Personal air vehicle

A personal air vehicle (PAV), also personal aerial vehicle, is an emerging type of aircraft proposed to provide on-demand aviation services.

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.[1]

The term was first used by NASA in 2003 when it established the Personal Air Vehicle Sector Project, as part of the Aeronautics Vehicle Systems Program. This project was part of 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 was to establish vehicle capability goals and the required technology investment strategies to achieve those breakthroughs.

Naming

Other names discussed include PIVITOLs (Personal Vertical TakeOff vehicles), Air-cars, PACs (Personal AirCraft), AVs (Air Vehicles). The term flying car is also sometimes used, although that term usually includes roadable aircraft, which do not come under the purview of PAVs.

History

The first technical paper to explain the difference in vehicle characteristics between PAVs and existing General Aviation single engine piston aircraft was "Personal Air Vehicles: A Rural/Regional and Intra-Urban On-Demand Transportation System" by NASA Langley Research Center manager Mark D. Moore.[2] Presented in September 2003 at an American Institute of Aeronautics and Astronautics (AIAA) conference as AIAA Paper 2003-2646; the paper established advanced concepts that would provide vehicle characteristics that dramatically enhanced the ease of use, safety, efficiency, field length performance, and affordability. Many additional papers were presented at AIAA and Society of Automotive Engineers (SAE) conferences through 2006 that further refined the definition of PAV capabilities, technologies, and concepts. In 2006, the Vehicle Systems Program 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 being provided for competitions: Personal Air Vehicle Challenge in 2007, awarding $250,000 in prizes; General Aviation Technology Challenge in 2008, awarding $350,000 in prizes; and Green Flight Challenge in 2011, awarding $1,500,000 in prizes. Each competition was completed for NASA by the Comparative Aircraft Flight Efficiency (CAFE) Foundation in Santa Rosa, California.

Benefits

Currently the doorstep-to-doorstep average speed for cars is 35 mph. In the greater Los Angeles area, this speed is predicted to degrade to 22 mph by year 2020. The U.S. Department of Transportation (DOT) states that 6.7 billion US gallons (25,000,000 m3) of gasoline are wasted in traffic jams each year.

A future system of travel by PAVs might avoid air traffic jams and could help to relieve those on highways.

PAV definition outline
  • Seats: Less than 5 passengers.
  • 150–200 mph (240–320 km/h) cruising speed.
  • Quiet.
  • Comfortable.
  • Reliable.
  • Able to be flown either autonomously, or at least by anyone with a driver’s license.
  • As affordable as travel by car or airliner.
  • Near all-weather capability enabled by synthetic vision systems.
  • Highly efficient (able to use alternative fuels, fuel cells, or electric batteries).
  • 800 miles (1,300 km) range.
  • Provide "door-to-door" transportation solutions. The original NASA proposal was doing this with small community airports that are at closer proximities to businesses and residences than large airports. More recent proposals are based around VTOL approaches.

Some private companies are using their own criteria for vehicles in this general category.

Barriers

Air traffic control

The Federal Aviation Administration (FAA) infrastructure 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.[3] 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 the United States that could be used for this type of transportation. This infrastructure is currently underutilized, used primarily by recreational aircraft.

Noise

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 a simple method of reducing noise was identified: Keep aircraft at a higher altitude during landing. This is called a Continuous Descent Approach (CDA).[4]

Range

Many proposed PAV aircraft are based on electric batteries, however they have low range due to the low specific energy of current batteries.[5] 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 a solution to this issue, owing to the much higher specific energy of hydrogen.[5][6]

Safety

Urban flight safety is a well-known problem for regulators and industry. For example, 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 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 a year.[7]

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.[8] Sikorsky Aircraft want to reach 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.[7]

Studies

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 the socio-technological environment.[9][10]

Progress

Fulfillment of the NASA vision for PAVs is likely to unfold over several decades. Several vehicle types exist which strive to meet the PAV definition:

Most vehicles in the above category do not meet all the requirements set by NASA. However, some vehicles come close. Ultrallight aircraft are of special interest since their energy usage is low. Hybrid forms of the vehicle types above can also be useful. Some hybrid forms that exist are:

  • the Opener Blackfly, an automated, electrically-powered personal VTOL with good energy efficiency.
  • the AeroVironment SkyTote, a combination of airplane and a helicopter. It is also fully automated, similar to driverless cars.
  • The Ornithopter, a similar helicopter/ornithopter hybrid.
  • The Theolia Windream One and Hunt Aviation[11] have come up with airship hybrids. Airships may also be foreseen with ground effect modifications.
  • The Solar Impulse and the electric airplane feature all-electric propulsion.

Autonomy

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 the sky (HITS) makes it much easier to control aircraft.[12] 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.[13]

PAV challenge

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.[14]

In 2008 the challenge was renamed as the General Aviation Technology Challenge.

The new prizes were:

  • The Community Noise Prize ($150,000)
  • The Green Prize ($50,000) (MPG)
  • The Aviation Safety Prize ($50,000) (Handling, eCFI)
  • The CAFE 400 Prize ($25,000) (Speed)
  • The Quietest LSA Prize ($10,000)

The winners were:

  • Community Noise Lambada N109UA $20,000
  • Green Prize no winner n/a
  • CAFE Safety Pipistrel N2471P $50,000
  • CAFE 400 Pipistrel N2471P $2,000
  • Quietest LSA Lambada N109UA $10,000
  • Shortest Takeoff Pipistrel N2471P $3,750
  • Best Angle of Climb Pipistrel N2471P $3,750
  • Best Glide Ratio at 100 MPH Flightdesign CTSW N135CT $3,750
  • Cabin Noise (tie) Lambada N109UA Pipistrel N2471P $3,750 ($1,875 each)

Other notable designs

List of Personal Air Vehicles with VTOL capability

See also

References
  1. Graham Warwick (May 6, 2016). "Problems Aerospace Still Has To Solve". Aviation Week & Space Technology.
  2. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20060005004.pdf
  3. FAA NGATS Archived 2006-10-17 at the Wayback Machine
  4. "Reducing Airplane Noise: Acoustical Engineers Find Simple Way to Reduce Airplane Noise". ScienceDaily. July 1, 2005.
  5. "Flying Car Startup Alaka'i Bets Hydrogen Outdoes Batteries". Wired. ISSN 1059-1028. Retrieved 2020-01-20.
  6. "Hydrogen-powered flying vehicle touted as Southern California traffic tonic". Reuters UK. 2019-05-30. Retrieved 2020-01-20.
  7. Guy Norris (Jan 26, 2018). "Reality Check for Urban eVTOL On Safety And Production". Aviation Week & Space Technology.
  8. Mark Huber (May 1, 2018). "Sikorsky Exec Stresses Urban Air Safety". AIN online.
  9. Czyzewski, Andrew. Personal flying vehicles project aims to end road congestion The Engineer (UK magazine), 22 June 2011. Accessed: 26 July 2011.
  10. myCopter European Union, 2011. Accessed: 26 July 2011.
  11. Bellows, Alan (2006-03-31). "Gravity powered plane". Damninteresting.com. Retrieved 2011-04-25.
  12. Harry Kraemer (2003-12-01). "Highway in the sky". Aviationtoday.com. Retrieved 2011-04-25.
  13. Gary Sanders (July 2004). "Boeing technical experts check the feasibility of Personal Air Vehicles". Boeing Frontiers.
  14. https://web.archive.org/web/20070307095341/http://cafefoundation.org/v2/pav_home.php

Further reading

Reports
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