The design of the HF is protected by a series of patents on the most distinguishing technological features: the fans. These patents are all the result of the fertile mind of Jay Carter. Below is a short description of the inventions most pertinent to the operation of the HF.
A very high inertia rotor blade with a twistable composite "I" beam-shaped spar with a
high edgewise stiffness extending from blade tip to blade tip for the purpose of making vertical take-offs and landings utilizing the rotor inertia, and for rotor stability at high Mu ratios (forward speed to rotor tip speed ratios greater than 1). Pat. #5,727,754 and Pat. #6,024,325.
A simple means of controlling rotor rpm at high rotor advance ratios. Pat. #5,727,754.
A simple means of providing rotor stability at high rotor advance ratios in gusty winds and turbulent conditions. Pat. #5,727,754.
A simple means of maintaining a nearly constant rotor rpm over varying aircraft speeds and aircraft pitch angles at high rotor advance ratios. Pat. #5,727,754.
A simple single control means by which the pilot can control aircraft pitch and roll whether the aircraft is supported mainly by the rotor or the wing or any combination thereof. Pat. #5,727,754.
A simple rotor disc angle control using a tilting spindle whereby the spindle tilting axis can be located on or near the rotor center of lift to provide the desired pilot stick control forces regardless of loads to the rotor. Pat. #5,727,754 and Pat. #5,853,145.
A free moving rotor head in the fore, aft and lateral directions to reduce the effect of oscillating loads of a rotating rotor on the main frame and a rotor tilt linkage geometry that prevents the rotor tilt angle from changing as the rotor mast moves. Pat. #5,853,145.
A control system that automatically tells the pilot when the aircraft is close to or at the speed necessary for its best lift to drag ratio regardless of weight or altitude. Pat. #5,727,754.
A lightweight propeller, flexible in the flatwise direction to reduce gyroscopic loads on the hub/shaft and a torsionally soft composite "I" beam prop spar which can be twisted inside a hollow blade to change the prop pitch without the need of a spindle, hub, or bearings. Pat. #6,155,784.
A variable pitch prop controlled by a computer utilizing feedback information on airspeed, prop rpm, air density, shaft hp, and prop position to position/hold the pitch/rpm for peak efficiency over a very wide range of operating conditions - static thrust at sea level to 400+ mph @ 45,000+ feet altitude. Pat. #5,997,250.
A simple lightweight rotor prerotator and torque limiting disengaging clutch. Pat. #6,077,041.
An improved rotor stability control to further reduce rotor flapping at rotor advance ratios (Mu) greater than 0.75. Patent # 6,405,980
An improved rotor design that reduces the force required to change both cyclic and collective pitch. Pat. #6,527,515
An improved prop controller that utilizes a two speed automatic transmission to significantly improve engine/prop efficiency and thrust at very high forward speeds. Pat. # 6,524,068
A heliplane design that uses two propellers capable of reverse thrust to counter rotor torque while in hover and providing very efficient forward thrust for high speed flight. When rotor is in autorotation, unloaded, and slowed down for low drag, the heliplane operates as a very efficient fixed wing aircraft. Pat.# 6,513,752
Tilting mast to control the pitch of the aircraft to keep the wing at its best L/D angle up until the rotor is basically unloaded. Keeps the aircraft parallel to the airflow from jump takeoffs through autorotation landings.