Tests to verify the extensionretraction mechanism, and to validate. Material based structural analysis of a typical landing gear. Mar 02, 2012 a 3d concept model of a retractable landing gear for a light aircraft. Do not manually retract the landing gear more than 20 turns. A bifurcation study to guide the design of a landing gear. Landing gear design in an automated design environment tu delft. The system components are brake unit, antiskid system, retraction system components. There was also a starduster built with a retractable landing gear called samsong there is a picture of it on the cover of the august 1969 sport aviation magazine along with a two page article starting on page 30. Large aircraft retraction systems are nearly always. Pivot angle of actuator at its hard point support is less than 4 degrees. Oct 21, 2016 four bar landing gear reatraction mechanism. Design and foldingunfolding dynamics of an overconstrained.
Landing gear, retraction, adams introduction in recent years a clear trend has developed in the aerospace industry towards the procurement of. The mission is to study air loads on a mechanical retractable landing gear. The landing gear design is iterative involving tradeoff studies between various configurations and their impact on weight and cost benefits. Pdf design of retraction mechanism of aircraft landing gear. Nov, 2012 a method of investigating quasistatic landing gear mechanisms is presented and applied to a threedimensional aircraft main landing gear mechanism model. Design of retraction mechanism of aircraft landing gear. The model has 19 static equilibrium equations and 20 equations describing the geometric constraints in the mechanism.
The analysis concluded that the landing gear design capable to perform during landing on. Landing gear configuration the first job of an aircraft designer in the landing gear design process is to select the landing. A more common use of electricity in gear retraction systems is that of an electrichydraulic system found in many cessna and piper aircraft. Schmelzer messierdowty incorporation 574 monarch ave. Design of a fuselagemounted main landing gear of a. I am submitting herewith a thesis written by eric joseph grandmont entitled a study of the cf188 landing gear upgrade. The doors and retraction mechanism of landing gear are mechanically. Design of retraction mechanism of aircraft landing gear 1.
First, a concept design of a foursidestay landing gear retraction system is presented. The details of the design of such items are out of scope of this textbook and the reader is referred to other references such as ref 1. Landing gear control lever the landing gear control lever, lo cated on the right side of the center instrument panel, initiates gear retraction and extension oper ations. Unfortunately there is no pictures of the actual landing gear assembly. The design is required to effectively retract and extend the landing gear in the time required for the class of helicopter.
Once the mechanism is selected, the dimension is obtained. A brief simulation of a floating link retraction mechanism carried out in matlab r2014a using simulink. The system uses an electric actuator on each leg, with a freefall system and uplocks. Mlg retraction kinematics and bogie positioning mechanism. An early example, the german bomber b combat aircraft design competition winner, the junkers ju 288, had a complex folding main landing gear unlike any other aircraft designed by either axis or allied sides in the war. A380 landing gear systems an overview major components and systems. Optimization of a main landing gear locking mechanism using. A computer aided modeling of a nose wheel landing gear mechanism of a light airplane is under consideration. Icao airport pavement design manual and requires a computer program. Mar 29, 2016 design and stiffness analysis of an overconstrained landing gear retraction mechanism with four sidestays january 2019 proceedings of the institution of mechanical engineers, part g.
This thesis was conducted in the design office of blackwing sweden ab, a swedish aircraft manufacturer. Gears nose landing gear 2 wheels body landing gear x2 bogie type, 6 wheels 4 braked wing landing gear x2 bogie type, 4 wheels 4 braked 4. This study is realised to verify if the structure is resistant enough for a landing and find the retraction speed of the system. This advisory circular ac describes an acceptable means for showing compliance with the requirements of title 14 of the code of federal regulations 14 cfr 25. The control switches, in turn, provide the necessary i n. Landing gear four bar retraction mechanism youtube. Given the weight and cg range of the aircraft, suitable configurations are. Integrated landing gear system retractionextension. Pdf optimization of a main landing gear locking mechanism. The most commonly used landing gear arrangement is the tricycletype landing gear. The landing gear attachment points were defined in the preliminary design phase of the demonstrator.
Dec 08, 2014 the alternative landing gear system uses the same locking mechanism to uplock as well as downlock the nlg, through clever mechanism design. Finally, this paper examines the statics and the stiffness coefficients of the retraction system with respect to its structure parameters. Warning indicators are provided in the flightdeck to show the pilot when the wheels are down and. A dual power source for the actuation mechanism is provided, two rightangle gearbox assemblies, two ballscrews drive assemblies, and two ballscrew and ball nut assemblies.
Integrated landing gear system retractionextension analysis using adams h. Neild and jason zheng jiang and james knowles and hong nie, journaljournal of aircraft, year2017, volume54. Numerical continuation analysis of a threedimensional. Preliminary design and analysis of landing gear retraction. When the handle is switched to \up the retracting landing gear sequence is executed, when the handle is switched to \down the extending landing gear sequence is executed. Design and stiffness analysis of an overconstrained landing. To command the retraction and outgoing of gears, an updown handle is provided to the pilot. Retracting the landing gear fully using the manual handcrank may damage the tangs on the worm gear shaft. The primary benefits of being able to retract the landing gear are increased climb performance and higher cruise airspeeds due to the resulting decrease in drag. A landing gear safety switch, sometimes referred to as a squat switch, is usually mounted in a bracket on one of the main gear shock struts figure 118.
Aircraft landing gear types and arrangement aircraft systems. The designed landing gear should be able to meet the specifications and requirements imposed by the. Introduction the design and positioning of the landing gear are determined by the unique characteristics associated with each aircraft, i. Additional components attached to and functioning with the landing gear may include steering devices and retracting mechanisms. Introduction design of retraction mechanism of aircraft landing gear is a very responsible area. In addition to the landing gear structural assemblies, we also offer fully integrated systems, including ata chapter 32 components, such as cockpit controls, electronic control units, braking systems, extension and retraction equipment, and steering control systems. Nov 12, 2018 this paper introduces the design of a specific landing gear retraction system presenting a mechanism with four redundant side stays and examines its dynamic behavior during the folding and unfolding processes. Electrically operated landing gear systems are also found on light aircraft. Tricycletype landing gear with dual main wheels on a learjet left and a cessna 172, also with tricycle gear right tricycletype landing gear is used on large and small aircraft with the. Optimization of landing gear fairings stanford university. Design and stiffness analysis of an overconstrained landing gear. Hence there is a requirement to retract the landing gear. Small and large aircraft landing gear retraction aircraft.
Design of retraction mechanism of aircraft landing gear article in mechanics and mechanical engineering 124. They are built from highstrength metals to withstand harsh operating conditions. Integrated landing gear system retractionextension analysis. The control lever has two positions, up and down, which mechanically operate the land ing gear control switches. In general, the followings are the landing gear parameters which are to be determined. I have examined the final electronic copy of this thesis for form and content and recommend that it be accepted in partial fulfillment of the requirements for the degree of master of science, with a major in aviation systems. To prevent accidental operation of the downlocks, and inadvertent landing gear retraction while the airplane is on the ground, electrically operated safety switches are installed. The nlg actuation mechanism provides retraction, extension, and kneeling operations.
In addition, some aspects of landing gear such shock absorber, retraction mechanism and brakes are assumed as nonaeronautical issues and may be determined by a mechanical engineer. Aug 22, 2012 design and stiffness analysis of an overconstrained landing gear retraction mechanism with four sidestays january 2019 proceedings of the institution of mechanical engineers, part g. In this work, a typical landing gear of boeing 747 aircraft is designed and meshed using ansa software tool, and then analyzed for structural safety using ansys. Fairing design that does not cover the wheel currently, the fairings of nonretractable landing gear cover the top half of the wheel as shown in fig. In the spirit of bifurcation analysis, solutions to these 39 steadystate equations are found and tracked, or continued.
A380 landing gear and systems the feet of the plane. The defined wheelbase of the demonstrator is shown in figure 4, while figure 5 gives a more detailed view of the landing gear geometry and the center of gravity cog limitations. Relationship between landing gear design requirements and landing gear parameters in order to allow for a landing gear to function effectively, the following design requirements are established. The landing gear, which is also called the undercarriage, is a complex system consisting of structural members, hydraulics, energy absorption components, brakes, wheels and tyres fig. The gear retracts aft into the wheel well, rotating about its trunnion pins.
Analyses on the properties of the landing gear retraction system with four sidestays show that the landing gear strut has a vertical motion, which decreases the working and storage spaces used for the system. Retractable landing gear systems may be operated either hydraulically or electrically or may employ a combination of the two systems. The landing gear design is restricted by these predesign decisions. The pilot has a set of lights giving the current position of gears and doors. The landing gear design combines the best in mechanical, structural and hydraulic design. The geometry and kinematics of the gear are functions of the parameters of the.672 179 484 875 634 162 691 480 294 526 413 254 662 999 236 823 1158 1087 224 1566 222 772 1096 79 344 925 735 724 564 109