Rocket Cars

Synopsis

This project will involve creating a set of rules and guidelines for HSL-sponsored Rocket Car races (fiascos?).

Examples From the World Around Us

• http://blog.makezine.com/archive/2010/04/rocket_powered_car_races.html (where the idea was sparked)
• http://www.rocketcarday.com/ (better videos from the same event Make picked up on)
• http://www.instructables.com/tag/?q=rocket%20car&sort=none (slew of 'ibles surrounding rocket cars)
• http://www.maximum-velocity.com/rocket_cars.htm (simple design, and available for purchase. Specifically, note how the car has eyehooks *on the bottom* for the string-track.)

Parts

Car

1. A model rocket engine
   1. Typically, a C6 engine is used.
   2. Whether or not to use an engine with an ejection charge is up for debate. On one hand, not having a small explosion at the end is safer, but we could have a lot of fun watching cars inadvertently explode :)
2. A car or some other wheeled vehicle
   1. In the cheapest and jerry-rigged fashion, a Hot Wheels car and a zip-tie were used.
   2. In a more elegant and creative fashion, custom vehicles are designed.
   3. Pinewood Derby cars might be a good place to start.

Track

1. Guides
   1. Single Guide-wire
      1. This allows the cars to stay on a straight line.
      2. If the car is imbalanced or too small, it can spiral around the wire.
   2. Double Guide-wire
      1. Prevents spiraling while the car is in motion
      2. Adds extra friction and ability for the car to jam, if a car's connectors aren't aligned properly
   3. Guide Positioning
      1. Side(s)
         1. Works for both single and double guides
         2. Probably the best layout for double guides. A single on the side encourages barrel rolls
         3. Potentially limits the width of the car (lane size notwithstanding)
      2. Top
         1. Usable with single/double guides
         2. Limits the height of the car
      3. Bottom
         1. Certainly a more "traditional" track feeling.
         2. Requires minimum ground-clearance
         3. Helps eliminate the chance of rolling/spinning when using a single-guide, if the wire is taut.
   4. Material
      1. Wire. Durable, fairly rigid, and won't burn up from the exhausts
      2. String. Cheap, easily replaced. Flammable.
2. Mounting
   1. 2x4 start and finish lines
      1. dirt cheap, and easy to work with
   2. L-Brackets for suspending the guides
      1. metal, sturdy, easily attached to 2x4s
      2. Doubles as a blast plate at the starting line
   3. Eyehooks
      1. Small, cheap, easy to tie things to.
      2. Does nothing to contain exhaust at launch time.
3. Eye-Candy/Extras
   1. Photogates
      1. tied to a computer, can provide data regarding velocity, acceleration, accurate time trials
   2. Finish Line Sensor
      1. Simple set of switches to indicate 1st, 2nd, 3rd places. Arduino, small tactile pushbuttons, and some LEDs would easily accomplish this.

Launch Mechanism

1. Requirements
   1. Need a way to fire off multiple rockets simultaneously.
      1. Make Volume 20 had a "Mega Launcher" from a boyscout troop. Pops 10 at a time (or individually) Schematics: http://makezine.com/20/megalauncher/ (Nate has all the parts to make this. consider 'em donated!)

1. Extras
   1. A digital countdown timer would be sweet
      1. The Mega Launcher has a countdown buzzer, I believe. A digital clock could easily be inserted

Rules

1. Use Common Sense
   1. If it looks unstable and unsafe, it probably is. Participants should decide as a group if a questionable car should race or not.
   2. Test your car, first. A simple track can be built at home pretty easily.
2. 3 Wheels
   1. In order to qualify, a minimum of three wheels must be on the ground a majority of the time. Bumpy asphalt can cause cars to jump and bounce, but it should be pretty obvious if a car is out of control
3. One Engine
   1. No tandem or multi-stage engines, period.
4. Car Size/Weight
   1. This is up for debate. The prior rules pretty well dictate how cars should be built. (Nate's opinion is "anything goes.")