Flexible coupling arrangements for drive systems

A drive system, comprising:

• a flexible coupling arrangement, comprising:
• an outer first member;
• an outer second member;
• an outer flexible coupling configured to transmit torque between the outer first member and the outer second member while allowing at least one of angular misalignment and axial misalignment between the outer first member and the outer second member;
• an inner first member;
• an inner second member;
• an inner flexible coupling configured to transmit torque between the inner first member and the inner second member while allowing at least one of angular misalignment and axial misalignment between the inner first member and the inner second member, the inner flexible coupling being positioned radially inward of the outer flexible coupling,
• wherein the outer flexible coupling comprises a first diaphragm element and a second diaphragm element, the first diaphragm element being connected to the second diaphragm element at an outer periphery of the first diaphragm element, wherein the inner flexible coupling includes a quill shaft;
• and
• a bearing assembly disposed externally of the first diaphragm element and the second diaphragm element and supporting the quill shaft for rotation within the outer flexible coupling;
• a first rotor assembly operably connected to the outer flexible coupling;
• and
• a second rotor assembly operably connected to the inner flexible coupling, wherein the first rotor assembly and the second rotor assembly are concentrically arranged for common rotation about a rotor assembly axis.