Landing Gear Design-1

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Aviation Solutions

CONCEPT DESIGN OF AIRCRAFT
LANDING GEAR

BY:

STEPHEN FRASER – 10023400
SAMUEL GOODCHILD - 10022449
JONATHAN LANGER – 09065339
JACK LAWLOR-ANDERSON – 09069837
MATTHEW SOUL – 09069387
ROBERT SWALLOW – 08069444

29/04/2013

CONTENTS
1

Introduction ........................................................................................................................ 4

2

Aims and Objectives ........................................................................................................... 6

3

2.1

Aim .............................................................................................................................. 6

2.2

Objectives .................................................................................................................... 6

Literature Review ............................................................................................................... 7
3.1

Background and Relevance ......................................................................................... 7

3.2

Landing Gear Design.................................................................................................... 8

3.2.1

Structural Integrity ............................................................................................... 8

3.2.2

Mounting.............................................................................................................. 9

3.2.3

Retraction........................................................................................................... 10

3.2.4

Ground Operations ............................................................................................ 10

3.2.5

Materials ............................................................................................................ 11

3.2.6

Summary ............................................................................................................ 12

4

Product Design Specification ............................................................................................ 13

5

Concept Design ................................................................................................................. 15
5.1

The Concepts ............................................................................................................. 15

5.1.1

Nose Landing Gear: ............................................................................................ 15

5.1.2

Main Landing Gear ............................................................................................. 15

5.2

Reasons for Concepts ................................................................................................ 15

5.3

Functional Analysis .................................................................................................... 17

5.4

Matrix Selection ........................................................................................................ 17

5.4.1

Nose Landing Gear ............................................................................................. 18

5.4.2

Main Landing Gear ............................................................................................. 19

6

Bill of Materials and Costing ............................................................................................. 21

7

Theoretical Analysis .......................................................................................................... 22

8

7.1

Hand Calculations ...................................................................................................... 22

7.2

Finite Element Analysis ............................................................................................. 25

7.2.1

Theory ................................................................................................................ 25

7.2.2

Application ......................................................................................................... 27

Final Design ....................................................................................................................... 32
8.1

Nose Landing Gear .................................................................................................... 32

8.2

Main Landing Gear .................................................................................................... 37
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8.3
9

Costing ....................................................................................................................... 42

Conclusion ........................................................................................................................ 44

10

References .................................................................................................................... 48

11

Bibliography .................................................................................................................. 49

12

Appendix ....................................................................................................................... 50

12.1 Appendix 1: Meeting Minutes................................................................................... 50
12.2 Appendix 2: Other Useful Documents ...................................................................... 61
12.2.1

Quote From SPP Canada Aircraft, INC ............................................................... 61

12.2.2

Specifications of Bearings Used ......................................................................... 62

12.3 Appendix 3: Engineering Drawings ........................................................................... 63

List of Figures, Tables and Equations
Figure 1 - Landing Gear in Action ............................................................................................... 4
Figure 2 - Santos-Dumont's 'No. 14 bis' ..................................................................................... 7
Figure 3 - Functional Analysis .................................................................................................. 17
Figure 4 - Graph of Wheel Base vs % Weight on NLG .............................................................. 23
Figure 5 - Determining Wheel Track ........................................................................................ 24
Figure 6 - Mesh Convergence graph for FEA ........................................................................... 26
Figure 7 - Solving time for Element Sizes in Mesh Convergence ............................................. 27
Figure 8 - CAD Model of MLG with mesh applied ................................................................... 28
Figure 9 - Boundary Conditions applied to NLG for FEA .......................................................... 29
Figure 10 - Bearing Loads applied to NLG for FEA ................................................................... 29
Figure 11 - Von Mises Stress obtained through static testing on the NLG .............................. 30
Figure 12 - Total life cycles for NLG from fatigue analysis ....................................................... 31
Figure 13 - CAD Model of the NLG fully deployed ................................................................... 32
Figure 14 - Example of an aircraft NLG failing to deploy correctly
(http://www.airlinesafety.com/editorials/JetBlueLAX.htm) ................................................... 33
Figure 16 - CAD Model of the NLG mid-retraction .................................................................. 33
Figure 15 - CAD Model of the NLG fully retracted ................................................................... 33
Figure 17 - Life Cycle Fatigue Analysis for NLG ........................................................................ 34
Figure 18 - Stress results for landing conditions for NLG ........................................................ 36
Figure 19 - Deflection results from FEA for the NLG ............................................................... 36
Figure 20 - Evidence that the MLG is unable to fit in the designated stowage space within
the fuselage.............................................................................................................................. 37
Figure 21 - CAD Model showing the bulge created to house the retracted MLG ................... 38
Figure 22 - CAD Model of the MLG fully deployed .................................................................. 39
Figure 23 - Fatigue study results for MLG ................................................................................ 40
Figure 24 - Overall von Mises stress results for MLG .............................................................. 41
Figure 25 - Bearing Load and Braking Torque applied to MLG ............................................... 41
Figure 26 - Deflection of the MLG from FEA ............................................................................ 42
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Figure 27 - Final design of the NLG, fully deployed ................................................................. 46
Figure 28 - Final design of the MLG, fully retracted ................................................................ 46
Table 1- Matrix Selection: Nose Landing Gear ........................................................................ 18
Table 2 - Nose Landing Gear Concepts .................................................................................... 18
Table 3 - Matrix Selection: Main Landing Gear ....................................................................... 19
Table 4 - Main Landing Gear Concepts .................................................................................... 19
Table 5 - Design Parameters .................................................................................................... 22
Table 6 - Dimensions for Landing Gear Positioning ................................................................. 24
Equation 1 - Distance from Nose of Aircraft to MLG ............................................................... 23
Equation 2 - Distance between the two wheels of the MLG (Wheel Track) ........................... 24

List of Abbreviations
BC – Boundary Conditions
BOM – Bill of Materials
MLG – Main Landing Gear
NLG – Nose Landing Gear
PDS – Product Design Specification

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1 INTRODUCTION
Aircraft are currently one of the most popular modes of transport. Not only do they provide
mass transport for passengers to fly locally, nationally and internationally, but they also
carry huge responsibility for success in the military, freight and logistics.
All aircraft utilise different methods of
landing, most land with a nose and main
body located landing gear, others land on
water through a boat hull shaped
fuselage. Each aircraft has a landing gear
specific to its needs. The Hercules (soon to
be replaced with the A400) carries huge
Figure 1 - Landing Gear in Action

loads and has short take-off and landing

capabilities, tanks, small Helicopters and passengers can all be carried on this military
service plane.
Not all planes are designed to take huge loads; Cessna's for example have simple landing
gears that do not retract, but simply hang from the plane. However, in the commercial flight
sector, and many other areas, it is considered that the drag forces caused by fixed landing
gear would outweigh the weight penalty of a retraction system when considering fuel
usage.
The plane specified for this project is required to Land 10,000 times or last for 10 years, with
a seating capacity for 30 passengers.
Since this is a standard passenger plane it will be required to land only on tarmac, and will
have no capability for a water landing and thus the landing gear will use wheels. The final
design must be able to retract into the fuselage so that the total surface area of the aircraft
is maintained, thus not increasing drag. Greater area means a greater fuel cost with respect
to drag and a decrease in the aircrafts flying dynamics. A potential issue with retraction
systems is their weight, which could have an inverse on fuel efficiency. However the drag
forces caused by a fixed landing gear would far outweigh the weight penalty of a retraction
mechanism due to the velocity at which aircraft fly.
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A well designed landing gear can be the difference between life and death for all on board,
and whilst they are a small part of the plane, a great deal of time and research must go into
the design of the aircraft’s landing gear.
The main task of the landing gear is to absorb horizontal and vertical energy (Young, 1986).
Once it is deployed, a landing gear must be a structural entity, able to support the speed of
take-off, the impact of landing and be capable of supporting the plane in its movement on
the ground. The tyres must be able to withstand the frictions associated with take-off and
landing and must be able to hold the static weight of the plane.

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2 AIMS AND OBJECTIVES
2.1 AIM
The main aim of this project is to design an aircraft landing gear for a 30 passenger aircraft,
matching the criteria set in the project brief. The main considerations in the design will be
cost, weight, stowage space and component life cycle.

2.2 OBJECTIVES
a) Produce a layout of the landing gear position with calculations to support final
positioning.
b) Calculate the design loads from the aircraft weights before take-off and landing.
c) To produce a concept design of the landing gear. This will include details such as
steering mechanisms and shock absorption proposals. Initially these will be
concept drawings, and later a CAD model will be made of the final design.
d) Perform Finite Element Analysis on the design and iterate into the design.
e) Predict the life of the landing gear based on FEA.
f) To propose a retraction method and estimate stowage space.
g) To make a weight estimation of the landing gear.
h) To make a cost estimation and cost breakdown of the landing gear, ensuring the
design is within the budget specified.
i) To understand the parameter limitations set within the brief and how these
compromise the design.
j) A project plan showing the relative times of your design stages is to be presented
along with the final solution.
k) Evaluate against design criteria in Project Brief.
l) To present the project in the form of a design package and also as a
presentation.

