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47-436: The Carter PAV ( Personal Air Vehicle ) is a two-bladed, compound autogyro developed by Carter Aviation Technologies to demonstrate slowed rotor technology. The design has an unpowered rotor mounted on top of the fuselage, wings like a conventional fixed-wing aircraft mounted underneath, and a controllable pitch pusher propeller at the rear of the fuselage. Heavy weights (75 pounds or 34 kilograms each) are placed in

94-416: A detached rotor blade killed several people on the helipad and one woman on Madison Avenue , ending that business for decades almost around the world. Current helicopter accident rates would be insufficient for urban mobility. The Sikorsky S-92 's safety-focused design still allows one fatal accident per million flight hours. This rate would lead to 150 accidents per year for 50,000 eVTOLs flying 3,000 hours

141-497: A few percent), whereas Carter uses RPM ranges between 100 and 350. Most aircraft have two energy parameters (speed and altitude) which the pilot can trade between, but Carter technology attempts to use rotor rotation as a third energy parameter. The purpose of the Slowed Rotor/Compound aircraft is to enhance the flight envelope compared to fixed-wing aircraft, helicopters and traditional autogyros , by minimizing

188-445: A fixed wing aircraft are wingspan and total wetted area . One method for estimating the zero-lift drag coefficient of an aircraft is the equivalent skin-friction method. For a well designed aircraft, zero-lift drag (or parasite drag) is mostly made up of skin friction drag plus a small percentage of pressure drag caused by flow separation. The method uses the equation where C fe {\displaystyle C_{\text{fe}}}

235-471: A high angle of attack and a gentle stall are also important. As the aircraft fuselage and control surfaces will also add drag and possibly some lift, it is fair to consider the L/D of the aircraft as a whole. The glide ratio , which is the ratio of an (unpowered) aircraft's forward motion to its descent, is (when flown at constant speed) numerically equal to the aircraft's L/D. This is especially of interest in

282-453: A simple method of reducing noise was identified: Keep aircraft at a higher altitude during landing. This is called a Continuous Descent Approach (CDA). Many proposed PAV aircraft are based on electric batteries , however they have low range due to the low specific energy of current batteries. This range may be insufficient to provide adequate safety margin to find a landing site in an emergency. Fuel cell aircraft have been proposed as

329-531: A solution to this issue, owing to the much higher specific energy of hydrogen . Urban flight safety is a well-known problem for regulators and industry. On May 16, 1977, the New York Airways accident of a Sikorsky S-61 helicopter shuttle from John F. Kennedy International Airport , which landed on the roof of the Pan Am Building (now MetLife Building ) when a landing gear collapsed and

376-780: A vertical flight safety of one failure per 10 million hours on high-utilization platforms by combining current rotorcraft experience with advances in autonomous flight, airspace integration and electric propulsion . NASA established the Personal Air Vehicle Sector Project in 2002, as part of their Vehicle Systems Program (VSP). This project was part of the NASA Vehicle Integration, Strategy, and Technology Assessment (VISTA) office, which also included sectors for Subsonic Transports, VTOL Aircraft, Supersonic Aircraft, and High Altitude Long Endurance Aircraft. The objective of each sector

423-410: A viscous fluid such as air. The aerofoil is often cambered and/or set at an angle of attack to the airflow. The lift then increases as the square of the airspeed. Whenever an aerodynamic body generates lift, this also creates lift-induced drag or induced drag. At low speeds an aircraft has to generate lift with a higher angle of attack , which results in a greater induced drag. This term dominates

470-428: A year. For Sikorsky Innovations, the emerging $ 30 billion urban air mobility market needs safety at least as good as FAR Part 29 governing over 7,000 lb (3.2 t) helicopters. By May 2018, Sikorsky flew an S-76 120 hours with full point-to-point, real time autonomous flight and terrain avoidance the hard way, with Level A software and redundancy , with a safety pilot. Sikorsky Aircraft want to reach

517-472: Is equipped with a performance enhancement system by Nitrous Express . The PAV has flight characteristics similar to other Carter aircraft. When stationary on the ground, the engine powers up the flat pitch rotor to 370 RPM, and the engine is then disengaged from the rotor to provide full power to the propeller. The rotor now has substantial rotational energy due to the tip weights (usable temporary eng1 equivalent to 1,000 horsepower or 750 kilowatts), and

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564-438: Is no fully accepted definition as yet of a personal air vehicle (PAV). Typically it is understood to be an autonomous electric aircraft with point-to-point VTOL capability. It may or may not be treated as a single-seat autonomous electric vehicle, as distinguished from the multi-seat eVTOL . It is intended to provide flight convenience similar to the private car in terms of accessibility and ease of operation, while also offering

