Of late lacking the ability to do anything constructive on the Sprint-T I have been setting my mind loose to create other things, like a recumbent cargo bike, for doing what cargo bikes do, but faster and more comfortably, and a special for the A Mod class in SCCA Solo racing using a lawnmower engine , or a motor out of an electric forklift. I like A Mod because the rules are so open, minimum wheel diameter 10″, minimum wheelbase 72″, minimum wheel track 42″, and minimum weight 900 pounds with driver and no fuel, no maximum engine size, no restriction on undercar aerodynamics, no restriction on overcar aerodynamics aside from a maximum of 20 ft2 total for all wings.
And I have been following the reports from Nashville, Toronto, and Grand Prairie with equal amounts of revulsion. Props to Canadian LEO for not shooting the driver in the sidewalk terror attack, likewise to MetroPD for managing to take a known armed crazy without further bloodshed. Unfortunately the one semi-local to me at this point appears to be suicide by cop. At least that’s the first report, which is wrong about half the time. But missing from all these reports is motive, why did they do what they did? The Canadian perp was described as “angry middle eastern man”, but what he’s angry about, nobody is saying. And I just read on Twitter the Nashville shooter belonged to a right-wing hate group, big surprise.
And Clint and Clyde have been acting like crazy cats because, well they’re cats and… Clint in particular has been howling at the windows and then changing his mind about going out about 3 times so far before finally walking out the door. That’s 3 times walking the length of the house and back plus standing waiting for Clint to make up his mind while looking out the door.
I have another trip to the Lab Rat Keeper tomorrow, so no post Tuesday.
I was walking and thinking about the Sprint-T. The main thing I was thinking about was torque control of the rear axle and how to do it without spending any more money than I already have. The current plan and existing hardware for locating the rear axle and also mounting the springs and shocks uses a part called a “swing arm” that I have shown a picture of in the past.
Well, I can slightly modify one piece to run a steel link with rod ends that runs from a bracket on the rear axle to a bracket on the nose of the swing arm. This would triangulate the swing arm and make it a rigid link that would prevent the axle from rotating under power and because it’s offset to the right also plant the wheel that lifts when power is applied. Basically what it amounts to is welding a pair of plates to the nose of the arm with a hole to run the mounting bolt through, then running the previously-mentioned link from a bracket under the axle to the nose of the swing arm. Now I couldn’t do this for the 3000 pound car this part is intended for, but for ~1500 pounds and 300 or so horsepower it should be adequate. And if it isn’t the part that would bend or break is not very expensive and is easy to replace, that being the rod end on the front. So I guess I would need to keep a pair of those rod ends and a pair of generic vice grip pliers to remove the broken bits from the swing arm for a roadside repair. But I should be good because the Speedway catalog torque arms for this size vehicle use the 5/8” rod end while this part uses the 3/4” rod end which is up to 30% stronger. And another benefit of controlling the rear axle rotation like this is the ability to almost instantly change the pinion angle from street to race and back again. It’s like a turnbuckle to control the pinion angle.
And with a torque arm this short I would need to run brake floaters to prevent wheel hop under heavy braking. The floater decouples the brake torque reaction from the rear axle and sends it directly to the frame via another radius link, making the rear frame area visually cluttered but dynamically simple. Because the Sprint-T has such limited wheel travel short links from the brake floater to the rear hoop of the roll bar will work in spite of there only being 5″ from the center of the axle to the roll hoop. Then instead of using spring rates and shock absorber settings to control the brake reaction at the possible detriment to handling and grip while turning I can leave those settings for hustling through the corners. And these links will be under very little load, because the torque reaction under braking would be forward from the axle, while the traction reaction from the axle would be backwards. So lightweight aluminum links would work fine between the floater and the frame.
And while I realize my little project isn’t as earth-friendly as riding a bicycle, it’s still an order of magnitude better than anything on this list . So, have a happy Earth Day anyway.
It took two days, but the NASCAR race from Bristol Speedway in TN is finally complete, and Kyle Busch and the #18 Skittles Camry won. It took extra time because there were still showers in the area. The racing was typical Bristol pushing and shoving, but not as extreme as usually.
I’m getting ready for another walk this afternoon to collect more Sweatcoins, and think about how to build the Sprint-T. I do my best thinking while walking, so I spend a lot of time thinking while I walk. Mostly I think about other things, because I’m not always thinking about cars or the Sprint-T in specific. Mostly just thinking at random.
