Showing papers on "Landing gear published in 2005"

Method and system for health monitoring of aircraft landing gear

Abstract: The invention relates to a new method and system for health monitoring of aircraft landing gear. The system includes sensors that are attached to the landing gear structure and equipment (e.g., one or more of brakes, tires, hydraulics, electrical systems and switches) and analyzed to report and alert personnel such as pilots, maintenance personnel, airline operators, ground crew and regulatory authorities of the health of the landing gear and the potential need for service, maintenance or replacement. The system monitors and reports critical health issues as real-time information which can be analyzed in conjunction with an extensive database of information and used to alert pilots or other relevant personnel to the condition of the landing gear and actions that may be required as a result.

Plasma Actuators for Landing Gear Noise Reduction

Abstract: A primary component of airframe noise on both takeoff and landing approach is due to the landing gear. The inherent bluff body characteristics of the landing gear give rise to large-scale flow separation that results in noise production through unsteady wake flow and large-scale vortex instability and deformation. In this paper the use of single dielectric barrier discharge plasma actuator technology for landing gear noise control is explored. Proof-of-concept experiments that use plasma actuators to create an effective "plasma fairing" which minimizes flow separation over the gear are presented. Nomenclature D = cylinder diameter D Re = Reynolds number based on cylinder diameter D St = Strouhal number based on cylinder diameter ∞ U = free stream velocity * b f = body force (per unit volume) vector φ = electric potential D λ = Debye length 0 e = electrical permittivity of free space

Flight Test Investigation of Add-On Treatments to Reduce Aircraft Airframe Noise

Abstract: A major task within the European Community funded Project SILENCE(R), was to flight-test high-lift devices low-noise modifications and landing gear noise reduction fairings. This work was part of the airframe noise reduction investigation that was initiated in 2001, with a design based on both computational and experimental work, aiming at modifications that fit the actual Airbus A340-300 test aircraft. Landing-gear fairings were designed and manufactured by both Airbus and Messier-Dowty. They are add-on elements that can be mounted on the existing gears without affecting the operation of the landing gear. The add-on treatment modifications (designed and manufactured by Airbus) on the high-lift devices consist of covering the numerous cavities in the slat-retraction system and flap-side edge space, that have been identified to be responsible for a significant part of the noise. The tests were conducted in September 2003 at Tarbes airport. To investigate the noise perceived on the ground, Airbus’ noise system of microphones was used. To help the result interpretation and detection of possible spurious effects, a large array of microphones was operated by ONERA and DLR. On board measurements (pressure and acceleration sensors, strain gages, etc.) were also implemented to assess local effect of devices. Back-to-back tests were achieved in 11 flights, by successively removing all modifications in small groups. Examples of the effect of SILENCE(R) devices is assessed for typical landing configuration and also for specific aerodynamic noise configurations, that were designed to separate the effects of landing gear and high-lift device noise reduction.

Methods and systems for operating aircraft landing gears

Abstract: Methods and systems for performing landing gear operations. In one embodiment, a method for retracting a landing gear is useable with an aircraft having a gear door that at least partially covers a gear well when the landing gear is extended. The method can include receiving a first signal during movement of the aircraft down a runway for takeoff. The first signal can correspond to at least a first aspect of motion of the aircraft, such as upward rotation of the aircraft for liftoff. The gear door can be opened in response to receiving the first signal. The method can further include receiving a second signal after the aircraft has lifted off of the runway. The second signal can correspond to a second aspect of motion of the aircraft, such as the aircraft achieving a positive rate of climb. In response to receiving the second signal, the landing gear can be retracted into the gear well.

Systems and methods for braking aircraft, including braking intermediate main gears and differential braking

Abstract: Systems and methods for braking aircraft are disclosed. These systems and methods can be employed on multi-main gear aircraft to reduce the radius with which the aircraft makes low speed, pivot turns. Further systems and methods can be used to correct the braking behavior of the aircraft during a turn when the actual or measured braking behavior of the aircraft deviates from the commanded turning behavior. For example, one system includes a controller operatively coupleable amongst a leftmost landing gear, a rightmost landing gear, and an intermediate landing gear of an aircraft. The controller can be configured to direct the application of brakes on wheels of the leftmost landing gear during a left turn, and direct the release of brakes on all wheels of the intermediate landing gear during the left turn. Another system includes a controller coupleable to left and right aircraft brakes, and is configured to receive a first signal corresponding to a commanded turn behavior, a second signal corresponding to an actual turn behavior, and, in response to an error value (based on the first and second signals) exceeding a threshold value, the controller can direct a change in braking force applied to at least one of the left and right aircraft brakes.

