The document analyzes the landing gear of the Fokker 100 commercial airplane. Traditional calculations are performed to determine the reaction forces at different points of the nose landing gear when subject to loads during landing. The landing gear is also analyzed using ANSYS software to observe deformations and compare results to theoretical calculations. This allows improvements to the landing gear design to optimize its performance.

1. Landing Gear-
Design and
Analysis Report
Shashank Datthatreya

2. Table of Content
SUMMARY .......................................................................................................................................1
THEORETICAL FRAMEWORK.............................................................................................................2
Historical Overview of the design of landing gear. ........................................................................2
Aircraft with Fixed Landing Gear...................................................................................................3
Function.......................................................................................................................................6
Main landing gears.......................................................................................................................6
Auxiliary landing...........................................................................................................................6
Classification................................................................................................................................6
Available landing gear..................................................................................................................7
Landing gear Problem Statement:....................................................................................................8
Material Properties: .....................................................................................................................8
CALCULATIONS.............................................................................................................................9
ANALYSIS OF THE LANDING GEAR USING ANSYS Software..............................................................13
ANSYS WORKBENCH...................................................................................................................19
CONCLUSIONS................................................................................................................................24
BIBLIOGRAPH.................................................................................................................................25

3. 1
SUMMARY
The lift required to balance the weight of the airplane and allow the flight is only obtained when
the acquirer has acquired the relative speed with the air, which may give rise to this stall; for that
the airplane, on the ground and rest, you can fly it is necessary, to gain this speed running on the
ground, either launched or effect of its own propellant, which is the procedure commonly used.,
therefore there is the airplane that give it a mount that allows you to run by land with as little
resistance as possible, both by reasoning as part of the air for that in the less distance you can
reach the required speed. At the same time, for which the airplane can pass from your flight speed
until the rest on the ground in the shortest possible space, it is necessary, also providing them with
a system that allows you to shoot, but slowing their movement as soon as possible, with the safety
of the landing.
In this project will analyze the mechanical elements of the nose landing gear of the commercial
airplane FOKKER100, which is subject to loads with the aim of determining the factors of
concentration of effort, these efforts will be analyzed using traditional methods, and also will be
analyzed using numerical methods in this case by means of the ANSYS software which are shown in
chapter IV.
Finally there will be a comparison of the theoretical results with the computational
software(ANSYS), to perform this comparison we get a vision of the deformations that are
generated on the landing gear to the landing, thanks to the option of analysis the outputs can be
used to improve and optimize the design of the landing gear.

4. 2
THEORETICAL FRAMEWORK
Historical Overview of the design of landing
gear.
From the 225 kilograms of the Flyer and the Wright brothers to the lastest Boeing airplane
additions, the Landing Gear has been adapted to the needs of aircraft each time considering speed
and weight.
In the first aircraft it was impossible to connect the structures of the landing gear to the wings due
to the structural fragility of the same, in such a way that prevailed for a long time the so-called
"landing gear in EUV", with landing gear anchored at any part of the structure of the engine, the
only area with sufficient strength to accommodate the landing gear. When it was poly-engines are
the same thing, the landing gear was installed beneath the benches of the motors.
The old aircraft monometer comprised of the landing gear in a very close landing, which further
complicated it and more importantly, exhibited little stability of tread during takeoff and landing.
All the aircraft of World War I had the tip of a landing gear without good brakes and with primitive
systems of cushioning, beams of elastic cords. The landing gear allowed very little load from side to
side so the cracks were the order of the day.
The vertical velocity of contact with the ground typical at the time was 4 or 5 m/s.
The designers of the aircraft of the years 20 knew that the reduction of friction in an airplane in
flight was important to improve the speed and fuel efficiency, as well as maneuverability and
controllability.
In 1927, NACA opened a new tunnel of the research on the propellant (PRT) in the worked Orio al
Serio memorial aeronautical denoting Chinese-mestisos that include Sangley in Virginia. The PRT
was a wind tunnel very large by the time, with a diameter of 20 feet (6.1 meters). It was designed
to allow the testing of a fuselage of integer aeroplane with the engine and the propeller, with a
simple part of the airplane or a model of the scale. The aeronautical engineering at NACA stated
that the landing gear of aircraft faced surrendered to a lot of friction, and the PRT was the first
wind tunnel that allowed that this testing.

