Examining Landing Gear Mechanisms Engineering Essay

The landing cogwheel is an of import portion of an aircraft every bit far as the take-offs and landings are concerned. The landing cogwheel mechanisms ( or constructions ) are pretty simple in instance of the commercial chopper as compared to the commercial aeroplanes. But, that is non the instance for the naval choppers. Because of the not-so-friendly landing conditions, the naval chopper must hold sophisticated landing cogwheel mechanism connected with its fuselage. The design of the landing cogwheel mechanism for the naval chopper should be such that the chopper can set down safely in aircraft bearer every bit good as in land ; besides, the mechanism should non neglect under the sea moving ridge excitement, while in land status.

Research on landing cogwheel

During the initial yearss of the human winging history, the circulars used to hold the “ Skids ” as landing cogwheels. The skids are still really much in usage for commercial choppers. But, for the aeroplanes and for the naval choppers wheels are used largely for the landing cogwheels. The wheels are connected with the daze absorbers to organize the landing cogwheels. The landing cogwheel, so, acquire connected with the fuselage in assorted manners based upon the size of the aircraft.

All the wheel based landing cogwheels can loosely be categorized in three chief classs:

Conventional

Tri-cycle

Tandem

Fig.1: Showing three basic types of wheel based landing cogwheels

Two front wheels and a rear tail wheel are used to organize the conventional landing cogwheel. The older aircrafts still have this type of set downing cogwheel. Land handling is bit hard here.

The tri-cycle constellations has two ( or multiple of two ) wheels at rear and lower limit of one nose wheel ( s ) at forepart. It gives better land managing comfort and used widely for little sized aircrafts. On the footing of the wheel agreements, different types of tri-cycle agreements are possible ( as shown below )

Fig.2: Showing different types of Tri-Cycle constellations ( as per Federal Aviation Administration terminology )

The multiples of landing cogwheels are placed in line to organize a complex tandem set downing gear system. Different combinations of tandem are possible ( as shown below ) :

Fig.3: Showing different types of Tandem constellations ( as per Federal Aviation Administration terminology )

Gestating Naval chopper Landing Gear

After analyzing different types of available set downing cogwheels constellations, I have decided to develop the landing gear construct of “ Single wheel chief cogwheel with double wheel nose cogwheel ” constellation. It ‘s a sort of tri-cycle constellation.

Fig.4: Showing the unsmooth landing cogwheel construct

I have decided to utilize lone tortuosity spring as daze absorbing elements for the construct.

Preliminary Design Calculations

In order further developing the construct, I have used the undermentioned informations:

Entire mass of the chopper = 5126 Kg

Sprung mass on each spring, m = 2563 Kg

Distance between the forepart and rear cogwheel = 5 m

Distance between the two rear gears= 2m

Normal landing:

Vertical descent velocity of the chopper = 0.5 m/sec

Vertical deck velocity = 0

So, the comparative velocity between the deck and the chopper, 5 =0. 5 m/sec=500 mm/sec

So, the kinetic energy of the chopper, KE = 0.5*m*v^2 = 320375000 kg-mm^2/sec^2

The energy stored in the tortuosity spring, SE= 0.5*k*r^2 =0.5*k

Where, k= spring rate in N-mm/degree

r=deformation of the spring =1 grade ( assumed )

Now, as

KE = SE aˆ¦aˆ¦.eqn.1

So, k= 640750000 N-mm/Degree

I will utilize this spring rate for remainder of the two landing conditions to happen out the distortions of the tortuosity springs.

Difficult landing:

Vertical descent velocity of the chopper = 3 m/sec

Vertical deck velocity = -3 m/sec

So, the comparative velocity between the deck and the chopper, v =6 m/sec=6000 mm/sec

K= 640750000 N-mm/degree

So, by utilizing the eqn.1:

r= 12 grade

Crush landing:

Vertical descent velocity of the chopper = 15 m/sec

Vertical deck velocity = 0m/sec

So, the comparative velocity between the deck and the chopper, v =15 m/sec=15000 mm/sec

K= 640750000 N-mm/degree

So, by utilizing the eqn.1:

r= 30 grade

So, I will get down my ADAMS design with the values obtained from this manus computation and bit by bit all right tune the values in order to run into the landing standards.

Converting the Conceptual Design to ADAMS Mechanisms

I have used the MSC ADAMS package for fixing two set downing gear mechanism design options out of the conceptual design and the manus computations. The two design options differ in footings of highs. Parametric design advantage of the ADAMS package is utilised for making the two design options.

While making the two mechanism design options, the undermentioned ADAMS options are utilised:

Point: Points are used for making basic locations of all the of import elements of the design ( like Centre of the wheels etc. )

Torus: Wheels of the landing cogwheels are created utilizing the toroid option.