Empirical Prediction of Aircraft Landing Gear Noise

Abstract: This report documents a semi-empirical/semi-analytical method for landing gear noise prediction The method is based on scaling laws of the theory of aerodynamic noise generation and correlation of these scaling laws with current available test data The former gives the method a sound theoretical foundation and the latter quantitatively determines the relations between the parameters of the landing gear assembly and the far field noise, enabling practical predictions of aircraft landing gear noise, both for parametric trends and for absolute noise levels The prediction model is validated by wind tunnel test data for an isolated Boeing 737 landing gear and by flight data for the Boeing 777 airplane In both cases, the predictions agree well with data, both in parametric trends and in absolute noise levels

Aircraft landing gear automated inspection and life limitation escalation system and method

Abstract: A system for use in monitoring, measuring, computing and displaying the landing loads experienced while aircraft are executing either normal, overweight or hard landing events. Pressure sensors and motion sensors are mounted in relation to each of the landing gear struts to monitor, measure and record the impact loads and aircraft sink rates; experienced by landing gear struts, as the aircraft landing gear initially come into contact with the ground. The computer of this system measures the landing loads experienced by each landing gear strut and determines if a hard landing event has occurred. Additional features include automating the inspections required to aircraft components, after overweight or hard landing events.

Aircraft landing gear kinetic energy monitor

Abstract: A system for use in monitoring, measuring, computing and displaying the Kinetic Energy generated and experienced while aircraft are executing either normal, overweight or hard landing events. Pressure sensors and motion sensors are mounted in relation to each of the landing gear struts to monitor, measure and record the impact loads and aircraft touch-down vertical velocities experienced by landing gear struts, as the aircraft landing gear initially comes into contact with the ground. Velocity adjustments are made to correct for errors caused by landing gear per-charge pressure and landing gear strut seal friction. The system also measures the landing loads experienced by each landing gear strut during the landing event and determines if aircraft limitations have been exceeded.

Retractable articulated landing gear

Abstract: A landing gear for an aircraft, characterized by upper and lower pintle frame members (38, 40) being connected to a telescoping shock strut (14) in a non-rigid manner that tolerates twisting when reacting to torsional loads applied to the landing gear, and/or by a pitch trim actuator (30) that positions a landing gear truck (16) proportionally to the retraction angle of a shock strut (14) during retraction and extension.

Landing gear noise attenuation

Abstract: A landing gear noise attenuator mitigates noise generated by airframe deployable landing gear. The noise attenuator can have a first position when the landing gear is in its deployed or down position, and a second position when the landing gear is in its up or stowed position. The noise attenuator may be an inflatable fairing that does not compromise limited space constraints associated with landing gear retraction and stowage. A truck fairing mounted under a truck beam can have a compliant edge to allow for non-destructive impingement of a deflected fire during certain conditions.

On-board device for measuring the mass and the position of the center of gravity of an aircraft

Abstract: The present invention relates to an on-board device for measuring the mass and the position of the center of gravity of an aircraft having a plurality of landing gears (T1, T2), each landing gear (T1, T2) being provided with at least one contact member (2) having a deformable element (3) that is deformable under the action of the weight of the aircraft when the aircraft is standing on a surface, and is remarkable in that the formable element (3) is provided with a bar (4) having an eddy current sensor (6) at its free end.

Complex Landing Gear Noise Prediction Using a Simple Toolkit

Abstract: This paper describes the initial development of a method for the prediction of the noise radiated by aircraft landing gear. Called the Landing Gear Model and Acoustic Prediction (LGMAP), it will eventually include all the geometric complexity of a realistic landing gear. This will be achieved by dividing the gear into a number of elements or objects. The noise from each of these elements is described by a simple acoustic model. Each object has three attributes; its geometry and location, and an upstream and downstream environment. This enables the ∞ow or noise from one element to interact with any other. The method is designed to allow improved element acoustic models to be introduced as they become available. This paper contains some initial examples for two objects; a cylinder element and a wheel model. The landing gear is divided into assemblies made up of these elements. The radiated noise is calculated in the time{ domain using a source{time{dominant solution to the Ffowcs Williams{Hawkings equation. This initial, rather crude, model is calibrated by comparison with experiment and existing noise prediction methods. The purpose of this paper is primarily to introduce the modeling philosophy rather than make extensive predictions. Though more than one example is given. The model is still in its early development stages and many important acoustic mechanisms are not included. Some of the future plans and necessary extensions to the model are discussed.

Commercial aircraft with a main deck and a lower deck

Abstract: In a commercial aircraft with a main deck (2) and a lower deck (5, 6), at least one passenger cabin (16, 16’) is also provided on the lower deck. The fuselage diameter lies on the order of a wide-body aircraft, and an energy-absorbing deformation structure (22, 23, 24) is arranged underneath the lower deck cabin. The invention proposes to arrange the wings (7) on the aircraft fuselage in accordance with the shoulder wing configuration, and to arrange the landing gear (10) outside on the fuselage such that the landing gear bays are spaced apart from one another by a certain distance that is defined by the positioning of the bottom longeron spars (9). This may provide that the lower deck volume situated underneath the main deck can be optimally utilized for payloads. The lower deck areas may also be interconnected in such a way that a significant useful width of the passage between the landing gear bays is achieved.

