Showing papers on "Landing gear published in 2015"

Adjustable landing gear assembly for unmanned aerial vehicles

Abstract: This disclosure describes a configuration of an unmanned aerial vehicle (UAV) landing gear assembly that includes adjustable landing gear extension that may be extended or contracted so that the body of the UAV is contained in a horizontal plane when the UAV is landed, even on sloping surfaces. For example, when a UAV is landing, the slope of the surface may be determined and the landing gear extensions adjusted based on the slope so that the body of the UAV remains approximately horizontal when the UAV lands and is supported by the landing gear extensions.

The Stochastic Robust Model Predictive Control of Shimmy Vibration in Aircraft Landing Gears

Abstract: This paper considers robust model predictive control (RMPC) methods for a linear parameter varying (LPV) system that has both probabilistic uncertain and time-varying parameters. The parameters are considered to be measured online. In this regard, the aircraft landing gear system is considered as an LPV system whose parameters variation can affect both stability and performance. By transforming this system into a convex combination of linear time-invariant vertices form with the tensor-product (TP) model transformation method, the landing gear system is represented as a polytopic linear parameter-varying system. A computationally efficient RMPC control signal law is calculated online by carrying out the convex optimization involving linear matrix inequalities (LMIs) in MPC which leads to finding the solutions that can guarantee the closed-loop robust stability and performance. The proposed controller can effectively suppress the shimmy vibration of the landing gear with variable taxiing velocity and wheel caster length, also with the probabilistic uncertain torsional spring stiffness.

Multi-rotor type unmanned aircraft system with fire detecting function

Abstract: The invention provides a multi-rotor type unmanned aircraft system with a fire detecting function. Six engine arms and a frame form a body frame of the multi-rotor type unmanned aircraft system; a motor and an electronic speed regulator are connected with each other to control the rotation speed of propeller blades; a landing gear is used for an aircraft to stably land during landing; an unmanned aircraft flight control system is used for controlling stable postures of the aircraft; a sensor is connected with the unmanned aircraft flight control system; a small-sized control computer is connected with laser distance measuring sensors through communication; a processed signal is input into the unmanned aircraft flight control system to control three-dimensional positions and postures of the aircraft indoors; high-definition cameras are connected with an image transmitting device to collect video images of environment; and the image transmitting device is used for transmitting a video image signal to a ground station device so as to realize real-time observation. The multi-rotor type unmanned aircraft system with the fire detecting function, provided by the invention, is advantaged in that the multi-rotor type unmanned aircraft system can autonomously fly under a complicated environment, automatically detect fires in real time, automatically avoid obstacles and protect personal safety; remote monitoring and remote real-time communication are realized; data can be saved and replayed and so on.

Nonlinearities in landing gear model incorporating inerter

Abstract: An inerter is a recently proposed two-node element in which the force across the two nodes is proportional to their relative acceleration Studies based on linearization have previously been conducted on the application of inerters to landing gear for light civil aircraft to improve the resistance of such gear to shimmy vibration Thus, the current research determines the effect of nonlinearities on the performance of the proposed model for aircraft landing gear in such vibration This model is analyzed through a Simulink simulation, and conclusions are drawn on this effect and on the well-posedness of the linearized model

Shimmy of an Aircraft Main Landing Gear With Geometric Coupling and Mechanical Freeplay

Abstract: The self-sustained oscillation of aircraft landing gear is an inherently nonlinear and dynamically complex phenomenon. Although such oscillations are ultimately driven from the interaction between the tyres and the ground, other effects, such as mechanical freeplay and geometric nonlinearity, may influence stability and add to the complexity of observed behaviour. This paper presents a bifurcation study of an aircraft main landing gear, which includes both mechanical freeplay, and significant geometric coupling, the latter achieved via consideration of a typical side-stay orientation. These aspects combine to produce complex oscillatory behaviour within the operating regime of the landing gear, including longitudinal and quasiperiodic shimmy. Moreover, asymmetric forces arising from the geometric orientation produce bifurcation results that are extremely sensitive to the properties at the freeplay/contact boundary. However this sensitivity is confined to the small amplitude dynamics of the system. This affects the interpretation of the bifurcation results; in particular bifurcations from high amplitude behaviour are found to form boundaries of greater confidence between the regions of different behaviour given uncertainty in the freeplay characteristics.