And I’m back. It was a little over 2 miles, and I’m a little under my max Sweatcoin collection for the day. I did the loop instead of the out-and-back so it’s a bit shorter and doesn’t get as many Sweatcoins but on the other hand I’m never more than a half mile from the house when I take the loop in case I have to bail back for any reason. And there were a couple of times when I felt like bailing when my legs started getting shaky. I feel better for a couple or hours after I get done with a walk, even when I feel crappy during the walk. I wish Mrs. the Poet could take walks, but she refuses to learn how to walk with a cane.
OK I’m taking a walk tonight to see if this latest update fixes things, but the app is tracking steps again around the house. I think maybe I’ll take the opportunity to buy a lottery ticket, as I keep telling Mrs. the Poet, the odds of winning are almost zero if you buy a ticket, but absolutely zero if you don’t buy a ticket. And we are among the teeming throngs who could live a comfortable life if that chunk of income was shifted down a bit.
We had a dry line move through this morning but it didn’t wake me up, and another forecast for this evening, but not much rain near Casa de El Poeta. It was mostly wind and lightning according to Mrs. the Poet. The cats were not even bothered by this morning’s rain, and I can’t find any evidence of the rain outside.
And just for a few minutes yesterday I was considering centerline seating on the Sprint-T to see around the engine, since raising the driver’s seat enough to see over the engine would also raise my butt high enough to clear the transmission tailhousing. But that was quickly discarded because of the previously discussed raised Center of Gravity issue. Also the issue of running the steering from the center to the steering box on the left side of the chassis with the engine in the way.
But other than that I don’t have anything worthwhile to post today.
I have made the decision. The engine will stick up, out, and sideways and I will look around or over as required because I put the bottom of the bucket body even with the bottom of the car. This will get the C of G as low as possible for best handling, and since handling is the #1 priority for this car inside the superset of [Win Goodguys Autocross], compromise will be made that prioritizes handling over things like seeing out of the car and gas mileage. The main reason the Sprint-T even exists as a concept is participating in autocross and solo racing and winning Goodguys. I’m not happy about not being able to see around or over the Pentastar leaving a big blind spot to the driver’s right front, which means the Sprint-T is not going to be a daily driver. And using it for trips between races is going to require some method of seeing what’s behind the engine. Maybe having two different seat inserts, one for racing and the other for just driving around? That would mean the shoulder belts wouldn’t work for the “just driving around” insert because they would put my shoulders too high to be safe. And the SCCA rules about roll bar heights above the driver’s helmet would mean that when my eyes were high enough to see over the engine just driving around the halo of the roll cage would be right next to my head. Not good, so the simple expedient of raising the driver’s seat is out. But the alternative is raising the body and everything above the body by roughly 7″ which in turn raises the Center of Gravity, which reduces speed at ultimate grip. And that runs counter to #1 priority in the superset of reasons to build the car. So, more thinking is required on this.
In other news my Sweatcoin app is completely screwed up and stuck at 100 Sweatcoins, not even counting the bonus coins for clicking on ads in the app. And I can’t buy anything in the shopping section of the app with 100 coins, except discounts for things I don’t want. This makes the app pretty much useless for me until I can start collecting more Sweatcoins.
On a tangent, I keep hearing a violin instrumental cover of the Twisted Sister song “I Wanna Rock” in a TV commercial, but I can’t see to find it to listen to minus the smarmy commercial voice-over. I really want to find it as a stand-alone. The concept sounds as crazy as AC-DC played on cellos and we all know how that turned out. So far all I can find is this duet with guitar which is good but not the music played during the commercial. Which I was able to find. Not as good as finding the music separately, but at least I know the name of the violinist. Damien Escobar. Now I need to find a clean track of the whole song minus the smarmy announcer and more than 60 seconds long.
I mentioned a while back I had a picture of a Pentastar with a tape measure in the picture for reference to scale the picture. Well here’s the picture for you to use.
Hmm, it doesn’t look as tall scaling from the side. If I measured right I might be able to get the engine inside the upper edge of the firewall without having to raise the body. The initial calculation was 22.5″ from the bottom of the bellhousing flange. I could make the hood top even with the windshield bottom and have like a cowl induction scoop.
