Composite Hub Bar:

Replace the conventional aluminum hub bar with an identical fiberglass/carbon composite hub bar. The composite hub bar would be made from unidirectional tape and the direction of the tape would be lengthwise, from blade grip to blade grip.

The result will be a hub bar that has high strength in;
~ tension (centrifugal blade forces)
~ inplane bending (lead/lag)
~ out-of-plane bending (flapping)
However, this hub bar will offer little resistance to rotation about it's longitudinal axis (pitch axis).

The pitches of the two blades will now be capable of change. This will allow for both blades to have their pitches increased; which will provide collected for jump-takeoffs. And/Or, allow one blade's pitch to be increased while the other blade's pitch is being decreased; which will provide cyclic control.

This hub bar should cost very little more than the aluminum hub bar that it replaces, particularly if made in some quantity. In addition, the composite hub bar can be both lighter and stronger than the aluminum one.