(Updated 2007-02-19)

When CarterCopter filed for its patent on rotorcraft flight at speeds above Mu-1 (Mu>1), no previous patents addressed the concept, which apparently was thought to be impossible. Flight above Mu-1 occurs when the rotorcraft's forward speed is greater than the tip speed of the rotor (more info). The CarterCopter patent describes how to greatly slow the rotor while maintaining rotor stability. Since the patent was filed, flight above Mu-1 was convincingly demonstrated using the CarterCopter Technology Demonstrator (more info). There can be no remaining doubt that the patented design works. The impact on aviation will be monumental.

To date, Carter Aviation Technologies has received seventeen U.S. patents and one design patent. We are still always learning and working on new ideas, and currently have another several patents pending, with more ideas on the way. Patents granted to date include:

Figure 3: Patents Granted

Important features provided by these patents include:

• 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.
  
  
• A landing gear system that extends and retracts, dampens oscillations, and provides extreme energy absorption capability in conjunction with a load limiting device to assure maximum energy absorption during a crash landing before the landing gear fails. The landing gear can also raise or lower while on the ground to facilitate loading and unloading. Pat. #5,944,283.
  
  
• A fuselage door for a pressurized aircraft fuselage in which tension loads caused by cabin pressure are carried through the door jam and door rather than around the door. Only cabin pressure is required to hold the door in place. Pat. #5,868,355.
  
  
• A tail boom design in which the booms extend below the prop tip so a wheels up landing can be made without damage to the prop. Pat. #5,865,399.
  
  
• 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 energy absorbing landing gear design using a controllable, variable viscosity fluid. Pat. # 6,474,598
  
  
• 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
  
  
• Trademark: