Today, most rotary-wing aircraft use massive and expensive swashplate-type control systems to simultaneously change pitch on all rotor blades, and also vary each rotor blade's pitch individually depending on its relative position in orbit.

This patent-pending design provides collective-cyclic control without using a conventional swashplate. Advantages include a more compact and lightweight mechanism, with an overall increase in aircraft payload, fuel economy, and reliability.

When the control shaft is displaced vertically within the hollow-drive shaft, rotor-blade pitch changes collectively, increasing or decreasing lift. Displacing the control shaft angularly, relative to the spinning shaft, skews the rotational plane of the control hub relative to the rotor axis. This changes rotor-blade pitch relative to its position in orbit, providing cyclic control.

David Rehm, Rehm Engineering (P), N70 W5334 Bridge Rd., Cedarburg, WI 53012; (414) 376-9053.