Aircraft landing gear initial touch-down velocity monitor

Abstract: A system for use in monitoring, measuring, computing and displaying the initial touch-down descent velocity experienced while aircraft are executing either normal, overweight or hard landing events. Pressure sensors and motion sensors are mounted in relation to each of the landing gear struts to monitor, measure and record the impact loads and aircraft touch-down vertical velocities experienced by landing gear struts, as the aircraft landing gear initially comes into contact with the ground. Velocity adjustments are made to correct for errors caused by landing gear per-charge pressure and landing gear strut seal friction. The system also measures the landing loads experienced by each landing gear strut during the landing event and determines if aircraft limitations have been exceeded.

Aerodynamic airflow deflector for aircraft landing gear

Abstract: An aerodynamic airflow deflecting device for a landing gear retracting into a housing of an aircraft, comprising at least one element for closing the housing that is, through the action of a control device, able to occupy a position for shielding at least a part of the landing gear against the aerodynamic airflow, thus constituting a noise reducing aerodynamic device. The closing element can in particular include at least one trap door element that is, through the action of the control device, movable between a first position for closing the housing, a second position allowing the landing gear to exit and a third position constituting said shielding position.

Data Analysis of Phoenix RLV Demonstrator Flight Test

Abstract: Within the framework of the German ASTRA (Advanced Systems and Technologies for RLV Application) program, the Phoenix project was established to implement experimental steps towards the development of a next generation space transportation system. The Phoenix vehicle was designed to flight demonstrate the automatic and un-powered horizontal landing of a representative, winged reusable launcher vehicle (RLV). The shape of the test vehicle was derived from the suborbital RLV concept Hopper. Three automatic landing tests were completed successfully in May 2004. Methods of system identification were applied to the flight data to evaluate the performance and to improve the design models and databases for future applications. A specific emphasis was placed on the evaluation of the on-board navigation system, air data sensor, aerodynamic model, landing gear effects and ground roll characteristics. This paper gives a brief overview of the Phoenix mission and elaborates on the flight data analysis and of the preceding wind tunnel campaigns, to allow a comparison of results from different approaches.

System and method of measuring weight of passengers and luggage, and weight distribution of aircraft

Abstract: In certain example embodiments there is provided a method and/or system for operating an aircraft, including (a) before an aircraft is loaded with passengers and luggage, performing a first measuring to measure a load on front landing gear strut(s) and rear landing gear strut(s) in order to obtain first weight data; and (b) after the aircraft has been loaded with passengers and luggage, performing a second measuring to measure a load on front landing gear strut(s) and rear landing gear strut(s) in order to obtain second weight data. Then, the first weight data is subtracted from the second weight data, while optionally compensating for fuel added to the aircraft between the times of the first and second measuring steps, in order to determine a total weight of the passengers and luggage on the aircraft. This total weight can be used in determining whether or not the plane is overloaded.

Hinged door for aircraft landing gear

Abstract: The door comprises a panel ( 14 ) formed from two rigid parts ( 14 a, 14 b ) hinged to each other edge to edge. A first part ( 14 a ) of these two parts is connected to the aircraft structure through a pivot pin ( 20 ) and a control means ( 22 ) is inserted between this first part ( 14 a ) and the structure. A kinematic control mechanism ( 16 ) connects the two parts ( 14 a, 14 b ) to the aircraft structure, so as to enable progressive and controlled folding of these parts when opening the door. Thus the landing gear door can be opened and closed without any risk of it coming into contact with the wheels when the landing gear is extended.

Nonlinear Aerodynamic Model Extraction from Flight-Test Data for the S-3B Viking

Abstract: Applied procedures for nonlinear aerodynamic model development and extraction from flight data for the S-3B Viking aircraft are addressed. The entire analysis procedure, from dynamic flight-test data management to final blending and validation of the upgraded aerodynamic model, was performed within the integrated data evaluation and analysis system developed by Science Applications International Corporation. A variety of parameter identification (PID) techniques were employed to develop a global, fully nonlinear longitudinal and lateral‐directional aerodynamic model. This effort included total aerodynamic coefficient reconstruction, equation error analysis for initial model structure development, and output error analysis for final model tuning. Data available from S-3B PID flight spanned a Mach range of 0.23‐0.60 which covered an adequate range of angle of attack for both nonlinear longitudinal and lateral‐directional analyses. Regions outside the identified model envelope were described by blending with the original S-3B aerodynamic database to create a full envelope model. Aircraft configurations investigated included cruise, maneuver, takeoff, and landing flap settings as well as retracted and extended landing gear. Standard flight-test maneuvers were flown under each configuration and are described. The available data allowed for the successful extraction of component coefficients for aircraft lift, side force, pitching, rolling, and yawing moments resulting in a simulation with high aerodynamic fidelity.

