What are some unique propulsion systems for a pinewood derby car project? (2024)

FAQs

What is the most aerodynamic Pinewood Derby car design? ›

But aerodynamics rule the day, and the best shape is a simple wedge. Just like a spoiler on the rear of a sports car, the wedge shape allows as much air to flow over the top of the car without hinderance while keeping the car pinned to the track.

A pinewood derby car converts gravitational potential energy to translational kinetic energy (and resulting velocity), rotational kinetic energy in the spinning wheels, and heat from friction.

The easiest way to reduce friction is to lubricate the surfaces that cause friction. Lubrication is an essential part of pinewood derby racing. Purchase a tube of dry PRO Graphite with moly and shoot it onto the axle shaft and inside the wheel bore. Spin the wheel so the graphite works in.

The car needs to be aerodynamically sound on both the top AND bottom. Any holes or cavities should be covered with vinyl, packing, or foil tape to reduce drag created by air catching in these features. The wheels are a significant source of drag.

No need to get crazy here, but simply having a wedge-shaped Pinewood Derby car instead of the standard block out of the box will equal a 1.4-car advantage at the finish line.

The sections are continuous, but the exact equation of motion on each part of the track differs. Throughout the entire motion of the car, the car experiences a number of forces. These forces include gravitational force (weight), normal force, drag force, and frictional force exerted on the wheel as a moment.

The Speed of Pinewood Derby Cars

The distribution plot below shows a range of speeds from 177 mph to 229 mph, with most cars exceeding 200 mph.

The farther the car drops (gravity), the more energy it releases and the faster it will go by the time it reaches the flat portion of the track. If the weight is placed towards the back of the car, it has longer to "drop" (by several inches) than if the weight is placed towards the front of the car.

Bending wood is a two-step process: first, softening the wood, then forming it. Steam or very hot to boiling water are good agents for softening wood. Wood can also be softened by creating multiple cuts on the back of the wood using a saw. This method is called kerf-cutting.

No wet lubricant is allowed. (Ex: NyOil, NyOil II, WD-40) Only one lubrication is allowed before the beginning of the first race, and then once again before the beginning of the first race of the semi-finals and finals.

Can you use glue on Pinewood Derby car? ›

Use an epoxy or nonresin glue, and make sure you don't get any on the surface of the axle where the wheel rides.

No loose materials of any kind (such as lead shot) are allowed in the car. No bent axels, and all 4 wheels need to be on the track. Once a car passes inspection and is entered into the race, only race committee members can touch it.

This spoiler, engine and exhaust pipes can be glued to just about any pinewood derby car. The parts in these kits can be painted to match the color of your car or polished for a chrome like finish.

Can a pinewood derby car be shorter than 7 inches? Yes, you can make your car shorter but it is not recommended. A shorter car will have a lower center of mass at the start so it will have less energy to convert into speed when going down the track.

To reduce drag even further, make your car as flat as possible. Try to use as few sharp edges on your car as possible, and make sure your front and rear windows are as smooth as possible. Finally, use as much aerodynamic material as possible.

As a Pinewood Derby® car speeds down the track, it has to move the air it encounters out of the way. This pushing of the air creates drag and slows the car. Therefore, with all other things being equal, a car with the smallest area pushing against the air will be the fastest.

This uneven or turbulent air movement that will slow the vehicle down is called drag. Vehicles have less resistance if they are rounded in the front and tapered off to a point in the rear (teardrop shape).

The most aerodynamic shape in nature is a teardrop, it has a drag coefficient (Cd) of 0.04. This is the reason why so many aerodynamically efficient cars often look like a well-used bar of soap.