5. 3
The evidence in the PRT showed immediately that the landing gear contributed up to 40% of
friction of the fuselage, which gave a shock to researchers. It was reviewed that the reduction of
friction produced by landing gear significantly improved the functioning of the airplane in flight.
Aircraft with Fixed Landing Gear
Engineers determined that there were several ways to reduce the friction of the landing gear. The
two methods were more obvious in getting the landing gear on the plane or reset a fixed landing
gear so that produce less friction while still highlighted below a plane.
Getting the landing gear was not exactly a new idea in 20 years. The plane of Wartin, built in 1917,
retractable gear was the Dayton Wright RB-1 1920 and Verville Sperry R-3 retractable gear were
also made in 1922. The majority of the planes they had fixed landing gear on the end of the
underpinnings of the metal because they were easier to designs and relatively lightweight.
When designing an airplane, the engineers established five requirements that were in conflict:
1. Operation
2. Weight
3. Cost
4. Reliability
5. Maintenance
The engineers found a better solution to the requirement of operation that was pulling the landing
gear fully inside the fuselage structure and covered, presenting a smooth surface that did not cause
any friction. But while that is ideal for a point of view of the operation, they determined that this
approach affected the other requirement was that more weight, cost, was less reliable, and
required more maintenance.

6. 4
The Boeing Monomail, which first appeared in 1930, and the Lockheed Orion are generally
regarded as the pioneers in the development of retractable landing gear, proving that it was
practical. But the designer Jack Northrop of the airplane, who was very interested in streamline of
the aircraft to improve operation, produced the Northrop alpha, beta, and gamma with the fixed
landing gears during these 30 years.
This aircraft had aerodynamized covers that extended down the fuselage, with the wheels sticking
out in the background. These were usually referred as the gear "trouser". Although the "trouser"
would not engage produced more friction than gear fully contracted, this remained a landing gear
uncovered substantial excess of the improvement. Remained lighter, cheaper, more reliable, and
easier to maintain than the retractable gear.
But during the 30s, many designers were willing to accept the other disadvantages of retractable
landing gear just to reach a better performance.
Airplane with Retractable landing gear
For the landing gear retractable improvements in the functioning were clearly achievable, since a
retractable landing gear with its engines and machinery associated with more weight than a fixed
gear, so requiring the highest elevation in the airplane and denying some of the advantages of the
low friction of the gear collapsed.
While the contraction of the gear could improve the functioning of the plane, it required a larger
engine and more fuel and not to mention more money.
As the speed of the aircraft continued to expand during the years 30, particularly while the airplane
began to reach speeds of 200 miles per hour (322 kilometers per hour), the growing weight of
retractable gear became less important than reduce friction. Today, the private plane of low speed
still has fixed landing gear due to concerns of the cost and maintenance.
But virtually the largest airplane that had fully retractable landing gear that was designed
presented engineers with a number of problems, particularly mounting them on the airplane
without affecting other parts of the design of the aircraft. The commercial passenger aircraft
large as the 747 and Airbus A340 have enough internal volume so that the landing gear can fit
inside the diameter of the fuselage.

7. 5
Aircraft with landing gear within the diameter of the fuselage
This is an example of a landing gear of tricycle which is used in the latest models of aircraft. This
type of landing gear makes the airplane easier to manage because the gear is steerable at nose.
Aircraft with landing gear of Tricycle
The fixed landing gear consists of two conventional wheels forward of the center of gravity of the
aircraft and a small wheel in the queue on the back. This configuration was nicknamed the
"taildragger."
Aircraft with conventional Landing Gear
The gamma of Northrop had the landing gear with the aerodynamic covers that extended
down the fuselage with the wheels that stuck up out of the structure.
Plane A-17 (1930) Gamma of Northrop

8. 6
Function
The role of the landing gear is to absorb the loads of landing, up to an acceptable value for the
conditions of resistance of the aircraft structure.
The landing gear consists of two fundamental sets: main and auxiliary.
Main landing gears
Supports most of the weight of the aircraft on the ground. Consists of two sets of one or more
wheels, each one at the side of the longitudinal axis of the airplane.
In addition to this wheel or combination of wheels, the main landing gear that includes other
mechanisms with diverse functions in the operation of the landing gear , such as shock absorbers,
brakes, hydraulic hammers, etc.
Auxiliary landing
It consists of a set of one or more wheels, located in the bow or in the area of tail of the plane,
which completes the function of the tripod.
Classification
The Landing Gears are usually classified as:
1. Fixed landing gears.
2. Retractable landing gears.
The landing gears are fixed during the flight they are permanently exposed to the air stream. They
are only used in small aircraft, low-speed where the increase in weight by adding a retract system
adversely influence on the total weight and the gain in speed wouldn't be much the performances.

9. 7
Available landing gear
There are two provisions of landing gear:
1. Conventional Landing gear
2. Tricycle Landing Gear
The conventional landing gear: This consists of two pillars of a structure underneath the wing or
fuselage to the height of the wing and a wheel or tail skid.
This type of landing gear has several disadvantages such as:
1. Does not allow good visibility of the pilot.
2. For blocked or detach the empennage has to produce a certain stall so that the plane is in a
horizontal position or the tail wheel in the air.
3. When the plane lands you can run the risk of a poor braking resulting in a summersault.
The steering system is performed by means of the tail skid commanded by cables or you can also
bring about a change in direction by applying the brake in one of the uprights and giving major
power in the case of the twin engine opposite that the brake is applied.
Configuring and nomenclature of the conventional Landing gear
The tricycle landing gear: This consists of two main pillars underneath the wing or fuselage and a
pillar in the nose of the plane. The amount of nose has a steering device.
In fact, all the aircraft have tricycles, but this designation has been generalized for those who carry
the third wheel in the bow, the tricycle landing gear has the same mission as the conventional

10. 8
landing gear, but simplifies the technique of the landing and allows pose the aircraft on the ground
in a horizontal position, eliminating the danger of damage, even when brakes are applied during
the landing.
The stability it provides the tricycle landing gear in the landing gear with tail wind or cross wind,
taking the support of the position of center of gravity (v. G. ), in front of the main wheels, and
travel in a straight line on the landing and taking off, are the most important advantages. This
condition is of particular importance for the aircraft to landing or blocked in small airstrips, with
crosswinds.
Landing gear Problem Statement:
Application of Loads as shown in below diagram.
Material Properties:
 Young’s modulus = 73000 MPa
 Poisson’s ratio = 0.33
ANALYSIS OF THE LANDING GEAR of FOKKER100 through traditional methods.
(We have considered the Tricycle Landing Gear type for the analysis.)

11. 9
CALCULATIONS
The landing gear comprises of 3 supporting structures to which it is attached; points A,B and C.
The horizontal component V and the vertical component D for the reactions at A, B and C are taken
into consideration.
Using the equilibrium theory, we can get each of the required forces and moments.
As we can calculate the total moment through AB,
MAB = -(15000 + 10000)64 + 24CV = 0
We can now determine CV,
CV = 6666lb
We can get CD acting on both ends as the reaction at C must have a line of action along the
respective line since the member is fixed at both ends.
CD = 66666(24/28) = 57142lb
CD = 66666(36.93/28) = 87900lb
By taking moments about a drag axis through point(A)
MA(D) = -60000 x 9 – 40000 x 29 – 66666 x19 +38(BV) = 0
We can get,
BV = 78070lb
We also know that
V = 0
By this we can obtain AV
V = -78070 + 60000 + 40000 + 66666 – VA = 0
And

12. 10
AV = 88596lb.
By taking moments about V-axis through point A
MA(V) = 57142 x 19 – 15000 x 9 – 10000 x 29 – 38.BD = 0
We can get
BD = 17386lb.
Similarly finding AD
D = 07
D = -57142 + 15000 + 10000 + 17386 + AD = 0
Which means,
AD = 14756lb.
Moments about V and D axes through point O give us the results
MO(V) = 5 x 10000 + 14756 x 19 – 17386 x 19 = 0
MO(D) = 20000 x 10 – 88596 x 19 + 78070 x 19 = 0
This brings us to the Oleo-strut reactions to be determined.
The loads applied to the wheels transfer to point(O).
Thus
Total V load at (O) = 60000 + 40000 = 100000
And
Total D load equals 15000 + 10000 = 25000.
These values bring us to the moments about V and D axes through (O), which then will be
MO(V) = (15000 – 10000).10 = 50000 in.lb
And
MO(D) = (60000 – 40000).10 = 200000 in.lb.

