Everyone knows a helicopter's rotors rotate (that's why they're called rotors). But the really clever thing about them is that the blades can swivel back and forth as they turn around—and that requires some amazingly intricate machinery.
It's easy to mimic a helicopter with your arms and your body's hidden structure makes the movements seem easy. Stand up with your arms... outstretched horizontally. Rotate your whole body slowlyon the spot. As you're turning around, swivel your arms at the shoulders. That's roughly what a helicopter does with its blades, except that it does it about 3-4 times each second as the blades are spinning round! Here are the main bits thatmake it work:
1. The blades are shaped like airfoils (airplane wings with a curved profile) so they generate lift as they spin.
2. Each blade can swivel as it spins.
3. Vertical rods push the blades up and down, making them swivel as they rotate.
4. A central axle connected to the engine makes the entire blade assembly rotate.
5. The cap above the rotors is missile proof to protect against enemy attacks.
6. There are two turbo-shaft jet engines, one on either side of the rotors. If one engine fails, there should still be enough power from the other engine to land the helicopter safely.