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Mousetrap Vehicle ‘12

Bro. Nigel Pratt bronigel@kellenberg.org Mr. Dennis Papesh papeshdr@holyangels.cc. Mousetrap Vehicle ‘12.

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Mousetrap Vehicle ‘12

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  1. Bro. Nigel Pratt bronigel@kellenberg.org Mr. Dennis Papesh papeshdr@holyangels.cc Mousetrap Vehicle ‘12

  2. DISCLAIMERThis presentation was prepared using draft rules.  There may be some changes in the final copy of the rules.  The rules which will be in your Coaches Manual and Student Manuals will be the official rules. WARNING!

  3. http://www.youtube.com/watch?v=Hqc9uexNL64 • The rules ARE very similar to what we have had with Wheeled Vehicle and Battery Buggy in the past. • WANNA WIN??? • Design your vehicle to…. • GO FAST • G0 STRAIGHT • GO A PRECISE DISTANCE • ….AND DO IT ALL CONSISTENTLY!!! This Year….

  4. Obviously, to go down a predetermined length track as fast as possible, predict its time, make it go straight as possible and stop on a dime….or at least the finish line!!! Goal….. (THIS CAR IS ILLEGAL FOR THE YEAR 2012!!!)

  5. Only one unmodified snap mousetrap (base must be < 6 x 12 cm) may be used as energy sources. • Unmodified means that all the original parts of the mousetrap(s) remain in place. • Things may be added to the mousetrap(s), but not removed. Careful, see rules!!! • They could be single spring or multiple spring mousetraps. • Holes (up to 4) may be made in the base, but only for attachment purposes. Parameters

  6. All parts of the vehicle must move as a whole, i.e. no anchors, tie downs, tethers, launching ramps, or other separate pieces are allowed. • All of the vehicle’s kinetic energy must originate from the mousetrap(s). • Conversion of the mechanical energy of the mousetrap(s) spring is permissible, but any additional energy sources must be at their lowest states at the beginning of the run. • Things can’t be added to increase its PE. Parameters (cont’d)

  7. The vehicle must have a “fixed point”. It must be a bent paper clip that extends down to 1.0 cm of the track’s surface. This fixed point will be used as the reference point on the vehicle for distance measurements. It MUST be easily accessible for the Event Supervisor. Parameters (cont’d)

  8. The entire vehicle must fit in a 100 cm x 35.0 cm box in ready to start mode. • There is no restriction on the vehicle’s height. Parameters (cont’d)

  9. Sighting devices which do not use electricity are permitted. All sighting devices can be removed from the vehicle before it does its runs. • A trigger must be built in that can be activated by using an unsharpened #2 pencil (to be supplied by the Event Supervisor.) The action must be up or down. • Besides the wheels, only the drive string is permitted to contact the floor at any time. Parameters (cont’D)

  10. The competition will be on a straight and level lane with a relatively smooth, hard, low-friction surface. • 1” Tape will be used to define the track’s starting line (which will be 1 m in length), a center line and a finish line. The track

  11. Starting Line Finish Line Centerline Tape Target Distance 10 m: Regionals 8-12 m (1 m inc): States 8-12 m (0.5 m inc): Nats The Track

  12. The students can chose to start their vehicle anywhere along the Start line. • A target may be placed on the track to aid in aligning the vehicle, but must be removed before starting each run. The competition

  13. The vehicle must be able to remain at the starting position without being touched until the trigger is released using a pencil, pen, dowel, or similar device. • which is not a part of and does not travel with the vehicle • It is considered a run if the vehicle moves any distance after the trigger has been released. • So if it doesn’t move, it’s not a considered a run. The competition (cont’d)

  14. The students may not push the vehicle nor will they be allowed to constrain the vehicle during release. • Once the vehicle is started, the students must stay behind the starting line until summoned by the Event supervisor to retrieve their vehicle. vehicle. The competition (cont’d)

  15. Teams will have 10 minutes of Event Time in which to get two runs started. • The Event Time will begin when the Event Supervisor finishes his instructions to the students. • Time needed for the Supervisor to take measurements after the first run will NOT be part of the Event Time. • If the second run has started before the 10 minute period has elapsed, it will be allowed to run to completion. The competition (cont’d)

  16. Teams may not follow their vehicle down the track. • They must wait until called by the Event Supervisor to observe their finish distance and pick up their vehicle. • At this point, the Event Time will resume. • Students may take any measurements and make any adjustments to their vehicle. But they cannot change their prediction time. The competition (cont’d)

