Latest Tips
Mike from Phoenix wrote in with an observation on how scales work, and how to use this to your advantage.
Keep reading →
I constantly hear from dads who remember from high school physics classes that mass doesn’t affect the rate at which something falls. If dropped in a vacuum, a bowling ball and a feather fall at exactly the same speed, so the same should be true of a Pinewood Derby car as well, right? If this logic holds up, a three ounce car should be just as fast as a five ounce car.
The problem with this logic is twofold. We’re not just testing the rate at which something falls; on most tracks, half the track is sloped and half is flat. And we aren’t running in a vacuum; there’s lots of friction involved.
Keep reading →
It’s important to make sure your car is exactly 5 ounces on race day. But I’d suggest keeping it slightly underweight until you get to the race. It’s always easier to add weight than it is to remove it.
Last year our Scout District race was held outside on a car lot in April. Almost every car that showed up was weighing in at 5.1 ounces — a tenth of an ounce too heavy. One disgruntled father set out to prove that our scale was wrong and produced a 5 ounce brass tare weight. We put the weight on the scale and it came in at exactly 5 ounces. The scale was right, all the cars were too heavy.
Every one of these cars had raced previously in their Pack races. Were the scales at all the other races wrong? Had everyone added weight between races? Why were they coming in so heavy?
Keep reading →
Those pinewood weights you buy at the craft store aren’t lead and aren’t very dense. Lead is nearly twice as heavy as that stuff. Don’t use it if you want to win.
Usually I melt lead bird shot into holes drilled in the car body. It’s an efficient way of weighting the car, but this year I tried tungsten beads. Tungsten more than one and a half times the weight of lead, and I was able to pack a lot of weight into a small area in the car body. But the problem with tungsten beads is that there’s a lot of wasted space in the car body.
Lead melts at about 600 degrees, a temperature you can reach with a propane torch. But tungsten melts at 6000 degrees, so melting it into the car body isn’t an option. Instead I had to pack the beads in, shaking the car to get the beads to settle.
Next year, I’ll be using tungsten powder instead. Just drill a hole, pour in the powder, and seal the hole back up. I’ll get all the efficiency of tungsten, but without the wasted space, allowing me to pack weight into a much smaller space. And it will be easier than trying to fit the beads into the car and easier than melting lead.
Previously
If you want to make sure you have a car that weighs in at exactly maximum weight, you’ll want to pick up a digital scale to test your weight at home. Digital kitchen scales can be bought for around $30, but make sure the one you’re buying can display measurements in ounces. A number of […]
If you’ve read the tips here and elsewhere you know if your weight should go in the front or the back. You know you should keep the weight low. But I’ve seen plenty of cars that meet these criteria but still don’t have the best weight placement.
Lots of people weight their cars with those non-lead […]
The scale you use to weigh your car while you build it might not register exactly the same as the official scale at your race’s registration. You might find out you need to add or remove weight at the race in order to meet your weight requirement.
When you build your car, make it about two […]
Most pinewood tracks are shaped something like this:
\
\
\
\_____________
But every once in a while you’ll see a track shaped like this:
___
\
\
\
\_____________
The first track has a starting gate where every car starts out […]
On most tracks, you want to put the weight as far back as you can on the car while still keeping the car stable. This maximizes the potential energy of the car. Potential energy is the energy your car has stored up while it waits to be dropped down the track.
Why does it matter […]
