Browse Topic: Vehicle ride
Advanced Air Mobility (AAM) faces operational challenges because a significant portion of AAM flight operations are likely to occur within the atmospheric boundary layer (ABL). In particular, terminal flight paths within the ABL roughness sublayer will involve flying through building wakes that will likely result in a considerable increase in significant dynamic and vibratory loads on the vehicle, affecting flight safety and ride quality. A new representative environmental method (REM) has been developed that provides real-time estimates of the unsteady wind environments, including the roughness sublayer. The approach has numerous advantages over computational fluid dynamics solutions of any fidelity, as no meshing is required and it can easily be modified to evaluate the sensitivity of different environmental factors on operations or design. This approach is explained, verified, and validated using computational and experimental data.
A piloted simulation study in the Vertical Motion Simulator at NASA Ames Research Center will investigate the handling and ride qualities of eVTOL configurations (lift-plus-cruise and tiltwing) for both civilian and military applications. The flight dynamics models were developed in the FLIGHTLAB modeling and analysis software environment, while explicit model-following control laws and high-fidelity powertrain models were developed in Simulink. The Joint Input-Output method was used to generate frequency responses for linear model verification, as the control effectors are highly correlated for these types of vehicles. The linear models were verified for the frequency range of interest for handling qualities. Once verified and tested individually, the three parts (flight dynamics model, control laws, and powertrain) will be integrated into the Vertical Motion Simulator for piloted simulation evaluations.
Small, highly maneuverable Urban Air Mobility (UAM) air taxis might exhibit motions during hover and low-speed flight that are unfamiliar to many passengers, and for which there are no established guidelines to predict passenger comfort. Researchers performed a study in the Armstrong Virtual Reality Passenger Ride Quality Laboratory to identify relationships between sudden motion characteristics and UAM passenger comfort and acceptance. Twenty-three volunteer test subjects from the Armstrong workforce each completed a 15-minute experience as a passenger in a virtual air taxi simulation. Subjects evaluated a series of flight maneuvers with varying levels of sudden motion using a five-point rating scale and indicated which motion(s) they found uncomfortable. Researchers then administered a post-test questionnaire to relate the passengers’ ratings to their willingness to fly on a real air taxi with similar levels of motion. The study results relate peak heave acceleration and jerk to
Helicopter aircrew are exposed to high levels of whole-body vibration (WBV) in fight operations, which may degrade their ride comfort and performance in the short-term, and contribute to some health issues in the long-term. This paper presents the latest development and flight test demonstration results of an active seat mount system that is designed to reduce helicopter aircrew WBV levels through active cancellation of the N/rev vibration peaks related to the helicopter main rotor speed. A prototype airworthy hardware of the active seat mount system has been developed based on previous bench-top-test designs to meet airframe integrity requirements for installation and flight testing on the Bell-412 helicopter. Extensive experimental results on human occupants using a shaker table facility and flight demonstrations on the NRC Bell-412 helicopter in representative flight conditions are presented and discussed. The active seat mount system has achieved significant reduction to the
The paper presents a novel strategy for minimum energy consumption in automatic conversion control of tiltrotor eVTOL aircraft, exemplified by the Aston Martin Volante Vision model. We introduce a tilt schedule methodology that strategically balances conversion and reconversion performance with climb, descent, and cruise phases to minimize overall energy expenditure. Our approach accounts for critical factors such as blade loading, operation handling qualities, and passenger ride comfort within a predefined conversion corridor. The optimized trajectories approximate the minimum energy pathway, essential for operational efficiency in urban air mobility. Analytical results demonstrate that our proposed conversion and reconversion phase profiles significantly reduce energy consumption, contributing to the sustainability of tiltrotor flight operations. This research not only enhances understanding of tiltrotor dynamics but also serves as a pivotal step toward achieving globally optimized
Flight mechanics modeling and real-time simulation of rotorcraft have many challenges including the aerodynamics and dynamics of the rotor system, rotor inflow, and wake-airframe interactions. Furthermore, interactional aerodynamic effects are difficult to characterize, in particular during early configuration down-selection. Rotorcraft configurations under consideration for advanced air mobility applications are trending toward designs with coaxial rotor systems and multiple distributed propellers / rotors in close-proximity with one another and the airframe. This proximity leads to strong coupling between the rotor inflow and lifting surfaces (e.g., tiltwing and lift+cruise urban air mobility concepts). This paper describes recent work toward the development of a general-purpose modeling framework for flight mechanics analysis and simulation of rotorcraft and aircraft configurations proposed for advanced air mobility applications. This modeling framework was developed for assessment
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