Rubber Band Powered Car 11 1.5 inches wide + launch + brake

baydood510 commented on my Rubber Band Powered Car #4 that his project was limited to 1.5 inches between the wheels as it had to run along a piece of wood 1.5 inches wide. That inspired me and gave me a few ideas. I am not trying to do his project, the car I have made this time is NOT designed to run along a piece of wood 1.5 inches wide, but I have made it so the wheels are less than 1.5 inches apart. I have also included a launch mechanism and a brake. Making the car as large as I did should make it easier to see these details. If I wanted to run along a piece of wood 1.5 inches wide then I would have to make the car much smaller and I would use smaller wheels. The main components are 4 x 45 rpm vinyl records (CDs/DVDs would work) 2 x 60 cm flower canes (previously I called these garden canes but I see the label says Flower Canes) Felt tip pens Milk Bottle tops Paperclips Rubber Bands Sticky tape The main tools are Hot Glue Gun Craft knife Hobby saw If you need guidance on making the CD wheels here is my old helpfile. /watch/e6KF1xGAewPc9ZyJMxv0v2BrSRPx2a5ALP=tsil?MrmfWuBjrRZjF Here is my old helpfile for putting rubber tyres on CDs /watch/e6KF1xGAewPc9ZyJMxv0v2BrSRPx2a5ALP=tsil?sxbCevnPunZPF Here is my old help file on connecting rubber bands /watch/e6KF1xGAewPc9ZyJMxv0v2BrSRPx2a5ALP=tsil?sbnkwdhuYbEuF Here is my Toy Cars playlist /playlist/PLA5a2xPRSrB3lGxxzEo_ZDnjnOtIlk50Q and my Rubber Band Power playlist /playlist/PLA5a2xPRSrB1otXh0w36OwsYIHZznUWp6 Rubber Band Powered Car #8 playlist /playlist/PLA5a2xPRSrB0zJ5RHjvsw46Mio6uJjF5_ 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 I cannot answer comments from people who have blocked replies, so if you don't get a reply to your question that may be the reason. It is probably worth reading my video description first because the answer may already be there. If you need a reply make sure your Google+ privacy settings allow replies from users that are not in your circles or add me to your circles first. Direct link: https://plus.google.com/settings Make sure "Who can comment on your public posts?" is set to "Anyone". I have over 1800 videos on YouTube covering a wide range of subjects. To find them follow my YouTube search guide /watch/wgcHOoOSBecSH or see my playlists /user/GrandadIsAnOldMan/playlists?flow=grid&view=1 Generally my projects are for my grandchildren to enjoy. OK, I enjoy them too. If anybody else likes them, that is a bonus. I like to keep my work as simple and basic as possible so that it can be copied easily and improved by anybody who wants to try themselves. I recycle or repurpose items rather than buy new and when I do buy I like to keep it cheap. /user/GrandadIsAnOldMan

Category