I think there might be some image problems here, the side view scales to exactly 18″ from bellhousing flange to crank pulley, and published data has that at almost 20″. I think the camera is fitted with a wide-angle lens that distorts the image, which means the previous scaling on the rear view is also suspect since it was shot by the same camera. I’m going to have to see if I can contact the photographer and ask if he ever measured how tall the engine was before he installed it in the car.
That should do for tonight with this one note: There was a published one day only special at the local grocery, $0.99/gallon milk Sunday only, so we skipped buying milk at $1.99/gallon yesterday. I walked to the store a mile away to get the good price today, and after I walked a mile there and another mile back, I checked the register tape. I didn’t check before I left because I also bought half off discount Cadbury Creme Eggs and there was a change in the total on the display that matched the $1 off the milk. So I didn’t check until I walked the mile home. Now I need to take the tape and the ad back and get the $1.
I can’t leave the house with the rain and thunderstorms and the flood watches, so I have been reading superhero books on my Kindle app and moving boxes representing assemblies around in my CAD program.
OK my current design method is to assign things a box that describes the space they occupy, rather than the actual object itself, and then move the boxes around until there’s no overlap. Some boxes are fixed, like the engine/transmission box and the body box, while some are not even fixed in size, like the radiator box that changes width depending on the radiator I’m trying to fit. I think there is a possibility the smallest radiator in the catalog will be enough to cool the Pentastar after seeing the stock radiator for one of the vehicles it is installed in by FCA. That simplifies packaging considerably, because I can figuratively put that radiator beside the steering box and have room left over for a bowling alley. The joker in the deck is the OEM radiator is double-row but the catalog radiator is double-double-row with 1/3 less frontal area but a 2.25X thicker core with more fins, and I lack the data to make a direct comparison. The “double-double” refers to the tubes in the core of the catalog radiator having more than twice the heat rejecting capacity of a round tube, making the double row core the equivalent of a 4-row. There is a simple formula for comparing radiators of different designs, but catalog descriptions rarely have enough information to allow its use. And that goes double in this case, with different chunks of the equation missing from the 2 catalog descriptions. But it is my SWAG that the 22″ catalog radiator will be roughly equal to the OEM radiator, especially after I learned the replacement OEM radiator was also used for much larger engines and is just sold as a replacement for the Pentastar because it fits the hole. Ima just hafta put a huge electric fan on the catalog radiator to make sure there’s enough airflow to remove the heat, which is what I would have had to do anyway, just maybe not as huge as I’m thinking about using now.
The radiator box combined with the steering box are the same width as the engine box, which is the same width as the firewall but extends a touch to the right because of offset to balance out my “big bones” sitting behind the steering wheel on the left. Which is a very roundabout way to say the radiator and steering box are together the same width as the firewall. And that I could install a wider radiator without increasing the frontal area of the car. This also means that there will be a large hole to the left of the engine that could be use as an escape path for cooling air, or a place to install an oil cooler facing sideways. Looking at the picture right now there are several places to install a small oil cooler, above the steering box there is a 5″ wide by 18″ tall space, there’s a 7″ tall space under the radiator that could run the width of the front end if the hoses would fit under the steering box. But as I don’t see any oil coolers near those sizes in the catalog…the question is moot.
And I just found a picture online of the engine in side view, with a tape measure in clear view to use to scale from and all the driven bits hanging off the front with the belt and pulleys exposed to measure. Something to make the engine box more accurate in the for and aft dimension, might mean a bigger box, might mean a smaller box, but either way it’s a more accurate box.
And writing note, when I get on a roll writing it’s pretty much stream of consciousness, but I still “feel” the punctuation and capitalization. What I don’t have a feel for is when I need a paragraph break. And my proofreader program knows fvck-all about paragraph breaks so I don’t get a blurb about needing a paragraph like I do about passive voice or homonyms. What I’m trying to say is I know I need more paragraph breaks in my writing, I just don’t always know where to put them.
No race to watch on the flat screen, and the weather is threatening so I can’t go for a walk. That means I have to post something here or go crazy. Going crazy is no fun, and I think you have figured out by now what choice I made.
