The research and development company Carter Aviation Technologies of Wichita Falls, TX is slowly developing its 4 place personal air vehicle (PAV) which utilizes technology demonstrated with the CarterCopter Technology Demonstrator (CCTD). Using the jump ability of an autogyro to get off the ground quickly the aircraft can then use its Slowed Rotor/Compound (SR/C) to travel to its destination at speeds exceeding current production helicopters, then spot-land in areas inaccessable to fixed-wing airplanes.
Jay Carter, CEO and principal designer of CarterCopters, LLC holds over 21 patents in the development of gyrocraft, including one which made the CCTD the first gyrocraft to exceed mu-1 in flight using the SR/C configuration. As a rotorcraft accelerates forward, the main rotor must travel faster than the relative air around it. The same air must also go over the retreating blade, causing instability. This imbalance in the geometry of the aircraft necessitates special care in its design.
Pusher rotorcraft like the Sikorsky X2 and the CCTD handle the retreating blade in different ways. The X2 helicopter utilizes a rigid powered rotor and counter-rotating blades which minimize the angle of attack in the retreating blades, therefore making lift negligible on that side. Lift of the airframe is then achieved using only the advancing portion of the rotor blades.
The CCTD, as well as the prototype PAV, Carter uses the SR/C concept for an autogyro which actually allows the gyrocraft to travel faster than the advancing blade itself, exceeding mu-1. This occurs by unloading the aircraft’s lift from the rotor and transitioning it to the wings in this hybrid aircraft. Cartercopters accomplished this goal with the CCTD on June 17th 2005.
Using the engine to pre-spin the rotor, Cartercopter autogyros are able to jump takeoff using little or no runway. It then accelerates forward using the rotor as the main lift device, a defining feature of all autogyros. The rotor’s weight is concentrated in the tips which stabilizes the blades as well as maintaining inertia for jump takeoffs and limited hover. As the aircraft increases speed, more lift is transferred to the main wings on the fuselage as the rotor is slowed by the oncoming air. As the aircraft slows for landing, the main rotor is once again loaded to accept more lift as the vehicle transitions away from the wings to achieve a low speed, low rollout landing.
The 2+2 PAV
The 2+2 PAV is an all new design being developed by Carter to incorporate new technologies for a safer, more economical mode of transportation. Shown at Airventure 2009 in Oshkosh, WI, the prototype is still under construction but operation is envisioned to begin by pre-spining the rotor, followed by a jump takeoff, reach 210 knots at 20,000 ft and land in a constrained environment. To be built under the FAA’s 51% rule, the Carter company is taking deposits for delivery at a later date.
Carter is also developing a new landing gear technology to decrease or eliminate bounce during a rough landing or a crash. Using accelerometers controlling valves and hydraulic fluid which changes its viscosity electrically, the PAV will be able to withstand landing impacts in excess of 2000 fps without injury to passengers or loss of aircraft. The current FAA requirement is 600 fps.