Mart,
Which of Sikorsky's 13 patents are you refering to?
6,655,915 ~ Drive system for the retraction/extension of variable diameter rotor systems
6,578,793 ~ Method and apparatus for fiber strap termination
6,568,906 ~ Conformal sliding bearing
6,454,532 ~ Harmonic drive system for the retraction/extension of variable diameter rotor systems
6,398,497 ~ Blade lock system for variable diameter rotor systems
6,030,177 ~ Drive system for a variable diameter tilt rotor
6,019,578 ~ Variable diameter rotor blade actuation system
5,735,670 ~ Rotor system having alternating length rotor blades and positioning means therefor for reducing blade-vortex interaction (BVI) noise
5,655,879 ~ Mounting arrangement for variable diameter rotor blade assemblies
5,642,982 ~ Retraction/extension mechanism for variable diameter rotors
5,636,969 ~ Torque tube/spar assembly for variable diameter helicopter rotors
5,620,304 ~ Rotor system having alternating length rotor blades and positioning means therefor for reducing blade-vortex interaction (BVI) noise
5,620,303 ~ Rotor system having alternating length rotor blades for reducing blade-vortex interaction (BVI) noise
Dave