Mathematical Model Research on Aircraft Landing Gear

Abstract: It is investigated the composition and the principle of the aircraft landing gears, and the model structure of it is set up. It is simulated in the MATLAB/SIMULINK, the result of the aircraft anti-skid system is also presented and the effect on the aircraft anti-skid system is analysed in details. The result shows that the aircraft landing gear system model established is basically rational andcorrect.Itishelpfultodesigntheaircraftanti-skidbrakingsystem,andtoimprovethebrakingefficiency andthebrakingperformance.

Landing gear door with controlled kinematic control

Abstract: An aircraft landing gear door comprises a rigid one-piece panel ( 14 ), hinged onto the aircraft structure by arms ( 18 ). The panel ( 14 ) is installed such that it pivots on the arms ( 18 ) in order to prevent any risk of contact between the panel ( 14 ) and the wheels ( 40 ) as the door opens and closes when the landing gear is extended, and a jack ( 34 ) automatically varies the angle Φ formed between these two parts, according to a predetermined kinematic law. A control system ( 28 ) automatically controls the jack ( 34 ) as a function of the jack ( 26 ) being actuated to control opening and closing of the door.

Aircarft nose landing gear with wheels pivoting during its retraction

Abstract: A landing gear assembly (10) comprises a landing gear strut assembly further comprising a landing gear strut (12) having a longitudinal axis and extending from an inboard end to an outboard end capable of attaching to a wheel (16), and a landing gear housing (18). The landing gear housing (18) has a longitudinal axis coincident with the landing gear strut (12) longitudinal axis and having an interior chamber capable of accepting a portion of the landing gear strut. The landing gear housing (18) is capable of pivotably coupling to an aircraft. The landing gear assembly further comprises a retraction linkage (28) having an inboard end capable of coupling to the aircraft and an outboard end coupled to the landing gear housing (18). The retraction linkage (28) is moveable to retract the landing gear strut (12) assembly into an aircraft landing gear compartment about the landing gear housing (18) pivotable aircraft coupling. The landing gear assembly (10) further comprises a steering linkage (27) capable of coupling and decoupling to the landing gear strut (12) and, when coupled, capable of steerably rotating the landing gear strut (12) with respect to the landing gear housing (18) about the coincident longitudinal axis. The landing gear assembly further comprises a planing linkage (26) that can gradually rotate the landing gear strut (12) into a planar position as the landing gear strut assembly (10) is retracted and decoupled from the steering linkage.

Mesh fender for protecting an aircraft against damage from foreign objects

Abstract: Aircraft including an airframe and landing gear including a wheel rotatably connected to the airframe. The landing gear further includes a fender connected to the airframe adjacent and generally above the wheel wherein the fender comprises a mesh having a plurality of openings.

Detachable skis for aircraft

Abstract: A wheel-through ski for the landing gear of an aircraft is disclosed. The ski has an airfoil shape, and the ski and its attachments are aerodynamically clean. The ski is provided with a three sided recess that permits the mounting of the ski on the aircraft without lifting the landing gear off the ground. The members of the articulated attachment between the ski and the aircraft are joined by a removable pin and are fixedly attached to the ski and landing gear. The ski is of aircraft construction. It has a thin skin, air frame-like internal structures, foam material internal cores that provide stiffness to the ski and wear strips on the bottom of the ski.

System for maneuvering an aircraft landing gear and aircraft comprising same

Abstract: The invention concerns a system for maneuvering an aircraft landing gear mounted in a landing gear box closed by a set of hatches, comprising: a general control unit of the landing gear box to trigger the different maneuvers, a control channel for the hatches (16), a control channel for the landing gear (15), the general control unit, the hatch control channel and the landing gear control channel being controlled by an electric power source, when the aircraft is in normal operating conditions, emergency operating conditions and in maintenance phase. The invention also concerns an aircraft comprising such a system.

Numerical Simulation of Gear Walk Instability in an Aircraft Landing Gear

Abstract: This paper deals with the simulation, in a multibody framework, of a particular type of landing gear-induced instability known as "gear walk". This low frequency fore-and-aft oscillation of the landing gear is primarily due to the coupling of the landing gear structural flexibility with the brake anti-skid control system characteristics. A case study of a landing gear known to suffer gear walk during normal landing conditions is presented. The multibody model components used for its simulation are explained and the numerical results obtained are presented and discussed.