Pine Wood Derby

[LWJ]

So as the father of a Cub Scout, a car enthusiast, and a fairly competitive person, it stands that I would enjoy the annual Pine Wood Derby event. This year was no exception. You start with a block of wood, four nails (axels) and four wheels. Shape it, massage it, paint, the bring it up to weight. You have a race car!

Some key decisions:

1) Where to place the weight?
2) How to reduce rolling resistance?
3) How to minimize scuffing on track?

You get the picture.

Below is a picture of my car. We had the race today. I expected my car to finish poorly for a couple of reasons and my boy's car to finish much better for some other reasons. It turns out that my car ran pretty good. Easily in the top 10% out of 84 total cars. For adult / non scout cars, it was the fastest. I haven't yet seen the final results, but I am curious.

Some design high-lights: runs on three wheels (less friction); three wheel independent suspension; axels with reduced contact area; and polished wheels.

[jyl]

How did you do the suspension? What mods are permitted?

[speedracing944]

We competed too. My son made a car which was a UW-Madison Bucky Badger Limo. My 5 year old daughter wanted to do an Alpine White 944 Turbo.







My son finish consistently in 3rd place and one 1st place finish for a 3rd overall out of 8 cars.

My daughter's car was finishing in 1st and 2nd place in the open class, 18 cars completed by mostly fathers, until another car jumped the track and collided with the 944. It developed a bad speed wobble after that and would finish nearly last place .
We managed a 8th place overall out of the 18 cars.

Speedy

[sammyg2]

The important part is teaching the kids about basic physics and good sportsmanship. Weight in the nose, careful alignment, polishing the wheel races with toothpaste to reduce drag, very light lubrication, areodynamically neutral. Like a whale shape.

I remeber a father who got kicked out for placing magnets in the nose of the car.
The starting gates were steel and when they dropped it pulled the car forward, giving an unfair advantage. Great. Some asshat teaching his kid to be a POS. Good lesson.

[javadog]

Originally Posted by sammyg2

... Weight in the nose...

Not necessarily...

JR

[speedracing944]

It is all about rule interpretation similar to what Singer did with the legendary 935.

Our track was inclined at the gate so placing the weight at the very tail is key as it pushes the center of gravity higher on the Z-axis thereby giving you more potential energy.

The 3 wheel trick is usually caught by our judges. The guy behind me was nailed and had to correct his car. The problem was he drilled the holes for the wheels.

I cambered our wheels slightly by shimming the groove with about 0.008" of shim. It wasn't noticeable but it was there.

Speedy

[vash]

i would love to participate in an adult version of the race. where do the scouts hide that track when not in use?

[jtfreels]

I have an idea..... proxy race, we each build a car, send it off to someone (with a track) who runs the races impartially.

Hmmmmm I wonder if dueller is dumb enough, I mean if he would volunteer to run it

Jay

[red-beard]

Weight in the rear. The tracks start inclined and end flat. You will be storing more energy with the weight in the rear.

Polish the axels. Fill the wheel holes with epoxy and redrill. Polish the inside of the wheels.

[vash]

Originally Posted by jtfreels

I have an idea..... proxy race, we each build a car, send it off to someone (with a track) who runs the races impartially.

Hmmmmm I wonder if dueller is dumb enough, I mean if he would volunteer to run it

Jay

his poor secretary........

[BeyGon]

Isn't the idea that the kids build these?

[javadog]

Yes, although most of the kids have less interest in the building of the cars, as opposed to racing them. Went through it with both of mine; they were in a hurry to finish, so they could race and didn't give any thought to making the cars go faster.

It's fun for adults because they tend to get a little more creative and some try to acyually do a little engineering. The local PCA chapter had a competition for adults a few years back, which was a lot of fun.

JR

[M.D. Holloway]

We competed in our 5th season. Last year I tried to convince the BSA to allow us to sell sponsorships as a fundraiser. The Pack was all for it but Council nixed it. I would like to see the Pack open up the race to any and all a few times a year as a fund raiser.

[M.D. Holloway]

no more than 5oz, 3/8 ground clearance, 7"long and be able to fit into a box to establish the correct wheel width. Wheels can not be sanded to a point and no liquid lube allowed.

In my 5 years of runs I have seen all sorts of cars win. I wish there was a logic to it but you are looking at several variables all which may or may not be dependent on each other.

[porsche4life]

I'm telling ya... As thin as possible at the front and not very thick in the rear.... exactly 5ozs... polished wheels and axles... only roll on 3 wheels....

[LWJ]

Yes. Most of you got it. Weight in the back. Three wheels if allowed. Our rules did not allow lengthened wheelbases but that is good if allowed. We could do graphite but no liquid lubes. No springs or suspension allowed but my design was ok'ed by the ref in advance as it uses the block of wood itself to suspend the car.

Agreed. The idea is to have the kids build the car. My boy did that. I let him do the activities that did not threaten to remove his fingers. I did the cutting.

As to JYL's question of how I did the suspension. I found a design on the web and copied it. Some very thin and vunerable pieces of wood. I suspect a drop would have shattered the whole thing. The suspension uses two long U shaped legs on the back wheels and the front (it rides on one wheel) is an independent piece. It would have worked better had I had the guts to thin stuff out even more.

All good fun. You should have seen the kid with the fast car. He was absolutely biting his nails at the end. Pretty cool.

[herr_oberst]

Apparently, you can buy milled wheels, graphite impregneted and milled axles, pinewood blocks with precision-drilled axle locations, tungsten weight, and books on speed secrets. All in good fun. Things sure have changed from when I was a little kid.

(But a Pelican Pinewood Derby Challenge™ sounds like a hoot!)

Pinewood Derby Cars - Design Plans - Speed Supplies - Free tips

[nynor]

i loved pinewood derby. sounds like y'all had as much fun as i remember.

there are adult pinewood derby leagues, with all kinds of classes, ranging from BSA boxed materials only, to anything goes.

[Taz's Master]

We're going European this year. France's Le Go, and England's Lotus 7. It's been a blast so far. Should neither win a race it will have been a success.

[lyon]

I won first place back in '82. Aerodynamics, wind resistance, a good wedge shape, sanded as smooth as possible, rounded, spray paint, gloss red. drill holes in evenly in the bottom, evenly, front and back. melt the lead and pour to fill, carve back excess lead. sand the wheels, round them a bit, graphite. that's how I won.