13. 11
We can get TE by considering moments about the axis OE
MOE = -50000 + TE = 0
Hence,
TE = 50000 in.lb
Taking moments about D axis through point D
MD(D) = 200000 – 28.ES = 0
get us,
ES = 7143lb.
Moments about D axis through point G are as follows
MG(D) = 200000 – 100000 x 17 – 66666 x 17 + 34.DFV = 0
Now,
DFV = 77451lb.
So at both ends,
DFS = 77451(17/28) = 47023lb
DF = 77451 (32.72/28) = 90503lb
we know V = 0
moments into consideration as follows
V = 100000 – 77451 + 66666 – DGV = 0,
gives us:
DGV = 89215
So at both ends,
DGS = 89215 . (17/28) = 54164lb

14. 12
DG = 89215(32.23/28) = 104190lb
Moments about S axis through point D are
MD(S) = -25000 x 35 + 28.ED = 0
gives us the unknown component
ED = 32143lb
Moments about D-axis through point (O)
MO(D) = 20000 + 54164 x 36 – 7143 x 64
= 200000 + 1949904 – 1692828 – 457150 = 0
MO(S) = 32143 x 64 – 57142 x 36 = 0
Top member AB gives reaction forces as follows
Taking moments about D-axis through point A,
MA(D) = -89215 x 2 – 77451 x 36 – 38.BV = 0
We get,
BV = 78070lb.
Also,
V = 0,
V = 89215 + 77451 – 78070 – AV = 0
which means,
AV = 88596lb.
Moments about V-axis through point A
MV(D) = 50000 + 32143 x 19 -38.BD = 0
Which means,

15. 13
BD = 17386
Similarly we know
D = 0
D = 17386 – 32143 + AD = 0
We obtain the last unknown component, AD
AD = 14757lb
The landing is considered as a free body while performing the stated numerical calculations. We
obtain 4 reaction forces resulting from the given applied forces.
Verification of the obtained reaction forces is done on the software ANSYS. This is discussed in the
following sections.
ANALYSIS OF THE LANDING GEAR USING
ANSYS Software
Development in the finite element (ANSYS software) is carried out in three different steps, the first
step is called pre-processor which is to develop modeling and the creation of the finite element
mesh, the second step is the restriction and implementation of the load, and the last is the solution
in which the results are displayed also known as post-processor.
The implementation and utilization of the software shows the places which have the highest
deformation and effort in the structure.
 ANSYS APDL

16. 14
The following steps are done in ANSYS APDL for the process of 2-D analysis of the Landing Gear
structure:
1. Type of Analysis selection
Specified in the program the kind of analysis that will be analyzed (structural type)
2. Element Type Selection
The material elements assigned for the structural analysis ,in this case LINK180 and BEAM188
are used. The main strut will try to bend and compress when load is acted upon, this part will
thus be modeled as a Beam. The rest of the 2 struts will face compression and tension, which
can be analyzed as a Link.

17. 15
3. Real Constraints
Real conslanding gearts for the LINK element is done before proceeding
4. Engineering Data
Material Properties as mentioned in the problem are input for the respective elements.

18. 16
5. 2-D model(free body diagram)
The modeling of the simplified structure of the landing gear is done.
6. Sections
Sections of the structure for the purpose of meshing are defined

19. 17
7. Meshing
Meshing is done, giving the inputs of element sizes.
8. Loads and Solution
Restriction and applications of the load is processed. After the Remote Forces are applied after
the Displacement support is given, the solution is done.

20. 18
For the determination of the efforts by finite element of the steel tube, the General Prostproc , Plot
Results and contour plot features are used.
Deformation is analyzed as shown

21. 19
ANSYS WORKBENCH
The following steps are done in ANSYS WorkBench to determine the reaction forces on a 3-D
component of the Landing Gear structure.
Material Properties
Geometry modeling (Modeling done in CATIA software and imported in ANSYS Workbench for
analysis)

22. 20
Meshing
Fine meshing done on the relevant edges, sides and contacts.
Sizing
Use Advanced Size Function Off
Relevance Center Fine
Element Size Default
Initial Size Seed Active Assembly
Smoothing High
Transition Fast
Span Angle Center Medium
Minimum Edge Length 2.54e-004 m
Inflation
Use Automatic Inflation None
Inflation Option Smooth Transition
Transition Ratio 0.272
Maximum Layers 5