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3 LITERATURE REVIEW
3.1 BACKGROUND AND RELEVANCE
The aeroplane is both a land-borne and airborne vehicle. Whilst its primary operation is to
fly, a significant proportion of a plane’s life is spent on the ground. This ground operation
requires a means, and this necessity led to the formation of the landing gear (Bruhn, 1973).
The first recorded flight of a plane with a wheeled landing gear was in 1906 by SantosDumont’s ‘No. 14 bis’ (Figure 2). This became the norm during World War 1 (WW1) which
saw the majority of aircraft adopt a fixed landing gear, mounted to the fuselage (Currey,
1988).
The 21 years between the first and
second world wars saw a significant
development in airframe design, which
was

matched

with

similar

advancements in landing gear design.
By the beginning of World War 2
(WW2) the retractable landing gear was
introduced and incorporated a variety
of shock absorption methods.
One of the first examples of a retractable landing gear is that used on the Bristol Jupiter in
the 1920s, on which the landing gear
could be hand-cranked into its stored

Figure 2 - Santos-Dumont's 'No. 14 bis'

position after take-off. This led to the majority of WW2 fighters making use of retractable
landing gears (Currey, 1988).
It was not until after WW2, however, that retractable landing gears became commonplace
on almost all aircraft and that landing gear design really took off.
Nowadays the aviation industry has grown significantly and flight is an integral part of life
for much of the world’s population. Planes unite the world by making it possible to travel

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vast distances in a relatively short amount of time, which has led to the expansion of global
organisations and worldwide logistics.

3.2 LANDING GEAR DESIGN
The landing gear of an aircraft has been described as the essential intermediary between
the aeroplane and catastrophe. This means that the proper design of this structurally
integral aircraft feature is essential for the continued success of the industry.
3.2.1 STRUCTURAL INTEGRITY
The landing gear constitutes a vital interface between the ground and the aircraft for the
taxi, take-off and landing phases of operation. In the book Mechanics of Flight, Kermode
defines the act of landing as ‘bringing a plane in contact with the ground at the lowest
possible vertical velocity and, somewhere near the lowest possible horizontal velocity
relative to the ground.’ (Kermode et al, 1996). To enable this, the landing gear of an airplane
must be capable of reacting to the largest local loads on the plane (Pink, 1995). Jack Pink
describes the main load bearing part of a modern landing gear as an oleo-pneumatic shock
strut which is composed of two telescoping cylinders (Bruhn, 1973) filled with oil and air,
and fulfils the function of dissipating the kinetic energy of vertical velocity on landing and to
provide ease and stability for ground manoeuvring (Pink, 1995). The landing gear must
enable the aircraft to roll up to its take-off position and take-off without external assistance
(Pink, 1995). To ensure this is possible, a landing gear consists of shock absorbers, wheels,
tyres, brakes, linkages, steering systems, and provisions for jacking and towing (Elsaie and
Santillan, 1987). Towing provisions must be given, on the nose gear in most cases, that
permit towing and pushing the airplane at full gross weight (Niu, 2002).
According to Pink’s paper on the structural integrity of landing gears, there are two basic
types of landing gears; cantilever and articulated. The cantilever is the most common,
mainly due to its cost and weight efficiency. In this configuration the shock strut supports
drag and side loads (Pink, 1995). Articulated gears offer a smoother taxi ride over bumpy
runways and are useful when stowage room is limited. The shock strut can be easily
removed, giving this configuration a maintenance advantage (Pink, 1995). Elsaie and

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Santillan describe a third type, known as tri-pod landing gear. This configuration consists of
three strut members which apex approximately in the wheel axle centreline with one
member designated the shock absorber. This provides good stability for all directions of tyre
loading (Elsaie and Santillan, 1987).
Dan McCosh considers a second crucial component in modern landing gear in the paper
‘Structural Considerations of Steel Landing Gear Springs’. Factors influencing the design of
the gear spring include the aircraft gross weight and wing loading, the maximum load factor
desired and the tyre size (McCosh, 1971). Fatigue cycle tests of gear springs are conducted
to insure a satisfactory service life, typically 20,000 load cycles (McCosh, 1971).
3.2.2 MOUNTING
Another major consideration in landing gear design is the mounting of the landing gears,
which is considered by Patrick Berry in his paper on landing gear design. The landing gear
itself usually accounts for 3-5% of the Maximum Take-Off Weight (MTOW), but the impact
on the airframe can be as much as 10-25% depending on the design (Berry, 1999). As such,
this is an important opportunity in the design process in which to save weight. Since the
landing gear is always tailored to the needs of specific aircraft it is possible to integrate it
efficiently into the plane (Berry, 1999). As suggested by Berry, Bruhn confirms that the
weight of the landing gear accounts for roughly 6% of the overall weight of the aircraft, and
therefore high strength/weight ratio is a paramount design requirement (Bruhn, 1973).
There are two options for the mounting of the main gears, wing-mounted or fuselage
mounted, and the optimal configuration for a particular aircraft is determined by whether it
is a high, low or mid-winged design (Berry, 1999). High or mid-winged aircraft usually favour
fuselage mountings. This is because, to be mounted on the wing, the gear will need to be
longer in order to reach the ground, causing it to be heavier than normal, which would
result in the gear mountings experiencing higher stresses due to the increased moments.
There are, however, ways in which to compensate for this in the retraction method, and the
lack of disruption to the wing box caused by retracting into the nacelle makes this an
attractive option in the overall picture (Berry, 1999). For a low wing aircraft, the same
retraction method is possible, and since the landing gear can be made shorter, there is a

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considerable weight saving also (Berry, 1999). The possibility of fuselage mounted main
gears depends mainly on the width of the fuselage, as well as the issue of where to retract
it. If the fuselage is not wide enough the stability of the aircraft could well be compromised
and the necessity for the landing gears to retract means that there will need to be a large
cut-out in the fuselage in which the landing gears can be housed. This will add a
considerable amount of weight to the aircraft, which is of course undesirable (Berry, 1999).
Gears that retract fore and aft should, if at all possible, retract forward. An aft retracting
gear will not free-fall down because of air force stream and requires extensive manual effort
to extend in an emergency (Niu, 2002). Whichever mounting option is chosen, the landing
gear must have all components attached the one structural part. Intermixing is not an
option. This is because the stiffness of the fuselage and the wing are different and hence
they deflect differently, which might cause damage to the main landing gear. It is also
important to use the most simple solution for the landing gear, as more joints means more
possibility of internal play (Berry, 1999).
3.2.3 RETRACTION
With regard to the issue of retracting the gears, Bruhn concludes that for aerodynamic
efficiency the gear must be retracted into the interior of the wing, nacelle or fuselage
(Bruhn, 1973). Retraction is a major consideration in landing gear design, and requires the
design of a mechanism that will implement retraction. It is considered that the drag forces
incurred by a fixed landing gear outweigh the weight penalty of the additional retraction
mechanism. The retraction mechanism must control the motion of the landing gear,
allowing it to move between the deployed and retracted states.
The ideal for any landing gear is that it retracts forward. This is so that, in the event of an
emergency, the landing gear can be manually let down, and fall into place. If the landing
gear were to be dropped into place from the rear, the air flow would prevent it from
reaching its full extension, and the plane would be unable to land in an emergency.
3.2.4 GROUND OPERATIONS
In order for the aircraft to be fully operational when it is on the ground, the nose landing
gear must be steerable and the wheels must incorporate brakes.
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The wheels, tyres and brakes are another crucial area when designing a landing gear. An
aircraft uses breaks to steer by different ways, to hold the aircraft stationery when parked,
to hold the aircraft while running up engines prior to take off, and to control the speed
properly while taxiing (Niu, 2002). According to McCosh choosing the optimal tyre size is
another matter of high importance, as tyre size and pressure can change the deflections and
bending moments. An increase in tyre size will normally result in a lower load factor due to
increased deflections (McCosh, 1971). The condition of one tyre or wheel failing on a
multiwheel gear must be considered, and after selecting the optimum tyre this condition
should be checked (Niu, 2002).
3.2.5 MATERIALS
As is the case with many sectors of the transport industry, aircraft landing gears have been
primarily dependent on steels as the main material. Steel has led the way in both aerospace
and automotive industries due to its ease of manufacture and formability. It also offers
desirable strength characteristics at a low cost. Steel is relatively cheap due to the ease with
which iron can be extracted from its ore and subsequently manufactured into steel. As a
result it is easily mass produced and so manufacturing processes over the 20 th century have
largely been constructed around the production of steel parts. This makes the introduction
of alternative materials such as aluminium, titanium and composites a difficult task, but one
that is necessary if industries are to move forwards.
More recently, whilst ultra high tensile (UHTS) steels are still in use, aluminium alloys have
become a staple material used in aircraft landing gear structures. The major attraction
towards aluminium lies in its low density, which is 1/3 rd that of steel. This means that,
theoretically, if steel were directly substituted by aluminium alloys a huge weight saving
could be achieved, and since during flight a landing gear is effectively a dead weight, this
weight saving would lead to a reduction in fuel consumption during flight. However an
important engineering characteristic of materials is ⁄ , a ratio which for steel and
aluminium is very similar. This means that with the weight saving of aluminium comes a
necessity to use more material in order to achieve the required strength.

