Preliminary Design Proposal
Project Panda: Nkiru Agomuoh, Jonathan Applewhite, Yamani Miller, Matthew Jacobs, Kalada Abbey
Dr. Cannon
Background: The purpose of the assignment is to design and build a catapult that will throw a ping-pong ball and hit a bull’s-eye eight feet away using an energy source of only springs, rubber bands, and/or gravity. The target bull’s-eye is nine inches above the ground. Midway between the catapult and target will be an eighteen inch high obstruction. The ping-pong ball is to be catapulted over the obstruction and hit the bull’s-eye. The connections of the catapult can be secured with glue, screws, string or rope. Use of any metal is to be limited to connections or springs. The combined cost of the materials cannot exceed $25. Project success will be based primarily on the accuracy and safety of the device and secondarily on the catapult’s weight and aesthetics.
Design 1: Counterbalance
The ping-pong ball is placed in a cup on one end of a lever and a weight is attached to the other end. To launch, the end with the ping-pong ball is lowered manually and then released. Gravity pulls the weight on the other end down, bringing the opposite end up and launches the ping-pong ball.
Design 2: Tension
The ping-pong ball is placed in a cup on one end of the launch arm. The other end of the arm is stuck between a series string wound together and secured, at both ends, around winding dowels. To launch, the dowels are wound, creating tension in the string, which holds the launching arm in an upright position. When arm is then pulled back and released, it snaps back in to the upright position, launching the ping-pong ball.
Design 3: Rubber Band
The ping-pong is placed in a cup on one end of the launch arm. The other end is secured to middle of the base. A rubber band is secured to the base opposite the ping-pong. The rubber band is stretched up over a raised medium and back down to attach to the launch arm while in tension. To launch, the launch arm is released and the pulled up towards the medium by the rubber band. The arm is stopped by the medium, while the ping-pong ball continues forward.
Design 4: Rubber Band 2
This design is similar to design 3, except the rubber band is attached to the medium, so then tension is built over a shorter distance.
1 <- Worst………..Best -> 4
Accuracy (x5) | Safety (x4) | Consistency (x3) | Durability (x2) | Cost | Overall | |
Counterbalance | 3 (15) | 4 (16) | 1 (3) | 4 (8) | 1 | 43 |
Tension | 4 (20) | 3 (12) | 4 (12) | 3 (6) | 2 | 52 |
Rubber Band | 1 (5) | 1 (4) | 2 (6) | 3 (6) | 3 | 24 |
Rubber Band 2 | 2 (10) | 2 (8) | 3 (9) | 3 (6) | 4 | 37 |
Design Matrix Recap: Starting with the most important, our criteria were accuracy, safety, consistency, durability, and cost. Points for accuracy are multiplied by 5, safety by 4, etc. We graded the designs from 1 to 4; 1 being the worst, 4 being the best. Our conclusion was that the tension design would be the best design because though it didn’t score very high in cost, it scored high in all the other (more important) criteria and received the highest overall score.
Expected Cost: The expected cost for this project is a rough estimate derived from the prices from Home Depot. Home Depot is the place we plan to buy our prospective materials for this project; the list is outlined below:
Wood …………..… $8
Twine ………..…… $4
Screws …………… $6
Sandpaper ……....... $4
Tax………………... $2
Total ………….… $24
No comments:
Post a Comment