Patent ID: 11858606
Assignee: SAAB AB
Field: Transport (Mechanical engineering)
Classification: CPC B | IPC B

Claim 9:
10. A method of manoeuvring a watercraft vehicle (1), the method comprising the steps of:
providing a watercraft vehicle comprising:
a drive motor arrangement (3) coupled to a control circuitry (5) configured for manoeuvring the watercraft vehicle (1);
a propeller shaft (9) coupled between the drive motor arrangement (3) and a propeller assembly (7), forming a propeller disc (11) during rotation of said propeller shaft (9) about an axis of rotation (RX);
a hub member (17) of the propeller shaft (9) coupled to the propeller assembly (7);
a first propeller blade (8) of the propeller assembly (7) hingedly coupled to a first oblique lag-pitch hinge (22′) of the hub member (17);
a second propeller blade (10) of the propeller assembly (7) hingedly coupled to a second oblique lag-pitch hinge (22″) of the hub member;
a first oblique axis (21′) of the first oblique lag-pitch hinge (22″) oriented in a direction oblique to the axis of rotation (RX);
a second oblique axis (21″) of the second oblique lag-pitch hinge (22″) oriented in a direction oblique to the axis of rotation (RX) and parallel with the first oblique axis (21′);
wherein the control circuitry (5) is configured to provide a first drive thrust (T′) in a first arc segment (13′) of the propeller disc (11) and to provide a second drive thrust (T″) in a second arc segment (13″) of the propeller disc (11) by controlling a rate of change of the rotational velocity of the propeller shaft (9), wherein a first propeller blade pitch change is achieved about the first oblique axis (21′) and a second propeller blade pitch change is achieved about the second oblique axis (21″);

rotating the propeller shaft (9) about the axis of rotation (RX) forming the propeller disc (11);
changing the rotational velocity for achieving said rate of change of rotational velocity in said first arc segment (13′) for providing a first propeller blade pitch change about the first oblique axis (21′) and for achieving said rate of change of rotational velocity in said second arc segment (13″) for providing a second propeller blade pitch change about the second oblique axis (21″);
increasing the angle of attack of the first propeller blade (8) by said first propeller blade pitch change generating larger thrust (T′) of the first propeller blade (8) in the first arc segment (13′);
decreasing the angle of attack of the second propeller blade (10) by said second propeller blade pitch change generating smaller thrust (T″) of the second propeller blade (10) in the second arc segment (13″), and
providing constant rate of rotation of the propeller shaft (9) for generating linear thrust.