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Another material which offers a further reduction in weight is carbon fibre, which is
emerging as the potential material of the future, with an impressive density and strength
combination which enables components to retain their useful properties whilst becoming
lighter. However the particular strengths of carbon fibre are not those which are useful in
the production of an aircraft landing gear, which is required to bear heavy loads in a number
of directions.
The majority of alternative materials for use in landing gears find their positives in a
reduction in weight. However this is invariably accompanied by an increase in cost and so,
as with the majority of engineering situations, a compromise is required. Currently, the
most common material used in landing gears is 300M Steel, which is a low-alloy, costeffective option (Serey, 2005).
3.2.6 SUMMARY
The landing gear of an aircraft is the only thing that separates a successful landing from a
complete disaster, making its design of utmost importance. It must be capable of
withstanding the loads required during take-off, landing and taxiing whilst also causing as
little disruption to aerodynamic efficiency of the plane during flight.
To enable this, landing gears must consist of a retracting mechanism which enables
deployment and retraction, and must be fully structural when deployed. The structural
stability of the landing gear depends on the shock strut, the position of mounting and the
tyre configuration chosen.
These considerations will now be taken forwards into the design of the landing gear
specified in Chapter 5.

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4 PRODUCT DESIGN SPECIFICATION
Product: Concept design of aircraft landing gear
Date: 26/10/2012
Revision: 1
1.0 Preliminary requirements
a) Provide adequate clearance between runway and all other parts of the aircraft (rear
fuselage, wing tips, engine pods)
b) Be able to absorb landing impact loads and absorb shock when taxing over rough
surfaces.
c) Provide adequate braking and manoeuvrability during taxiing.
2.0 Performance
a) Withstand applied static loads
b) Withstand applied dynamics loads
c) Landing gear should deploy and withstand a descent velocity of 3.07 m/s
d) Withstand horizontal forces from braking and acceleration.
3.0 Ground Requirements
a) Ability to isolate steering system to enable taxiing of aircraft without causing damage
or failure to aircraft steering system.
b) All landing gear should have external ground locks to prevent the retraction of
landing gear when on the ground.
c) Downlocks must not be stressed by ground loads.
d) Breaking should be adequate to prevent roll back of the aircraft at a gradient of 1:10
with full engine thrust.
4.0 Stowage and Retraction
a) Wheels should stop rotating when in the stowed position
b) Landing gear should retract forward to allow free fall into the airstream in an
emergency
5.0 Economy
a) Effects of landing gear weight should be considered in the design and manufacturing
stage and be kept to a minimum.
6.0 Target production cost
a) Cost no more than £20 000
7.0 Quantity
a) One off design concept.
8.0 Competition
a) Consideration should be given to current landing gear design with the possibility to
improve upon existing designs.
9.0 Service life
a) Life prediction of 10 000 cycles
10.0 Environment
a) All assemblies and components should withstand variations in temperature, from -65
deg C at maximum altitude to 50 dec C during landing and breaking
b) All rotating and actuating components should be protected from the effects of dirt or
dusty environment.
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11.0 Size
a) Stowage space target 4.5 m3
i. 3.5m3 for Main landing gear
ii. 1m3 for the Nose landing gear
12.0 Weight
a) Total weight of landing gear is to be no more than 460kg
i. 370 Kg Main landing gear
ii. 90 Kg Nose landing gear
13.0 Maintenance
a) Designed to reduce down time during maintenance intervals
b) Readily availability of parts
c) Availability of specialised tools for maintenance.
d) Components should be as much as possible interchangeable between left and right
landing gears to reduce production costs
14.0 Manufacturing
a) Components must be fabricated from forging
15.0 Materials
a) Selected materials should be high strength, high stiffness, low cost and weight.
b) Material should possess adequate machinability, weldability & forgeability.
c) Resist corrosion, hydrogen embrittlement, crack initiation and propagation.
16.0 Ergonomics
a) Lifting eyes
b) Jacking points
c) Lubrication points
d) Landing gear system should be integrated with aircrafts central hydraulic system
e) Prevent the possibility of dirt, mud or water collecting during aircraft transit
17.0 Finish
a) Suitable coating to protect against corrosion
18.0 Testing (The following test requirements are necessary to receive certification)
a) Drop testing
b) Ultimate static testing
c) Limit load testing
d) Fatigue testing
e) Photostress
f) Strain gauge surveys
g) Element tests
h) Retraction / extension testing
i) Enviromental testing.
19.0 Safety
a) Provide a secondary means of releasing landing gear in the event of a failure.
b) Uplocks are releasable in an emergency by positive mechanical means.
20.0 Disposal
a) Design for disassembly and end of life

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5 CONCEPT DESIGN
5.1 THE CONCEPTS
5.1.1 NOSE LANDING GEAR:


Cantilever landing gear, Single wheel



Cantilever landing gear, Dual wheels



Articulated landing gear, Single Wheel



Articulated landing gear, Dual Wheels

5.1.2 MAIN LANDING GEAR


Cantilever landing gear, Dual wheels



Cantilever landing gear, Tandem wheels



Articulated landing gear, Dual wheels



Articulated landing gear, Tandem wheels

5.2 REASONS FOR CONCEPTS
Having researched the industry and reviewed current literature on aircraft landing gear, it
was clear that the two most common and useful types of landing gear are cantilever and
articulated. As discussed in Chapter 3, a cantilever landing gear consists of a shock strut
which is built in to the main supporting arm, with the wheels directly below. This type of
landing gear is both cost and weight efficient, leading to its prominence in the industry. In
an articulated landing gear, the wheels are off-axis, with the shock strut running from the
main supporting arm to the wheels. An articulated landing gear is particularly useful when
stowage space is limited. There is also a type of landing gear known as Semi-Articulated,
however these are rarely seen outside of the military and are unnecessarily complex for
what is required in this instance.
Wheel configurations are also a key aspect of the concepts to be designed, and so these
were also researched comprehensively. The choice of wheel configuration is based firstly on
the load it is required to take, and secondly on the weight it will add and stowage space it
will take up. Calculations show that two wheels on each landing gear will be satisfactory to
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bear the loads that will be exerted through their life cycle, and more than two would add
excess weight and volume to the landing gear. As a result of these calculations, the three
wheel configurations to be considered are single, dual and tandem. Single consists of just
one wheel and will only be considered for the NLG, dual consists of two wheels parallel to
one another, whilst a tandem wheel configuration has two wheels one in front of the other.
As discussed in Chapter 3, the ideal for any landing gear is that it retracts forward. This is so
that, in the event of an emergency, the landing gear can be manually let down, and fall into
place. If the landing gear were to be dropped into place from the rear, the air flow would
prevent it from reaching its full extension, and the plane would be unable to land in an
emergency. The NLG will therefore be forward retracting. There are, however, other factors
which need to be considered in the design of the main landing gear, and these factors
dictate that the retraction must be lateral.
This decision has been made because the plane is high winged, and therefore the landing
gear must be fuselage mounted. This is because, to mount the landing gear to a high wing
would require it to be of considerable length, thus making it heavier and causing it to be
subjected to greater stresses. So why lateral? The stability of a landing gear is based largely
on the wheel track, the distance between the two main landing gears. The governing factor
for the wheel track for fuselage mounted landing gear is the turnover angle. This is the angle
that the landing gear arm is at when measured from the horizontal. In order to get the
desired turnover angle, and subsequently the desired wheel track, the landing gear must
open laterally.

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5.3 FUNCTIONAL ANALYSIS

Figure 3 - Functional Analysis

A major step in the concept design process is the functional analysis (Figure 3). A functional
analysis provides a detailed overview of the interactions between components, and
between components and the environment and factors affecting them. This allows for
potentially harmful interactions to be noted and for alternatives or solutions to be sought. It
can also draw attention to areas where more interaction may be necessary or where the
components could be better configured and utilised to increase the efficiency of the system.

5.4 MATRIX SELECTION
Having derived four concepts for NLG and MLG using research and calculations it was then
necessary to choose one design for each to be carried forward onto the next stage of the
process. This was done using the matrix selection process. In this process a number of
design criterion are ranked by their importance in electing a concept to develop further.
This ranking is known as the ‘weighting factor’ and is taken out of 10. Each design is then
rated out of 10 for its fulfilment of these criteria, and these ratings are multiplied by the
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weighting factor to give a weighted score. These scores can then be summed to give a final
score, the highest of which is the winner and therefore the chosen design.
5.4.1 NOSE LANDING GEAR
Design A
Selection
Criteria

Design B

Design C

Design D

Weight
Factor
(/10)

Score
(/10)

Weighted
Score

Score
(/10)

Weighted
Score

Score
(/10)

Weighted
Score

Score
(/10)

Weighted
Score

10

8

80

10

100

6

60

8

80

10

4

40

10

100

4

40

10

100

8

9

72

8

64

7

56

6

48

8

9

72

7

56

8

64

5

40

Ease
of
Maintenance
Stowage Size

7

7

49

5

35

9

63

7

49

7

7

49

5

35

9

63

7

49

Cost

7

9

63

8

56

8

56

7

49

Simplicity
of
layout
Meet
Ergonomic
Requirements
Ease
Of
Manufacture
Ease
of
Disposal
Total Score

6

8

48

7

42

6

36

5

30

6

9

54

9

54

9

54

9

54

5

9

45

7

35

7

35

5

25

3

5

15

5

15

5

15

5

15

Fulfilment
Function
Safety

of

Efficiency
Operation
Weight

of

Rank

587

592

542

539

2nd

1st

3rd

4

th

Table 1- Matrix Selection: Nose Landing Gear

Design A
Design B
Design C
Design D
Cantilever/Single Cantilever/Dual Articulated/Single Articulated/Dual
Table 2 - Nose Landing Gear Concepts

From the four concepts for the Nose Landing Gear, Table 1 and Table 2 show that the
cantilever gear with the dual wheel configuration was selected as the best design to be
developed.
The main criteria which show the cantilever landing gear as the best option are its low cost
and weight. Since the nose landing gear presents no complications in retraction or
mounting, the superior stowage characteristics of the articulated landing gear are not
required.

