Ideas for Upcoming Design Projects

This is a place to list any ideas for projects throughout the year.  The goal is to use Energy as a common thread throughout all of the design projects, but it is ok to be flexible with that.

I have been trying to come up with things that can be used as a competition.  I think it helps to provide a realistic aspect of real engineering - the cheapest/most efficient/most functional design wins out. 

1. Bottle Rockets/Diet Coke  & Mentos cars - This focuses on the conversion of energy between potential energy (in the form of pressure) into kinetic energy (something moving).  Can turn it into a contest - see who can design the rocket that stays in the air the longest or who can design a car that travels the farthest with a fixed amount of "fuel".
2. Solar Heating Competition - We can use this as a way to talk about the different possibilities for creating solar energy.  One possibility is to focus the sun's energy on a single point to heat water and create energy from steam.  This provides a relatively inexpensive way to generate electricity from the sun and offers a way to store energy without having to worry about things like batteries.  The students could come up with a design for heating a fixed amount of water (say 500 mL) using the sun's energy to try and be the team with the greatest temperature change.
3. Perpetual Motion Machine - The students would come up with a design for an apparatus to swing an object (like a pendulum) for as long as possible.  The objective is to design a machine that will swing for the longest time.  I haven't really thought through this one completely, but it was an idea I had the other day. 
4. Rube Goldberg Machine Contest - (http://www.rubemachine.com/, http://web.mit.edu/museum/rubegoldbergcontest/2008/index.html ) These links are provided as a resource to get a better understanding of the Rube Goldberg Machine.  Also, there is a section in Pee Wee Herman (http://www.youtube.com/watch?v=rYyD55elKJA&feature=related) and Family Guy too, apparently. The idea for this project will be to design 10 tasks that need to be completed and specify input & output conditions for each stage.  Then each group will have a stage that is responsible for accomplishing a single task and accepting the proper input and giving the appropriate output.  For example a stage could be defined as needing to be triggered by a spring at 10 cm above the ground, accomplishing the task of turning on a fan, and then trigger the next stage by cutting a string 30 cm above the ground.  This will take a significant amount of planning on our part - we'd have to come up with an overall machine design and then divide up the tasks (not necessarily make each stage, but know how we want to link the stages).  However, it would also teach some critical engineering concepts about working within a larger organization.  For example, engineers that work on microprocessors design only small portions of the total chip and are given input and output conditions and asked to accomplish some task, like adding two numbers together. This will also emphasize the importance of project management and provide an opportunity for the project managers to act as true managers.  MIT also has a competition for grades 7-9 where the students are given materials, a constrained space, and are told to accomplish a task.