the A/C in the donor vehicle and cooling the car by leaving the windows off. That would save even more weight but lower the gas mileage on the Interstate a bit. Basically all I really need is something to cover the cluster and seat when I’m not driving. I could make a snap-on cover like old hot rods and sports cars used in the ’40s and ’50s, called a tonneau. These days a tonneau is basically the thing that goes over the pickup bed when it’s empty, but back then it kept the interior clean and dry when the roof was down or if there wasn’t any roof at all. I bet I could make something with the HDPE sheet and some Velcro™ and get the same effect and roll it up inside the car when I was driving.

And I think I have meandered across the screen enough for today.

Still thinking

One of the things that has been gnawing on me a little is I missed another Ride of Silence this year. For those new to my blog since I dropped the bike wrecks click on the tag RoS or Ride of Silence to see previous posts about it. I started missing the RoS when the tumor on my neck got so big that I couldn’t ride any bikes. But after Chris Christie was removed from my neck I got to the point I could ride bikes with a very upright riding position or recumbents, but not very far. Well now I can’t ride anything except a bus or car because Arthur Dent is causing troubles. I have a pain that starts in the middle of the dent and radiates to the end of the trapezius in one direction and up the back of my neck in the other, and makes my deltoid and rotator cuff tingle like they are trying to go to sleep. It’s very annoying but not much of an impediment except to bike riding at the moment, but it feels like it is trying to get worse.

I’m stalled on the Mid-Bucket (aka the Thunderbolt Grease Slapper 2) ATM because I lack cash for parts or raw stock. I still haven’t replaced my ID since the last time I lost my wallet, because I needed my ATM card to get the cash to pay for it. ATM card should finally get here this week and I will renew my ID early so I can go to Nashville and see the eclipse this August. When I get stalled on one project my mind starts on a new project immediately, in this case a lighter weight version of the Sprint-T with the Pentastar V6. Basically it is just the same as the V8 version with lighter components because of less weight and lower power. Remember the vicious circle of too heavy so other parts have to be stronger and heavier making the car heavier so other things need to be stronger…? Well this is the benign circle of less weight allowing for less heavy supporting and connecting parts. And the weight came to under 1400 pounds with the balance almost 50-50 I can use all the same size wheels and tires on each corner. If I could have gotten one of those free things would have been a lot easier.

Pole Day for the Indy 500 is on the idiot box so this is time to wrap this up. Congrats to Kyle Busch on winning the All-Star race last night in a masterful performance. Condolences to Sebastien Bourdais on that wreck at Indy yesterday and wishes for a quick recovery.

Opus the Unkillable

My biggest impediment is my sense of esthetics

My main guide to engineering is the math, but after that is my sense of engineering esthetics. And sometimes that gets in the way of finishing a design. Seriously, the single 3″ tube would have worked fine for the de Dion suspension, but a truss would weigh less and be stiffer, by a small amount on both counts. And the new truss is much simpler both to build and to mount than the previous truss of 0.5″ thinwall tubing with a plethora of tiny triangles in two planes as it is just 7, 1.5″ X 0.120 wall round tubes in a single plane. The tube diameter and wall thickness are enough to hold the toe and camber alignment while the truss is strong enough to take all the vertical and horizontal forces with a huge safety margin. The truss weighs 20 pounds with brackets, not including the filler wire from the welds. This compares to the 3″ tube which comes to exactly the same weight but not as stiff vertically. Or as pretty to look at, which as I wrote earlier is an equal criteria after weight.

I mean face it, the 3″ tube would work just fine and probably less than 3 people out of 100 would be able to feel the difference in stiffness compared to the truss. Even fewer than that would care about the looks of the truss compared to the single tube. TBH even I am just the slightest bit ambivalent about the difference in appearance between the truss and the single tube. There is the simplicity of the single tube across the back of the car, but on the other hand there is the zen-ness of the collection of triangles running across the back of the car, even if it is hidden by the bodywork for aerodynamic reasons. There is also the fact that I can lower the roll center by almost 2″ in the rear to reduce oversteer slightly with the truss. And finally there is the cost issue, a single 58″ 3″ X 0.120 wall tube is less than half the price of the 132″ of 1″ X 0.120 I would need for the truss.