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As for wheel choice, the safety of the landing gear is of paramount importance, and
research and calculations show that using a single wheel is not a viable option. It is unlikely
that the single wheel would be able to withstand the forces that it will subject too.
Regardless of that, in the event of the tyre becoming damaged there would be no backup
option, making this option too risky.
5.4.2 MAIN LANDING GEAR
Design A

Design B

Design C

Design D

Selection
Criteria

Weight
Factor (/10)

Score
(/10)

Weighted
Score

Score
(/10)

Weighted
Score

Score
(/10)

Weighted
Score

Score
(/10)

Weighted
Score

Fulfilment of
Function
Safety
Efficiency of
Operation
Weight
Ease
of
Maintenance
Stowage Size
Cost
Simplicity of
layout
Meet
Ergonomic
Requirements
Ease
Of
Manufacture
Ease
of
Disposal
Total Score

10

8

80

8

80

10

100

10

100

10
8

8
9

80
72

6
8

60
64

8
8

80
64

6
7

60
56

8
7

9
7

72
49

7
5

56
35

7
9

56
63

5
7

40
49

7
7
6

6
9
8

42
63
48

5
7
6

35
49
36

10
7
6

70
49
36

8
5
4

56
35
24

6

9

54

9

54

9

54

9

54

5

8

40

6

30

6

30

4

20

3

5

15

5

15

5

15

5

15

615

514

617

509

Rank
2nd
Table 3 - Matrix Selection: Main Landing Gear

3rd

1st

4th

Design A
Design B
Design C
Design D
Cantilever/Dual Cantilever/Tandem Articulated/Dual Articulated/Tandem
Table 4 - Main Landing Gear Concepts

From the four concepts for the Main Landing Gear, Table 3 and Table 4 show that the
articulated gear with the dual wheel configuration was selected as the best design to be
developed.
The two main areas of strength for the articulated gear are its ease of maintenance and
stowage size. In this application the most important aspect is the stowage size, since the
MLG must retract into a restricted space. In this type of landing gear the wheels can be
folded in towards the main strut, as opposed to the cantilever where the wheel is fixed in
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position. This allows the landing gear to occupy a smaller volume upon retraction, making it
an attractive option.
Similarly to the case with the NLG, the dual wheel configuration was chosen for its superior
safety. With the tandem wheels, should the front wheel become damaged the debris could
damage the rear wheel as it flies off, and should the rear wheel become damaged the plane
could become unbalanced.

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Volume
(m^3)

Material Cost (£)

Manufacutring Cost (£/kg)

Labour Cost at ### / hr

Cost / £

AL 7175

0.011848

29.92

5.50

60

912.83

300M

0.00093939

5.86

5.50

60

226.16

300M
300M
300M
300M
300M
AL 7175
AL 7175
AL 7175
300M
AL 7175

0.001614756
0.00053086
0.00169544
0.00043073
0.000444874
6.09525E-05
0.00055636
0.00057738
0.00190066
0.000783586

10.08
3.31
10.58
2.69
2.78
0.15
1.40
1.46
11.86
1.98

5.50

60
60
20
60
60
60
60
60
60
60

379.35
366.63
113.30
62.69
152.78
90.15
46.40
46.46
611.86
121.97

Title

Quantity

Part/Drawing No.

Manufacture Description

Material

Material Name

Nose Landing Gear
Trunnion

1

NLG-01

Drop forging and CNC Milling

Aluminium

Drag Strut Rod

1

NLG-02

Drop forging and CNC Milling

Steel

Drag Strut Brace
Torque Link
Axle
Towing Fitting
Actuator Mounting Plate
Steering Collar
Upper Steering Actuator Plate
Lower Steering Actuator Plate
Shock Strut (Absorber)
Steering Actuator Centre Plate
Drag Strut Assembly Actuator
Gear Actuation Cylinder
Steering Actuator Cylinder
Bearing - 61808
Bearing - 3210 A/2ZT9/MT33
Bearing - C6006 V
Bearing - K15x21x21
Bearing - 7202 BEGAP
Bearing - NU 202 ECP
Bearing - 32926

1
2
1
1
1
1
1
1
1
1
2
1
1
2
2
2
2
1
1
1

NLG-03
NLG-04
NLG-05
NLG-06
NLG-07
NLG-08
NLG-09
NLG-10
NLG-11
NLG-12

Drop forging and CNC Milling
CNC Milling
Drop forging and CNC Milling
CNC Milling
CNC Milling
CNC Milling
CNC Milling
CNC Milling
CNC Milling
CNC Milling

Steel
Steel
Steel
Steel
Steel
Aluminium
Aluminium
Aluminium
Steel
Aluminium

5.50

Details provided in section 8.3 of the report.
20% Added to total
cost to account for
Bearings

Outsourced Components

Manufactured Components

6 BILL OF MATERIALS AND COSTING

Outsourced
Components

Manufactured Components

3130.60
Main Landing Gear
Main strut
Trailing arm
Side Strut

2
2
2

MLG-01
MLG-02
MLG-03

Drop forging and CNC Milling
Drop forging and CNC Milling
Tubular Cut, Welding, CNC Milling

Aluminium
Aluminium
Aluminium

AL 7175
AL 7175
AL 7175

0.0228
0.006771435
0.002691994

57.57
17.10
6.80

5.50
5.50
5.94

60
60
60

2182.14
1180.41
273.55

Trailing Arm Axle
Main Strut Axle

2
2

MLG-04
MLG-05

Tubular Cut, Drilled Holes
Tubular Cut, Drilled Holes

Steel
Steel

300M
300M

0.000730027
0.002464437

4.56
15.38

1.96
2.80

20
20

61.43
168.40

Main Strut-Trailing Arm Link

2

MLG-06

Drop forging and CNC Milling

Titanium

Ti - 6AL - 6V - 2Sn

0.001131663

177.76

5.50

60

770.29

Shock Strut-Trailing Arm Link
Actuator Mounting Link

2
4

MLG-07
MLG-08

Drop forging and CNC Milling
Drop forging and CNC Milling

Titanium
Titanium

Ti - 6AL - 6V - 2Sn
Ti - 6AL - 6V - 2Sn

0.001791523
0.000475528

281.41
74.70

5.50
5.50

60
60

1009.53
824.81

Retraction Piston Mount
Side Strut Pin
Actuator-Main Strut Pin
Primary Retraction Piston
Secondary Retraction Piston
Shock Strut

4
2
4
2
2
2

MLG-09
MLG-10
MLG-11

CNC Milling
Tubular Cut, Welding, CNC Milling
Tubular Cut, Welding, CNC Milling

Aluminium
Titanium
Titanium

AL 7175
Ti - 6AL - 6V - 2Sn
Ti - 6AL - 6V - 2Sn

0.000485206
0.000771971
0.000408979

1.23
121.26
64.24

2.67
2.14

60
60
60

364.90
404.66
560.37

Bearings and Pins

Details provided in section 8.3 of the report.

20% Added to total cost to account for Bearings
7800.511614
Total Cost

13,117.33

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7 THEORETICAL ANALYSIS
7.1 HAND CALCULATIONS
In order to design a concept that will be practically viable hand calculations were done in
order to determine the positioning and sizing of the landing gears. These calculations were
done based on given design parameters which are shown in Table 5. Unless otherwise
stated, all constants used in formulae can be found in Table 5.
Design Parameters
Mass Limits:
Main LG =
Nose LG =
Wing Dimensions:
Wing Root Chord (CR) =
Wing Tip Chord (CT) =
Wing Span (B) =
Wing Sweep Angle (front) (SW) =
Mean Aerodynamic Chord (MAC) =
Wing leading edge aft to nose (WRD) =
Attachment Point of fuselage to MAC ratio
(A) =

370
90

kg
kg

2.746
0.994
17.05
11.6
2.007
9.22

m
m
m
deg
m
m

0.55

Velocity:
Aircraft decent Velocity =
Landing gear design velocity =

3.66
3.07

m/s
m/s

Weights:
Take-off weight (WTO) =
Landing Weight (WL) =
Empty Weight =

11600
11250
6880

kg
kg
kg

Centre of Gravity:
CG_aft =
CG_fwd =
CG_z1 (aft) =
CG_z2 (fwd) =

10.67
10.59
0.331
0.164

m
m
m
m

Other Parameters:
U=
W=

7.192
1.476

m
m

Table 5 - Design Parameters

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The first step in the design process was to determine the positioning of each landing gear
along the length of the plane. The first task was to determine the length between the nose
of the plane and the main landing. This calculation is shown in Equation 1 with the distance
denoted as X_MLG.
(

)

Equation 1 - Distance from Nose of Aircraft to MLG

This value is required in order to correctly position the NLG, as it affects the percentage load
which is carried by this gear. The positioning is done using Figure 4. The graph shows the
percentage load taken by the NLG depending on its distance from the MLG, known as the
wheel base. The choice of positioning relies on some compromise being reached, since
having too great a weight on the NLG will hinder its steering capabilities and having too little
could affect the balance of the aircraft. From Figure 4, it was decided that having the NLG
bear 12% of the load was a good compromise between steerability and balance of the
aircraft.

