Browse Topic: Landing gear
With advanced air mobility (AAM) vehicles becoming an increasingly popular topic in aviation, the Eagle Flight Research Center (EFRC) at Embry-Riddle Aeronautical University continues to investigate control strategies that enhance aircraft resilience to total power unit failures. Utilizing a distributed electric propulsion (DEP) quad-heli test bed, the EFRC has explored a variety of control laws and hardware configurations to evaluate their effectiveness under failure conditions, including sustained flight with a completely inoperative rotor. The aircraft utilizes a fractional-order PID (FOPID) controller that has recently been developed and shown to outperform conventional PID controller used previously in both nominal and failure scenarios. The use of a FOPID controller offers improved stability and tracking performance. Another development is the implementation of a split-rotation rotor configuration—where the left-side rotors rotate clockwise and the right-side rotors rotate
Ground vibration testing (GVT) is an important phase of the development, or the structural modification of an aircraft program. The modes of vibration and their associated parameters extracted from the GVT are used to modify the structural model of the aircraft to make more reliable dynamics predictions to satisfy certification authorities. Due to the high cost and the extensive preparations for such tests, a new method of vibration testing called taxi vibration testing (TVT) rooted in operational modal analysis (OMA) was recently proposed and investigated by the German Institute for Aerospace Research (DLR) as alternative to conventional GVT. In this investigation, a computational framework based on fully coupled flexible multibody dynamics for TVT is presented to further investigate the applicability of the TVT to flexible airframes. The time domain decomposition (TDD) method for OMA was used to postprocess the response of the airframe during a TVT. The framework was then used to
The intent of this SAE Aerospace Information Report (AIR) is to document the design requirements and approaches for the crashworthy design of aircraft landing gear. This document covers the field of commercial and military airplanes and helicopters. This summary of crashworthy landing gear design requirements and approaches may be used as a reference for future aircraft.
ABSTRACT
Rotorcraft, like most machines, require periodic lubrication tasks to ensure continued safe and reliable operation. Optimal lubrication intervals are desired to maintain system performance while minimizing aircraft downtime and maintenance labor. Boeing and AMRRI conducted a Lubrication Optimization Study (LOS) on the H-47 Chinook helicopter to establish the necessary engineering artifacts to define the grease lubrication intervals for selected Drive, Rotor, and Landing Gear components. Grease samples were collected from these components by H-47 operators from multiple nations and submitted for a laboratory analysis to characterize how wear, properties and contaminants change as time and aircraft hours accumulate. The LOS also revealed opportunities to further evaluate and leverage the data produced in this study, including determining superior performance of specific lubricants within the Mil-Spec designation, testing of greases for compatibility5 when mixed, and enhancing new grease
The Naval Nose Landing Gear (NLG) structural assembly consists of components with complex structural geometry and critical functionalities. The landing gear components are subjected to high static and dynamic loads, so they must be appropriately designed, dimensioned, and made by materials with mechanical characteristics that meet high strength, stiffness, and less weight requirements. This article contributes to the shape, size, and material optimization for the NLG of a supersonic naval aircraft for the estimated static loads. The estimated modal frequency values of the NLG assembly using Finite Element Analysis (FEA) software were compared with available Ground Vibration Test data of an aircraft to literally prove the accuracy and suitability of finite element (FE) model that can be used for any further analysis. Static structural analysis was performed for the critical landing load cases, and the Reserve Factor (RF) values of the landing gear components were calculated to determine
Robotic landing gear (RLG) enhance the landing capabilities of vertical take-off and landing (VTOL) aircraft on sloped, rough, and even mobile landing surfaces. This DARPA funded research demonstrates the design, integration, and ground and flight testing of a RLG system for the commercial S-100 Camcopter, expanding the aircraft's landing capabilities to currently inaccessible terrains with slopes at and above 15°. Lagrange unconstrained and multibody dynamic simulations are elucidated and implemented to design a force feedback controller, state estimation algorithms, and drivetrain components that permit the rotorcraft fuselage to remain level on rough terrain. The system is then demonstrated using ground and flight experiments, and performance metrics are found to match design metrics. An asymmetry in left and right leg landings during flight testing is observed and analyzed as arising due to inertial cross coupling inherent to landing with three-legged rotorcraft. Finally, future
A high-fidelity engineering simulation model has been developed in FLIGHTLAB for a Sikorsky production helicopter to support future design modifications. The simulation model consists of major subsystems for main rotor, tail rotor, fuselage, empennage, landing gear, flight control system, and propulsion system. As the manufacturer, Sikorsky was able to provide a complete and validated set of model data and a large database of flight test records to ensure the model quality and fidelity. Although the model correlation with test data is satisfactory in most flight conditions including hover, low-speed flight, level flight, and vertical climb, some model-data discrepancies were seen in the forward climb/descent and autorotation test cases. An additional study was conducted at Sikorsky to investigate these discrepancies. Based on the study, a set of model enhancements were developed to improve the model correlation with test data in forward climb/descent and autorotation. These
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