And even while I’m thinking about the rear suspension I’m still thinking about the cockpit and a possible roof and side windows. Mrs. the Poet is still saying there is no way I’m going to be able to get in and out going through the top of the roll cage after climbing the side of the frame. I have zero doubts about getting in and out of my own car, if for no other reason than I will have lots of time to use the frame as exercise gear to get my upper body strength up. Or I could screw together some black pipe for a dipping rig and chinup bar and continuously build my upper body every day. 😀

And I think I need to go to bed now, and so become the Nighty Knight.

It happened again!

I was thinking while walking again, and I wondered if a single 3″ OD 0.120 wall tube weighed more or less than the complex truss of half-inch tubing I designed for the de Dion suspension that still needed more work to actually support putting a spring on it. So when I got home I looked up my truss calculations and found I was putting just shy of 15 pounds of tubes in the version that just kept the rear wheels pointed in the right direction.

Then I ran a quick bending load calculation on the 3″ tube and it won’t need any extra support aside from the gusseting action of the spring mount (I mount coilovers in double shear mounts and tie them with bulkheads). Then I looked up how much it would weigh…18 pounds for just the bare tube, 20 with the brackets to make the upright adjustable.

Five pounds, I spent hours with a calculator, and paper and pencil for a design that saved 5 pounds and still needed more work to get right. Five freaking pounds, at minimum wage those pounds cost me about $20 each, maybe more. Probably more. A classic case of over-design. Now granted it would take a huge shunt to make a rear wheel point in the wrong direction and there is a good chance the tire would get knocked off the rim or the rim bend or break first, but the fact remains I couldn’t mount a spring anywhere except the upright or trailing arm without redesigning the truss, and adding weight, when I discovered that there was no way to balance the handling without moving the rear springs inboard. Now the fun part is moving the spring mounts on the frame inboard to prevent frame flex.

There are a couple of ways I can move those mounts in to get the springs off the ends of the axle. One is just change the mounting point to the crossmember and make that a truss to handle the bending load. Or I could continue to mount the springs to the heavily triangulated intersection of the upper frame rail, lower frame rail, center top hoop of the roll cage to upper frame rail brace, crossmember, lower crossmember to watt’s link center mount brace and taillight mount (that’s the intersection of 5 tubes in 3 different planes triangulating the mount to kingdom come) and move that complex intersection inboard a few inches as needed. Right now that intersection exists only on paper, not in steel, so moving it is just a matter of changing a drawing. This would also have an effect on the engine mounts as the tubes they mount on get moved inboard an as yet to be determined amount.

Now I’m going to open up a beer and eventually go to bed.

Opus the Unkillable

Late Night thoughts

I’m awake at 0424 and thinking again, about enclosing the cockpit to protect the instrument cluster &tc. I was also thinking I could use the HDPE to make a fake rag top. Using the white HDPE to make the roof hatch look like a “regular” Bucket top until I use it to get in the car, with the side windows to make it look like a “normal” car.

I’m also trying to figure out how and where to mount the mirrors for street driving, and I’m leaning to a pair just inside the windshield posts for my side view mirrors and another pair on either side of the seat for directly behind me.

I’m going to go to bed now and let this ferment a while, then come back and complete it.

OK I’m back it’s right at 1800 and the ideas about the top and windows have been rolling around since I got up and started sipping coffee. Part of the problem is ventilation. Gluing the side windows in would be easier and better looking, but leaving the windows shut in the summer while waiting to make a race run would make for a very uncomfortable car. Somehow I have to keep air moving through the car even when it is not running. Maybe a solar powered fan of some kind? And definitely hook up the AC for summer driving. Fixed windows and top with no AC would be looking for heat illness issues especially here in TX during the day. And with the Goodguys event just down the road in Ft. Worth I will definitely be driving during the heat of a TX spring and summer.

Mirrors are another issue, but I think 4 small ones should do the job. Put 1 each at the lower corners of the windshield for side views and blind spots and 2 more on either side of the seat at the top of the windshield for direct behind views and I think we’re covered for that. Just make sure the field of view is not obstructed and I can adjust the mirrors to work as long as they are not obstructed.

Now how to construct this top, well I’m still figuring that part out. The back part was easy to figure out. Most of the back will be a flat window except the part that wraps around the corners of the body, which will be molded to the radius of the corner all the way up to the top surface just like it was a rag top, and the side part will be on a diagonal like a traditional rag top.

And this in white.

The top on mine will more closely follow the top picture in that the top will be level front to back, but much lower because I won’t be sitting as high in the body as the seats in that car.

And now I want to go for a walk, so Bye!