On really good thing about the Pentastar for the Sprint-T is its extremely short length. There’s 43″ between the firewall and the centerline of the front axle on the Sprint-T and allowing for movement the steering linkage is 7″ behind that so 36″ from the firewall to the effective limit on the space. There’s a 3.5″ thick radiator to leave room for and a 9″ long steering box with a steering shaft that has to snake around the radiator, that goes between the radiator and the axle. Measuring the space from the part where the Pitman arm bolts to the rearmost part of the box as installed on the car and adding the working length of the Pitman arm (7″) I get another 12.5″ between the steering linkage and the radiator leaving just 23.5″ unless I put the radiator over the steering box like they do on the Speedway T-Bucket kit. Putting the radiator in the space between the front of the box and the steering linkage solves a lot of steering issues at the cost of raising the CofG slightly, but the radiator is only 19″ tall and there is literally 27″ to put it in. Mounting the steering linkage below the axle leaves even more room for the radiator in front of the steering box because the radiator can go over the linkage and still leave room for the axle to travel up and down. At this point in the design the radiator is a box that is 26″ wide by 19″ tall and 3.5″ thick that can be moved back and forth and up and down until room has been found for everything else. Anyway, the engine is a 20″ box in front of the firewall that leaves 16″ for everything else. And here you are reading in real time my thought processes as I build the front end of the car.
Recentering my thoughts, there is 16″ between the steering linkage and the front of the engine, the problem is the steering box and the radiator are trying to be in the same bit behind the axle. I could put the radiator on the right and the steering box on the left and have room for both. The steering box is 4.5″ from the mounting face to the right side of the box, 5.2″ total width, and I have 34″ of width to play with behind the axle, 17″ on either side of center. That means I could stuff a 28″ radiator in the car and still not hang out past the frame rails/4-bar if I put the radiator next to the steering box. If I choose to slide the radiator between the steering box and the steering linkage then I have more room for radiator width, but only just, and the radiator outlet would have to be passenger side to prevent interference. The widest radiator I can get a passenger side outlet at the places I’m looking is 31″ which is the inside to inside width of the bottom frame rails when I build to a width of 34″, serendipitous isn’t it?
And it’s time to check e-mail and get ready for bed.
In the last post I mentioned I had a model of the Pentastar V6 for designing the frame. I want to emphasize this is a drafting model of the space the engine occupies during operation, so that I leave enough room to get components out of damage range when the car is being driven. The actual engine is not that big. I’m just trying to make sure the car can be controlled while I’m driving it.
I was getting ready for another test walk to see if the Sweatcoin step algorithm changed depending on what level of membership you selected. It totally does, but that’s another post. I decided to trim the nail on the toe that has been hurting when I walk on the assumption that that was what was causing the pain, and it was, but I also discovered I had a small callus on the end of the toe. Not on the bottom like you would expect, but on the very end of the toe, under where the nail sticks out when it needs cutting. I find this slightly bizarre, to have a wear callus in an area that does not normally get wear. Another sign I need to buy larger shoes, perhaps? Along the same lines I was going through some of my “Left-Over” shoes and noticed that while they were all the same US size most were 42.5 European while the current set is 42 European. The European sizes 42 and 42.5 both translate as 8½US depending on the manufacturer, but I actually need that .5 to keep from rubbing the end of my toe next to the big toe, the piggy that stayed home in the children’s game.
On the Sprint-T front, I have made a model of the Pentastar V-6 for designing the frame. I’m still a bit fuzzy about oil pans, and may just make a low-profile pan of my own when I build the actual car because I have a ton of space left to right and forward from the rear of the block, just not much room to let the bottom of the pan extend down below the block. So anyway the current space-occupying model is based on the rear face of the engine using the crank centerline as the datum. The left side of the block extends 9.5″ from the crank, the right and bottom of the block are both 8″ from the crank, and the block goes to 27″ wide centered on the crank (13.5″ left and right) from 8.5″ above the crank centerline to 21″ above, and everything goes forward 20″ from the rear face of the block. I know this is not accurate but it does cover all the bits that hang off the side of the engine. Now the front is another can of worms but there’s nothing hanging off the front that I need to build around as the structural bits and controls are on the left side of the frame and it appears the potentially interfering item is on the right side. Now If I was going to keep the AC the story would be different because the AC compressor hangs down close to where steering columns and shafts usually go. Working from the inside and sliding the engine as far to the right as it will go this still leaves 8.5″ at the firewall, and a full foot just 10″ behind the firewall. Now I need to recalculate how much offset I can get, with the inside width of the firewall being 26″ and the right side of the bellhousing being 8″ from the crank that makes the crank 5″ to the right of center which is about 0.3″ to the left of balancing out my weight in the driver’s seat. So I’ll still need to hang something off the right side of the frame to get balanced.
And I need to wrap this up, and check e-mail etc.