611-558: Is not currently capable of handling the increase in aircraft traffic that would be generated by PAVs. The FAA plan to upgrade forms the Next Generation Air Transportation System , planned for 2025. An interim plan is to use smaller airports. Modeling by NASA and others have shown that PAVs using smaller community airports would not interfere with commercial traffic at larger airports. Currently there are over 10,000 public and private small airports in

658-435: Is the equivalent skin friction coefficient, S wet {\displaystyle S_{\text{wet}}} is the wetted area and S ref {\displaystyle S_{\text{ref}}} is the wing reference area. The equivalent skin friction coefficient accounts for both separation drag and skin friction drag and is a fairly consistent value for aircraft types of the same class. Substituting this into

705-550: Is wingspan. The term b 2 / S wet {\displaystyle b^{2}/S_{\text{wet}}} is known as the wetted aspect ratio. The equation demonstrates the importance of wetted aspect ratio in achieving an aerodynamically efficient design. At supersonic speeds L/D values are lower. Concorde had a lift/drag ratio of about 7 at Mach 2, whereas a 747 has about 17 at about mach 0.85. Dietrich Küchemann developed an empirical relationship for predicting L/D ratio for high Mach numbers: where M

752-462: The lift and drag coefficients C L and C D . The varying ratio of lift to drag with AoA is often plotted in terms of these coefficients. For any given value of lift, the AoA varies with speed. Graphs of C L and C D vs. speed are referred to as drag curves . Speed is shown increasing from left to right. The lift/drag ratio is given by the slope from the origin to some point on the curve and so

799-426: The span efficiency factor , a number less than but close to unity for long, straight-edged wings, and C D , 0 {\displaystyle C_{D,0}} the zero-lift drag coefficient . Most importantly, the maximum lift-to-drag ratio is independent of the weight of the aircraft, the area of the wing, or the wing loading. It can be shown that two main drivers of maximum lift-to-drag ratio for

846-664: The Carter Personal Air Vehicle. "Critical Design Review " (CDR) for AAI Corporation was performed around January 2010 when the prototype was already being built. Usually a CDR is performed before a vehicle is built. In 2014, Carter said they bought back the license from AAI and is seeking production partners outside USA, hoping for production 3–5 years later. The PAV was taxi tested in autumn of 2010 at Olney Airport after FAA Special Airworthiness Certificate on 27 July 2010, and performed traffic pattern movement on 2 December 2010, piloted by Larry Neal at

893-667: The FAA to change the PAVs certificate from research and development to demonstration. The second PAV (called PAV-II, registration N210AV) was flight approved in March 2014, and demonstrated at Sun 'n Fun air festival and MacDill Air Force Base in 2014, both in Florida. In July 2014, it was displayed at Oshkosh Airshow . Carter says it has flown 186 kn (344 km/h; 214 mph) at 18,000 feet (5,500 m). The first non-Carter pilots flew

940-414: The L/D is specified when in straight and level flight. For a glider it determines the glide ratio , of distance travelled against loss of height. The term is calculated for any particular airspeed by measuring the lift generated, then dividing by the drag at that speed. These vary with speed, so the results are typically plotted on a 2-dimensional graph. In almost all cases the graph forms a U-shape, due to

987-491: The PAV reached Mu-1 on 7 November 2013. It also achieved a speed of 174 kn (322 km/h; 200 mph), and the rotor was slowed down to 113 rpm. The PAV flew its first public show flight outside Olney when it flew to Wichita Falls later that month. Carter says the PAV has achieved a speed of 204 miles per hour (328 km/h) at an altitude of 16,000 feet (4,900 m), a Mu of 1.13 and an L/D of 11.6-15. Carter has applied to

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1034-525: The PAV-II. The tip weights had been made of tungsten , while the current (2013) are made of steel. Suppliers for the aircraft include Blue Mountain Avionics for avionics and air-to-ground video and telemetry , and Sky Ox Oxygen Systems as the PAV is not pressurized. 60 channels of information convey sensor measurements from the aircraft to a ground computer, and 4 video cameras tape the flights. The engine

1081-592: The United States that could be used for this type of transportation. This infrastructure is currently underutilized, used primarily by recreational aircraft. Noise from PAVs could also upset communities if they operate near homes and businesses. Without lower noise levels that enable residential landings, any PAV must take off and land at an FAA-controlled airfield, where higher sound levels have been approved. Studies have explored ways to make helicopters and aircraft less noisy, but noise levels remain high. In 2005

1128-617: The VSP was replaced by new NASA Aeronautics initiatives. PAV technology development efforts at NASA shifted to a prize-based investment, with NASA Centennial Challenge Prize funds of $ 250,000 being provided for a Personal Air Vehicle Challenge in 2007. The European Union is funding a 3-leg € 4.2m study (under the Seventh Framework Programme ) of technologies and impacts for PAVs; Human-aircraft interaction, Automation of aerial systems in cluttered environments, and Exploring

