# A Survey of the Effects of Vehicle Configuration on Urban Air Mobility +
## 2 Aerial Urban Vehicle Configurations and Concepts
### Specifications of Current UAM Aircraft
A large number of companies and researchers are focusing on multirotor aircraft from bi-rotors, quadrotors to more than four rotors. There were many more models of balloons to be studied, but considering their similarity, we only selected four typical and popular models in our list. There were no in-service or under-development aircraft even in the early stages in other groups, so we did not consider them in our selected list. This study revealed some interesting results. First, most of the companies seem to be focusing on personal and family vehicles with a passenger capacity of up to 5 including a pilot. The ranges of 4-5 passengers also contain air-taxies as well. The next place belongs to personal vehicles with up to 2 passengers. It should be mentioned that some aircraft have more than one seating plan and we have considered each of those separately. Figure 21 illustrates the distribution of the passenger capacity among the studied aircraft. While this research work attempts to provide a comprehensive review and propose a logical classification system for urban air mobilities, the proposed classification may not fully capture the current market dynamics due to their rapid evolution and diversity. If we group the studied aircraft by their configuration, we will find more interesting results. Figure 22 represents each aircraft in a configuration-passenger capacity group by a circle. For example, 4 aircraft with more than 8 passengers among the studied UAM aircraft use an HTOL configuration. This is more than two other groups, which is due to the higher capabilities of HTOL aircraft for carrying heavier cargo. However, these results are mostly valid for fuel-powered HTOL configurations. Research shows an average of 2 passengers for eHTOL aircraft [98]. This figure also shows the limited range of passengers for HTOL configurations, this is while VTOL and hybrid configurations can provide a wider range of passenger capacities. Another interesting result of this comparison is the focus on 4-5-passenger aircraft on the hybrid configurations. This is while, for 1-2 passengers, the focus is on VTOL configurations. Taking other specifications into account, and calculating average values for each configuration provides us with interesting results. Table 15 summarizes average specifications of different configurations. It should be noted that some specifications are not available for a number of aircraft. In those cases, we did not take them into account if it was not possible to estimate them. According to this table, it can be said that the most focused  
Figure 21: Distribution of passenger capacity among the studied aircraft. configurations in HTOL are fixed-wing and helicopter. For VTOL, they are multirotors and lighter than air configurations. Tilt-rotor, dual system, and tilt-wing are the most popular hybrid configurations. Lighter-than-air and fixed-wing configurations have high payload capacity, number of passengers, and range. While fixed-wing aircraft are fast, balloons and airships are pretty slow with an average speed of 110 km/h. Helicopter, tilt-wing, and tilt-rotor aircraft have a medium range of 4-7 passengers and similar speeds. However, due to the fact that most helicopters are fuel-powered, they have higher range and endurance. They are also designed to have a higher service ceiling with an average of about 5 km. The multirotor and dual system configuration are being used for less than 4 passengers. While multirotors have lower speed, flight height, endurance, and range, dual systems are designed for higher heights and longer flights. The majority of configurations have medium dimensions with about 5 to 15 m in length or wing span. There are a few number of small aircraft with less than 5 m length between helicopters, multirotors, and dual systems. The rest of the configurations including fixed-wing and lighter than air are large aircraft with more than 15 m and up to 55 m dimensions. The majority of multirotor and hybrid aircraft are electric-powered or use hybrid power.