"Ash78, voting early and often" (ash78)
01/17/2018 at 15:41 • Filed to: None
7
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"Ash78, voting early and often" (ash78)
01/17/2018 at 15:41 • Filed to: None | 7
| 23 |
Last update:
!!! UNKNOWN CONTENT TYPE !!!
Covered the hollowed out underbody with masking tape, painted the whole thing, then installed the wheels after a few days coating them with graphite lube. This thing ended up looking a little more like a generic LeMans/IMSA car than the Porsche 917 specifically, but I’m still happy with the results. Literally zero kids in the scout pack had any kind of wheel fairings last year, so a full widebody design should stand out (it took two kits cobbled together, then a lot of hollowing out to keep the weight and balance in line).
We still have stripes, headlights, windscreen and other touchups left to do, but the 5.0 oz weight limit is spot on, all the weight is in the rear, and we’re ready to go!
Naturally it looks like a crossover version of the old Mercedes CLR race car because we have to maintain a standard ground clearance.
ttyymmnn
> Ash78, voting early and often
01/17/2018 at 16:01 |
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My own pinewood derby story:
Back in about 1975, I was living with my mom and her third husband. He was an electrical engineer (or at least claimed to be), and when I brought the kit home from a pack meeting, he was certain he would be able to design the winning car. After all, he was an engineer . Rather than carving, he used a belt sander to round off the nose and taper the rear. It looked pretty good, kind of like a 30s Indy car. He drilled out the cockpit to insert a lead weight, and devised a system whereby you could add or take away wood screws to get the car up to the greatest total weight without going over the limit. I painted it blue, but my mom detailed it with a slick red-on-white racing stripe. Aside from painting the car blue, my only other contribution to the entire process was picking this wooden Playskool guy as my driver. I thought the pot on his head was a nice touch.
The car looked great. And it came in last place in every race it ran. I won the Square Wheel Award, which was a plaque with half a derby car, uncarved, glued on the front, with both wheels sawed flat.
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Ash78, voting early and often
> ttyymmnn
01/17/2018 at 16:06 |
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LMAO!! Love it.
My son is trying to help, but the competition by its very design means that it’s too delicate for most 7-year-olds’ attention spans. He’s definitely helping more with the paint, design, naming, etc.
Next year I want a big hollow box that looks like an uncarved car, maybe in UPS livery. I’m still convinced that proper weighting and good wheels are all that matter.
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ttyymmnn
> Ash78, voting early and often
01/17/2018 at 16:09 |
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I’m no engineer, but I think it’s mostly down to the wheels and friction—or a lack thereof. I can’t imagine there’s much aero going on over that short distance, and by proper weighting I would think it’s more of a COG issue than a total weight issue. I wish I still had that car. It’s the sort of thing I would have kept, one of the relics of one chapter of my childhood. But I lost track of it in the move to VA, and it, along with the plaque, most likely ended up in a landfill.
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ttyymmnn
> Ash78, voting early and often
01/17/2018 at 16:09 |
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I’m no engineer, but I think it’s mostly down to the wheels and friction—or a lack thereof. I can’t imagine there’s much aero going on over that short distance, and by proper weighting I would think it’s more of a COG issue than a total weight issue. I wish I still had that car. It’s the sort of thing I would have kept, one of the relics of one chapter of my childhood. But I lost track of it in the move to VA, and it, along with the plaque, most likely ended up in a landfill.
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Ash78, voting early and often
> ttyymmnn
01/17/2018 at 16:12 |
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5 ounces, Cg roughly an inch in front of the rear wheels, and the weights as high up as you can get them (for maximum falling distance). That’s supposed to be the recipe. Of course, a sloppy alignment and all bets are off.
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ttyymmnn
> Ash78, voting early and often
01/17/2018 at 16:18 |
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a sloppy alignment and all bets are off.
Yup. I don’t know how they do it now, but in my day, the wheels were one-sided hollow plastic, the axles were a rectangle of wood with a channel in it, and the wheels were held on with a flathead nail driven into the channel on the axle. Do the rules say that you have to use what comes in the kit? Or can you engineer your own axles/hubs?
Mechanically
> Ash78, voting early and often
01/17/2018 at 16:36 |
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Yup. 90% in the allignment.
RamblinRover Luxury-Yacht
> ttyymmnn
01/17/2018 at 16:36 |
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As far as I’m aware, it has to be the included parts, though obviously you can graphite the brads and the wheel hub/wood interface.