1175-462: The aircraft in 2015. Computer aided design and X-plane flight simulation were used during development. Unlike the twin-boom CarterCopter, the PAV has a single tailboom. A tilting mast allows the rotor to be tilted 15 degrees forward and 30 degrees aft to allow different centres of gravity and wing angle-of-attacks . Helicopter rotors are designed to operate at a fixed RPM (within a narrow range of

1222-465: The aircraft, and it is not in volume production . The PAV flew traffic patterns with wings at Olney in January 2012, and has since flown winged test flights. It flew a few hours at a time, but its flight certificate restricted it to within 5 miles (8.0 km) of Olney. As of June 2012, development of the PAV is a year behind schedule due to various technical problems, and a delay of a further year

1269-511: The airflow and the wing aspect ratio . The L/D ratio is inversely proportional to the energy required for a given flightpath, so that doubling the L/D ratio will require only half of the energy for the same distance travelled. This results directly in better fuel economy . The L/D ratio can also be used for water craft and land vehicles. The L/D ratios for hydrofoil boats and displacement craft are determined similarly to aircraft. Lift can be created when an aerofoil-shaped body travels through

1316-644: The challenge was renamed as the General Aviation Technology Challenge. The new prizes were: The winners were: Lift to drag ratio In aerodynamics , the lift-to-drag ratio (or L/D ratio ) is the lift generated by an aerodynamic body such as an aerofoil or aircraft, divided by the aerodynamic drag caused by moving through air. It describes the aerodynamic efficiency under given flight conditions. The L/D ratio for any given body will vary according to these flight conditions. For an aerofoil wing or powered aircraft,

1363-520: The controls and co-pilot Robert Luna. Larry Neal was also one of the pilots of the CarterCopter at Olney in 2005. The first flight occurred on 5 January 2011 at Olney without wings and lasted 36 minutes, which qualified Carter for a milestone payment. Carter stated that the PAV performed its first zero-roll jump take-off on 18 January 2011, to a height of 120 feet (37 m). Eight jump take-offs were performed. There are some electrical issues with

1410-459: The dangerous areas of the stall speed diagram / height-velocity diagram as well as moving the speed limit up. The PAV has traditional airplane-like controls (Vernier type), but the stick also controls the rotor. Most controls were automated in 2011, and jump-takeoff is performed at the push of a button. Materials used include glass fiber, aluminum, titanium, and steel, as well as autoclaved carbon/epoxy prepreg with aramid honeycomb core on

1457-527: The design and operation of high performance sailplanes , which can have glide ratios almost 60 to 1 (60 units of distance forward for each unit of descent) in the best cases, but with 30:1 being considered good performance for general recreational use. Achieving a glider's best L/D in practice requires precise control of airspeed and smooth and restrained operation of the controls to reduce drag from deflected control surfaces. In zero wind conditions, L/D will equal distance traveled divided by altitude lost. Achieving

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1504-562: The equation for maximum lift-to-drag ratio, along with the equation for aspect ratio ( b 2 / S ref {\displaystyle b^{2}/S_{\text{ref}}} ), yields the equation ( L / D ) max = 1 2 π ε C fe b 2 S wet , {\displaystyle (L/D)_{\text{max}}={\frac {1}{2}}{\sqrt {{\frac {\pi \varepsilon }{C_{\text{fe}}}}{\frac {b^{2}}{S_{\text{wet}}}}}},} where b

1551-632: The low-speed side of the graph of lift versus velocity. Form drag is caused by movement of the body through air. This type of drag, known also as air resistance or profile drag varies with the square of speed (see drag equation ). For this reason profile drag is more pronounced at greater speeds, forming the right side of the lift/velocity graph's U shape. Profile drag is lowered primarily by streamlining and reducing cross section. The total drag on any aerodynamic body thus has two components, induced drag and form drag. The rates of change of lift and drag with angle of attack (AoA) are called respectively

1598-451: The maximum L/D is not dependent on weight or wing loading, but with greater wing loading the maximum L/D occurs at a faster airspeed. Also, the faster airspeed means the aircraft will fly at greater Reynolds number and this will usually bring about a lower zero-lift drag coefficient . Mathematically, the maximum lift-to-drag ratio can be estimated as where AR is the aspect ratio , ε {\displaystyle \varepsilon }

1645-444: The maximum L/D ratio does not occur at the point of least drag coefficient, the leftmost point. Instead, it occurs at a slightly greater speed. Designers will typically select a wing design which produces an L/D peak at the chosen cruising speed for a powered fixed-wing aircraft, thereby maximizing economy. Like all things in aeronautical engineering , the lift-to-drag ratio is not the only consideration for wing design. Performance at

