What would be the fastest design for a Pine Wood Derby car?

Answer

I can't claim that these ideas will guarantee you the fastest car, but should yeild a fast car nonetheless.

First of all, create your own little wind tunnel using an appropriate sized, household fan. You don't need a tunnel. Test several model designs by placing little streamers made from toilet tissue etc. on the key areas of the model car. Put the model in the wind stream to see how it performs. A slippery wind flow is what you are looking for. If you have access to a stick of incense etc. you can use it to see the air flow over the body by placing a burning incense stick into the air stream, in front of, the car body. Note how the smoke flows over the model. Again, you are looking for a slippery flow.

You have two aerodynamic approaches:

1. Create a car that pierces through the air like a missle or rocket. Make it very sleek and aerodynamic. Create a leading edge and a trailing edge, (football shaped).

2. How about the "Golf Ball Effect." Golf balls don't actually fly through the air although they can take spin from the club. A golf ball simply pierces the air and falls to earth like a round stone. You can use the same principle for your derby car and come up with an innovative, drag cheating design.

Make it like a golf ball.

In other words create a rounded shaped car body with plenty of dimples all over the entire surface. (like a golf ball). The dimples will create little eddys in the air stream that will allow the car to move through the air with less resistance or "drag" as it is called. (The same way a golf ball works) This approach is currently being applied to boat hulls to reduce drag from the water flowing over the hull. It is also being applied by a few exotic, sportscar makers, on the side mirrors, to reduce the drag the side mirrors create.

Finally, make sure all moving parts such as axels and wheels are as free from drag and heat as possible. Drag is you enemy! Make sure all moving parts, especially axels and wheels are built with somewhat loose tolerances and plenty of lubrication. I recommend using a Teflon, dry spray lubricant. Do NOT use WD-40, dirt, dust, and grime will stick to it like glue! Use a dry lubricant like Silicone spray and/or Teflon spray. Ball bearings are your friend if the bearings are the right size and kept clean and lubricated.

Keep the weight and center of gravity in the middle of the car, or slightly forward of center if necessary. DO NOT put the weight in the back.

If you were to drop a small sledge hammer from a rooftop, which end would hit the ground? Obviously it would be the heavy, iron hammer head, not the end of the handle. The same physics are at work on your car design since it is a gravity issue. Put the weight in the middle or forward of middle and you will have greater steering control, (on front wheel steering).

Answer

Well, what I did to win the derby back in '82 was to cut most of the back half off, and glue it on top of the front half, leaving enough of a flat bed in the back for the rear axle (it comes out looking like a big-rig, without the trailer). So then slap some blue and red paint on it so it looks like Optimus Prime, and let her rip.

The fun little surprise is when the cars are sitting on top of the track, all 4 wheels are touching. But once released, the front-heavy truck actually races with only its front wheels touching the track. Without the back end touching, the resistance is lessend, and the beast hauls. This was a total surprise to me, as at 8 years old, I was just trying to make it look cool. But it was a total blow-out. Won every race by a mile.

The next year, I wanted to make a sleek little Delorean looking thing, which I did. It probably would have done so-so as it was, but it was way under the max allowable weight. So then my mom stepped in with the idea of hollowing out the center of the car from the underside, and glueing in enough quarters to bring the weight up to max. The low, central center of gravity got me a repeat of the previous year, only this time, all wheels touched.

The following year was going to be something sick, as I had planned to remake the truck only this time deliberately balanced with quarters. Unfortunately, I wasn't in the scouts after that. So, unless they have changed the rules in the last 20 years, this'll probably blow them all away.

First answer by ID3513159367. Last edit by ID1197648835. Question popularity: 130 [recommend question]