Wheel Base vs % Weight on NLG
18%
17%
16%
15%

% Weight on NLG

14%
13%
LM
CG_aft

12%
11%

LM
CG_fwd

10%
9%
8%
7%
6%
6

7

8

9
Wheel Base (m)

10

11

12

Figure 4 - Graph of Wheel Base vs % Weight on NLG

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Having determined the distance between the NLG and the MLG, the next step was to
determine the wheel track. Wheel track is the term used to describe the distance between
the two wheels of the MLG. This distance relies on the angle at which the MLG protrudes
from the fuselage. This is shown as angle ‘b’ in Figure 5 and it is recommended that this
angle between 55° as the figure shows. The wheel track itself is calculated using angle ‘a’,
shown highlighted in Figure 5. The formula for this is shown in Equation 2.
(

( ))

Equation 2 - Distance between the two wheels of the MLG (Wheel Track)

The final positioning dimensions for the landing gear are shown in Table 6.
Aft
Wheel Base (m)
Wheel Track (m)

Fwd
9.42
4.88

10.08
4.64

Table 6 - Dimensions for Landing Gear Positioning

Figure 5 - Determining Wheel Track

Once the positioning of the landing gear was confirmed, it was necessary to calculate the
required dimensions for the key components in the landing gears. The necessary size of each
part was related to the loading conditions to which it would be subjected. The calculations
for this were done using a number of stress analysis formulae which relate material
properties and forces applied in order to provide dimensions which will ensure that the
component is able to withstand the loads (Fellows, 2012).

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7.2 FINITE ELEMENT ANALYSIS
7.2.1 THEORY
Having completed the final concept design using parameters determined as described in
section 7.1, the model could then be validated using the finite element method. Finite
Element Analysis (FEA) is used in order to predict the behaviour of a model in response to
loads that it will be subjected to. FEA allows for model development to be carried out at low
cost and can result in the removal of unnecessary mass should it be determined that the
design would still retain sufficient strength properties without it.
FEA often provides an accurate approximation; however since it is a process that is
fundamentally based on certain assumptions there are inevitably errors. Generally the
prediction given by FEA is sufficient, but there are some cases where it is not. However,
since this project is purely conceptual the estimate provided by FEA will be considered as an
accurate approximation.
The accuracy of the simulation is highly dependent on correct application of initial boundary
conditions. In order for the program to provide a sufficient prediction, the model must be
constrained in the correct planes, the material properties adequately specified and the loads
applied correctly. The misinterpretation of the necessary boundary conditions will lead to
further erroneous and inaccurate prediction of results.
Another factor which influences the accuracy of the finite element method is the choice of
element size. FEA relies on nodes, which are discrete points on the model where response
will be predicted. From each individual node a full picture can be compiled, and thus a
prediction made on the part’s response to the loading conditions to which it is subjected. It
follows, therefore, that having a higher node density will result in a more accurate
simulation, and the number of nodes is dependent on the distance between each node,
known as the element size (Gerguri, 2013). In theory, having as small an element size as
possible will give the most accurate result since a finer mesh can more accurately follow a
curved geometry; however this is not always the case, since there is inevitably an eventual
limit to the accuracy of a computer simulation. To determine the point at which reducing the
element size will cause only an increase in work load and computational cost and not
accuracy, a mesh convergence graph is created. This graph is shown in Figure 6 and depicts
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the point at which decreasing the element size will no longer improve the simulation. This
allows for the optimum mesh to be created with the greatest accuracy, whilst not causing
unnecessary computing time and costs.

Mesh Convergence

9000
8000
7000
Max Stress Value, MPa

Element
Size/Max
Value

6000
5000
4000

Linear
(Element
Size/Max
Value)

3000
2000
1000
0
0

10

20
30
Element Size, mm

40

50

Figure 6 - Mesh Convergence graph for FEA

Figure 6 shows no clear point of convergence, which is due to an inability to reduce the
mesh size past 10mm. Upon using an 8mm element size, the software was unable to create
the mesh on the ‘main strut’. This is because the part is large, and using that small an
element size will result in too large a mesh for the software. A comparison with Figure 7
shows that the increase in maximum stress value which results from elements smaller than
14 mm coincides with a dramatic rise in solving time. Therefore, in order to avoid
unnecessary computing time and costs, the chosen element size will be larger than 14mm.
Figure 6 shows a low gradient section of the graph between 20mm and 14mm, and so the
element size to be used will be taken from this range. Plotting a line of best fit on this graph
shows the average through the mesh convergence, and determines that the optimum mesh
for use in the FE Analysis is 17mm. It should be noted that the mesh convergence and
computational time testing was carried out on a preliminary model, and therefore the actual
computational time for the final model was significantly greater than 3 minutes.

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Meshing and Solving Time for Varying Element
Sizes

250

Time, seconds

200

150
Mesh Time
100

Solve Time

50

0
0

10

20

30

40

50

Element Size, mm
Figure 7 - Solving time for Element Sizes in Mesh Convergence

7.2.2 APPLICATION
Having concluded on the optimum mesh size for use in the FEA, it now had to be applied.
Once the chosen mesh size has been applied, it is then possible to use the mesh control
feature to reduce the mesh size in areas where this is required. The use of mesh control can
be due to a confined geometry, where a part is particularly small and simply requires a
proportionally smaller element size, or it can be used to gain more accurate results for a
crucial area of the model where there is greater interest in the behaviour caused by the
applied loading conditions. In the case of mesh control, Solidworks will use a growth ratio to
control the transition between the standard mesh and the refined mesh, known as the
element size growth ratio. Figure 8 shows the MLG with the mesh applied.

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Figure 8 - CAD Model of MLG with mesh applied

With the mesh applied, the model was then constrained, replicating the fuselage mounting
conditions. An example is given in Figure 9, which shows an example of boundary conditions
applied to the NLG (represented by the green arrows).
In order for an accurate simulation to be produced each part was then assigned the material
that it was expected to be manufactured from. This allows for the simulation to take into
account material properties which are essential to the prediction. Following this application
of materials, the bearing load must be specified. A bearing load is a predefined
representation of the interaction between the model and the forces which it will encounter.
Bearing loads develop between contacting cylindrical faces and it is crucial that the faces
which interrelate are specified to ensure that the simulation correctly represents the
actuality of an aircraft landing on a tarmac runway. The bearing loads applied to the NLG are
shown in Figure 10.

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Figure 9 - Boundary Conditions applied to NLG for FEA

Figure 10 - Bearing Loads applied to NLG for FEA

Once the model has been fully defined in this way, a solution can then be run under static
conditions. The simulation produces a von Mises stress distribution which indicates areas of
high stress concentration or component failure in conjunction with the predefined material
yield stresses (Figure 11). This allows for alterations to be made to the model where
necessary. Modifications could include removing unnecessary material from an area of low
stress, adding more material to an area of high stress, or even changing the material of a
component to one with more suitable properties for the loads encountered.

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Figure 11 - Von Mises Stress obtained through static testing on the NLG

Once a finalised model has been developed using the information obtained in the static
simulation, fatigue analysis can be run. Fatigue analysis is the process by which FEA can
determine how many cycles the model will be able to go through before it fails when
exposed to a cyclic load. Due to imperfections in the software, the prediction given by
Solidworks is a gross overestimation. To overcome this issue it is suggested that the values
given by the simulation are halved to give a more realistic forecast (Gerguri, 2013). An
example of a fatigue test is shown in Figure 12.

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Figure 12 - Total life cycles for NLG from fatigue analysis

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8 FINAL DESIGN
8.1 NOSE LANDING GEAR
In Chapter 7 it was shown that the NLG is to bear 12% of the loads that the aircraft is
subjected to. This relatively low loading condition can be exploited to enable the landing
gear to be made lighter. As discussed in Chapter 5, this weight saving potential is aided by
the fact that the NLG is able to simply retract forwards into the nose of the plane with no
major complications. This meant that a simple cantilever landing gear design could be used
for NLG, a design renowned for its low cost and weight characteristics as well as its relative
simplicity.

