# A Survey of the Effects of Vehicle Configuration on Urban Air Mobility +
## 2 Aerial Urban Vehicle Configurations and Concepts
### Hybrid
#### 2.3.5. Gyrodyne  
Another configuration One of the other configurations in the dual-system category is called Gyrodyne. The Fairey Rotodyne (Figure 19a) is one of the early examples of gyrodynes proposed for civilian transport applications. Developed in the 1950s, it combined the features of both a fixed-wing airplane and a helicopter. Its fuselage was like that of a conventional aircraft using a double rudder tail configuration. Additionally, it had short, straight, anhedral wings with two 3000 hp, Napier Eland H.E1-3 2 turboprop engines mounted under them, which would not only provide the power for the propellers during the cruise, but also power the four-bladed (27.5 m) rotor used for vertical take-off and landing. After taking off, the power would gradually be transferred from the rotor to the propellers as forward airspeed began to increase until the rotor was completely unpowered and allowed to auto-rotate. During cruise flight, about 60 percent of the total lift was  
Figure 18: Tilting mechanism of Lilium: (**a**) vertical take-off and landing, (**b**) cruise mode [90]. \begin{table}
\begin{tabular}{c c} \hline \hline
**Advantages** & **Disadvantages** \\ \hline No need for runway (VTOL) & Complex transition phase \\ Efficiency & \\ Comparatively inexpensive & \\ Simple structure (among hybrids) & \\ Higher endurance compared to VTOLs & \\ \hline \hline \end{tabular}
\end{table} 
Table 12: Advantages and disadvantages of tilt-rotor hybrid configuration. generated by the wings, and the remaining 40 percent was provided by the auto-rotating rotors. Furthermore, due to the fact that the propellers were capable of counteracting the torque from the rotors, tail rotors were not required. The final model (The Rotodyne Z) could transport up to 65 passengers to/with a maximum range of 1180 km with/and a maximum speed of 320 km/h. In terms of fuel consumption, while the Fairy Rotodyne was not as efficient as fixed-wing aircraft, it beat the helicopters of its time not only due to the presence of fixed-wings, but also because it could take-off and land horizontally in case a runway was present (which would drastically reduce fuel consumption). Even when compared with modern VTOL like helicopters and hybrid aircraft like tiltrotors, the Fairey Rotodyne seems to be a superior choice in terms of passenger capacity. Finally, it should be noted that like other dual-system configurations, gyrodynes in general are mechanically simpler than other hybrid configurations due to the distinction between the VTOL and horizontal flight systems. Compared to other hybrid aircraft of the same class such as the Bell Boeing V-22 Osprey, the Fairey Rotodyne seems to offer a more maintenance friendly design direction that is less prone to mechanical problems. One of the main drawbacks of the Fairey Rotodyne which partially led to its downfall, was the extreme levels of noise that it produced during take-off and landing which made it problematic for civilian application. Had the development not been canceled, this problem may have been addressed, yet the noise is one of the main challenges that gyrodynes in general face when it comes to their viability for UAM applications [95]. Table 13 sums up the advantages and disadvantages of this configuration. Another configuration is introduced by Jaunt Air Mobility. The ROSA (Figure 19b) is Jaunt's attempt to design a viable hybrid solution for UAM applications. This configuration is in fact based on Carter-Copter's design introduced in 2004 which was a 4-seat Personal Air Vehicle (PAV) aircraft with more than 1000 takeoffs and landings and 100 h of flight testing, with a speed of up to 344 km/h and a max altitude of up to 5500 m. This configuration