I made the car “Sling Shot” to enter in the recent 2012 Milwaukee “Nerdy Derby.” During a few initial test runs, my car proved to be more than 10 times faster than the super-clever winning car made by HaveBlue. Unfortunately, my car was banned from competition because it was considered a threat to the spectators’ safety! The consensus was that it had “too much momentum, or energy,” and would hurt someone if it went off the track and hit them. What does too much energy mean, you ask? Well, kinetic energy is ½ X Mass X Velocity^2. Really then, the car was banned because the velocity is too high: It is just too fast! I’ve already minimized the mass by making the car out of pine, although I could have made it from Balsa Wood, or even entertaining alternate materials such as these.
Anyway, its no fun to think of how to slow Sling Shot down so that its slow enough to safely race, but still fast enough to win. Instead, I made some new car prototypes that amp up the speed and danger. If I’m going to be banned in the future, I may as well get banned with style!
Below is a photo of Sling Shot, which traveled the 40′ track length is 0.1 or 0.2 seconds, for an approximate average speed of 300 feet per second, or 200 mph! Note that the block is anchored to the finish line, thereby stretching the surgical tubing which acts as a spring to propel the car.
I realized that the dominant energy loss mechanism is air resistance – largely because Sling Shot’s wheels don’t even touch the track. You see, the car doesn’t follow the contour of the track, it just heads directly to the finish line, through mid-air. I spent some time engineering a more aerodynamic shape to further boost Sling Shot’s speed, searching for a shape that would really slice through the air. I even consulted a team of highly trained German aeronautical engineer friends, who all approved of my slingshot propelled Henckel Car. With the improved aerodynamic design, it should easily be faster than the 200mph Sling Shot car shown above.
The other car I built this weekend is also based on Sling Shot, but incorporates some classy chandelier bulbs. The numerous ‘safety’ lights alert the time keeper of the imminent arrival of the derby car – for safety.
I made the car “Sling Shot” to enter in the 2012 Milwaukee “Nerdy Derby” at Barcamp7 this weekend. A lot of people were talking about adding motors and fancy electronics, but my car is powered by a spring – a 10 foot length of surgical tubing that is stretched to another block of wood that must be clamped down. I added wheels, but they aren’t necessary – they don’t actually even touch the track.
Check out what may end up being the only two runs the car has. Fortunately, JRock captured some video of them. I’d estimate that the car took 0.1 or 0.2 seconds to travel the 40 foot length of the race track, giving an average speed of 300 feet per second (200 mph!). The great part about this “sling shot” design is that the car is accelerated by the surgical tubing spring throughout the first 30 feet of the track – until the surgical tubing is completely unstretched. “Beautiful!”
The Great Milwaukee Race is a scavenger hunt/series of challenges across downtown Milwaukee that was started in 2010 by Fit Milwaukee and friends. This year’s event was put on by Fit Milwaukee, AJ Bombers and Performance Running Outfitters. In 2010, 50 teams of 2-4 racers competed in the inaugural race. This year 75 teams raced throughout downtown Milwaukee and along the lakefront to find all 10 of the challenge locations and get their passports stamped.
The post i made a couple weeks ago (I’m welding! I’m a welder now!) about my Ridiculously Large Jacks was a preview of the challenge that we would run at the race. After the initial batch of jacks was finished, Sean, Kevin, Adam and David helped me fine tune the game a bit in our hangar before the event itself.
Shane helped me run the event on race day and it worked like this:
Team would decode the clue to our location and decide on when they should come to our station.
When they showed up, they had to nominate two players.
One player was the bouncer and was in charge of bouncing and catching a kickball.
The other player (the grabber) donned a pair of gardening gloves and had to pick up the jacks.
On the first bounce, the grabber would have to pick up and hold onto one jack before the bouncer caught the ball.
On the second bounce, the grabber would have to pick up 2 more jacks while holding onto the previous jacks.
Repeat for 3 and 4 jacks.
The game only took a couple of minutes when done correctly, but some teams were faster than others. We also saw a variety of techniques. Some grabbers would try to stash the nearly 12″ diameter jacks under their arms. Some folks spread the jacks out between their hands and used them like claws to scoop up the remaining jacks. One women even stashed the jacks in her running shorts, but they were a bit heavier than she bargained for.
We were stationed at the underpass at water and pearson, across from Trocadero. After watching what was happening for a while, the Trocadero bartenders popped out to see what was happening up close. We invited them to play a game and they did pretty well! Another couple came by to watch and started laughing at the silliness they saw so we invited them to play as well. They had a few close calls with some wild bounces, but took care of the round with only a couple of do-overs. They looked pretty happy by the end of the game.
We heard really good feedback from racers and the organizers of the event. The game was odd enough to give people pause before they jumped in, but easy enough that it could be completed in a couple of minutes. The fun we had with this has led us to discuss making some more oversized games to bring to parks in the area. Stay tuned for more info on this front.
Thanks again to Fit Milwaukee and the other Great Milwaukee Race organizers for letting us be a part of this event and thanks to the racers for being such good sports!
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