Mission Possible C. Kevin Kha

Transcription

1 Mission Possible C Kevin Kha Disclaimer: This presentation was prepared using draft rules. There may be some changes in the final copy of the rules.

2 Overview Build a machine to accomplish a certain task via a series of (unrelated) steps. Team of Up to 2 Can Bring: Device, Tools, Data, Documentation Impound Required At State and Nationals Only Eye Protection C Required Mission Possible C

3 Basics of This Event 30 minutes to set up device (for points.) Start Task: Detach & remove a magnet from the device. Final Task: Activate a recording that plays The End. Target Time for device to run to completion; cannot have an electronic timer (any action powered by electricity that takes >10s). Mission Possible C

4 Changes From Last Year Simpler! Electronic components allowed now. 12 set, pre-defined actions. Mission Possible C

5 Coaching Tips Practice a lot. Simplicity and reliability are priorities. Make sure students learn IMA (Ideal Mechanical Advantage) Let students have fun ripping apart junk or trash or stuff to MacGyver some new stuff into their device. Students should plan (and maybe prototype/build) the individual Actions before assembling into the complete Device. Mission Possible C

6 Coaching Tips Safety precautions for electricity, flames, and chemicals allowed. Students should try to limit the size of flames they need. Devices should be designed to not make a mess (should not be baking soda, vinegar, sand, etc. left behind). Mission Possible C

7 Common Pitfalls No or incomplete Action Sequence List (ASL). Required for credit. Template can be found online! Device should also be numbered correspondingly. Building to the exact dimensions (or trying to.) Some piece of the device, nail, screw, etc. sticks out. Just build slightly smaller. Not knowing what IMA is. Parallel / Dead End Actions Mission Possible C

8 Design Tips Localized and labelled batteries and switches. Makes it harder for any accidents to trigger your whole device and require setting up again. Mission Possible C

9 Sample Devices and Designs Mission Possible C

10 Design Ideas Start Action The competitor must detach and remove a magnet from the device. The action of the competitor detaching the magnet must begin the chain of events due to the removal of the magnetic force. Magnet holds up some kind of weight. Weight drops.

11 Design Ideas 1 A chemical reaction that inflates a balloon so that the balloon strikes an object that is at least 20 cm away from the balloon, so that the action of striking the object continues the sequence of events. Classic vinegar-baking soda reaction. May need a lot to get a balloon to expand 20cm. Possibly those long, thin balloons might be more conservative?

12 Design Ideas 2 An endothermic action that begins the next action as a result of the reduction in temperature. Vinegar and baking soda is endothermic, but may not be enough. Can use cooling pack, but chemicals inside may be dangerous (i.e. leave them in the pack.) Cool a bimetallic strip (bends in response to temperature change), or trigger an electronic temperature sensor. May not need to be a chemical reaction, so a Peltier cooler might work. (Be sure to properly heatsink the Peltier or it can burn out.)

13 Design Ideas 3 An exothermic action that activates a photocell with the light produced from the action and begins the next action. Not necessarily a chemical reaction? Lighting a lightbulb (incandescent especially) or an LED is exothermic. Or light a candle.

14 Design Ideas 4 Uses electricity to light a candle and begins the next action. Nichrome wire (can be found in hair dryers and toasters) gets very hot when electricity is passed through it. Beware risk of burns when prototyping/testing this out. Rocket motor starters. *Sounds like this action leads perfectly to Action 3

15 Design Ideas 5 Use an infrared beam where the transmitter and receiver are at least 20 cm apart and begins the next action. May require buying the electronic components, and need some circuit experience. See a tutorial here:

16 Design Ideas 6 Use light to initiate a chemical reaction to begin the next action. Photoreactive chemicals are pretty dangerous I think and difficult to transport. Light + magnifying glass + match? (See laser policy.) Wild idea: UV LEDs photocatalyze the decomposition of H2O2, and use the O2 bubbles to do something. Keep away from flames.

17 Design Ideas 7 A Pulley system with an IMA of at least 7, that lifts an object that is at least 500g at least 10 vertical cm before the object initiates the next action. Self explanatory. Take note that the object has to initiate the next action, not the pulley.

18 Design Ideas 8 Use the mechanical advantage of all 3 classes of levers in sequence to begin the next action. Self-explanatory.

19 Design Ideas 9 A Pulley system that has an IMA of 0.50 that lifts an object that is at least 500g at least 10 vertical cm before the object initiates the next action. Self-explanatory, similar to #7.

20 Design Ideas 10 Flip a standard unmodified american quarter airborne so that it goes from heads up to tails up and begins the next action. Maybe drop a weight on a lever, which flips the coin, which lands on a mousetrap or button or something. May be the hardest action to attempt.

21 Design Ideas 11 A thermal reaction using the expansion of gas to activate the next action. Light a candle or use some nichrome wire to heat up some air. Syringe or balloon to take expansion of the gas. Flammable gases are prohibited; do NOT boil alcohol (lower boiling point, and flash point).

22 Design Ideas 12 Activation of a student made electromagnet that begins the next action. Wrap some wire around a nail. Use thicker wire, and beware of the electromagnet heating up quickly. If possible, add some switch to automatically deactivate the electromagnet once the Action is complete.

23 Design Ideas Final Task The device must play a recording of the phrase The End to signal the end of competition. This phrase must be clearly audible, and demonstrated for the judges prior to the run. Maybe one of those holiday/birthday cards that allow you to record a message.

24 Design Ideas Mechanical Timer Sand timer (sand pours onto a counter-weighted lever.) Amount of counterweight determines the length of time. Mechanical alarm clock. Design the rest of the device to have a repeatable, constant run time.

25 Resources _B _C Mission Possible C