The only rubber-band powered helicopters I have found on instructables so far (except the butterfly ones) require some form of kit or special parts which must be bought, so for me (making all of the individual parts from scratch makes finishing a project a little more rewarding to me), I prefer making every part from stuff which most people will already have lying around at home. That is the purpose of this instructable.
This helicopter uses coaxial or contra-rotating blades instead of a main lifting rotor and smaller anti-torque tailrotor, because this design is easier to make and is more practical for rubber-power. I have also made "normal"-looking rubber band helicopters but they require more parts and time to make. They also do not fly for as long as this design can and they don't work without an auto-stabilizing flybar system, plus you have to add a pulley system to spin the tailrotor and this creates a bigger probability of a part not working from over-complication of what should be a much simpler machine.
Throughout this instructable I include dimensions (in brackets) of parts on this helicopter but your scale will probably be different to mine so provided you keep your scale correct to the photographs your helicopter should work just as well as mine.
To make one like this one, you will need:
- A bamboo chopstick (or other strong, light wood if you prefer)
- Thin wood offcuts (I used balsa)
- Aluminium from a can (make sure the can you use is aluminium first, you can do this with a magnet because aluminium is not magnetic under normal conditions.)
- Foam sheet(s)(I use the kind of polystyrene found in food packaging)
- 2 Pins
- A paperclip (You won't need the actual paperclip, just the plastic insulation around it. If you don't have a paperclip with this insulation on it, then you will need to find a small tube that one of your pins can easily fit through without too much wiggle-room.)
- 4 Small Beads
- Plastic (From an ice-cream or yoghurt container)
- An Elastic/Rubber Band (I find that many small ones strung together works better than one bigger one)
- Tape (Most types of glue dissolve the polystyrene foam)
- Craft knife/scalpel
This is a fun toy to use and does not take much time to make (and it will cost you virtually nothing since most people throw away the majority of materials needed).
Step 1: Frame/Body
Start by making the 2 main fuselage/body beams. Do this by splitting a bamboo chopstick (the one I used was cut to 180mm long) into 2 equally sized strips. It is important that the 2 halves are the same size or the helicopter may become unbalanced. I cut a slit in the middle of the stick and stick the knife through it, then I cut with the grain to both ends. Shave bamboo off of both sticks so that they are lighter, but still not too bendy.(my final measurements of either beam are 180 x 2 x 4 mm) [See picture 2]
Next come the joins/separators on both ends of these beams. One is just a wooden rectangle, the other is composed of 2 smaller wooden rectangles and a tube which I will explain how to get now. "Un-bend" a paperclip and use a sharp knife to make a circular cut (through the plastic insulation) around any point on it. Pull on both ends of the insulation until one part of it comes off the paperclip. Cut this tube to size and use it for this step. (the tube I cut for this helicopter was cut to 7 mm)
Cut a rectangle (mine measured 10 x 6 x 1.6 mm) from a piece of wood for the bottom end of the helicopter frame. Then cut 2 smaller rectangles from the same thin piece of wood (either of the two on mine measured 4 x 6 x 1.6 mm) for the top end of the frame.
Glue the bottom separator to the "inner" bottom edge of one of the frame beams, also glue one of the top separators to the top of this beam. Then glue the paperclip tube onto this top separator.[See picture 4] Glue the other top separator onto the other main beam and then glue this onto the existing frame construction [See picture 5]
Now, to strengthen the 2 ends of the frame and the joins there, you will use some aluminium from a can. The bottom end is simple, just cut a rectangle from the can (mine measured 14 x 16 mm) and bend it in half, in a sharp-cornered "U" shape. [See picture 6] Then glue it over the BOTTOM separator. [See picture 7]
Then for the top, cut a strip of aluminium (mine was 35 x 6 mm) and wrap/coil it around the top part of the frame and then glue it on there. [See last two pictures] Be careful not to get any glue into the tube or you will have to start from there again.