I'm psyched that it's Pinewood Derby time! I'm even more psyched that my boy is super excited about it! I've told him that I will help him, but that he had to do as much of the work as was safe to do. His car will be his car, and I won't compete through him. BUT...
Our Pack has a Dad's Division, explicitly to keep dads from taking over the kid's cars. It is fiercely competitive and I want to do well. The color scheme is set, but otherwise I'm wide open to ideas. So, come on, what are your tips, tricks and almost-but-not-quite cheats?!
We have to deliver the cars Jan 30. Family vacay starts today, so I wont actually start building until the 4th or 5th, which means I've got a couple of weeks to firm up a design.
Weight biased as far to the rear as you can (more potential energy)
Axles polished to a mirror finish, lock graphite on the wheels (reduce friction)
Nose like a .45 bullet ("punch a big hole in the air and drive a sleek little car in behind it")
Wheels inboard of the outer edge of the body if allowed; if not then you will need to get the air away from them with nearly flat projections in front of the wheels. Think "aeroscreen".
It won't go fast enough to make skin friction drag important, so no need to polish beyond what's needed to make the paint or stain look good.
The biggest part is putting the weight just in front of the rear axle and maxing the weight. I need to get my son started on his too maybe over the vacation I can get him to draw the shape he wants.
If your rules allow it, bend the axles a bit so that you're running some negative camber and only running on the edge of the wheel. You can also bend just one axle up front so that you're running on three wheels (one front, two rear).
ManhattanM (fka NY535iManual) said:
I'm psyched that it's Pinewood Derby time! I'm even more psyched that my boy is super excited about it! I've told him that I will help him, but that he had to do as much of the work as was safe to do. His car will be his car, and I won't compete through him. BUT...
Our Pack has a Dad's Division, explicitly to keep dads from taking over the kid's cars. It is fiercely competitive and I want to do well. The color scheme is set, but otherwise I'm wide open to ideas. So, come on, what are your tips, tricks and almost-but-not-quite cheats?!
We have to deliver the cars Jan 30. Family vacay starts today, so I wont actually start building until the 4th or 5th, which means I've got a couple of weeks to firm up a design.
That's the thing that annoys me about Pinewood derby - too many dads take over the scout's build. Having a separate division for them is a good idea, let the kid do his own work and learn from it and have fun. That's how it was when I was a scout.
I would think alignment of the wheels is key.
any misalignment front/rear or left/right will create drag.
I like the Dad's Division idea. Very cool idea to let father/son work side by side and have the scout learn by seeing and doing rather than just having dad do all the cutting, polishing, finishing. When I was a scout, I had to plead with my dad to let me do my own work. We had a funny dynamic growing up...
The weight distribution really depends on what the track looks like. If it is a constant slope from the start to finish line then moving weight back doesn’t do anything for you. Since this is the easiest track to build it’s pretty common.
I read somewhere that the best result was from a wedge. Can't find it now.
Essentially, the idea was to move as much of the mass to the rear of the car as possible, since that ends up increasing the potential energy (the mass is higher on the ramp when the car starts and passes the flat area of the track latter) and reducing friction as much as possible.
The things I remember is that if you tweak the front axle so that one wheel *barely* touches the track, it will reduce rolling resistance. Polishing the axles is also supposed to help, as well as making sure that the wheels are absolutely round. I would guess that moving the axles as far to the ends of the car as the rules will allow would help with stability
Finally. I would imagine some kind of super slick lube for the axles / wheels would also help
I did the pinewood derby cars. Even bought a small bandsaw and drill press to host "derby car build" parties with all the scouts. There are a ton of little tips and tricks that you can try. And I tried them all. Turns out the real trick is build LOTS of cars and eventually you'll get one where the stars align and smile down upon you. Set up your own track and run your cars over and over, eventually the fast one will win out.
5 ounces exactly, you'll want a precise scale for that as well.
I took 2nd in 3rd grade and won in 4th grade. Had some help from the pops, but it was on me to do the finishing work.
Anywho as I recall -
I won with a wedge design that was heavy in the back - like a reverse teardrop. The other car was a flat wedge with a steel plate on the bottom to max weight.
We used a beam balance my dad got from work to get the weight right under legal max by like 1/2 a gram.
Polishing the axles and using graphite sparingly made a smooth running car. We put the axles (nails) in the wheels and spun them with a drill in the wheels with some graphite as lube to get them all polished up and make a poor mans oillite bearing.
Glue the axles in using epoxy, don't just rely on the block of wood to hold them.
Spend the time to get the wheels lined up straight. Never played with the camber but it would work as long as you can keep the car tracking straight. We did make a set of cheater wheels one year (rules specified that axles and wheels had to be stock) that were tapered and repolished so they rode on the outside edges - the inside was cosmetic. Basically spin the wheels and sand them to a taper, then polish them back to look like they are unmodified. Took 2nd that year so maybe cheating does not pay.
We also had Test n Tune the night before with the official track set up in a garage instead of the school gym. Was nice to get some run time before the big show.
If you run on the same track year over year have the wife record wins by lane and graph it to determine the fastest lane. This one can be valuable if you get to chose where the car goes.
Max weight and smooth running axles and a straight running car are 99%, the rest is gonna come down to chance.
Our scoring was on a 4-wide track, winner gets 4 points, 2nd gets 3 points, so on so forth for an hour of open racing, round robin style. Then we would have the scouts add up their cards and do a single elimination bracket with the top 16 scouts. Basically whoever got the most points over the hour of open racing. If their were ties for the 16th seed, heads up elimination would determine who was #16.
