# A Survey of the Effects of Vehicle Configuration on Urban Air Mobility +
## 2 Aerial Urban Vehicle Configurations and Concepts
### Horizontal Take-Off and Landing (HTOL)
#### 2.1.3 Magnus Effect  
There are a few concepts around Magnus-effect amongst air taxis, one example is the iCar concept, which is a car-plane concept for one-person use. iCar uses a Magnus wing to produce lift along with two rotors that can be embedded in the tires. It is powered by a gas turbine which in driving mode feeds an electrical generator, through which the wheels are motorized. During cruise flight, the engine drives the electrical generator but also provides direct mechanical power to the wing's propellers, which its movement is also partially driven by electrical engines to make it more responsive to piloting and modulations in power. A rear principal set of telescoping Flettner rotors is hidden within oversized wheels when iCar is used as a vehicle. When it is used as an aircraft, these wings telescope outward, and the hubcaps of the front wheels swivel forward to become propellers. The biggest advantage of using spinning cylinder wings is size efficiency [33]. The Icarus is another \begin{table}
\begin{tabular}{c c} \hline \hline
**Advantages** & **Disadvantages** \\ \hline Roadability & Complex structure \\ Adaptive flight and robustness & Need for runway and infrastructure \\ High endurance & Low efficiency \\ High speed & Vulnerability to failure \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Advantages and disadvantages of flying car configuration. Figure 6: Different views of Transition: (**a**) flying mode, (**b**) car mode [29], (**c**) Maverick flying car [30]. conceptual design inspired by the iCar. It is a single-seat transportation vehicle similar to a motorcycle. As conceptualized, the vehicle can use a 150 hp engine to provide power to four rotating cylinders, each having a length of about 6 ft and being powered by a 7.5 kW electric motor and a rearmounted propeller which would provide forward thrust. In order to maintain stability during flight, the four cylinders would be individually controlled by an onboard flight management computer. The vehicle was mostly intended for recreational purposes [34]. Figure 7 illustrates a view of these concepts. The significant advantages of a Magnus-effect mechanism are high-lift force or relatively high wing-loading and stall resistance in some specific types of Magnus wings. But using Magnus wings and rotors are more complex compared to a conventional wing and need additional control mechanisms. The gyroscopic effects may help to increase stability but make major issues in control particularly in low airspeeds (in low Raynolds numbers and specific ranges of velocity ratios, a negative Magnus force may cause the lift to break down). Due to this, there is a need for other control mechanisms like control surfaces to control the roll [15; 35]. Table 3 summarizes the advantages and disadvantages of this configuration. As we mentioned, there are certain limitations to Magnus's propulsion unit, such as the fixed velocity ratio between airspeed and circumferential speed, which can lead to a negative Magnus force in flight at low-velocity ratios and within a certain range of Reynolds number which consequently results in a stall. A motor is necessary to rotate the cylinder at high speed to generate lift force. In the case of motor failure, the rotating cylinder may continue to produce lift, so this configuration is robust to engine failure at least for a short period of time. But the gyroscopic moment can affect the aircraft's yaw, roll, or pitch. The propulsion unit is also vulnerable to object impact, as damage to the cylinder's surface can hinder its performance and the aircraft may experience negative force or gyroscopic moment [35].