  17. Measurements made by the Event Supervisor are the only ones that will be used as the official distances. • Teams who wish to file an appeal must leave their vehicle with the Event Supervisor. The competition (cont’d)

  18. The RUN SCORE will be the sum of the Distance Score + Time Score + Center Line Bonus + Predicted Time Score. • LOW SCORE shall determine the winner. scoring

  19. The Distance Score is the distance from the fixed point to the Target Line in millimeters. This is a point to line measurement. • The Time Score is 10 times the official Run Time measured in seconds (to 0.01s accuracy). • A Center Line Bonus of -20 points is awarded if the center tape remains completely within the vehicle’s track (the Center Tape is not visible outside of any wheel) while the vehicle travels between the start and finish line as determined by the fixed point. • The Predicted Time Score is 10 times the absolute value of the difference between the Predicted Time and Run Time Scoring –

  20. If the vehicle starts moving in the wrong direction, it is considered a “failed” run. • If the vehicle is inadvertently started, it is considered a “failed” run • If the vehicle does NOT move after being triggered, the students can try again. Failure to move will not count as a run. Scoring – Run violations

  21. There will be 3 tiers of scoring • 1: A clean run. • 2: Any run which has a run violation. • 3: Any run which has a construction or a run and construction violation. • If the device cannot start one run or has 2 “failed” runs, the team will receive participation points. Scoring – Tiers

  22. 1st Tie Breaker • The team with the lower Distance Score of the counted run. • 2nd Tie Breaker • The 2nd Run Score Scoring

  23. So for a basic construction: • http://www.youtube.com/watch?v=OOobN0bUxqs&feature=fvw • Things to consider and discuss • Dimensions of the vehicle • Keep in mind: KINETIC ENERGY • Mass, friction, efficiency of energy transfer • Experienced coach Wisdom re: rulers • Experienced coach Wisdom re: axles So how do you make a good one?

  24. Wheels • # - 3 wheeled v. 4 wheeled • Type – Rubber, balsa, plastic (DVD’s), etc… • Diameter – Should both axles have the same size wheels? • Thick v. Thin • Energy Transfer: How will you transfer the energy of the spring to the axle for maximum speed? • Directly v. Indirect (spring, rubber band) • Torque issues are very important here – Axle thickness • The thicker the axle, the faster the vehicle!!! • Do you want to have the energy delivered very fast to the wheels and use momentum to travel down the course or should the energy be applied at a constant (but slow) rate to the wheels?

  25. Squeeze out EVERY mJ you can….

  26. Mousetraps – Check different manufacturers (Victors, Tomcat, Bonide, D-con, Snap E, Clean Catch, etc…) for Spring Constant – which has more energy to deliver?? • Suggestion: Design the vehicle for quick mousetrap replacement. Velcro, wire ties, etc…. • String issues • entanglement, “free string” getting caught in the axles/wheels • Type – String that stretches or doesn’t • Release mechanism – the string needs to go free!!! • Length of drive arm – short v. long • Please, please forgive us for the following… • http://www.youtube.com/watch?v=wZDSfRe5opo • Let’s take a moment and brainstorm!!!…..

  27. Ideas: • Long drive arm v. short drive arm??? • Torque and wheel diameter • Use the string to act as brake • Use the wing nut/axle brake • http://www.youtube.com/watch?v=RJwFtkFSuJM

  28. For a very basic kit, go to http://www.docfizzix.com/ • He also has a book: http://www.docfizzix.com/how_work.htm • Watch out for….. • Recoil: Choose the right string, or plan on a brake that will stop it on a dime. Don’t allow it to shake back and forth. • Aim: As the competition gets more intense, the difference of just a few cm will drastically affect the results. Use “sights.” and a target. • SPEED. SPEED. SPEED. SPEED. • Build cleanly and solidly!!! • PRACTICE. PRACTICE. PRACTICE. • Know the quirks of your vehicle • Find out what type of surface the competition will be on.

  29. (a lot of these are based on last year’s (Div. C 2011) rules where the vehicle had to reverse and come back.) • Uses one mousetrap each way: • http://www.youtube.com/watch?v=sIqMcze4034 • Uses both mousetraps simultaneously • http://www.youtube.com/watch?v=lkgQYco0-5g • http://www.youtube.com/watch?v=IA1JPcdBkHE • http://www.youtube.com/watch?v=q1Rr1vZLSvg Some Good Moustrap Videos…

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