Colorado State University - 1983
 

Objective

Provide the opportunity for students to compete for prizes, fame, and glory by desiging and building a vehicle to achieve the following objetives. Each tank will: travel down an inclined plane in a minimum amount of time, stop within a specified area, and fire a projectile to a target. The basic thought, while designing this contest, was to keep the vehicles as simple as possible, thus encouraging the greatest participation.

Overview

The course consists of a 2 ft wide by 16 ft long ramp, inclined at 20 degrees. Two photocell sets will measure the time it takes for the tank to travel 12 ft down the ramp.  A 2.5 ft high wall is installed at the bottom of the ramp, and the target is placed 10 ft beyond this wall.  An area in which the tank should stop, called the stopping zone, will indicate the accuracy of the vehicle. The accuracy of the projectile and launcher system will be determined by a bulls-eye target.

Specifications

The Contest Prizes will be awarded to those students whose tank achieves the lowest "Operation Score" (S), as calculated from Equation 1.

   S = ? (3t + 4R + D)        [1]

Where: S = Operation Score
 t  = Elapsed time (sec)
 R = Distance tank extends outside of the stopping zone boundary (in)
 D = Distance projectile lands away from target (in)
and the summation indicates the sum over the number of tank runs.

The elapsed time (t) is measured in seconds. The distance (R), will be measured normal to the stopping zone boundarys and parallel to the ramp surface, in inches. If any part of the tank should extend over a boundary, or over a corner of the stopping zone, all extending distances will be measured, but only the greatest value will be chosen for R (Fig. 2). The distance between the projectile's first impact and the targed (D), is also measured in inches. Dimensionless parameters have been carefully applied to Equation 1 so that Score (S), has the units of fame and glory!

All tanks will make 2-4 runs, depending upon the number of entrants, and the lowest total score will determine the winner. The lighest tank weight will break any ties. Awards will also be given in the categories of: (1) Simplest Design, (2) Manufacturing Quality (Workmanship), and (3) Most Innovative Approach.

The Ramp

The 16 ft long surface of the ramp is constructed from one 4'x8'x3/4" sheet of compressed clipboard or particle board cut lengthwise (this is not plywood). The ramp is inclined at an angle of 20 degrees from the horizontal and is level across the surface. The starting line is 1.5 ft down from the top of the ramp and is the position of the first photocell. The second photocell, and the top boundary of the stopping zone, is 12 ft down from the starting line, See Fig. 1. All photocells are 3 inches above the ramp surface.

The dimensions of the stopping zone are 1.25 ft wide by 1.5 ft long. The zone boundaries as well as a centerline will be inked onto the ramp surface. A 2.5 ft high veritcle wall is attached to the bottom of the ramp. The target is 1 inch in diameter and placed 10 ft from the ramp side of the wall on the centerline.

NOTICE: BECAUSE OF THE SCORE EQUALTION, THE STOPPING ZONE SIZE OF 15" X 18" LIMITS THE SIZE OF YOUR TANK! HINT 1, YOU MIGHT WANT TO MAKE IT EVEN SMALLER, DEPENDING UPON THE ACCURACY OF YOUR TANK'S ROLLING AND BRAKING SYSTEMS. HING 2, THE CONSTANTS OF EQUATION 1 PUT APPROXIMATELY EQUAL WEIGHT FOR TIME (t) VERSUS PROJECTILE ACCURACY (D).

A 1/8 inch thick by 16 inch wide sheet of aluminum will project 4 inches above (and normal to) the ramp at the starting line. This mechanism will release a tank by dropping through a slot cut through the ramp.

The Tank

1) Devices that penetrate or abrade the ramp surface may not be used (e.g. sandpaper pads on the ramp surface many not be used, but rubber pads may).

2) Chemical or incendiary devices may not be used.   However, the small CO2 pressurized cartridges may be included within your tank design if adequate safety precaustions are taken. Be aware that these devices can be dangerous if not handled properly.

3) No human intervention permitted once the tank is released, nor active external control of the tank during oepration (e.g., no control or guide wires, remote controls, etc.)

4) External aiming and positioning devices may be used during the set-up period but the ramp and target area must be clear of all devices before releasing the tank. (No homing units or cruise missiles!)

5) Minimum projectile dimetion, in any direction is 3/8 inch. Maximum projectile dimension, in any direction is 1 inch (i.e. it does not have to e spherical).

6) All measurements (R, D) will be taken when all motion ceases.

7) For expediency, a setup period of 90 seconds between the time the entrant is called and the time the tank is released will be imposed. Please have your tank rady when called (and a good pit crew if needed).

8) A maximum of 4 minutes is allowed for each tank run (a run is between the time of release and when all motion ceases.

9) Vehicles do not have to be stopped before firing projectile. The projectile may be released from any point on the course.

10) The wall can be considered to be completely rigid.

11) Judge decisions are final

12) Limit 3 tanks per school.
 

There are hundreds of ways to achieve the objectives, as well as the fame and glory! We found: 5 ways to improve he time part of the score; 8 ways to improve accuracy; 6 different projectile mechanisms; and over 15 stopping systems. We are looking for good examples of creative engineering, but when in doubt, the simpler idea is usually the better.