Whirlybird Pull Launcher

Here is my pull string whirlybird design.  The two halves of the launcher are held together with screws and house a spindle.  The spindle is attached to the pull handle by a string such that when the string is pulled it rotates the spindle.  The whirlybird itself features a square section of its shaft that engages the spindle.

In order to build this device you'll need to print one spindle, pull handle, handle left and handle right.  Also you'll need to print at least one bird.  I print my birds at 0.1 layer height to make them smoother.  I do a little filing of the moving parts and square hole in the spindle for smoothness.

Additionally, you will need some string, 3 screws, 3 nuts and some lubricant.  I use 8-32 size screws and nuts.  For lubricant, I lubricate the surfaces of the spindle where it touches the handle pieces with anti-seize graphite lubricant.  You should be able to get all this at your friendly local hardware store. 

Assembly:

• Cut a piece of string such that it is slightly longer than your maximum pull (hand to hand with arms outstretched).  It is important that the string is long enough so that you cant completely unwind it when you pull to launch so that you you don't damage the spindle or accidentally pull the launcher out of your other hand at the end of your pull.
• Tie a knot at the very end of the string large enough that it won't pull through the string hole in the spindle.  You may want to fuse the knot with a lighter so that it doesn't untie.
• Feed the string through the spindle such that the knot rest against the flat cutaway surface of the spindle string hole.
• Tie the other end of the sting to the pull handle.
• Lubricate the spindle outer diameter and the corresponding rear surface of the spindle cutout in the handle pieces.  I experienced serious seizing without lubrication,
• Place the spindle into the left handle piece so that when unwound it would produce a counterclockwise rotation looking down on the handle (as if looking into the hole where you insert the bird) with the string coming out the rear cutout in the handle piece.
• Mate the right handle piece to the left handle piece and install the screws and nuts.  (if you don't want to use screws, you could probably wrap the handle in duct tape too)

Wind the spindle evenly as possible and insert your bird of choice.  Head outside to play in an open area and give the pull handle a good long pull while holding the assembled launcher in the other hand and send the bird flying through the air.

I plan to add additional bird designs here as I continue to experiment with their design. So, be sure to check back for more!

-Classic Bird: So far I've achieved the highest altitudes with this design.

-Triple Bird: I haven't gotten quite as high of altitudes out of this one, but I do seem to get more air time from it as it seems to hover longer and descend slower.

I really had fun with this one and I hope you do too!

I made the 3d models using Solidworks.