Figure 13 - CAD Model of the NLG fully deployed

Figure 13 conveys the simplicity of the NLG model. The cantilever design consists of a
parallel trunnion and shock absorber which reduces the number of moving parts, simplifying
the design and therefore decreasing the cost.
As previously discussed, the main function of the NLG is to balance the aircraft and provide it
with the ability to steer when the plane is grounded. The steering is controlled by the torque
link, which is attached to the steering actuator cylinder. Having the actuator attached to the
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trunnion ensures that the wheels are not able to turn independently of the rest of the
landing gear, avoiding issues in landing which could subsequently occur as evidenced in
Figure 14.

Figure 14 - Example of an aircraft NLG failing to deploy correctly
(http://www.airlinesafety.com/editorials/JetBlueLAX.htm)

One of the major design specifications for the NLG was the stowage space, which was to be
1

, as specified in the Product Design Specification (Chapter 4). As was explained in

Chapter 5 the NLG is able to make use of forward retraction, which is the ideal case. Since
the landing gear will be withdrawing in only one plane of motion, directly into the nose of
the aircraft, the mechanism used to actuate this motion need only be simple. Figure 15
shows the NLG mid-retraction and clearly shows the ease with which the mechanism draws
it into its designated stowage space, into which it fits as required (Figure 16).

Figure 16 - CAD Model of the NLG fully retracted
Figure 15 - CAD Model of the NLG mid-retraction

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Another major consideration for the design of the NLG is its weight. The target weight
defined in the PDS was 90 kg; however the final design was unable to match this
requirement. The final model of the NLG has a weight of 130 kg. However, Figure 17 shows
that the FEA expects this landing gear to last for 500,000 cycles (taking into account the
overestimation of Solidworks), which is 50 times the number of cycles required in the PDS.
Therefore it can be said that the NLG would be capable of meeting both the requirement for
10,000 landings and the weight specification, however the design time was not adequate for
this possibility to be realised. It would have been possible to trim the wall thicknesses of the
NLG, simultaneously reducing the weight and total life of the landing, thus eventually
arriving at an instance where the landing gear weighs the specified 90 kg, and is still capable
of fulfilling a life of 10,000 landings.

Figure 17 - Life Cycle Fatigue Analysis for NLG

A crucial area of engineering design, as discussed in Chapter 3, is material selection.
Materials provide the characteristics of strength and durability which most directly influence
the behaviour of the landing gear design. One of the main materials currently used in aircraft
landing gears is 300M steel, and the design process was such that initially all components
were assigned this material. It was then a case of finding the optimum compromise between
weight, cost and combination of material properties to provide the desired load bearing
capabilities and fatigue life. This has resulted in the NLG being comprised of steel
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components and aluminium components, as well as bearings and other small parts made
from titanium. Titanium could not be used extensively due to its incredibly high cost, which
is 35 times that of aluminium. The suitability of the bearings used is outlined in Appendix 2
of this report.
Relating to the material choice is the manufacturing process used to produce the
component. The PDS states that all components that required forming should be forged. This
will be done using a process known as drop forging, which is a process specifically used for
shaping metals. Forging is a process that allows for large parts to be made with superior
mechanical properties than would be provided by a casting (Engineering Student, 2011). All
other parts will either cut to shape or milled in a CNC machine.
Another important factor for consideration is the aforementioned ability to withstand the
loads that the landing gear will be subjected to in the process of landing. It has already been
mentioned that the NLG is forecast to last for 500,000 landings, but it is important to
consider the stresses applied at each landing. Figure 18 shows clearly that the landing gear
did not fail under the load applied to represent the plane landing. It can be seen from Figure
18 that at no point do the stresses in the NLG reach its yield strength, which is 455 MPa. This
evidence, coupled with the fatigue study results evidences the fact that the NLG has been
over-engineered, and could be made to be within the weight specification were it
appropriately designed.

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Figure 18 - Stress results for landing conditions for NLG

A final area of interest from the FEA results which further confirms the fact that the NLG has
been over-engineered, is the deformation caused to the landing gear when the aircraft
touches down on the runway. Figure 19 show the
FEA results for the deflection of the NLG, and shows
that the maximum deflection that occurs is just
0.000048989 mm which is evidently well below any
value which need cause concern, thus confirming
that a reduction in wall thickness to reduce weight
would be perfectly justified.

Figure 19 - Deflection results from FEA for the NLG

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8.2 MAIN LANDING GEAR
The MLG presents a more complex design task than the NLG. As discussed in Chapter 5 the
MLG must be fuselage mounted, but must also have the necessary track width for the
aircraft to operate as required. This means that the MLG cannot simply retract forwards, but
must also have some facility for lateral movement. This means that a more complex design
with more moving parts is required. As such it is necessary for the landing gear to be able to
fold into a smaller relative volume than the NLG. This requires that an articulated style
landing gear be used, as discussed in Chapter 5.

Figure 20 - Evidence that the MLG is unable to fit in the designated stowage space within the fuselage

As with the NLG, the specification for stowage space given in Chapter 4 is a key factor for
consideration in the design of the MLG. Section 11.0 of the PDS stipulates that the stowage
space provided inside the fuselage for the MLG is 3.5

. It was known prior to designing the

landing gear that fitting the landing gear into this space was a task that had never previously been
achieved, and this proved to be the case for this design, as is evidenced in Figure 20 . To overcome
this issue, it was necessary to create a bulge in the aircraft fuselage, which is shown in Figure 21 .
This will inevitably have an adverse effect on the drag forces experience by the aircraft, however the
possibility of streamlining the bulge makes it a preferably option in comparison to having the landing
gear protruding. The primary cause of the MLG being unable to fit in the allowed stowage space is

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the tyres. The tyres chosen are too large to fit inside the fuselage, however the smaller tyre option
would be unable to withstand the required loads on landing, and so a compromise between size and
performance was required.

Figure 21 - CAD Model showing the bulge created to house the retracted MLG

Weight is also an important aspect of the PDS, and every attempt must be made to adhere
to the specified weight of the landing gear. The proposed weight for the MLG is 370 kg for
both sides. This means that each side should weigh no more than 185 kg. The landing gear
design shown in Figure 22 weighs a total of 186 kg, which is only 1 kg more than the PDS
allows, showing that a very efficient design has been produced for the MLG. This does not
however include the weight of bearings and other small parts which are to be purchased. To
account for this approximately 10% should added to the overall to ensure that there is not
an under estimation. This makes the approximate weight of each MLG 203 kg. Figure 23
shows that, as was the case with the NLG, there is a degree of over-engineering in this
landing gear which is likely to be the cause of the extra weight.

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Figure 22 - CAD Model of the MLG fully deployed

Despite Figure 23 depicting that the majority of the MLG will last for 500,000 landings (again
taking into account the overestimation given by Solidworks) there are some areas of the
landing gear that demonstrate an increased rate of fatigue. This is due to the necessity to
model a shock strut and bearings for the sake of the FE Analysis, whilst in reality these
components will be outsourced. On top of this it can be reasonably assumed that the shock
absorber will absorb all of the energy of landing (Chartier et al, n.d.). However, in FE Analysis
there is only a capability to treat the shock absorber as a rigid body, which in actuality it is
not. As a result the FEA results showed the stress experienced to 80% greater than the yield
strength of the model. Based on the aforementioned assumption on the absorption of the
shock strut, it can be expected that this component absorb this excess stress. To account for
this in the simulation 20% of the actual load was applied to the rigid body model. Since the
shock absorber is to be purchased, rather than manufactured, it is already known that it is
able to withstand the required loads from the figures provided by the manufacturer from
which they will be sourced. This is also evidenced by Figure 24, which shows the same areas
of supposed weakness under static loading conditions. Outside of these areas, the majority
of the landing gear is shown to operate well below the yield strength at the applied bearing
loads of 60 kN and braking torque of 3.6kNm, which are shown in Figure 25.

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Figure 23 - Fatigue study results for MLG

Similarly to the NLG, the major material of use in the MLG is 300M steel, replaced with
aluminium where possible to save weight whilst retaining strength, and making used of
titanium bearings and links. As with the NLG all components will be manufacturing using the
drop forging technique where necessary, otherwise by cutting and milling processes.

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Figure 24 - Overall von Mises stress results for MLG

Figure 25 - Bearing Load and Braking Torque applied to MLG

Figure 26 shows the results for the delfection of the MLG upon landing, and as with the NLG
there is no cause for concern in this area. The maximum deformation is 40mm which, whilst
much more noticable than the deflection of the NLG, is still not a value which will effect the
landing gear’s ability to function as required.

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Figure 26 - Deflection of the MLG from FEA

8.3 COSTING
As is the case with any design project, there is a budget to adhere to. Chapter 4 states that
the design project is permitted to cost no more than £20,000. Cost is one of the most
important parts of the PDS, and there is minimal tolerance for over spending in industry.
Whilst marginally failing to adhere to specifications such as weight will cause problems,
compromises can be made to either overcome this or convince the customer that there is no
alternative. In the case of the budget, it is simply not possible to increase the funds available.
Money is a finite resource, which means that fiscal responsibility is of paramount importance
in any design project.
An issue that was encountered in budgeting is the difficulty of obtaining prices for bearings.
Since bearings costs are not readily available from suppliers, 20% has been added to the
total cost to adequately account for them.
A similar issue occurred with the other parts that are to be outsourced. A number of
companies were contacted requesting quotes, however only one reply was received. Canada
Aircraft provided a quote for an actuator at approximately £20,000 for one. This value is the
entire budget for this project; however this actuator if for an executive aircraft and therefore
the cost of parts is well above what would be expected in a commercial aircraft. Full details
of the quote received can be found in Appendix 2. The result of this enquiry therefore, is
that no specific costs could be found for the actuators that are to be outsourced. However
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the Bill of Materials found in Chapter 6 shows that there is £6882 remaining with which to
purchase the remaining parts. It is reasonable to assume that, for the application that is
required of them, these parts could be sourced within budget.
As detailed in the Bill of Materials, all other parts are to be manufactured in-house and
approximate costs for the full process of developing these components are provided.

