Jinx wrote: > Assuming you had a 1m diameter propellor, with one long arm > (counterweighted on the other side) to do the kicking. Get it > spinning to 15rps (=> 100mph). That gives you 60ms after it passes > the back of the sled to drop it so it hits the sled solidly next > time around. Not impossible, just wonder about the damage from a > sudden impact like that. I'd prefer it if the sled was accelerated > gradually So put a spring behind your sled, and have the arm hit THAT. Shouldn't take too many tests to find the right spring rate and to create an rpm-to-sled-velocity lookup table. Dropping the axle would be easier if your arm weren't (heavily) counterweighted; it seems pretty straightforward to arrange things so the arm's centrifugal force would push it down. -Andy === Andrew Warren -- aiw@cypress.com === Principal Design Engineer === Cypress Semiconductor Corporation === === Opinions expressed above do not === necessarily represent those of === Cypress Semiconductor Corporation -- 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