Link: All the structural members ( like top frame, axels etc ) are created utilizing this option.

Box: This tool is used for making the set downing deck of the air trade bearer.

Tortuosity Spring: This is for making the forepart and rear tortuosity springs.

Hinge Joint: This option is for making all the revolute articulations of the mechanism.

Translational Joint: This option is used for making the translational articulations.

Contact: The contacts between the wheels and the deck are created utilizing this option.

e.1. ADAMS Mechanism Option-1

The mechanism option-1 expressions like below:

Fig.5: Showing the ADAMS Mechanism option-1 Agreement

The points tabular array for the mechanism option-1 expressions like below:

Fig.6: Showing the point tabular array for the mechanism option-1

e.2. ADAMS Mechanism Option-2

The mechanism option-2 expressions like below:

Fig.7: Showing the ADAMS Mechanism option-2 Agreement

The points tabular array for the mechanism option-2 expressions like below:

Fig.8: Showing the point tabular array for the mechanism option-2

e.3. Choosing the Optimum ADAMS Landing Gear Mechanism

The choice of the best design out of the two options is done by detecting the acceleration values. The acceleration secret plans for the difficult landing conditions ( descent speed of the chopper = 3 m/sec and upward deck velocity = 3m/sec ) for both the constructs are shown below:

Fig.9: Showing the difficult landing status acceleration secret plans for both the constructs

The above secret plan is demoing that the maximal acceleration value for the design -2 is more than

50 m/sec2.

The acceleration secret plans for the crush set downing status ( descent speed of the chopper =15 m/sec and upward deck velocity = 0 m/sec ) for both the options are shown below:

Fig.10: Showing the crush set downing status acceleration secret plans for both the constructs

The above secret plan is demoing that the maximal acceleration value for the design option-2 is much higher in instance of the crush set downing status.

So, on the footing of the above two trials, it can be concluded that the design option-1 is better among the two options. Hence, I have selected the design option-1 for farther analysis.

Testing the Selected ADAMS mechanism ( design option-1 ) Against the Specified Landing Conditionss

Normal Landing Condition: The acceleration secret plan for normal landing status ( descent speed of the chopper = 0.5 m/sec and upward deck velocity = 0m/sec ) for the design option-1 is shown below:

Fig.11: Showing the normal landing status acceleration secret plans for the Design Option-1

The above secret plan is demoing that the maximal acceleration value for normal landing status for the design option-1 is 7.5 m/sec2.

Hard Landing Condition: The acceleration secret plan for normal landing status ( descent speed of the chopper = 3 m/sec and upward deck velocity = 3m/sec ) for the design option-1 is shown below:

Fig.12: Showing the difficult landing status acceleration secret plans for the Design Option-1

The above secret plan is demoing that the maximal acceleration value for difficult landing status for the design option-1 is 48.1 m/sec2.

Crush Landing Condition: The acceleration secret plan for normal landing status ( descent speed of the chopper = 15 m/sec and upward deck velocity = 0m/sec ) for the design option-1 is shown below:

Fig.13: Showing the crush set downing status acceleration secret plans for the Design Option-1

The above secret plan is demoing that the maximal acceleration value for difficult landing status for the design option-1 is 119.6 m/sec2.

Runing the Vibration Analysis for the Selected ADAMS Mechanism

The quiver analysis is performed for the Design option-1 utilizing the ADAMS quiver circuit board. For imitating the sea moving ridge oscillations, two acceleration actuators are used at forepart and the rear axles. One end product channel is created at the COG of the top frame. The end product channel is used for mensurating the acceleration at the COG of the frame.

Fig.14: Showing the Frequency Response Analysis secret plan for the Design Option-1

The choice of the above frequence response secret plan indicates the resonating frequence for the design option-1. So, the resonating frequence here is 64.5 Hz.

Amalgamate Results for Design Option-1

Parameters

Valuess

Maximum Normal Landing Acceleration ( m/sec2 )

7.5

Maximum Normal Landing Acceleration ( m/sec2 )

48.1

Maximum Normal Landing Acceleration ( m/sec2 )

119.6

Resonating Frequency ( Hz )

64.5

Discussion

Task-1: This undertaking is covered in the section-c and section-d.

Task-2: This undertaking is covered in Section-f.

Task-3: This undertaking is covered in section-g.

Task-4: This undertaking is covered in section-e.

Decision

The ADAMS is a powerful tool for making and proving a mechanism under specified conditions. The parametric characteristic of ADAMS helps making different design loops easier.

The design option-1 passed all the landing conditions specified for the assignment. Besides, the resonating frequence observed for the design option-1 is 64.5 Hz.