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9 CONCLUSION
The aim of this project was to conceptually design the landing gear for a small commercial
aircraft. A number of options were to be considered for both the Nose Landing Gear and the
Main Landing Gear, and one concept taken forward for each to CAD modelling and Finite
Element Analysis.
The first task was to produce a Project Plan. In generating this document, a greater
understanding of the industry was gained. A Product Design Specification was published
using the criterion provided, and through extensive research into the subject area both the
current basis for aircraft landing gear design and the importance of this area of study were
uncovered.
It was found that the two most common types of landing gear in current use are the
cantilever landing gear and the articulated landing gear. As with all engineering solutions
both of these options have advantages and disadvantages, and having become familiar with
these landing gear types it was necessary to determine how their characteristics might
benefit the aircraft in question.
The cantilever landing gear type is a simple option, in which the main strut and the shock
absorber are aligned to operate as one continuous part. This option is particularly renowned
for its cost and weight efficiency.
The articulated landing gear type is a more complex option, in which the shock strut is offaxis. This allows for the landing gear to retract more tightly, which a useful feature where
stowage space is limited.
Alongside the landing gear design itself in design considerations, is the wheel configuration
to be used. For the small aircraft in question it would be unnecessary to use more than two
wheels on any single landing gear. Therefore the options considered for wheel configuration
were; single, dual and tandem.
Having determined the key features of the landing gear for discussion, the requirements for
each of the NLG and MLG were considered, and an initial set of concepts sketched. These
concepts were then put through a matrix selection process in order to conclude on the ideal
option for each landing gear.
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It was determined that for the NLG, a cantilever landing gear would be used with dual
wheels, and for the MLG an articulate landing gear would also be coupled with dual wheels.
With the landing gear concepts chosen, they would now be taken forward to the design
stage. In this stage calculations were done to determine positioning on the aircraft and sizing
of components and CAD models were then produced for each concept. Following this, FEA
was run on these models to determine their adherence to the specified performance and
design criterion.
For the NLG, the FEA evidenced that the landing gear was over-engineered. It was
determined to be capable of lasting 50 times as long as required, and withstanding far
greater forces than necessary. The disadvantage of this apparently exceptional design was
the weight, which was found to be 40 kg greater than specified in the PDS. It is believed
however, that the required weight saving could be achieved through the reduction in wall
thickness of some components whilst remaining able to withstand the mandatory 10,000
landings. The NLG was also found to fit the stowage space provided with ease, whilst making
use of the optimum retraction method of forward retraction, as discussed in Chapter 3.
For the MLG, it was found that over-engineering had not occurred to the same extent as
with the NLG. There was only a slight discrepancy in the landing gear weight, and it also was
able to withstand the required loading conditions and number of landings that was specified.
With regard to the stowage space of the MLG, the size of tyre required to withstand the
loads applied during landing caused the landing gear to be unable to fit into the designated
space within the fuselage. As a result it was necessary to create a bulge in the aircraft
fuselage. Due to the need to mount the MLG to the fuselage, but also have a great enough
track width, this landing gear could not merely retract forwards, but was also required to
move in the lateral plane.
One of the most important aspects of any project in the current economic climate is the
budget, which for this project was £20,000. This budget was diligently adhered to
throughout the project and as a result no loss has been incurred on this project. In fact, were
the possibility of removing material from the NLG realised, the cost of this design could have
been further reduced.

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Figure 27 and Figure 28 show the final designs the NLG and MLG respectively.

Figure 27 - Final design of the NLG, fully deployed

Figure 28 - Final design of the MLG, fully retracted

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In general this project ran smoothly. The group aspect of this task was fully exploited and all
team members’ strengths made full use of. This allowed for the project to run with a high
degree of efficiency, with all tasks completed well.
With final concepts chosen in Semester 1, Semester 2 could be fully devoted to the tasks of
modelling and simulation. This diligence in time keeping allowed for the CAD models to be
created with care, significantly reducing the possibility of errors occurring.
Were this project to be continued, the NLG could be improved as discussed. The main issue
with the MLG is that it fails to fit in the designated stowage space. This issue is one that
could not be easily rectified given any time constraint, or lack thereof.
The landing gear forms a vital intermediary between the aircraft and catastrophe, and it can
be firmly predicted that the designs detailed in this report would fulfil this task should they
be taken forward to manufacture.

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10 REFERENCES
Airline Safety. (2013). Image. [Online]. Availably at:
http://www.airlinesafety.com/editorials/JetBlueLAX.htm
Berry, P. (1999). Landing Gear Design in the Conceptual Design Phase, Paper 5, SAE Technical
Paper 1999-01-5523, doi:10.4271/1999-01-5523.
Bruhn, E.F. (1973). Analysis and design of flight vehicle structures. Jacobs: Indianapolis.
Chartier, B., Tuohy, B., Retallack, J., Tennant, S. (n.d.) Research Project: Landing Gear Shock
Absorber. S.I. : s.n. [Online] Available at: ftp://ftp.uniduisburg.de/FlightGear/Docs/Landing_Gear_Shock_Absorber.pdf
Currey, N.S. (1988). Aircraft landing gear design: principles and practices. AIAA: Washington
D.C.
Elsaie, A. and Santillan, R. (1987). Structural Optimization of Landing Gears Using
STARSTRUC, SAE Technical Paper 871047, doi:10.4271/871047.
Engineering Student. (2011). Drop Forging – Closed Die (Impression Die). Available at:
http://www.engineerstudent.co.uk/closed_die_drop_forging.html
Fellows, N. (2012). Stress Analysis 2 Module Handbook. Oxford Brookes University : Oxford.
Gerguri, S. (2013). Group Design FEA 2013. Oxford Brookes University : Oxford.
Kermode, A. C., Barnard D. R., Philpott, D. R (eds.) (date). Mechanics of Flight. 10th ed.
[location: publisher]
McCosh, D. (1971). Structural Considerations of Steel Landing Gear Springs, SAE Technical
Paper 710400, doi:10.4271/710400.
Niu, M. C. Y. (2002). Aircraft Structural Design. 2nd ed. Hong Kong: Hong Kong Conmilit Press
LTD.
Pink, J. (1995). Structural Integrity of Landing Gears, SAE Technical Paper 952021,
doi10.4271952021.
Serey, J-P. (2005). Trends in landing gear material. SAE 100 Future Look. Pp 46. [Online].
Available at: www.sae.org/aeromag/features/futurelook/09-2005/2-25-8-46.pdf (Accessed:
26 April 2013).
Young, D.W. (1986). Aircraft Landing Gears – The Past, Present and Future. IMechE Paper
864752.

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11 BIBLIOGRAPHY
British Standards. (n.d.). ISO metric threads, Part 1: Principles and Basic Data. BS 36431:2007. S.I : s.n.
Code 7700. (2013). Landing Gear Uplocks/Downlocks. Available at: http://code7700.com/g450_landing_gear_uplocks_downlocks.html
SSPCA. (2013). Side Brace Actuator Quote. Available at: http://www.sppca.com/products/business.html

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12 APPENDIX
12.1 APPENDIX 1: MEETING MINUTES
Document Reference: Meeting 1

GDP:

COMPANY NAME: Absolute Aviation
Group Meeting:
Day: Wednesday

Date: 31/10/12

Room: Sports Bar

Attendees:

Apologies:

Stephen Fraser

Samuel Goodchild

Jonathan Langer

Matthew Soul

Jack Lawlor-Anderson

Robert Swallow

Meeting Objective: Run through and research general landing gear designs and beginning of
concepts
1

2

Action:

AGENDA


Design Concepts



Research into existing concepts



Discussion on different solutions to current problems on landing gear.

