How can I design a stable spring launcher for my ISU project?

[rainbows]

i need to design a spring launcher that can shoot a spring given various stretch lengths and angles
here is a somewhat close example

http://www.efreaks.org/pics/2004-03-09_Physics/pages/000_0031.htm"

i don't quite understand how to join the 2 wooden pieces together that would give me the flexiblity of changing the angle upon my leisure.( from 0-90 degrees)..the above example uses hinges but that doesn't seem stable enough..cause they might move with some force...it needs to be stable

 

[dotman]

Hello,

You could use something like a threaded rod, that you turn, and it rotates the platform. Like a C-clamp, except without the C.

Amateur astronomers sometimes use the same idea for cheap camera mounts to track the stars-- they call them barndoor trackers, and its the same idea-- although you would need a bigger range.

Just a thought. You could also use curved metal brackets that the platform locks into with wingnuts or some such contraption.