# A Survey of the Effects of Vehicle Configuration on Urban Air Mobility +
## 2 Aerial Urban Vehicle Configurations and Concepts
### Hybrid
#### 2.3.2 Tilt-Body  
In the tilt-body configuration, the entire body experiences a tilting or rotational motion. This configuration has certain advantages like high cruise speed and high controllability, however, the major challenge with tilt-body aircraft, similar to other hybrid concepts, is their complex dynamics and control during the transition phase [15]. In addition, this configuration is problematic regarding passenger comfort in flight, especially during take-off and landing. Opener's BlackFly is an example of a tilt-body AUV. It uses two wings with eight propulsion units. The wings are equipped with control surfaces to provide the aircraft with better flight control. This all-electric, personal aerial vehicle takes off and lands  
Figure 15: Some examples of dual-system hybrid aircraft: (**a**) Hyundai-Uber air taxi, (**b**) Wisk, (**c**) Tetra Aviation MK-5.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Advantages** & **Disadvantages** \\ \hline No need for runway (VTOL) & Low efficiency \\ Simple structure & Inactive engines in each phase are dead weight \\ Smaller profile & Comparatively expensive \\ Simple control & \\ Longer endurance compared to VTOLs & \\ Robustness against faults & \\ \hline \hline \end{tabular}
\end{table}
Table 9: Advantages and disadvantages of dual-system hybrid configurations.  
vertically. During the take-off, landing, and hover flight, its body tilts to a semi-vertical situation to use the propulsion force of the rotors for the neutralization of weight force. Such a flight mechanism provides BlackFly with a range of 65 km and a maximum speed of 130 km/h, albeit at the cost of discomfort for the passenger [82]. Figure 16 illustrates the tilting mechanism of BlackFly. Tilt-body aircraft are more suitable for cargo transportation purposes due to their uncomfortable flight experience, however a summarization of their advantage and disadvantages is provided in Table 10.  
Like other hybrid configurations, a tilt-body aircraft has three phases: VTOL, Transition, and fixed-wing cruise. The tilt-body aircraft does not have any actuators to change the propulsion unit or wing angle. Instead, it has a fixed wing with control surfaces that allows for VTOL and fixed-wing flying. Since there are no moving actuators, the only possible failure is with the propulsion unit, which is similar to fixed-wing and multirotor failures. In cruise mode, the controller can use the elevator or the aileron to provide a range of robustness against external disturbances. However, the aircraft is still vulnerable to wind in VTOL mode due to the effective wing surface and lake of applicable control surfaces [84].  
The transition mode in this configuration can be risky because the fixed-angle wing and changing body position and rotation can cause a difficult flight situation for the controller. If a propulsion unit fails in transition mode, it can be challenging to stabilize the aircraft as the center of gravity changes. Therefore, the aerodynamic design of the fuselage is crucial, especially in cruise mode, where the main body has a large angle with the horizon, resulting in significant aerodynamic drag [84].