Aircraft Random Vibration Analysis using Active Landing Gears

Abstract: In this article, random vibration analysis of full aircraft with passive and active landing gears has been done by numerical simulations on random runway profile. The mathematical model of full aircraft with active landing gears and modelling of runway profiles have been developed for analysing the aircraft bounce, pitch, roll accelerations, displacement and shock strut travel while taxiing on random runways. The results show that vibration levels of the aircraft by the active landing gear system is less than the conventional landing gear system while taxiing on different grades of random runways. Comparison results also show that the active system improves the ride comfort and easiness of pilot handling and thus, increases the fatigue life of the aircraft.

Improving safety of runway overrun through foamed concrete aircraft arresting system: an experimental study

Abstract: Aircraft may overrun the ends of runways, sometimes with disastrous consequences. Because of the capability of high energy absorption, a foamed concrete arresting system can be employed to safely decelerate and stop the overrunning aircraft. In order to evaluate the performance of the foamed concrete arrestor system, a full-scale arresting test with an instrumented Boeing 737-300 aircraft has been conducted. The test bed of 140 m long by 15 m wide and 0.32 m deep was constructed to demonstrate the effectiveness of safely stopping the Boeing 737 aircraft entering the bed at 40 knots. In the test, the deceleration experienced by the aircraft was recorded in addition to its instantaneous speed, dynamic responses of the landing gear, and rut depths. Then, the validity of the analytical prediction model developed in previous study was examined by means of the full-scale test data. The results of the full-scale test show that the foamed concrete arrestor could provide an effective deceleration without exceeding the design allowable stresses on the landing gear during arrest process. Using the analytical model, the sensitivity of aircraft stopping distance was evaluated as a function of arrestor material compressive strength, aircraft weight, and arrestor-bed thickness. Based on these investigations, it is recommended that the foamed concrete system can be used as an alternative civil aircraft arresting system to improve the runway safety.

Characterization of Low Noise Technologies Applied to a Full Scale Fuselage Mounted Nose Landing Gear

Abstract: The negative impact of aircraft noise includes effects on population’s health, land use planning and economic issues such as building restrictions and operating restrictions for airports. Thus, the reduction of noise generated by aircraft at take-off and approach is an essential consideration in the development of new commercial aircraft. Among the different aircraft noise sources, landing gear noise is one of the most significant during approach. This research presents results from the European Clean Sky funded ALLEGRA project, which investigated a full-scale Nose Landing Gear (NLG) model featuring the belly fuselage, bay cavity and hydraulic dressing. Tests were performed for a variety of wind speeds and yaw angles. In this paper, a characterization of the noise generated by the full-scale Nose Landing Gear (NLG) model is presented and the different techniques used for characterizing acoustic sources on the NLG are described. The landing gear noise source is characterized in terms of OASPL, directivity, source spectra, PNL and PNLT. A comparison between the NLG with and without the application of low noise technology is presented.Copyright © 2015 by ASME

An Assessment of Flap and Main Landing Gear Noise Abatement Concepts

Abstract: A detailed assessment of the acoustic performance of several noise reduction concepts for aircraft flaps and landing gear is presented. Consideration is given to the best performing concepts within the suite of technologies that were evaluated in the NASA Langley Research Center 14- by 22-Foot Subsonic Tunnel using an 18 percent scale, semi-span, high-fidelity Gulfstream aircraft model as a test bed. Microphone array measurements were obtained with the model in a landing configuration (flap deflected 39 degrees and the main landing gear deployed or retracted). The effectiveness of each concept over the range of pitch angles, speeds, and directivity angles tested is presented. Comparison of the acoustic spectra, obtained from integration of the beamform maps between the untreated baseline and treated configurations, clearly demonstrates that the flap and gear concepts maintain noise reduction benefits over the entire range of the directivity angles tested.

