What are helicopter blades made from?
Plastic on the outside, with a honeycomb centre (made of glass fibre or carbon fibre)
Metal.
If I recall, steel, but IANAHP or M so hopefully someone like Johnny LA who flies them will be along shortly, or maybe Sam Stone, who always seems to know a lot about aircraft, or someone else more authoritative than me.
Or hibernicus…
And metal (aluminium) on the leading edge.
I can tell you they’re pretty light. I could easily pick up a CH-47 blade at the Boeing plant (though I probably wasn’t supposed to).
Not me… I make no claim to authority. In fact now I think of it there is probably a wide variety of materials in use for main rotor blades. But the ones I’m aware of are composite.
Rotor blades can be made from a combination of metal or composite material (even fiberglass). There isn’t “one” material that fits the bill. The main structural part of the blade is a spar, usually shaped like a D, that incorporates the shape of the leading edge - could be aluminum (like a UH-1) titanium (like the UH-60) or composite (OH-58D). Aft of that is usually some kind of “filler” material, like aluminum honeycomb, or composite honeycomb, that holds up the shape of the aft part of the blade. The skin can be either metal or composite. Usually, there will be some metal on the leading edge, for durability (rain or sand erosion), even if the main structure is composite. There also may be layers of copper or other conductive material (not structural) to avoid trouble with lightning strikes.
An important considreration is that the center of mass for the blade cross section be at the quarter chord ( 1/4 of the way back from the leading edge) or forward. This is important for stability.
Trim tabs can be added to the trailing edge, or incorporated into the entire trailing edge to help with blade tracking (i.e. bendable tabs to get each blade to fly in the same plane).
Pretty much answered by Race Bannon: It depends on the helicopter. IIRC, the Bell 47 (MASH) had wooden blades.