Wheeled Vehicle

Wheeled Vehicle is a physics event in which the participants must construct a vehicle powered only by a non-metallic elastic solid device. The participants must be able to adjust the vehicle to travel a specified distance as chosen by the event supervisor and also be able to predict the time in which the vehicle will reach its defined destination.

Basic Construction Parameters
The vehicle should be designed to travel between 5 and 10 meters and stay inside a 1.5 meter wide lane.

The calibration intervals include: Regionals: 0.5 meters States: 10cm Nationals: 1cm

The vehicle must also be only powered by the energy stored in the elastic solid device and must be triggered by actuating a release mechanism with a pencil, dowel ,etc.

For more detailed rule clarifications see:

Designs
The most popular ways used to power devices are:


 * 1) rubber bands
 * 2) fishing poles
 * 3) bungee cords

You also will need a braking mechanism, so you can accurately stop. Here are some things to think about:
 * 1) It has got to be accurate
 * 2) Somewhat simple so that there's not a whole lot of room for error
 * 3) It has to be very reliable, so that it will work perfectly every time

Braking Mechanism
Another thing to think about is a braking mechanism, which is almost always built differently by each team to accommodate their vehicle. There are systems that you can easily adapt to your device. (for those of you familiar with Scrambler this part should be familiar to you) Before we go about discussing are braking mechanism, let's think of what we want to accomplish.
 * 1) Good accuracy
 * 2) A somewhat simple design so that there's not a whole lot of chance for error
 * 3) A relatively strong and reliable system. (Meaning we want it to stop essentially on the spot specified, and do this repeatedly with little to no error.

With this laid out, we know what we want and we can start designing a mechanism. There are many different kinds of mechanisms that have been used, so there are many other things you can use.

Threaded Rod and Nut
One of the mechanisms commonly used on a vehicle is the threaded rod and nut design. It has been used by many in Scrambler and Wheeled Vehicle, and is usually very reliable. The details of how you build it and how you implement it is up to you, but the general idea will be discussed. First off, you need a threaded rod a nut (preferably a wing nut) and something to hold the nut. So first off, we need to know how many revolutions of the wheel it will take for us to reach 10 meters. We do this by using the formula for the circumference of a circle, which in this case is our wheel: C=pi*diameter(of the wheel). After figuring that out (in cm), divide 1000 by the circumference and you will know the amount of revolutions of the wheel you will need to reach the maximum distance.

Here is a picture of a braking mechanism:

First, start by looking at the blue line which in this case is our axle (which is the threaded rod). The red line represents the wing nut, the green circles represent the wheels, and the green line is the rod that holds the wing nut in place. As the wheels and axle spin, the wingnut will move down towards the chassis between the wheel and the inner assembly. Eventually, this nut will hit the chassis and lock up the axle, preventing the car from traveling more. In order to use this system for calibration, all you would have to do is start the nut on the chassis and then wind it out to the distance you need thinking about how much distance you get per turn of the wheel you can easily figure this out using the formula above. AS you might have figured out, there is one minor flaw in doing this: you cannot turn the wing nut until you move that green rod in the diagram to make it removable.

Competition
For the competition, you need to wear goggles, and you may also bring any tools or computing device to assist you in calculating distance/time. The vehicle must be impounded before competition starts, and the event supervisor may not announce the target distance until the last vehicle is impounded. As said earlier, the competition will be in a 1.5 m wide lane and will be on a relatively smooth level corridor. Before you run the vehicle, you will be asked to predict the vehicle's travel time. This prediction cannot be changed for the second run. You will have a total of 10 minutes to run your vehicle. You will be able to trigger your vehicle once the supervisor indicates you may do so.

Helpful Links
http://www.soinc.org/events/wheeledveh

http://www.tx.ncsu.edu/science_olympiad/Event_information/Wheeled_vehicle/wheeled_vehicle.htm