# A Survey of the Effects of Vehicle Configuration on Urban Air Mobility +
## 4 Conclusions  
In this paper, we studied the different configurations of aircraft in urban air mobility applications. According to the available aircraft and research in UAM, we considered three main categories; horizontal takeoff and landing, vertical takeoff and landing, and hybrid aircraft which are a combination of the VTOL and HTOL configurations. Each of these categories and their sub-categories has different advantages and disadvantages that are studied in detail. Considering the specifications of 52 popular and important aircraft from different categories, we provided average ranges of some key specifications like range, endurance, speed, cargo capacity, number of passengers, source of energy, and service ceiling for each aircraft category. This survey reveals that most of the UAM solutions are focusing on 4-5 passengers. The main focus among HTOL configurations is on fixed-wing, while VTOL configurations mainly include helicopters, multirotors and lighter-than-air configurations. The most popular hybrid configurations are tiltrotor, dual system, and tilt-wing. Fixed-wing aircraft are known for their high speed, payload capacity, passenger capacity, and long range, which make them ideal for long-distance travels and missions, however their reliance on takeoff and landing runways limits their urban usages. Morphing-wing designs enhance adaptability and efficiency in HTOL configurations, but introduce mechanical complexity and consequently higher failure risks. While Magnus-effect planes offer compact size, high lift, and stability but face aerodynamic challenges. Gyroplanes have shown to be simple, affordable, and require shorter runways, though they are slower and have shorter ranges. Balloons and airships are slow but excel in payload capacity and range, making them suitable for cargo transport or surveillance. VTOL configurations, such as helicopters, are well-suited for urban environments due to their hover capability and ability to carry 4-7 passengers, but they are noisy, mechanically complex, and less maneuverable, with single-engine failures posing risks despite their autorotation safety feature. Multirotors, with their simple design and ease of maintenance, are ideal for short urban trips but are limited to fewer than four passengers, lower speeds, shorter endurance, and limited range. Cyclocopters, with their 360-degree thrust capability, are highly maneuverable and suitable for mid-range flights, though their unique rotor systems require further study regarding failure modes. Hybrid configurations, such as tilt-wing and tilt-rotor aircraft, combine VTOL and HTOL benefits, offering vertical takeoff and landing without runways, medium range, and the ability to carry 4-7 passengers. However, their complex designs, especially during transition phases, can introduce failure risks. Dual systems simplify the transition between VTOL and HTOL modes but are less efficient due to separate propulsion systems and may struggle with synchronization during failures. Hybrid and multirotor aircraft are often electric-powered or use hybrid systems, but their payload capacity is limited by battery weight, restricting them to short flights with less than an hour of endurance. Hybrid configurations have attempted to address this by increasing their maximum cruise speed. In terms of size, most UAM aircraft have medium dimensions of 5-15 m, though smaller designs (under 5 m) and larger ones (up to 55 m) also exist. Fixed-wing, helicopter, and lighter-than-air aircraft are primarily fuel-powered, while hybrid and multirotor designs lean toward electric or hybrid power. In summary, based on the studied aircraft, each configuration has unique advantages and limitations, with fault tolerance, failure recovery, payload capacity, and endurance being critical considerations for UAM applications. Different applications in UAM can be divided into transportation, emergency response, cargo delivery, aerial surveillance, and entertainment.