Fitting brake and launch mechanisms to Rubber Band Powered Cars

I was asked 2 questions about my Rubber Band Powered Cars by Mira Yang and I have produced this video to answer them. I believe the questions were 1. How to fit a launch mechanism 2. How to fit a brake. I have now modified my Rubber Band Powered Car #8 to fit the launch mechanism and the brake. I did the work on #8 because this is the model that I have used to try to answer all previous questions I have received. Some helpfiles Making the CD wheels /watch/MrmfWuBjrRZjf CD Wheels with Cardboard Hubs /watch/ETGI2ntr1sJrI Putting rubber tyres on CDs /watch/sxbCevnPunZPC Connecting rubber bands /watch/sbnkwdhuYbEuk Connecting the band to the axle /watch/QJFUolxYPw0YU Here is a selection of related playlists Toy Cars /playlist/PLA5a2xPRSrB3lGxxzEo_ZDnjnOtIlk50Q Rubber Band Power playlist /playlist/PLA5a2xPRSrB1otXh0w36OwsYIHZznUWp6 Rubber Band Power Cars /playlist/PLA5a2xPRSrB3g5RiX8Kf_uUBOL0Tb7AS0 Rubber Band Power Car #8 /playlist/PLA5a2xPRSrB0zJ5RHjvsw46Mio6uJjF5_ Rubber Band Power Car Back to Basics /playlist/PLA5a2xPRSrB3WKst8ubr8A_eAPMQlPGw- RBPC for Snowman plays247 /playlist/PLA5a2xPRSrB0F2PNcApzXxp_nFkUjnCMt Other People's Rubber Band Cars /playlist/PLA5a2xPRSrB0dbQ1TpU4qJx4m85zK7MFa Rubber Band Powered Boats /playlist/PLA5a2xPRSrB1Pi_dNuFbsZd8q2G_zyjFS Rubber Band Power Planes /playlist/PLA5a2xPRSrB1iBkfCc2jzfTK6LA9Sh7vi Some of the cars in this playlist stop or drop an object at a specified distance, you should be able to work out a general idea from watching them. /playlist/PLA5a2xPRSrB04L6RpUAs5akmK3jqmahPL Getting the distance right, the main issue is the ratio of the axle to the wheel circumference magnifies any minor inaccuracies. The exact length of the string is critical if you need accuracy, it is wrapping round your axle so each revolution of the wheel wraps up a relatively small length of string. Here is some maths and I apologize if this rambles a bit and I may lose you, I am not a maths teacher. The circumference of a circle is pi x diameter A CD is about 5 inches in diameter so the circumference is about 15.7 inches. If you are using a CD for the wheel the car travels about 15.7 inches or 37.7 cm for each rotation. If you are using a bbq skewer as the axle let's say it is about 5mm diameter so it's circumference is about 15.7 mm This means for every turn of the wheel the car travels 37.7 cm but only wraps 15.7 mm of string. When the car travels 5 metres 5/37.7 gives you 13.26 revolutions 13.26 x 15.7 mm = 208.182 mm of string Put another way (37.7 centimetres) / (15.7 millimetres) = 24.0127389 so any inaccuracy in your string is magnified 24 times. 1 cm stretch would be equivalent to a 24 cm over-run. If you are using thicker string and it wraps over itself as it winds up that changes the diameter significantly so the amount wrapped with each turn changes. If you get any wheel spin then that will cause you problems too. Just moving the wheel a quarter of a turn when adjusting it on the start line would make 9 cm difference in the run. Let's say the distance your trigger mechanism or release lever travels before releasing the load is just 5mm so 5 x 24 is 120mm traveled by the car. The bottom line is that this method has lots of drawbacks. I put this playlist together of other people's brake mechanisms. /playlist/PLA5a2xPRSrB3MyidvKMT3DqU1vNy9Atsf My Channel page /c/GrandadIsAnOldMan Oldest videos /c/GrandadIsAnOldMan/videos?flow=grid&view=0&sort=da Most Popular /c/GrandadIsAnOldMan/videos?sort=p&flow=grid&view=0 Newest videos /c/GrandadIsAnOldMan/videos?sort=dd&view=0&flow=grid Playlists /c/GrandadIsAnOldMan/playlists?flow=grid&view=1 Facebook https://www.facebook.com/grandadisanoldman/ Merchandise - Check both of these links if you are interested as the prices will vary and the shipping charges will be different. http://www.redbubble.com/people/grandadiaom/portfolio http://grandadisanoldman.cottoncart.com/ I have thousands of videos on YouTube, to find one try my search guides /watch/wgcHOoOSBecSH or /watch/kRYwkwgU4jZUw My "GrandadsOtherChannel" channel is generally where I will host the videos that give extra detail or longer versions of the videos I post on my main channel /c/GrandadsOtherChannel

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