Current electric vertical takeoff and landing aircraft (eVTOL) configurations for Urban Air Mobility (UAM) applications often require performance-hindering equipment only used for a specific operation (e.g., takeoff or cruising). The need for such equipment, such as separate lift and thrust mechanisms, often stems from the challenge posed by transitioning from hovering to forward flight. For example, tilt-wing eVTOLs have complex transition periods that can result in large pitching movements or wing stalling without adequate propulsion, potentially causing catastrophic loss of control.
Increased equipment requirements for eVTOLs also increase system mass, negatively impacting performance. Innovators at NASA’s Langley Research Center recognized this issue and have developed a novel eVTOL solution design. The technology is a distributed electric propulsion, modular wing aircraft capable of vertical takeoff and landing, without requiring near 90° wing tilt. Instead, NASA’s eVTOL uses large flaps and a fixed slight wing tilt to generate upward force, enabling VTOL operations, benign transition from hovering to forward flight, and increased safety and simplicity of operations.
NASA’s design instead uses a slight wing angle and large flaps designed to deflect slipstream generated by the propellers to create a net positive force in the vertical direction, all while preventing forward movement. This unique configuration allows for takeoff and landing operations without the need for near 90° wing tilt angles. After takeoff, the transition to forward flight only requires a slight change in attitude of the vehicle and retraction of the flaps. Similar solutions require large changes in attitude to accomplish this transition, which is often undesirable, especially for air taxi operations that involve passengers. Given the effectiveness of this configuration for generating upward force, the requirement for wing angle tilt has been reduced from near 90° to approximately 15° during takeoff.
Further iterations may reduce this requirement even further to 0°. By eliminating the need for near 90° wing tilt, NASA’s eVTOL design removes the need for mechanisms to perform active tilting of the wings or rotors, reducing system mass, and thereby, improving performance. Flaps represent the only components that require actuation for takeoff and landing operations.
Innovators at NASA leveraged the Langley Aerodrome 8 (LA-8), a modular testbed vehicle that allows for rapid prototyping and testing of eVTOLs, to design and test this novel concept.