An Assessment of Flap and Main Landing Gear Noise Abatement Concepts

Abstract: A detailed assessment of the acoustic performance of several noise reduction concepts for aircraft flaps and landing gear is presented. Consideration is given to the best performing concepts within the suite of technologies that were evaluated in the NASA Langley Research Center 14- by 22-Foot Subsonic Tunnel using an 18 percent scale, semi-span, high-fidelity Gulfstream aircraft model as a test bed. Microphone array measurements were obtained with the model in a landing configuration (flap deflected 39 degrees and the main landing gear deployed or retracted). The effectiveness of each concept over the range of pitch angles, speeds, and directivity angles tested is presented. Comparison of the acoustic spectra, obtained from integration of the beamform maps between the untreated baseline and treated configurations, clearly demonstrates that the flap and gear concepts maintain noise reduction benefits over the entire range of the directivity angles tested.

Hard-landing Simulation by a Hierarchical Aircraft Landing Model and an Extended Inertia Relief Technique

Abstract: In this work, an efficient aircraft landing simulation strategy is proposed to develop an efficient and reliable hard-landing monitoring procedure. Landing stage is the most dangerous moment during operation cycle of aircraft and it may cause structural damage when hard-landing occurs. Therefore, the occurrence of hard-landing should be reported accurately to guarantee the structural integrity of aircraft. In order to accurately determine whether hard-landing occurs or not from given landing conditions, full nonlinear structural dynamic simulation can be performed, but this approach is highly timeconsuming. Thus, a more efficient approach for aircraft landing simulation which uses a hierarchical aircraft landing model and an extended inertia relief technique is proposed. The proposed aircraft landing model is composed of a multi-body dynamics model equipped with landing gear and tire models to extract the impact force and inertia force at touch-down and a linear dynamic structural model with an extended inertia relief method to analyze the structural response subject to the prescribed rigid body motion and the forces extracted from the multi-body dynamics model. The numerical examples show the efficiency and practical advantages of the proposed landing model as an essential component of aircraft hard-landing monitoring procedure.

Aeroacoustic Source Separation on a Full Scale Nose Landing Gear Featuring Combinations of Low Noise Technologies

Abstract: The reduction of noise generated by aircraft at take-off and approach is crucial in the design of new commercial aircraft. Landing gear noise is significant contribution to the total noise sources during approach. The noise is generated by the interaction between the non-aerodynamic components of the landing gear and the flow, which leads to turbulence generated noise. This research presents results from the European Clean Sky funded ALLEGRA project. The project investigated a full-scale Nose Landing Gear (NLG) model featuring the belly fuselage, bay cavity and hydraulic dressing. A number of low noise treatments were applied to the NLG model including a ramp door spoiler, a wheel axel wind shield, wheel hub caps and perforated fairings. Over 250 far field sensors were deployed in a number of microphone arrays. Since technologies were tested both in isolation and in combination the additive effects of the technologies can be assessed. This study describes the different techniques used to quantify the contribution of each technology to the global noise reduction. The noise reduction technologies will be assessed as a function of frequency range and through beamforming techniques such as source deletion.Copyright © 2015 by ASME

System Noise Assessment of Blended-Wing-Body Aircraft with Open Rotor Propulsion

Abstract: An aircraft system noise study is presented for the hybrid wing–body aircraft concept with open-rotor engines mounted on the upper surface of the airframe. The aircraft chosen for the study is of a size comparable to the Boeing 787 aircraft. It is shown that, for such a hybrid wing–body aircraft, the cumulative effective perceived noise level is about 24 dB below the current aircraft noise regulations of stage 4. Although this makes the design acoustically viable in meeting the regulatory requirements, even with the consideration of more stringent noise regulations in the next decade or so, the design will likely meet stiff competition from aircraft with turbofan engines. The noise levels of the hybrid wing–body design are held up by the inherently high noise levels of the open-rotor engines and the limitation on the shielding benefit due to the practical design constraint on the engine location. Furthermore, it is shown that the hybrid wing–body design has high levels of noise from the main landing gear,...

