5 ms·

My son just joined the boy scouts (or Tiger Cubs or whatever it's called when they're in the 1st grade). I need to review this for... uhmm.. research purposes.

rubidium 11y ago
Not to ruin the story, but he placed 4th out of 4. You'd be better off spending time on getting your tires perfect and figuring out which lane is fastest :)
- peejaybee 11y ago
  The latter won't matter if they do as my pack did, where each race had three heats and each car raced in all three lanes. But yeah, get your wheels right and polish the heck out of your axles.
  - smoyer 11y ago
    A couple more hints (I have an entire PDF document on speeding up PWD cars). 1) You don't need 4 wheels (except to stay on the track). Lift one of them up slightly so the car is only resting on three wheels. Don't lift the forth wheel up high enough that it's not able to help guide the car along the guide rail. 2) Make sure the car rolls straight. There's a lot of friction against the guide rail if your car is constantly trying to turn into it. 3) Make sure the inside of your wheels are sanded smooth. You want any friction due to contact with the guide rail to be minimized. 4) Put as much weight as possible at the back of your car. Since that weight is higher up the launch hill, it will end up pushing the are longer. Think of it this way: Gravity will stop pulling a front-weighted car when it reaches the roll-out. With a rear weighted car, the back will continue to be pushed when the front wheels are on the roll-out. You get an extra car length worth of gravity. Many PWD events mandate the use of the stock wheels and axles. The fastest car I ever saw used layers of teflon tubing inside the wheel hub and hypodermic needles for the axles - very smooth bearing surfaces. Beyond the tips above, the most important tip is to eliminate friction in the wheel-to-axle bearing. Good luck!
    - emerongi 11y ago
      I think it's good to have the car not roll perfectly straight, but a little bit to one side. If it rolls too straight, it's going to bump from one side to the other and lose much more energy.
      - smoyer 11y ago
        Have you done A/B testing on that? I'm genuinely curious about which would win.
      - ezl 11y ago
        The energy you lose from lateral collisions has very small impact on the forward movement rolling as straight as possible might bump from side to side, but between the left and right side the wheels will be rotating with as little friction as possible. deliberately going to one side guarantees that the wheels will never reach max speed.
    - krisneuharth 11y ago
      Link?
      - smoyer 11y ago
        I paid for the PDF as a guide about 15 years ago and couldn't find a link to the same document. If I remember correctly, these were just four of the twenty-some tips. (We ended up with a second and third place car out of fields of about 80).
CIPHERSTONE 11y ago
Just a comment, as fun as PWD can be, don't be that parent that clearly did all the work. The purpose is not to make a car NASA would be proud of, but to make the car with your son to end up with a car he made and is proud of. Usually this results in a car that looks like and reflects the age of the scout (e.g. a Tiger Scout's (Kindergarten) car does not look like a Webelos (5th Grade) car. Seriously suggest to your pack leadership that they add three races: -Adult/Sibling -Adult Scouter -Adult Vintage The first give you and your other non-scout kids an opportunity to be a part of things. You can make your NASA approved car that ultimately loses to the simple block of wood that five year old suzie makes. The second gives the scouts a chance to cheer on their den leaders. The third let's them see what PWD cars from pack in the day looked like. Just some suggestions from an old Cubmaster.
- strictnein 11y ago
  Oh, I won't be, my comment was mostly tongue-in-cheek and also remembering how my the creations of my father and I never did that well. Obviously you have to help a 6 or 7 year old to a degree, but I plan to be as hands-off as possible, when the time comes. I like your idea of multiple races. I'll have to go and find my old PWD cars. They're somewhere...
  - CIPHERSTONE 11y ago
    It's really a blast to see the old cars, and the adult race is fun because then you can see some really great adult designs.
- georgeecollins 11y ago
  Thumbs up to this. My son did a pinewood derby when we were living on the peninsula and many (if not most) of the cars looked like they could only have been made by an adult. Not just like an adult helped, like everything was too polished to be made by a kid of the appropriate age. It just misses the point.

