Wooden Helicopter blades?

[Evan]

Wooden rotor blades are the only type that doesn't have an FAA life limit. Aluminum and composite both are absolute life limited in hours of operation and composites have a higher mandatory overload margin than wood. Wooden rotors are allowed to operate for as long as they pass inspection. The Bell 47 has wooden blades and many still have the originals. I have worked on wooden aircraft and they are both lighter and stronger than metal aircraft. The biggest problem with wood is that you can't get the types of wood needed anymore. Try to find straight grain Sitka Spruce. The requirement is that it must be completely clear and the grain may not slope more than one inch in 12 feet.

[Circlip]

Shortage of Balsa in Europe for us to make toy aero's is down to the wind turbine manufacturers using it for turbine blade cores. First home built model gas turbines used plywood for the construction of the impellor - it was derided by the UK's "Muddle Ingineer"" but when you read the numbers it has a very high factor of safety built in.

Regards Ian.

[Black_Moons]

Lots of helicopters have wooden blades. Wood has excellent tensile strength for its weight. It also has an indefinite fatigue life as long as it is kept below failure.

Wow, didn't know it had such a great fatigue life. I would of assumed eventualy fibers would start to tear when stressed near its limit.

That said, the fact that wood is made of fibers all layed out in one direction makes it great for use in helicopters as blades. Note how much sag there is to the blades of a helicopter that is not spining, those blades can hardly support there own weight under static forces, its the g forces of rotating around a center axis that pulls them out, basicly suspending the helicopter from multiple wooden tight-ropes! And as you know, a 2x4 can support an insane amount of weight when in pure compression and even more when in tension, as you don't have buckling to worry about anymore.

[Evan]

Lots of helicopters have wooden blades. Wood has excellent tensile strength for its weight. It also has an indefinite fatigue life as long as it is kept below failure.

[darryl]

Well, they use wooden propellers on airplanes. I would think on a chopper the weak point would be the attachment of the blades to the hub. Model helicopters use wooden blades, and the attachment looks downright scary to me.

The spruce goose was a wooden airplane-

[A.K. Boomer]

I was watching the local news tonight about the waldo canyon fire and because it's about 80% contained they are lightening up on the coverage some and talking about some of the arsenal in which was used to fight the fire ---

one of the tools is the Kayman K-max helicopter --- it was designed specifically for hi load carrying so it can dump a fair amount of water or slurry for its size, this is a cutting edge "synchropter" and can lift as much as it's empty payload weight,,, but the thing that blew me away is it's got wooden blades!

I would think with all the high tech materials that wood would not even come close --- and Iv never heard of it being used on a heli-blade,, airplane yes - it was once the standard -- but big diff,,, lots of length applying torsional forces...

http://en.wikipedia.org/wiki/Kaman_K-MAX