Monthly Archives: November 2019

I’m going out for commercial reasons on Black Friday

or as I tried to tweet “Cover me while I throw my Grenade while I have to buy something on Black Friday.”

My phone bill is due tomorrow and I have other things to do tomorrow.

No News is just no news

Between YouTube and Twitter and clogging the toilet I have been Way Too Busy to put something on the blog. The Big Thing At The House last week was a big fight about moving my projects in-progress off the dining room table to replace the tablecloth, because unless I do it parts get lost, and I Didn’t Want To Do It. And the odd capitalization is on purpose for vocal intonation a la A. A. Milne.

One of the reasons I haven’t had much to talk about is we are waiting for Mrs. the Poet to decide on when she wants to get an operation to fix her back. She has scoliosis and stenosis, which combine to cause her Great Pain pretty much all the time, and sometimes her legs just Stop Working so she falls down, and yells at me to stand there and not help her get back up, which I don’t understand at all. I mean yelling at me to be there I understand, but yelling at me to leave her alone and not help her up? 🤷‍♀️ That I do not understand at all. Why yell for me to come and not help you? And I have no idea why she is putting the operation off, her insurance has already approved it and all they need is for her to say when.

On other things the money to fix the storm doors and pay the property taxes is on the way, so we can fix the broken doors and also open the doors to allow some fresh air to enter without inviting the neighborhood bugs into the house. This would be good because the house gets stuffy in the Summer and Winter because we have to Keep Things Closed Up to keep cold air either inside or outside as appropriate, and we need to let the joint air out a bit in Spring and Fall. Now we have the option of letting some fresh air in.

I have been trying to get something done with the Mini Sprint-T chassis so I will have something to show where the Bits And Pieces will go on the 1/1 version. That and so I’ll have something to point to and tell people what I want for Christmas, “That, in full scale.” I mean, I already have lots of the parts, some need welding to other parts, but I have most of the front end in the house. I have the axle, both spindles, the steering arms, all the brakes and hubs, the brackets that weld to the axle to mount the 4-link, and associated Bit And Pieces. Basically all I need to call it a Complete Front End are the links for the 4-link, the track bar, springs and shocks, and the steering drag link and tie rod. The steering box is one of those things that is frame or front axle, but I need one of those, too. And I have been trying to replicate those parts in 1/25 scale for the Mini Sprint-T.

Well, that brings you up to date Dear Reader, so it is time to proof and publish the post. I will see you the next time I have Something To Say. Happy Thanksgiving, safe Black Friday.

Still stuck on imagi-building that A-MOD car

I have a mind that must chew on problems to solve, not social problems, physically solvable problems like bicycles or race cars. And the one that’s occupying my mind is the A-MOD car. Like all good engineering problems it has a simple premise: Make the quickest car possible on an autocross course within these constraints; 72″ minimum wheelbase, 42″ minimum tread, 900 pounds minimum weight with driver and full fluids, and 10″ minimum wheel diameter. There are safety rules common to every car in the series, and because having a really stiff suspension is a huge advantage you have to have sprung suspension, not that actual springs are required, there are cars that are riding around on actual hockey pucks between the suspension and the frame, but something that isn’t a solid piece of metal against another non-moving piece of metal.

Anywho, working through those minor strictures I have evolved literally thousands of cars with uncountable variations of “suspension” over the last few weeks. But what I keep coming back to is a single-pivot rear suspension with a solid axle and a single disk brake halting the axle. It’s simple, strong, and fairly lightweight. And relatively easy to adapt to a chain drive. Another thing is it works extremely well with a common trope in cars this size, mounting the engine on the rear suspension. Basically this is done to simplify the drivetrain and shorten the chain on chain drives. It’s really bad for unsprung weight so I’m only doing the designs as due diligence to make sure I’m covering all the bases, and because researching this adds to the knowledge base for other designers, and what I learned to pass on to other designers is the unsprung weight is pretty close to zero if the Center of Mass of the engine is mounted right at the pivot point of the suspension which is physically impossible unless the rear swing arm is mounted in such a way as to create a virtual pivot point in or near the CG of the engine, which kinda negates the purpose of mounting the engine on the swingarm in the first place, simplifying the rear suspension and drivetrain.

Another suspension I have been looking at is the classic 4 link and panhard rod with the forward pivot of the 4 link even with the front drive sprocket of the chain drive and the rear pivot right on the centerline of the rear axle so the chain and the suspension swing through very close to the same arc and making having the same chain tension through the suspension travel simple.

Another thing I have been looking at is mounting the rear part of the chain drive solidly to the rest of the frame and using CV axles to run the power to the wheels as shown in a book I bought, How to Build Motorcycle-Engined Race Cars by Tony Pashley. and in this video by Vasily Builds where he modifies his swingarm buggy into IRS. Way more complex to build but less unsprung weight than almost anything else, but the 4 link is lighter overall, allowing weight to be added where it will do the most good, making the final decision a tossup or a painstaking virtual build of both to see which would be better. I have the time but not the software to do the virtual build, and the 4 link is both cheaper and easier. And since I have more time than money, cheaper is the way to go on this one.