1692-442: The maximum distance for altitude lost in wind conditions requires further modification of the best airspeed, as does alternating cruising and thermaling. To achieve high speed across country, glider pilots anticipating strong thermals often load their gliders (sailplanes) with water ballast : the increased wing loading means optimum glide ratio at greater airspeed, but at the cost of climbing more slowly in thermals. As noted below,

1739-458: The rotor blades are pitched to push air down and lift the aircraft in a jump takeoff . While altitude is reached, the aircraft transitions into forward flight using the pusher propeller, and the rotor shifts to autorotation (windmilling) with air flowing up through the rotor. As speed increases, the air flow increases rotor RPM like other autogyros. Once sufficient airspeed is reached (around 70–85 miles per hour or 113–137 kilometres per hour) for

1786-477: The rotor tips to enhance rotational energy and to reduce flapping. When the CarterCopter was damaged in 2005 due to a gear-up landing caused by pilot error, the cost of repair was deemed higher than the cost of making a new aircraft with the added benefit of incorporating lessons learned from the first aircraft. Design of the PAV was begun during 2005. Several changes and development problems occurred along

1833-465: The sky (HITS) makes it much easier to control aircraft. Also, Phantom Works is working on designing a system that allows to automate PAVs. The PAVs are designated their own "lanes" in the sky, thereby ensuring the avoidance of possible collisions. In addition, the different PAVs are also capable of detecting each other and communicating with each other, further decreasing the risk of collisions. The Federal Aviation Administration (FAA) infrastructure

1880-892: The small wings to provide lift, rotor blades are feathered to reduce rotor speed to 100 RPM and minimize drag, and lift is provided mostly by the wings when speed reaches 150 miles per hour (240 km/h). Rotor lift is reduced to 10%, and flight efficiency is somewhat below that of a commercial jet plane . Data from Jane's All the World's Aircraft General characteristics Performance Related development Personal Air Vehicle The emergence of this alternative to traditional ground transport methods has been enabled by unmanned aerial vehicle technologies and electric propulsion . Barriers include aviation safety , airworthiness , operating costs , usability , airspace integration, aircraft noise and emissions , tackled first by small UAS certification then experience. There

1927-557: The socio-technological environment. NASA Langley has researched and prototyped the necessary PAV technologies and has dedicated the largest cash prize in the history of GA to the PAV that can demonstrate the best overall combination of performance. The PAV flight competition for this prize, known as the first annual PAV Challenge , was held Aug 4-12, 2007 and hosted the CAFE Foundation in Santa Rosa, California. In 2008

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1974-408: The speed and routing efficiencies made possible by direct point-to-point flight. The PAV differs from conventional general aviation types in being usable by people with no pilot qualifications. Besides the fabrication of personal air vehicles, the creation of autonomous systems for PAVs is also being researched. First off, synthetic vision electronic flight instrument systems (EFIS) as Highway in

2021-414: The two main components of drag. The L/D may be calculated using computational fluid dynamics or computer simulation . It is measured empirically by testing in a wind tunnel or in free flight test . The L/D ratio is affected by both the form drag of the body and by the induced drag associated with creating a lifting force. It depends principally on the lift and drag coefficients, angle of attack to

2068-541: The unmanned Kaman K-MAX , but over a future range of 1,300 nautical miles (2,400 km) compared to the demonstrated 150 nautical miles (280 km) or more of the K-MAX. The agreement committed CarterCopters to developing the technology to maturity, in exchange for exclusive rights to develop UAVs for the next 40 years. The first product in the AAI agreement was to be an autonomous slowed rotor/compound (SR/C) aircraft based on

2115-490: The way; twin boom was deemed unnecessary, so a single boom was constructed, and flaws in rotor blades and hub were revealed during testing and then corrected. On 16 November 2009, the AAI Corporation (a division of Textron ) signed a 40-year exclusive license agreement with the company concerning all unmanned aircraft systems , one of which was intended to deliver 3,000 pounds (1,400 kg) of cargo similar to

2162-558: Was caused by rotor RPM software control issues. Carter received funding from the Wichita Falls Economic Development Corporation in 2010 to complete the PAV. Carter views the lack of a PAV flight simulator as a mistake, and attempts to build one. The previous CarterCopter was designed using a flight simulator. Carter says that the PAV has a lift to drag ratio of 10–15, and reached an advance ratio of 0.85 in 2012. According to Carter,

2209-484: Was to establish vehicle capability goals and the required technology investment strategies to achieve those breakthroughs. The difference in vehicle characteristics between PAVs and existing General Aviation single engine piston aircraft was set out in 2003 at an American Institute of Aeronautics and Astronautics (AIAA) conference. Advanced concepts would be needed to dramatically enhance ease of use, safety, efficiency, field length performance, and affordability. In 2006

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