What doomed one that somebody in my family did was loose axles. The cars were picked up by the rear axle to check numbers, and this pinched the wheels on too tight. So, it would have one good race, followed by atrocious ones. Took us a while to figure out - would have been wise to superglue the brads at an ideal depth.
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ttyymmnn
> RamblinRover Luxury-Yacht
01/17/2018 at 16:56 |
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Next time, engineer a solid axle, then saw the heads off the nails and glue them to the outside of the wheels. Then it will look like you’re using the nails, when you really have the whole alignment and wheel depth thing set. Sure, it’s a bit of a cheat. But that sort of thing happens all the time in F1. ;)
Chariotoflove
> Ash78, voting early and often
01/17/2018 at 16:58 |
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I remember my Pinewood Derby days. As I recall, my car took third place in the Pack. I figure it’s mostly the luck of which kit you get from the crate.
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RamblinRover Luxury-Yacht
> ttyymmnn
01/17/2018 at 17:04 |
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If you overbore the wheels, coat the bores with aluminum vapor deposition and rebore, and use a knurling machine to put a retaining ring on the brad axles after reassembly to the exact correct width, it’s not cheating because you’re using all the original parts.
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Ash78, voting early and often
> Chariotoflove
01/17/2018 at 17:04 |
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$3 for aftermarket Revell wheels, a custom drilled wheelbase, and another $5 for graphite lube and you will already have a big advantage.
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ttyymmnn
> RamblinRover Luxury-Yacht
01/17/2018 at 17:20 |
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Wow—you’ve really thought about this, haven’t you?
Full of the sound of the Gran Fury, signifying nothing.
> Ash78, voting early and often
01/17/2018 at 17:40 |
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Back in ‘76 or ‘77 I actually won the derby in my pack, and 40+ years later I still have the car and the trophy. I know it’s standard issue now, but back then graphite lube was unheard of and the key to my victory. I even raced against the winners from the previous few years and, not surprisingly, beat them all.
My father had passed away a couple of years prior, so thankfully I got some help from some of the other dads in the pack. I sketched out what I wanted, and one of the guys, a mechanic at Western Airlines, carved it out, obviously using some pretty decent equipment. OK, it looked nothing like my drawing, but then again it would probably have been difficult to decipher the drawing of a child. I wasn’t going to complain since it was better than the hand-carved PoS I made myself the previous year, and I was happy that someone with some skills lent me a hand.
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RamblinRover Luxury-Yacht
> ttyymmnn
01/17/2018 at 17:54 |
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This will surprise you, perhaps, but those exact cheaty steps were spur of the moment. I have, however, had others as ideas.
McMike
> ttyymmnn
01/17/2018 at 18:11 |
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My dad wanted to make a moving weight on the inside of the car that would fall forward in the chassis as soon as the car pitched down on the track.
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Chariotoflove
> Ash78, voting early and often
01/17/2018 at 18:48 |
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We did the graphite, and we put some metal weights in, but that was about it.
My daughter is in Girls Scouts instead, but she still loves cars. There are more car building projects in our future.
plak424
> Ash78, voting early and often
01/17/2018 at 19:19 |
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Looks great! Looks very similar to one I made for a pinewood derby we had at work a few years ago.
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Ash78, voting early and often
> RamblinRover Luxury-Yacht
01/17/2018 at 23:57 |
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Aftermarket parts are ok, provided they’re on the “official” list. The brads included in the kit are horrid — they have large burrs just under the head. And the plastic on the wheels needs polishing. You can DIY but the kits are basically more finished versions of the real thing.
Yes, gluing the wheels in at a specific depth definitely helps minimize play, as well as handling mishaps like the one you mentioned....
davesaddiction @ opposite-lock.com
> Ash78, voting early and often
01/19/2018 at 10:51 |
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Nice! My daughter’s took 2nd place last year. We’ll see how her Batgirl-mobile does this year.
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davesaddiction @ opposite-lock.com
> ttyymmnn
01/19/2018 at 10:52 |
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Hahaha! Great story.
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davesaddiction @ opposite-lock.com
> ttyymmnn
01/19/2018 at 10:55 |
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I did a lot of research a few years ago, and the fastest cars (if the rules allow it), actually run just on the inside edges of 3 wheels (axles are put in at a slight angle), with the center of mass just ahead of the rear wheels.
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davesaddiction @ opposite-lock.com
> RamblinRover Luxury-Yacht
01/19/2018 at 10:58 |
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I like the way you think!