All-terrain telescopic landing gear of unmanned helicopter

Abstract: The utility model discloses an all-terrain telescopic landing gear of an unmanned helicopter The all-terrain telescopic landing gear comprises a bracket, wherein a control device is arranged on a bracket body; a first magnet and a second magnet are arranged in the control device; bracket legs of the bracket are respectively a telescopic leg comprising an inner leg and an outer leg which are fixedly connected with each other through a clip; the first magnet of the control device is connected with each clip through a first connection rope; and the second magnet of the control device is connected with the upper end of each inner leg through a second connection rope According to the all-terrain telescopic landing gear, stretching of the bracket legs is achieved by utilizing magnetic force of the small magnets and the gravity of the bracket legs of the landing gear; taking off and landing of the unmanned helicopter on a slope are ensured by changing the length of each bracket leg; the all-terrain telescopic landing gear has the advantages of being ingenious in design, simple in structure, high in pertinence, easy to operate, light in weight and the like; and the bracket legs can stretch out and draw back flexibly, thereby meeting taking off and landing requirements of the unmanned helicopter in all terrains such as flat grounds, high mountains and hills

Selection and analysis of the landing gear for unmanned aerial vehicle for sae aero design series

Abstract: UAV-Unmanned Aerial Vehicle commonly known as Drones are extensively being used these years. Today drones are used in various applications like Military, Commercial Cargo Transport, and 3-D Mapping etc. For supporting the weight of the plane, and shock absorption functions, landing gear design is highly essential. Society of Automotive Engineers (SAE) conducts 'Aero Design Series' competition annually in the United States of America (USA). This papers explains and gives details about the landing gears and significance of selecting the optimum one for the respective plane required to compete in the challenge. The gears were selected on various factors and methods depending upon the design and the load bearing capacity of the UAV.

Multi-position landing gear

Abstract: A multi-position landing gear for an aircraft may include a first landing skid disposed on a bottom side of the aircraft, and a second landing skid disposed on one of a top side or the bottom side of the aircraft, wherein the first landing skid and the second landing skid are rotatable relative to the aircraft.

Aircraft landing gear wheel-drive system

Abstract: An aircraft landing gear wheel-drive system includes a first wheel drive unit for driving a first landing gear wheel of the aircraft and a second wheel drive unit for driving a second landing gear wheel of the aircraft. The first wheel drive unit has a first range of torque to speed (T/S) ratios. The second wheel drive unit has a second range of T/S ratios. The first range of T/S ratios is greater than the second range of T/S ratios.

Design and Analysis Aircraft Nose and Nose Landing Gear

Abstract: Tri-cycle arrangement landing gear is extensively used as it is simple; convenient both structurally as well as aerodynamically. Though it is advantageous over other configuration is has its own draw backs. Factors like its weight drag, sudden application of load, acoustics, fatigue etc tend to slow down its performance and life. Among main landing gear and nose landing gear; the former carries about 85% of total weight of aircraft and latter carries around 12-15% of weight. The nose landing gear is also a source of noise and its effect is prominent when compared to main landing gear. In this project the executive jet aircraft are studied thoroughly and a nose landing gear similar to those of executive jets is modeled using CATIA. The same geometry is imported to ANSYS ICEM and flow on the body is analyzed for different angle of attack. Pressure variation, temperature, density and velocity distribution around the body is noted and then Coefficient for Lift and Drag are plotted against angle of attack for obtained results. It is also important to check the strength and stiffness of designed landing gear. Hence using ANSYS APDL and Explicit; Static structural and Impact test has been carried out for designed geometry. Stress distribution and deformation was noted for two distinct materials such as steel and aluminum alloy and primary results of acoustics has been compared with the available data.

Modelling and Control of a Fixed-wing UAV for Landings on Mobile Landing Platforms

Abstract: Landing on mobile landing platforms could eliminate the need for landing gear. This would particularly benefit high altitude solar UAV, which typically have a very limited payload. Such landings would however require a precise and decoupled control of the UAV’s altitude and speed. In this thesis, a small UAV is modelled, and a flight control system suitable for such landings is developed. The aerodynamic properties of the UAV were estimated using the vortex lattice method. Propeller performance data was obtained from the manufacturer and used in the propulsion model. The complete UAV model was validated using data from test flights. A comparison of period and damping of the dynamic modes showed a good agreement (<10% error) with the flight data, except for the phugoid damping, which was too low in the model. The model was used to design two flight control systems, one consisting of three SISO loops for altitude, airspeed and course; and another using a TECS-based controller for airspeed and altitude. Extensive testing in simulation and flight revealed a superior performance of the TECS-based controller, especially in the ability to decouple altitude and airspeed responses.

