System Design Project (Biodegradable Rally Car)

To design a car model that is built entirely out of biodegradable parts and have the ability to move down a ramp.  Definitions of these specifications are as follows.

Biodegradable: Capable of being decomposed by biological agents, especially bacteria. 

Car Model:  The car model must be a minimum of 5 inches long, 2 inches wide and 2 inches tall.  The car model cannot exceed the maximum dimensions of 10 inches long, 6 inches wide, and 6 inches tall.

Ramp:  The ramp will be approximately 6 feet in length with a 55 degree angle.  The car should have the ability to move freely down the ramp with the power of gravity and no initial, or extremely limited, momentum.

The planning phase has been complete and the car model will need to be completed and tested on Monday, May 16^th.  The PERT diagram below is a suggested timeline for this project.

Design:  During this phase one needs to think, brainstorm, sketch, and write down thoughts and ideas.  At the end of this phase the general structure of the car should be thought through, and plans to build it are made.

Finishing the Report:  During this phase this report is to be finished.  Please fill in the sections designated in the report.

Implementation: This phase is over 2 days, but could be condensed to one.  The implementation phase is the building of the car, and involves going to the grocery store to purchase materials.  Then the car should be built right before the testing phase so as to avoid rotting of the biodegradable materials.

Testing:  The car should be built before coming to class.  During this phase the car is to be tested to view if meets the specifications above; the car will be inspected to make sure that all parts are biodegradable.  A ramp will be placed in the classroom and the car will be tested to see if it can roll down to the bottom with limited initial momentum. Furthermore, the cars will be timed, and the fastest time will receive a prize.

The output for the analysis phase is a system requirements report.  The requirements for the car model are as follows:

• All parts of the car must be biodegradable.  We will define biodegradable further by saying that a substance is considered biodegradable if it can decompose within 1 year.  If you are unsure if something is biodegradable look it up on the web; a helpful website is http://en.wikipedia.org/wiki/Biodegradation

Biodegradable matter is generally organic material such as plant and animal matter and other substances originating from living organisms.  Some biodegradable substances are:

food products                   sugar cane pulp products             biodegradable paper cups

If you know something will be questioned as to its biodegradableness please bring proof that it will biodegrade in a year, such as the products packaging, or research you found online.  Also write this into the design section of the report.

• The car must be within the size limits.
  • Minimum size is 5 inches long, 2 inches wide and 2 inches tall. 
  • Maximum dimensions of 10 inches long, 6 inches wide, and 6 inches tall.
  • The car must have the ability to move freely down a ramp with gravity being the only force.  Number of wheels or sliding mechanism is up to the designer, but the car must move.

In the design phase one must identify potential solutions, evaluate those solutions, and select the components to be used.  Therefore you must come up with at least 2 solutions to the design of the car, analyze those solutions, and then use the best choice.

Solution 1:  [Write a design for the car here, you can also sketch out your design]

Butternut Squash car. Use an appropriately sized Butternut Squash for the body as it has a fairly hard shell to hold the axle hubs secure. Use a pasta (Penne Rigato) for the axle hub to allow the shaft to turn easier. Use jawbreaker suckers (round) for the wheel and axle hubs.  (I would use either round suckers or perhaps some hard candy if I can find a suitable one.

Solution 2:  [Write a design for the car here, you can also sketch out your design]

My second Idea is to mold a car. Using sugar and melted marshmallows I would make a slurry and then either press mold it into a form or shape it by hand. I could design it to be any shape I want and once frozen or dry It should hold it’s form well. I would use the spaghetti axle’s and oreo wheels.

Now use the chart below to fill in and evaluate your 2 solutions.  In order to change the chart just double click the chart, and to stop editing it just click anywhere outside of the spreadsheet.  Reference your book pages 579 for more information about the chart.  You will need to fill in the last 2 criterion with what you feel is good criterion, also feel free to change the other criterion that are given.  Then you will need to make a Raw Score from 1-10 based on your assumptions about your 2 designs.  Note that the Excel table is already set up to calculate your weighted scores.

[Now explain your decisions about the Raw Scores given for each solution in a brief paragraph.  Then explain which solution is your choice, how it meets the criteria, and why it is the best solution.]

I thought the Butternut squash would be a little easier to build and more fun to detail overall. I chose it based on the ease of carving I thought I could make a more functional design. As well as add some elements of humor.

[Here you will explain your design, it needs to be a minimum of 2 pages in length and include a diagram or sketch of your car design.  Please describe the following]

Design Methodology: [Why you chose certain aspects of your design.]

Well, the car I chose is the Butternut Squash car. It has a fairly hard shell and I thought I could put wheels and fairly firm axles together for it. I plan to use spaghetti strands glued together with elmers and water to make a secure and solid axle. I plan to test out and try to find various cookies to use as wheels. These items will all be biodegradable. http://cloroxconnects.com/posts/7db6c2fcfe

The main body is a butternut squash, It is a fairly simple plant about 8 inches long and 4 inchs around.

I found a squash that was fairly level on the ground and carved out fender slots for the wheels to go.

After some errors in the initial design and a few mockups (prototypes) I finally decided to try a staggered wheel design. The main problem is that I could not find a way to make a firm axle all the way across the squash and connect the two wheels. I tried spaghetti strands glued together but after a little while the moisture from the squash saturated the axle and it sagged. No joy. I then tried suckers stuck up at a slight angle to let the weight of the car keep them in and roll but it does not roll very well. So I finally went back to the carved squash and drilled more holes and staggered the wheels for the car. The weight was too high so I had to carve out most of the interior to get the weight down.

The butternut squash is fully biodegradable and the suckers are sugar with a hard paper stem so they will deteriorate fast.

Sketch: [Make a diagram of your car, this can be made with software or drawn by hand]

I first tried the alternate suggestion over the weekend. I found the sugar care with marshmallow to stiffen and secure it did not work at all as I thought It would. It ….slumped….slowly…..;-). It was not at all an acceptable solution.

The main car is as follows.

The main body is a butternut squash, It is a fairly simple plant about 8 inches long and 4 inchs around.

I found a squash that was fairly level on the ground and carved out fender slots for the wheels to go.

After some errors in the initial design and a few mockups (prototypes) I finally decided to try a staggered wheel design. The main problem is that I could not find a way to make a firm axle all the way across the squash and connect the two wheels. I tried spaghetti strands glued together but after a little while the moisture from the squash saturated the axle and it sagged. No joy. I then tried suckers stuck up at a slight angle to let the weight of the car keep them in and roll but it does not roll very well. So I finally went back to the carved squash and drilled more holes and staggered the wheels for the car. The weight was too high so I had to carve out most of the interior to get the weight down.

The butternut squash is fully biodegradable and the suckers are sugar with a hard paper stem so they will deteriorate fast.

As in any system after time your car will have to undergo changes and be maintained.  The car will only need to last to the end of testing and then can be maintained in your freezer or in the trash.