Rob Fonhof wrote:

Just a theoretical question that someone may be able to help with.
Alot of helicopters have only two rotor blades, ie:Robinsons, Bells, etc.
Others have multiples, ie:dauphins with 4, Hughes etc.
If a blade is thrown on a two blade, bend over and kiss your rear bye bye.
What would happen if you had a 4, 5, or even 6 blade?Would you still be able
to autorotate? I know the airframe would probably vibrate violently, but
would it be survivable in an autorotate, or even low power to at least get
to the ground.
Have there been instances in the past where this has happened with a 2
blade.
Thanks in advance.
Rob Fonhof




I did see some article (I don t know where) stating the Sikorsky S-61
could survive a thrown blade. I find this hard to believe, since
throwing a blade would create an enormous out of balance on the order of
60,000 lb at about 5 Hz. If the ship remained in one piece and weighed
20,000 Lb. The pilot would feel the equivalent of someone shaking them
back and forth 5 time per second at 3 g's or more if it were empty. I
see a persons neck breaking in a short time. And in fact this is usually
the scenario I've been told. If you throw a blade the ocupants will be
dead before the aircraft hits the ground.

Opinions posted here are my own and do not represent the company I work for.

John Roncallo