rubidium 11y ago

Not to ruin the story, but he placed 4th out of 4. You'd be better off spending time on getting your tires perfect and figuring out which lane is fastest :)

peejaybee 11y ago
The latter won't matter if they do as my pack did, where each race had three heats and each car raced in all three lanes. But yeah, get your wheels right and polish the heck out of your axles.
- smoyer 11y ago
  A couple more hints (I have an entire PDF document on speeding up PWD cars). 1) You don't need 4 wheels (except to stay on the track). Lift one of them up slightly so the car is only resting on three wheels. Don't lift the forth wheel up high enough that it's not able to help guide the car along the guide rail. 2) Make sure the car rolls straight. There's a lot of friction against the guide rail if your car is constantly trying to turn into it. 3) Make sure the inside of your wheels are sanded smooth. You want any friction due to contact with the guide rail to be minimized. 4) Put as much weight as possible at the back of your car. Since that weight is higher up the launch hill, it will end up pushing the are longer. Think of it this way: Gravity will stop pulling a front-weighted car when it reaches the roll-out. With a rear weighted car, the back will continue to be pushed when the front wheels are on the roll-out. You get an extra car length worth of gravity. Many PWD events mandate the use of the stock wheels and axles. The fastest car I ever saw used layers of teflon tubing inside the wheel hub and hypodermic needles for the axles - very smooth bearing surfaces. Beyond the tips above, the most important tip is to eliminate friction in the wheel-to-axle bearing. Good luck!
  - emerongi 11y ago
    I think it's good to have the car not roll perfectly straight, but a little bit to one side. If it rolls too straight, it's going to bump from one side to the other and lose much more energy.
    - smoyer 11y ago
      Have you done A/B testing on that? I'm genuinely curious about which would win.
    - ezl 11y ago
      The energy you lose from lateral collisions has very small impact on the forward movement rolling as straight as possible might bump from side to side, but between the left and right side the wheels will be rotating with as little friction as possible. deliberately going to one side guarantees that the wheels will never reach max speed.
  - krisneuharth 11y ago
    Link?
    - smoyer 11y ago
      I paid for the PDF as a guide about 15 years ago and couldn't find a link to the same document. If I remember correctly, these were just four of the twenty-some tips. (We ended up with a second and third place car out of fields of about 80).

CIPHERSTONE 11y ago

Just a comment, as fun as PWD can be, don't be that parent that clearly did all the work. The purpose is not to make a car NASA would be proud of, but to make the car with your son to end up with a car he made and is proud of. Usually this results in a car that looks like and reflects the age of the scout (e.g. a Tiger Scout's (Kindergarten) car does not look like a Webelos (5th Grade) car. Seriously suggest to your pack leadership that they add three races: -Adult/Sibling -Adult Scouter -Adult Vintage The first give you and your other non-scout kids an opportunity to be a part of things. You can make your NASA approved car that ultimately loses to the simple block of wood that five year old suzie makes. The second gives the scouts a chance to cheer on their den leaders. The third let's them see what PWD cars from pack in the day looked like. Just some suggestions from an old Cubmaster.

strictnein 11y ago
Oh, I won't be, my comment was mostly tongue-in-cheek and also remembering how my the creations of my father and I never did that well. Obviously you have to help a 6 or 7 year old to a degree, but I plan to be as hands-off as possible, when the time comes. I like your idea of multiple races. I'll have to go and find my old PWD cars. They're somewhere...
- CIPHERSTONE 11y ago
  It's really a blast to see the old cars, and the adult race is fun because then you can see some really great adult designs.
georgeecollins 11y ago
Thumbs up to this. My son did a pinewood derby when we were living on the peninsula and many (if not most) of the cars looked like they could only have been made by an adult. Not just like an adult helped, like everything was too polished to be made by a kid of the appropriate age. It just misses the point.