But I would still rather be building the Sprint-T. This is just something to keep my mind occupied so I don’t build a doomsday device and just destroy everything. Speaking of which, I can’t find my yellowcake, I have the lemon and the cinnamon, but not the yellowcake. (Mad scientist in-joke, you don’t have to laugh if you don’t get it, but if you don’t get it and want to get it google “Nigerian yellowcake” for the source of the joke.)

Going back to my roots for a post

Longtime readers will know this blog was originally started as a bike safety news amalgamation site, but I had to stop because of all the blood and gore and stupidity. Well, I manage to avoid most of the blood and gore these days, but the stupid, teh stoopid it burns us.

Seriously, the people in charge of keeping cyclists from getting hit on a national scale have proposed a national helmet law. But the other national body charged with safe streets says they’re full of donkey dust not in those specific words, but politely.

And as I have pointed out in this blog in the distant past (4 or 5 years ago?) even if bike helmets were made that prevented 100% of head injury in wrecks with motor vehicles, most cyclists would still die anyway from massive blunt force trauma to the torso or legs. In my wreck if I wasn’t dead for 2-4 minutes and my heart was still pumping I would have bled out from the massive holes in my legs, because as soon as they revived me I started gushing blood from my leg. And as I have discovered I’m basically a superhero without a supervillain to face, so my experience is way off the end of the bell curve on both the severity of that wreck, and on surviving it. Seriously how many times can you count on the cyclist getting hit having such resistance to blunt force trauma. “Nah, it’ll be OK, he’s basically Superman.” Seriously THAT DOESN’T HAPPEN IN REAL LIFE.

So fight helmet laws in your city and state, and most definitely fight a national helmet law.

We now return you to the usual nonsense this blog posts these days.

Nothing much to write about since putting my head through the door

Basically my mind won’t stop building A-MOD cars and it’s been keeping me awake at night. How much of that is related to last week’s adventure in DIY home-wrecking and how much is just frustration at not being able to build anything (or even able to type anything as I will explain later)?

I have been thinking about taking the driveline out of one of those AWD quadbikes and stretching it out to the required wheelbase and track for an A-MOD car. Basically that would require making one new drive shaft and 2 new axles to put everything on one side of the car so the driver could sit beside the engine instead of over it, and get everything as close to the center as possible. Quadbikes are literally available all over the place out here because nobody can find parts to fix them so when they break they get thrown away, and because nobody does routine maintenance on them they break with appalling frequency. So they are literally available for towing fees or “How much you wanna pay me to haul that off?” If you get one that has good parts support they are somewhat fixable but those are not the kind that get thrown away, otherwise you try to find a bunch so you fix one and use the rest for parts. So the build process is basically find a quad, cut off the front end and build new pickup points for the front suspension that moves the wheelbase out to 72″ and the track to 42″ and widen the rear to match the front. Then move the controls to the side and down so that the CG is close to centered on the new layout with the driver and because the driver is on the same plane as the rest of the vehicle the vertical CG is lowered a bunch. Swap out race slicks for the all-terrain tires of the quad and semi-instant A-MOD car!

The other idea that has been prancing through my mind is a variation of the sidewinder build trailing A-arm rear suspension that puts the pivot point of the suspension next to the output shaft of the transmission so that chain tension wouldn’t change much as the rear suspension traveled through its range. Basically the design change was a single structural member from the pivot point of the A-arm to the rear axle bearing support next to the chainline, to prevent flex from the chain pulling the axle forward, and one diagonal that runs from the pivot behind the engine to the far support bearing while another runs from the chainline support to the support on the driver’s side of the axle, with another running in front of the rear axle sprocket to the engine side bearing support on the axle to prevent flex when cornering. The best way I can describe this is it will look like a flattened A with one leg missing and a line up the middle and another leg to the center on the side away from the driver from overhead. Because I plan on running the same size tire on both ends it will have only one spring and shock absorber on that center bearing support, as close to the axle as possible to get what is technically a “zero roll stiffness” suspension so that all the roll stiffness is in the front and the car will corner on the outside front and both rear tires to prevent massive oversteer under power. Having the full length and width support only on the side away from the driver allows the driver to sit further back in the car while still allowing for suspension travel.

Now, about that typing issue mentioned earlier. Basically what it comes down to is stuff from the cuts on my hands got all stiff and I couldn’t hit the keys with my fingers. Long story is some of the cuts opened up and started bleeding so I had to put bigger bandaids on them with more antiseptic, leaving me with two fingers that couldn’t bend, the index and third fingers, and typing became a single-handed operation of hunt and peck. And slowly because sympathetic pain every time I moved the fingers of the other hand because I use both hands to type and I kept trying to use the injured hand. So no new posts until the hand healed enough that I could type. But now I’m better (or as the saying goes “good enough”) I’m doing another post.