23. 21
Growth Rate 1.2
Inflation Algorithm Pre
View Advanced Options No
Patch Conforming Options
Triangle Surface Mesher Program Controlled
Loads and Constraints
Remote force applied on wheel-1
Remote force applied on wheel-2

24. 22
Applied forces on each component tabulated below:
Object
Name
Displacement
Remote
Displacement
Remote
Displacement
2
Remote
Displacement
3
Remote
Force
Remote
Force 2
State Fully Defined
Scope
Scoping
Method
Geometry Selection
Geometry 4 Faces 1 Face 2 Faces
Coordinate
System
Global Coordinate System
X
Coordinate
1.0773 m
-5.2505e-020
m
4.2071e-006
m
4.1831e-005
m
4.4498e-010
m
Y
Coordinate
-1.2803 m 0.4826 m -0.4826 m 0.254 m -0.254 m
Z
Coordinate
-0.15569 m -3.81e-002 m -1.5878 m
Location Defined
Definition
Type Displacement Remote Displacement Remote Force
Define By Components Components
Coordinate
System
Global
Coordinate
System
X
Component
0. m (ramped)
-44482 N
(ramped)
-66723 N
(ramped)
Y
Component
0. m (ramped) 0. N (ramped)
Z
Component
0. m
(ramped)
Free 0. m (ramped)
1.7793e+005
N (ramped)
2.6689e+005
N (ramped)
Static structural analysis solution
Total Deformation Plot

25. 23
Equavalent Stress
Forces and reaction forces at each component tabulated
Definition
Type Force Reaction
Moment
Reaction
Location
Method
Boundary Condition
Boundary
Condition
Displacement
Remote
Displacement
Remote
Displacement 2
Remote
Displacement 3
Remote
Displacement
Results
X Axis
2.0148e+005
N
-46201 N -26692 N -17385 N 0. N·m
Y Axis 302.09 N 1486.1 N -1.1393e+005 N 1.1215e+005 N 0. N·m
Z Axis 2.684e+005 N 0. N -3.3476e+005 N -3.7846e+005 N 57829 N·m
Total
3.3561e+005
N
46225 N 3.5462e+005 N 3.9511e+005 N 57829 N·m
The results obtained showed that the structural analysis done on structure of materials Alluminium
allow and structural steel can verify the results obtained from numerical approach, which are
identical.

26. 24
CONCLUSIONS
The method of finite elements has acquired a great importance in the solution of engineering problems,
physicists, etc. , as previously it was virtually impossible to resolve cases by traditional mathematical
methods. In this one would have to model a structure through prototypes which are proving physically
until you find the best design. This circumstance forced to perform prototypes, testing and making
results in high cost in both economic and development time.
The Finite Element model allows you to perform a mathematical calculation of the real system, easier
and more economical to change than a prototype. However, it should never cease to be a method of
calculating approximate due to the basic assumptions of the method. The finite element is used in the
design and improvement of products and industrial applications, as well as in the simulation of physical
and biological systems complex.
The calculations are performed on a mesh of points (called nodes), which serve to turn a basis for
domain in finite elements. The generation of the mesh is usually performed with special programs called
mesh generators, at an earlier stage in the calculations is called pre-process. In accordance with these
relationships of connectivity relates the value of a set of unknown variables defined in each node and
called degrees of freedom. The set of relationships between the value of a given variable between the
nodes can be written in the form of a system of linear equations, the number of equations of the system
is proportional to the number of nodes.
The result of the stresses and deformations vary due to the shielding already that if you reduce the
value tends to be less accurate and by increasing the amount of prominent the result tends to be more
exact.

27. 25
BIBLIOGRAPH

 Analysis and Design of Flight Vehicle structures, E. F. Bruhn
 Aircraft Design, A Conceptual Approach, Raymer
 Aircraft landing gear design principles and principles, 1988 Nnorman S Currey
 Design and Construction of ultra-light planes, Beaujon Herbert 
 Fundamentals of aerodynamics / John D. Anderson, Jr. 3Ed. Boston, Mcgraw-hill, c2001.
 Aircraft structures for Engineering Students, Megson, Fourth Edition, 2006