Second thought... a falling weight that kick the sled and give it a big push to start? the weight can be from hard rubber so the maximum force can be apply to the sled with no damage to the sled. Tal -----Original Message----- From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Tal Sent: Friday, January 09, 2004 2:34 AM To: PICLIST@MITVMA.MIT.EDU Subject: Re: [EE]: Sled propulsion A firework maybe? Tal -----Original Message----- From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Jinx Sent: Friday, January 09, 2004 2:30 AM To: PICLIST@MITVMA.MIT.EDU Subject: [EE]: Sled propulsion Does anyone have suggestions (and hopefully practical experience) for methods of propelling a sled on a track ? Sled weighs about 500g, hopefully much less but it will be > 200g. Length of travel can be anything up to 2m. Shorter is better but not important. It's required that the sled reach full speed by the end of the track (obviously !). This speed needs to be accurately set from 10m/s to 45m/s My thoughts - Air (how would speed be regulated ? Bleeder valve ?) Electromagnetism (ie rail gun - ambitious ?) Things like shotgun cartidges are out. Driving force has to be something reasonably non-consumable (eg air, electricity) and that can be reset fairly quickly and repeatably, say within 20s Water would be too messy I don't know if motorisation in some form would work. For example direct drive with a stepper or clutching a flywheel At the end of the track I thought the sled could be sent down a downward curve, deccelerated with electromagnets or track braking and then travel upside-down in a loop to get back to the start position TIA ============================================== Research is what I'm doing when I don't know what I'm doing - Wernher von Braun -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics