Naval Helicopter Landing Gear Engineering Essay

naval Helicopter land Gear Engineering turn upThe come cant over, is a twist (or mechanism) attached to the fuselage (or the body) of the aircraft, helps the aircraft during land, take-off and ground achieveling operations. The land ge atomic number 18d wheel plays important role absorbing the dis sulfurt (or thrust) while get and thus ensure lower grind related injuries and material damages. For achieving this crush worthiness require optimum see of the effluxs of the arrive inclines.I welcome started the process of the optimum cast of the set down accessory mechanism with theoretical hand tallys. After I established a tight goal by hand calculation I shifted to the ADAMS tool. The ADAMS tool seemed to be very powerful for achieving the optimum mechanism design solution through number of iterations.For the sake of simplicity, I turn over considered non-retrac confuse type of landing shift for this study. Also, I have considered apply only helical comp ression work and no torsion make for this design study.Research on Naval Helicopter landing place GearThe naval whirlybirds operate in overmuch severe landing conditions compared to the commercial choppers. Hence, while designing the naval helicopter landing gear all the necessary landing conditions should be taken care. In this section I am going to discuss well-nigh the types of landing gear and few practical examples roughly the usage of the landing gears.History and evolutionThe first wheeled landing gear appeared in Santos-Dumonts No.14 bis on 1906 soon after the Wright brothers famous flight.Initially, the landing gear apply to have bungee as rape absorbing elements.The Ford trimotor landing gear, which use rubber discs and rebound cables, was the predecessor of the modern days shock absorbing landing gear.During World War-II, the shock absorbing landing gear had invented make headway. Use of the leaping and lever came into the landing gear administration design. After the world war, the landing gear design matured further to give modern days sophisticated landing gear system.Types of Landing Gears All of the landing gear used in helicopters can be broadly classified in three categoriesTail dragger Landing Gear Two main gears are set(p) under the mid(prenominal) of the fuselage and one low-down gear is placed under the tail of the helicopter for the tail dragger landing gear arrangement. This type of landing gears are used in older helicopters (e.g. Seahawk)Tri Cycle Landing Gear In this configuration, there are one nose wheel and two main gears at the mid of the fuselage. Most of the modern helicopter has this landing gear configuration.Tandem Landing Gear Large aircrafts use multiple wheels in line for each of the landing gears and this configuration is known as Tandem.Examples about the usage of the landing gears in naval helicoptersLanding Gear for Seahawk S70B The Seahawk is an US naval aircraft fabricate by Sikorsky Aircraft in Stra tford, Connecticut.Fig.1 Showing a Seahawk in operation (Image source http//www.naval-technology.com/projects/seahawk/seahawk2.html)The chopper has energy absorbing two-wheel tail dragger type of landing gear arrangements. The landing gear design is much simpler compared to the other naval helicopters.Boeing Vertol CH-46 Sea nickname Sea Knight is a marine transport helicopter, manufactured by Boeing Vertol.Fig.2 Showing a Sea Knight(Image source http//en.wikipedia.org/wiki/FileUSMC_CH-46.jpg)The Sea knight has trike type of landing gear system. Each of the landing gear has equal wheels.Sikorsky SH-3 Sea King The Sea King is an anti-submarine amphibian helicopter manufactured by Sikorsky. It is fitted with retractable type trail dragger landing gear arrangement.MH-53E Sea Dragon This is a three engine powered magnanimous navy helicopter designed for heavy lifting and Airborne Mine Countermeasures (AMCM). It is fitted with twin-wheel trike configuration of landing gear system.De velopment of the Landing Gear mechanicsThe landing gear mechanism should be strong enough to keep back the specified stringent landing conditions of this assignment. I am planning to develop a landing gear mechanism using two biramous rear landing gears and a nose landing gear. All the landing gear leave behind use helical compression springs only.Fig.3 Top idea of the landing gear arrangements for the conceptAs the above figure shows, the concept will have the centre of gravity somewhere in betwixt the front and the rear landing gears.Selection of the proper compression spring is the key to the success of the mechanism. Hence I have started with the hand calculation to arrive at the preliminary spring design parameters.Hand calculationTotal mass = 5126 kgHence, Sprung mass on each spring = 1025.2 kgFor zero initial velocitySay, max. Deformation of spring =35 mmSo, spring rate K = 292.9142857 N/mmFor pattern landingInitial velocity of helicopter = 0.5 m/sec jumpstart rate k = 292.9142857 N/mmNow, using the formulae 0.5*m*v2=0.5*k*x2 grievous bodily harm deformation of the springs =0.935414347 mmFor hard landingInitial velocity of helicopter = 3 m/secInitial velocity of deck = 3 m/secSo, Relative velocity between the helicopter and the deck = 6 m/secSpring rate k =292.9142857 N/mmSo, Max deformation of the springs = 11.22 mmFor crush landingInitial velocity of helicopter = 15 m/secSpring rate k = 292.9142857 N/mmSo, Max deformation of the springs =28.06 mmSince, the deformation values from the hand calculation are well below 30 mm with the spring rate of 292 N/mm. So, I think it is good to go up with these values and check the securenessup departs and vibration results by creating the ADAMS model.Developing ADAMS stickThe ADAMS models of the landing gear mechanism are created by the ADAMS/View. I have come out with two ADAMS design based on the already discussed mechanism concept. The following steps are followed to create each of the ADAMS models u nit of measurement Setting I choose to use the units as Length Millimeters, fate Kg, Force Newton, Time Second, Angle Degree, and absolute frequency Hertz. Following consistent units are important for getting accurate results.Gravity Setting I unrestrained the gravity.Points Points are the basic building block of the whole mechanism.Box This resource was used for creating the deck.Torus All the wheels were created using the torus plectron.Link The social system and the axels were created using the link options.Translational Spring Damper This option was use for creating all the helical compression springs of the designs.Contact The contact option was used for simulating the contacts between the deck and the wheels.Revolute Joint The control sticks between the wheels and the axels were created using the revolute joint option of ADAMS.Translational Joint For simulating the unsloped seam speed of the helicopter and vertical speed of the deck it was required to create tr ansitional joints between the structure and space and between deck and space.ADAMS Mechanism Design-1Fig.4 ADAMS model of the design option-1.Fig.5 ADAMS manoeuvre table for the design option-1.ADAMS Mechanism Design-2Fig.6 ADAMS model of the design option-2Fig.7 ADAMS point table for the design option-2The basic difference between the design opton-1 and the design option-2 is in the height of the design. After reviewing the initial displacement results (which I will open in the next section) of the option-1, I have decided to increase the height, as for the specified test condition the structure is tearting the deck for design option-1.Result Comparison for Option-1 and Option-2Fig.8 Deflection plot of the structure for crush landing conditionThe above plot is viewing the comparison of the deflection of the decease frame (structure connected to the fuselage), it shows that the option-1 has much higher deflection. The deflection value for the option-1 is until now higher than the clearance between the structure and the deck. Means, for option-1, the structure will hit the ground for extreme condition. So, Option-2 is a better design.Testing ADAMS model in Various Landing ConditionsDifferent landing conditions specified for this assignment is bastard in ADAMS for the design option-2.Normal landing Here the vertical descent speed of 0.5 m/sec is applied at the translational joint between the structure and space. Result is shown belowFig.9 Normal landing speedup plotThe result for the normal landing test for the design option-2 is show that the maximum quickening is 6.8 m/sec2.Hard Landing For the hard landing test, I applied vertical descent speed of 3m/sec at the joint between the structure and space and vertical deck speed of 3m/sec at the joint between the deck and space. Here is the resultFig.10 Hard landing acceleration plotThe above plot is showing that the maximum acceleration value for the hard landing test of the design option-2 is 19.3 m/sec2 .Crush Landing In order to simulate the crush landing condition, I applied the vertical approach speed of 15 m/sec at the joint between the structure and space, retentivity the deck stationary.The result of the crush landing test is shown belowFig.11 quickening plot for the crush landing testThe above plot is showing that the maximum acceleration value for the crush landing test is 206.6m/sec2. lead Vibration Analysis in ADAMSThe naval helicopter will be kept in landed condition over the aircraft carrier. The aircraft carrier will be oscillating continuously under the influence of the sea waves. The intention of the vibration analysis is to find out the resonating frequency of the landing gear mechanism under the sea oscillation.For simulating the sea wave oscillation, I created five kinetic actuators placed at the centre of each of the axels and placed one output channel at the centre of gravity of the top out structure.Frequency response analysis The frequency response analysis (FRA) shows the involution of acceleration for each frequency values. The FRA plot for the design option-2 is shown belowFig.12 Frequency response plot for the design option-2The FRA plot above is showing a pick at 2.5 Hz. The pick is the resonating frequency of the landing gear mechanism.Results of the Different ADAMS AnalysisMaximum acceleration for normal landing = 6.8 m/sec2.Maximum acceleration for hard landing = 19.3 m/sec2.Maximum acceleration for crush landing = 206.6 m/sec2.Resonating frequency of the mechanism = 2.5 Hz. destinationThe conceptual design of the naval landing gear is simulated using ADAMS for the specified landing conditions. The results from the simulation are showing that the maximum acceleration values are well below the specified maximum get for this assignment. The ADAMS vibration simulation is showing the resonating frequency for the mechanism as 2.5 Hz.