The following slideshow and talk were presented at the Uber Elevate Summit on April 25 th, 2017. The text included here is an approximate transcript of the speech given by Jay Carter, founder and CEO of Carter Aviation Technologies. --- Hi. I'm Jay Carter, Jr., CEO of Carter Aviation, and I'm proud to introduce the Mooney/Carter Air Taxi. The idea of being involved in the development of a practical, electric powered, quiet, safe VTOL air taxi, is near and dear to my heart. But first, let me also provide you with a brief history of what came before Carter Aviation and our current design that we're working on with Mooney, to give you a full understanding of this design.
While in college, I earned my pilot s license and designed and built two gyros with guidance from my father. The second was mostly composite - and this was in the `60s! My father was a filament winding composites pioneer in the early days of the space program and taught me all about composites, and was the best design engineer I have ever known. I owe him a great deal and miss him very much. This experience led to a job in R&D at Bell helicopters where I was one of the three co-inventors of the proprotor system for their XV-15 tiltrotor. I left Bell in 1970. Working with another machinist, and again with guidance from my father, we built a steam powered automobile that became the first car in the world to pass the original 1977 emission standards. It so impressed the editor of Popular Science, that he put it on the cover of the October 1974 edition. Because of the oil embargo and the increasing cost of electricity in the early '70s, I developed a very lightweight, cost effective wind turbine. It was a two bladed, downwind, teetering rotor design, which eliminates the gyroscopic loads of all 3 bladed turbines. We used a self erecting tower to eliminate cranes. We sold, installed, and maintained them all over the world.
I sold the wind turbine company in 1992, leaving the company in 94. Itching for another project, I convinced my wife to let me build a 5 place autogyro just for us and our three kids. Intuitively, I knew that by adding a wing to unload the rotor, the performance would be better than a regular gyro. What I didn't realize until I started going through the calculations, was just how much the rotor could be slowed by unloading it, and how much this would improve performance. The rotor rotational drag is a function of rpm cubed, so dropping the rotor rpm by a factor of 3 in cruise reduces this drag component by a factor of 27, and results in a rotor drag at cruise less than 15% of the total aircraft profile drag. We call this design a Slowed Rotor/Compound aircraft, and it's a game changer. It has been a team effort of investors, smart dedicated employees and consultants, who developed this concept over 23 years with 22 patents approved and 5 pending. The rotor provides the lift for hover, and a decreasing share of the lift as the aircraft accelerates, until the wing is able to provide virtually all the lift at about 150 mph. This allows the small high aspect ratio wing, and its corresponding profile drag, to be less than 1/5 that of a similar fixed wing aircraft. It is this combination of dramatically reduced rotor and wing drag that allows a slowed rotor compound aircraft to compete with GA aircraft in speed and efficiency based on the same hp, weight, wing span, and drag coefficients. Plus, you gain VTOL capabilities and a low disk loaded high inertia auto-rotating rotor that acts like an emergency parachute, only better because it works at any altitude or speed, and provides directional control to the landing spot. I knew there'd be issues with slowing the rotor, so to confirm we'd solved these issues, we built a 1/6 scale rotor and mounted it on a 8 boom in front of a pickup truck. We were able to confirm the rotor rpm control method and rotor stability at low rpm, to the point we were able to go down the highway at 80 mph with the rotor tip speed slowed to 10 mph. Not only was the rotor stable, it was so stable the rotor flapping did not exceed 15 from the turbulence caused from semi trucks passing in the other direction. With this test, we knew we had a game changer, and started construction of the aircraft, to include testing and developing our unique, simple, lightweight rotor and high static thrust prop, low drag rotor hub, tilting mast, and extreme energy absorbing landing gear. These two aircraft are the only aircraft in the world to have slowed the rotor in flight to the point the aircraft was flying faster than the tip speed of the rotor, and in the process demonstrated an efficiency over two times better than the best helicopter.
This is our preferred design concept for the urban air taxi configuration. We evaluated many different concepts and compared them head to head within the Uber Elevate trade space. It has a 34 dia rotor and wing span, for an efficient low disk and span loading. Also note the large 10 ft diameter pivotal tail rotor/thruster is used to counter rotor torque during hover, and then as the aircraft accelerates and the rotor converts from helicopter to autogyro mode, it rotates to provide 100% thrust. There's no torque going to the rotor above about 100 mph. The cabin width is 54 wide for a very roomy & comfortable luxury passenger feel. Note that 95% of the population are smaller than the passenger size shown.
There are many safety and performance features incorporated in our Air Taxi. Key safety features include durable electric motors, batteries in the nose, redundant mechanical control linkage for an optionally piloted configuration, simple lightweight twisting carbon spar for the rotor and prop, and our fail-safe extreme energy absorbing landing gear, with no rebound. Key performance features include low rotor and prop disk loading, a small high aspect wing, a low drag streamlined hub, a SR/C main rotor, a scimitar prop with a wide chord for high static thrust and a very streamlined airframe. In a trade for quietness and passenger comfort, with a wide chord main rotor and propeller, we can keep the rpm low for very low noise takeoffs and landings, and with the tall soft tilting mast, isolate all the rotor vibrations for near jet plane smoothness, and keep the aircraft level when the mast and rotor are tilted forward for takeoffs and tilted aft during landings.
This slide shows key performance parameters and two graphs, which show the effect of hover rotor tip speed on empty weight and range at 175 mph cruise. We used drag coefficients based on experimental flight test data of what we actually achieved and not expected improvements. We selected an empty weight with batteries of 3200 lbs, so we could carry an 800 lb payload or four 200 lb people, and keep the gross weight at 4000 lbs. We sized the thrust drive motor to provide for a 175 mph cruise at 5000 ft density altitude. 300 W-hr/kg energy density batteries. We used In Figure 1, you can see as we reduced the hover rotor tip speed from 600 to 450 ft/s, the empty weight without batteries increased by 213 lbs, to 2213 lbs. On figure 2, again see as we reduced from 600 to 450 ft/s, the range at 175 mph also dropped by 46 miles, to 113 miles. We feel these compromises are worth the quieter operation for takeoff and landings. Note that the rotor tip speed will be at its maximum during hover, but the tip speed of the advancing blade will decrease as airspeed increases because of the reduced rotor rpm as we transition into SR/C cruise. Bottom line This aircraft configuration can be extremely quiet and still meet range requirements. It's simple. Its performance has already been exceeded with Carter s second prototype. It has unparalleled safety with its high inertia auto-rotating rotor and direct mechanical linkage to all flight surfaces, which allow an optionally piloted or autonomous system to safely land in almost any failure event including a total power train electrical failure. I'm really looking forward to your questions during Q&A. Thank you very much.