Main landing gear three-way loading test device

Abstract: The invention belongs to the technology of helicopter main landing gear fatigue tests, and relates to a main landing gear three-way loading test device. The main landing gear three-way loading test device can solve the problem that a current test device cannot carry out a three-way loading test on a main landing gear with two tires. The main landing gear three-way loading test device disclosed by the invention comprises a wheel shaft arranged at the bottom end of a vertical buffer support, wherein airplane wheel artificial pieces for simulating helicopter tires are arranged on the rotating shaft; the airplane wheel artificial pieces comprise a first airplane wheel artificial piece and a second airplane wheel artificial piece which are symmetrically arranged on the left side and the right side by taking the axis of the buffer support as the center. The main landing gear three-way loading test device further comprises a first loading piece, a second loading piece and a third loading piece. According to the main landing gear three-way loading test device disclosed by the invention, the design of a three-way loading structure is simplified, the device is simple and practical, and the structure and loaded characteristic of the airplane wheels of the main landing gear with two tires can be simulated more truly and accurately.

System for determining weight-on-wheels using lidar

Abstract: A system and method for determining weight on wheels for an aircraft with at least one landing gear; a sensor associated with machinery Light Detection And Ranging scanner; a processor; and memory having instructions stored thereon that, when executed by the processor, cause the system to receive signals indicative of LIDAR image information for a landing gear; evaluate the LIDAR image information against a landing gear model; determine information indicative that the landing gear is locked in response to the evaluating of the LIDAR image information; and determine information indicative that the landing gear is compressed in response to the evaluating of the LIDAR image information against the landing gear model.

Active landing gear damper

Abstract: An active landing gear damping system and method for decelerating a vehicle during a terrain impact event, such as an aircraft landing or crash. The system monitors aircraft state data and terrain information to predict an impact of the vehicle with the terrain. The system can then determine a target damper force for each landing gear of the vehicle and a predicted damper velocity at the time of impact. Each landing gear can include an adjustable damper valve, wherein adjustment of the damper valves varies the damping coefficient of the respective dampers. The system can adjust valves of the respective dampers to provide the target force based on the predicted damper velocity. After an impact begins, the system can continuously monitor and adjust the valve to maintain the target force.

Analytical and Experimental Investigation of Base–Extension Separation Mechanism for Spacecraft Landing

Abstract: Future planetary exploration requires spacecraft to land softly on rough terrain and in severe environments. Since conventional landing methods have problems such as high rebounds and excessive resource consumption, the base–extension separation mechanism, which combines springs and separable units, is proposed as a novel landing mechanism. Although the mechanism performed good soft landings, the performance evaluation was limited. Therefore, this study evaluated its performance multilaterally. The proposed technology was analytically compared with two other landing technologies: a generalized-hybrid momentum exchange impact damper and an aluminum foam landing gear. The proposed technology suppressed rebound and acceleration better than the generalized momentum exchange impact damper. Once the components of the proposed technology had been lightened, its energy conversion efficiency matched that of the aluminum foam landing gear. In addition, experiments were conducted using small-scale models to confirm ...

Test instrument to test the status of landing gear uplock, landing gear down lock, door uplock & door open limit

