Obviously you can play with the design depending on what materials you have lying around, but this should give you a rough idea of what direction to go...
Date Made: June 2013
Approx Cost: £0 (recycled materials)
Approx Time: 0.5 to 1 hrs
Step 1: What You Need
*some fairly stiff plastic (I used the packaging from a roller blind)
*a big thick elastic band (I used one about 200mm long)
*a picture hook
*a piece of dowel (I used the adjuster from a venetian blind, which already had the hook screwed in the end)
Tools you need are:
*some extra strong glue
*a hacksaw to cut the wood (I used a dremel)
*scissors or knife to cut the plastic
Step 2: Make Propellers
Next fold them on an angle about 30mm from one end as per the photo.
Make them both match.
Step 3: Make Main Body
Cut a slot in one end almost the same length as the fold line.
In the other end cut a small hook along the same plane as the slot, that way the propellers wont catch on the body when released. Make the hook small, but check the elastic band will latch on to it. If this is too big, it will catch on launch and misfire.
Step 4: Form Helicopter
Next glue the propeller in to the slot on the dowel. Make sure the glue is strong and can take some good force - if it doesn't, you will hurt yourself later!
Only fix the propellers to the body below the fold, so that when releases they can bend at the fold line.
Trim the propeller so that it tapers in to the width of the body
Finally fold the propellers along the fold lines.
Step 5: Form Handle
Screw the picture hook in to the end of the dowel.
Fix the elastic band to the hook. I did this by putting the elastic band through and then closing the hook with pliers. You could alternatively do it by means of a knot, glue, staple or you could drill a hole through the dowel.
Step 6: Launch
Clip the open hook of the body in to the elastic band, pull back and release!
The helicopter should fly in to the air like a rocket, and then spin down like a helicopter!
You may need to play with the weightings etc depending on the materials you use, so you could put blu-tak on the end to make the front heavier etc.
WARNING: be careful of your hands and face! If this misfires and it hits your hand/face, it really hurts (I know from experience!), and if it hits you in the eyes it could do some real damage. So best to wear gloves/glasses whilst testing! Also make sure that the picture hook is completely closed, so that the elastic band doesn't sneak out and hit you in the face!
Here is a video, you cant really see it whilst in the sky, but you can see it spin to the ground.
Step 7: 3D Model
Please note that this 3d model should really be classed as a prototype as I do not have access to a 3d printer so cannot print and check that this is strong enough for the purpose intended. I presume different materials would behave differently anyway.