Rotor assemblies for vehicle propulsion

1 . A rotor assembly for generating thrust for a vehicle, the rotor assembly comprising:

a rotor hub; and

a plurality of rotor blade assemblies coupled to the rotor hub, each rotor blade assembly having a pitch change axis and each rotor blade assembly including:

a metallic bearing race having a conical end that extends radially outwardly relative to the pitch change axis;

a composite rotor blade having a root section with an outer surface that is radially outwardly tapered relative to the pitch change axis; and

a metallic coupling assembly having an inner surface that is radially inwardly tapered relative to the pitch change axis and a conical end that extends radially inwardly relative to the pitch change axis;

wherein, the outer surface of the root section of the rotor blade is received within the inner surface of the coupling assembly to provide a centrifugal force seat for the rotor blade, the coupling assembly including at least two circumferentially distributed coupling members, the coupling assembly configured to couple the rotor blade to the bearing race and to provide a centrifugal force load path therebetween; and

wherein, the conical end of the bearing race is received within the conical end of the coupling assembly to provide a centrifugal force load path therebetween.

2 . The rotor assembly as recited in claim 1 further comprising a duct and a plurality of stators coupling the duct to the rotor hub such that the rotor blade assemblies are disposed within the duct.

3 . The rotor assembly as recited in claim 1 wherein each bearing race further comprises a ball bearing race and a roller bearing race.

4 . The rotor assembly as recited in claim 1 wherein each bearing race is a steel bearing race.

5 . The rotor assembly as recited in claim 1 wherein each rotor blade is a carbon fiber rotor blade.

6 . The rotor assembly as recited in claim 1 wherein each coupling assembly is a titanium coupling assembly.

7 . The rotor assembly as recited in claim 1 wherein each rotor blade assembly further comprises a conical wear ring disposed between the conical end of the bearing race and the conical end of the coupling assembly.

8 . The rotor assembly as recited in claim 7 wherein each conical wear ring is a segmented conical wear ring.

9 . The rotor assembly as recited in claim 1 wherein each rotor blade assembly further comprises at least one circumferential band positioned around the coupling assembly configured to circumferentially secure the coupling assembly about the root section of the rotor blade.

10 . The rotor assembly as recited in claim 1 wherein each rotor blade assembly further comprises a metallic ring disposed within the root section of the rotor blade.

11 . The rotor assembly as recited in claim 1 wherein each rotor blade assembly further comprises an anti-rotation element configured to prevent relative rotation between the coupling assembly and the rotor blade.

12 . The rotor assembly as recited in claim 11 wherein, for each rotor blade assembly, the anti-rotation element further comprises at least one anti-rotation key disposed between the coupling assembly and the rotor blade.

13 . A vehicle operable for forward motion responsive to thrust, the vehicle comprising:

a rotor assembly including a rotor hub and a plurality of rotor blade assemblies coupled to the rotor hub, each rotor blade assembly having a pitch change axis and each rotor blade assembly including:

a metallic bearing race having a conical end that extends radially outwardly relative to the pitch change axis;

a composite rotor blade having a root section with an outer surface that is radially outwardly tapered relative to the pitch change axis; and

a metallic coupling assembly having an inner surface that is radially inwardly tapered relative to the pitch change axis and a conical end that extends radially inwardly relative to the pitch change axis;

wherein, the outer surface of the root section of the rotor blade is received within the inner surface of the coupling assembly to provide a centrifugal force seat for the rotor blade, the coupling assembly including at least two circumferentially distributed coupling members, the coupling assembly configured to couple the rotor blade to the bearing race and to provide a centrifugal force load path therebetween; and

wherein, the conical end of the bearing race is received within the conical end of the coupling assembly to provide a centrifugal force load path therebetween.

14 . The vehicle as recited in claim 13 wherein the rotor assembly is configured to produce thrust when rotating in a working fluid of air.

15 . The vehicle as recited in claim 13 wherein the vehicle is an amphibious air-cushion vehicle.

16 . The vehicle as recited in claim 13 further comprising a duct and a plurality of stators coupling the duct to the rotor hub such that the rotor blade assemblies are disposed within the duct.

17 . The vehicle as recited in claim 13 wherein each rotor blade assembly further comprises a conical wear ring disposed between the conical end of the bearing race and the conical end of the coupling assembly.

18 . The vehicle as recited in claim 13 wherein each rotor blade assembly further comprises at least one circumferential band positioned around the coupling assembly configured to circumferentially secure the coupling assembly about the root section of the rotor blade.

19 . The vehicle as recited in claim 13 wherein each rotor blade assembly further comprises a metallic ring disposed within the root section of the rotor blade.

20 . The vehicle as recited in claim 13 wherein each rotor blade assembly further comprises at least one anti-rotation key disposed between the coupling assembly and the rotor blade.