Abstract: The Invented test Instrument (Figl) is a simple, cost effective, efficient and a user friendly instrument to test the status of Landing Gear Unlocks, Landing Gear Down Locks, Door Unlocks & Door Open Limits. Previously, there were no automated instruments available to test the status of Landing Gear Uplock, Landing Gear Down Lock, Door Uplock & Door Open Limit. The checking was done manually, hence it was time consuming & human errors reduced the accuracy. The Invented test Instrument has mating connectors to connect with the of Landing Gear Unlocks, Landing Gear Down Locks, Door Unlocks & Door Open Limits. The instrument (Fig2) is operated by batteries & the below mentioned status are displayed with LED's • Landing Gear Uplocks are in uplocked or unlocked condition • Landing Gear Down Locks are in down locked or released condition • Door Uplocks are in locked or unlocked condition • Door Open Limit is attained or not The advantages are as mentioned below, • Time required to resolve the snag is minimal. It takes only 10 seconds to check each unit. It takes less than 15 minutes to check all Landing Gear uplocks (3 Nos), Landing Gear Down locks (3 Nos) & Door uplocks (12 Nos) & Door Open limits (4Nos) • No logistics are required (i.e. multimeter, pins with pigtail/sockets with pigtail etc.) • All human errors are eliminated. • Single person is enough. With a little training even unskilled employee can do this job accurately. Very easy, just mate the connector and switch on the instrument. The LED's will glow to indicate the Uplock, Downlock & Open Limit status.

Multibody rigid models and 3D FE models in numerical analysis of transport aircraft main landing gear

Abstract: Dynamic analyses of a transport aircraft landing gear are conducted to determine the effort of such a complex system and provide capabilities to predict their behaviour under hazardous conditions. This kind of investigation with the use of numerical methods implementation is much easier and less expensive than stand tests. Various 3D models of the landing gear part are defined for the multistage static FE analysis. A complete system of the main landing gear was mapped as a deformable 3D numerical model for dynamic analysis with the use of LS-Dyna code. In this 3D deformable FE model, developed in a drop test simulation, the following matters were taken into consideration: contact problems between collaborating elements, the phenomena of energy absorption by a gas-liquid damper placed in the landing gear and the response of the landing gear during the touchdown of a flexible wheel with the ground. The results of numerical analyses for the selected drop tests and the results from the experiments carried out on a real landing gear were used for verification of FE models and a methodology of the landing gear dynamics analysis. The results obtained from the various simulations of the touchdown have proved the effectiveness of the 3D numerical model and how many problems can be solved in the course of only one numerical run, e.g. geometric and material nonlinearities, a question of contact between the mating components, investigation of the landing gear kinematics, investigation of the energy dissipation problem in the whole system and the stresses influence on the structure behaviour, which can appear in some elements due to overload.

Analysis of a Skid Type Landing Gear of a Rotary Wing UAV by Experimental and Numerical Methods

Abstract: The objective of this study was to analyze the results obtained from tests done by simulating the crash landing of a rotary wing unmanned air vehicle with a skid type landing gear. The experimental and computational methods were used in the simulation tests. In the rst portion of the test; namely with the experimental method, the impact loads induced by the simulated crash landing and the stresses, strains, deformations generated by these loads, were recorded by drop test apparatus. In the second portion of the test with the computational method, free falling of the skid type landing gear was modeled and crash landing test was simulated numerically by using ANSYS code. Experimental methods were applied on four skid landing gear specimens with di erent shapes. Each of the test samples used in the following test was evolved because each sample was developed and redesigned based on the feedback results obtained from the former test. The rst three test specimens were manufactured from 2024 T3, 7075 T6 and 6061 T6 aluminum alloys respectively and all of them were curved in Π-form with a solid cross section. The last and fourth specimen was also manufactured from 6061 T6 aluminum alloy and it was curved in a hollow semi-circle form (∩-form). It is concluded that the last and fourth developed specimen was the best in absorbing the impact energy and enduring the crash.

Aircraft retractable landing gear and aircraft

Abstract: The utility model belongs to aircraft structure field especially relates to an aircraft retractable landing gear and aircraft The utility model discloses an aircraft retractable landing gear includes parallel four -link mechanism and drive arrangement, the drive arrangement drive parallel four -link mechanism draws in in or opens The utility model provides an aircraft retractable landing gear includes parallel four -link mechanism and drive arrangement, and when the aircraft took off, the drive arrangement drive parallel four -link mechanism drew in in, avoids sheltering from the cloud platform on the aircraft, when the aircraft fell to the ground, drive arrangement drive parallel four -link mechanism opened in order to support the aircraft, in addition, after the aircraft fell to the ground, the aircraft retractable landing gear can be packed up, the carrying of the aircraft of being convenient for