In order to vector thrust effectively with a propeller system, a special type of cyclic mechanism is needed. Through an intense R&D process, it was discovered that a flexible cam constructed of flex-steel could bend while keeping the action seamless and still posses the required strength. Our unique cam has a flex-steel race at it's core and solid individual plates built around it that move and form it's shape. The propellers follow the curves of the race via linkages and cam-following bearings. The plates can move together and control the pitch equally for standard variable pitch functions. When one side of the cam is set at a zero thrust, the other half has the ability to vector thrust in virtually any direction based on pitch control inputs. Many new VTOL aircraft concepts are now possible thanks to this unique pitch control system.
For a helicopter, our cam divides the 2 halves into individually controlled surfaces just like with thrust vectoring. In this case, the benefit is in the finite, independent control of the retreating rotor blades versus the advancing rotor blades.
When you fly forward in a helicopter, the air traveling over the advancing blades give's them more lift while giving the retreating blades less lift. This phenomenon requires cyclic input from the swashplate to counter the rotor's dissymmetry of lift. A swashplate is flat and tilts to perform this counter measure in a straight line. Our cam is flat on each side with a transition in the middle but does not tilt. This allows us to hold a high pitch on the retreating side for a longer duration than with any other technology while holding a low pitch on the advancing side at the same time. We do this without going over a pre-determined angle of attack, avoiding a stall.
On our scaled prototype, the flexible cam retrofits to an existing swashplate retaining the swashplate functionality. It’s only when you fly forward that you have the option to tilt your swashplate or to bend the cam. Bending the cam allows you to take advantage of it's unique control characteristics like higher cruise and top speeds.
For many types and sizes of helicopters, we believe the reduced need for rotor teetering and flapping and the reduction of drag in the advancing blades will likely add additional speed and efficiency gains. The ability to manipulate rotor chord width and rotor speeds around our system could net even more gains. We believe rigid as well as fully-articulated helicopter rotor systems could benefit from this technology.