引领城市空中出租车变革（英） Volocopter 2019-6.pdf

PIONEERING THE URBAN AIR TAXI REVOLUTION 1.0THE CASE FOR URBAN AIR TRANSPORTATION THE URBAN AIR TAXI MISSION SAFETY “Fast-Forwarding to a Future of On-Demand Urban Air Transportation”; October 2016 2 Porsche Consulting; “The Future of Vertical Mobility”; March 2018 3 Roland Berger GmbH; “Urban air mobility: The rise of a new mode of transportation”; November 2018 4 McKinsey Company for Future Mobility; “Taxiing for take-off: The flying cab in your future”; January 2019Pioneering the Urban Air Taxi Revolution 9 To visualize this relationship between disc loading, tip speed and noise, consider the following two applications for lifting the weight of one person. The slow-mov- ing large rotors of the human powered multicopter can hardly be heard, while the “jet pack” solution with its small, fast-spinning rotors generates a lot of noise (compare to Figure 4). The above holds true in the critical vertical take-off and landing phase, where the distance to people on the ground is smallest. In cruise flight at sufficient speed, generating lift using wings may be an efficient way to reduce noise signature, although vertical noise emissions by conventional propellers may negate part of this advantage. When looking at the urban air taxi mission, the most critical phases in terms of noise emission are take-off and landing. It is in these phases that the aircraft has the greatest impact on the surrounding area and people. Aircraft like the Volo- copter with a large rotor area and low disc loading will be more likely to comply with strict noise regulations and be granted access to densely populated areas. It is important to note that a large rotor disc area can be achieved by using a few large rotors or numerous smaller rotors. Slower tip speeds can be achieved by using a large number of small rotors, which in turn reduces noise coming from the rotor tips. In addition, a large number of smaller rotors is perceived to be quieter than one larger rotor. This is because various weak noise sources spread noise over a broad frequency spectrum, which is less disturbing to the human ear than one prominent noise source.           
 Figure 4 Difference in noise lifting the same payload (Source: Aerovelo, Martin Jet Pack)Pioneering the Urban Air Taxi Revolution 10 Volocopter has taken all of the above factors into account in the design of its air taxi. As a result, Volocopter has emerged as the air taxi with the lowest noise signature that is best suited to fly into the populated centers of megacities without adding to the present noise pollution. RANGE & SPEED One of the most hotly-debated questions about urban air taxis focuses on the required range of an eVTOL for the urban air taxi mission. Compared to con- ventional aircraft, urban air taxis fly very short distances and thus only require a limited range to offer useful capabilities. Uber’s Elevate paper suggests that urban air taxis will mainly be useful to so-called “mega commuters,” people who commute more than 160 km per day, therefore making a minimum useful range for these commuters half of that distance (80 km). The paper also suggests that there would be no opportunity to re - charge the batteries between flights, which means that the air taxi would have to fly the return trip (160 km) without recharging. The authors assert that for shorter range commutes, the ground infrastructure requirements would be too cumbersome for practical purposes.                        
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) R22    Gw LwMw  3f 5 ( ) 5–6 ( ) 65 ( ) 3 ( ) 6 ( ) 82 ( ) 9 ( ) 1 ( ) 3 q   Figure 5 The Volocopter can be integrated into the city without adding significantly more noise pollution