- Jan 15, 2001
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background: I am a senior computer engineering major and my part of this competition was the finish line detector. This is our 2nd annual race and it went WAY better than last year.
The finish line detector is using a circuit board I designed to decide who won. There is a laser pointer bouncing off of mirrors horizontally across the track right where the blue light is seen, which terminates on a photodiode. If anyone cares or is interested in the board design/circuit, I'll post pictures.
The cars are made out of standard pinewood derby kits but modified to fit a B6-4 rocket engine. The track length is 115 feet and the average velocity is around 150mph by the end of the acceleration. The track is gutter downspout with a line cut through each piece, which is used to hold the cars down rollercoaster style with a nail and washer. The joints are smooth and the track is level (but not very straight unfortunately) so for the most part the only real unfair aspect is the differing ignition times. It's all for fun, though, so it isn't a big deal.
Anyway, here is the video. I thought ATOT might enjoy this. For your viewing pleasure, I cut out everything from the video except the races. It's basically my version of cliffs.
Last tidbit of information: The detector has a resolution of 62.5ns, which means if the cars are going 150mph at the finish line, it can accurately detect the winner by a separation of 1.7/10000 of an inch, or 5 times thinner than a normal trash bag.
The finish line detector is using a circuit board I designed to decide who won. There is a laser pointer bouncing off of mirrors horizontally across the track right where the blue light is seen, which terminates on a photodiode. If anyone cares or is interested in the board design/circuit, I'll post pictures.
The cars are made out of standard pinewood derby kits but modified to fit a B6-4 rocket engine. The track length is 115 feet and the average velocity is around 150mph by the end of the acceleration. The track is gutter downspout with a line cut through each piece, which is used to hold the cars down rollercoaster style with a nail and washer. The joints are smooth and the track is level (but not very straight unfortunately) so for the most part the only real unfair aspect is the differing ignition times. It's all for fun, though, so it isn't a big deal.
Anyway, here is the video. I thought ATOT might enjoy this. For your viewing pleasure, I cut out everything from the video except the races. It's basically my version of cliffs.
Last tidbit of information: The detector has a resolution of 62.5ns, which means if the cars are going 150mph at the finish line, it can accurately detect the winner by a separation of 1.7/10000 of an inch, or 5 times thinner than a normal trash bag.
Also what was in the box at the finish line to stop the cars? This looks really fun!!! 
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