Actions from previous minutes
N/A

3

4

Actions (e.g. relate to AGENDA items)


Concept drawn up for critical analysis



Existing concepts analysed and discuss



Forward retracting gears discussed



Matrix Selection method discussed



Tyre Configuration discussed

A.O.B




5

Discussed actuator mechanism
Simplicity of retraction design
Lightweighting concepts/possibilities

Date and Time of next meeting

Print Name:

Sign:

Date:
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Document Reference: Meeting 2

GDP:

COMPANY NAME: Absolute Aviation
Group Meeting:
Day: Monday

Date: 5/11/2012

Attendees:

Room: WHT/LIB 2

Apologies:

Stephen Fraser

Jonathan Langer

Samuel Goodchild

Jack Lawlor-Anderson

Matthew Soul
Robert Swallow
Meeting Objective: Decide/Discuss concepts – retraction method, tyre configuration
1

2

3

4

Action:

AGENDA


Discuss retraction



Discuss wheel configuration



Discuss all above in relation to turnover angle

Actions from previous minutes


New meeting arranged



Preliminary concept drawn up



Forward retracting MLG not feasible

Actions (e.g. relate to AGENDA items)


Forward retracting MLG cannot be achieved to get required turnover angle



Concepts for MLG decided



Have concepts drawn up by next meeting

A.O.B
N/A

5

Date and Time of next meeting

Print Name:

Sign:

Date:

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Document Reference: Meeting 3

GDP:

COMPANY NAME: Absolute Aviation
Group Meeting:
Day: Monday

Date: 12/11/12

Attendees:

Room: WHT/LIB 2
Apologies:

Stephen Fraser
Samuel Goodchild
Jonathan Langer
Jack Lawlor-Anderson
Matthew Soul
Robert Swallow
Meeting Objective: Review concept sketches and discuss theoretical validation
1

2

AGENDA


Compare concept sketches



Discuss pros and cons



Discuss calculations

Actions from previous minutes


3

4

Action:

MLG concepts drawn up

Actions (e.g. relate to AGENDA items)


Use matrix selection to determine which concept to take forward



Calculate turnover angle and % weight on NLG

A.O.B
N/A

5

Date and Time of next meeting

Print Name:

Sign:

Date:

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Document Reference: Meeting 4

GDP:

COMPANY NAME: Absolute Aviation
Group Meeting:
Day: Monday
Attendees:

Date: 19/11/12
Room: WHT/LIB 3
Apologies:

Stephen Fraser
Samuel Goodchild
Jonathan Langer
Jack Lawlor-Anderson
Matthew Soul
Robert Swallow
Meeting Objective: Confirm MLG and NLG concepts chosen
1

2

3

4

AGENDA


Review matrix selection



Discuss criterion and scoring



Finalise concepts for MLG and NLG

Actions from previous minutes


Turnover angle, & weight on NLG and any other calculations completed



Matrix selection completed

Actions (e.g. relate to AGENDA items)


MLG concept chosen – Articulated with Dual Wheels



NLG concept chosen – Cantilever with Dual Wheels

A.O.B


5

Action:

Discuss who may be prepared to give presentation (SF, RS, JLA & JL all willing).

Date and Time of next meeting

Print Name:

Sign:

Date:

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Document Reference: Meeting 5

GDP:

COMPANY NAME: Absolute Aviation
Group Meeting:
Day: Monday
Attendees:

Date: 26/11/12

Room: WHT/LIB 2
Apologies:

Stephen Fraser
Samuel Goodchild
Jonathan Langer
Jack Lawlor-Anderson
Matthew Soul
Robert Swallow
Meeting Objective: Final detailed sketches of concepts
1

2

AGENDA


Assign task of sketching



Decide who will present



Plan what to present

Actions from previous minutes


3

4

Concepts chosen

Actions (e.g. relate to AGENDA items)


JL to sketch final concepts



SF & BS to do presentation



All to attend presentation requirements lecture this evening

A.O.B


5

Action:

JLa to create functional analysis

Date and Time of next meeting

Print Name:

Sign:

Date:

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Document Reference: Meeting 6

GDP:

COMPANY NAME: Absolute Aviation
Group Meeting:
Day: Monday
Attendees:

Date: 3/12/12

Room: WHT/LIB 1
Apologies:

Stephen Fraser
Samuel Goodchild
Jonathan Langer
Jack Lawlor-Anderson
Matthew Soul
Robert Swallow
Meeting Objective: Prepare slideshow for presentation
1

AGENDA


2

3

4

Action:

Compile all required information into powerpoint for presentation

Actions from previous minutes


Final concept sketches present



Lecture on presentation requirements attended last Monday

Actions (e.g. relate to AGENDA items)


Ensure all required information is present in slideshow



Begin to compile presentation script for RS and SF to learn

A.O.B
N/A

5

Date and Time of next meeting

Print Name:

Sign:

Date:

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Document Reference: Meeting 7

GDP:

COMPANY NAME: Absolute Aviation
Group Meeting:
Day: Monday
Attendees:

Date: 10/12/12

Room: WHT/LIB 2
Apologies:

Stephen Fraser
Samuel Goodchild
Jonathan Langer
Jack Lawlor-Anderson
Matthew Soul
Robert Swallow
Meeting Objective: Practice Presentation
1

2

AGENDA


RS and SF to practice presentation



Others to take notes of issues, write script etc.

Actions from previous minutes


3

4

Action:

Have presentation powerpoint ready

Actions (e.g. relate to AGENDA items)


BS and SF to present this evening



Day spent practicing to avoid mistakes!

A.O.B
N/A

5

Date and Time of next meeting

Print Name:

Sign:

Date:

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Document Reference: Meeting 8

GDP:

COMPANY NAME: Absolute Aviation
Group Meeting:
Day: Monday
Attendees:

Date: 4/02/13

Room: WHT/LIB 3
Apologies:

Stephen Fraser
Samuel Goodchild
Jonathan Langer
Jack Lawlor-Anderson
Matthew Soul
Robert Swallow
Meeting Objective: Assign tasks for work towards final report
1

2

AGENDA


Discuss work required this semester



Assign tasks

Actions from previous minutes


3

4

Action:

Review presentation grades

Actions (e.g. relate to AGENDA items)


JLa to work chiefly on the NLG



MS to initially clear up any errors in hand calculations which came to light in presentation



SG and RS to work chiefly on MLG



JL to finalise design for retraction



SF to begin working on compiling report

A.O.B

N/A
5

Date and Time of next meeting

Print Name:

Sign:

Date:

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Document Reference: Meeting 9

GDP:

COMPANY NAME: Absolute Aviation
Group Meeting:
Day: Monday
Attendees:

Date: 11/02/13

Room: WHT/LIB 1
Apologies:

Stephen Fraser
Samuel Goodchild
Jonathan Langer
Jack Lawlor-Anderson
Matthew Soul
Robert Swallow
Meeting Objective: Ensure work is continuing as required
1

AGENDA


2

3

4

Action:

Overview what has been achieved in the past week

Actions from previous minutes


Hand Calculations should now be correct



A final report document has been created, project plan sections inserted

Actions (e.g. relate to AGENDA items)


Project plan sections to be expanded and depth added for final report



New hand calculations to be used to take forward concepts

A.O.B

N/A
5

Date and Time of next meeting

Print Name:

Sign:

Date:

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Document Reference: Meeting 10

GDP:

COMPANY NAME: Absolute Aviation
Group Meeting:
Day: Monday
Attendees:

Date: 18/02/13

Room: WHT/LIB 3
Apologies:

Stephen Fraser
Samuel Goodchild
Jonathan Langer
Jack Lawlor-Anderson
Matthew Soul
Robert Swallow
Meeting Objective: Ensure work is continuing as required
1

AGENDA


2

3

4

Action:

Check progress in all areas

Actions from previous minutes


Final report beginning to take shape



Concepts ready to begin being modeled

Actions (e.g. relate to AGENDA items)


Attend lecture of FEA



Continue work

A.O.B

N/A
5

Date and Time of next meeting

Print Name:

Sign:

Date:
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Document Reference: Meeting 11

GDP:

COMPANY NAME: Absolute Aviation
Group Meeting:
Day: Monday
Attendees:

Date: 25/02/13

Room: WHT/LIB 2
Apologies:

Stephen Fraser
Samuel Goodchild
Jonathan Langer
Jack Lawlor-Anderson
Matthew Soul
Robert Swallow
Meeting Objective: Make a big step on CAD modeling
1

2

AGENDA


Ensure all work is continuing to plan



Discuss putting particular emphasis on CAD modeling

Actions from previous minutes


3

4

Action:

FEA process is now known

Actions (e.g. relate to AGENDA items)


Make some headway with CAD modeling



Informal meetings to be held to further work, fewer formal meetings

A.O.B

N/A
5

Date and Time of next meeting

Print Name:

Sign:

Date:
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12.2 APPENDIX 2: OTHER USEFUL DOCUMENTS
12.2.1 QUOTE FROM SPP CANADA AIRCRAFT, INC

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12.2.2 SPECIFICATIONS OF BEARINGS USED
Bearings which are only subjected to force whilst stationary have be specified to bearing
static load conditions

Top of the side strut - http://www.skf.com/uk/products/bearings-units-housings/sphericalplain-bearings-bushings-rod-ends/radial-spherical-plain-bearings-requiringmaintenance/steel-onsteel/index.html?prodid=183025006&imperial=false&[email protected]
4 X lower trail arm link bearings - http://www.skf.com/uk/products/bearings-unitshousings/roller-bearings/tapered-roller-bearings/singlerow/index.html?prodid=1310002010&imperial=false&[email protected]#
Pin bearing for the side strut - http://www.skf.com/uk/products/bearings-unitshousings/roller-bearings/carb-toroidal-roller-bearings/cylindrical-boresealed/index.html?prodid=1580576910&imperial=false&[email protected]
Top of trail arm link 2x - http://www.skf.com/uk/products/bearings-units-housings/rollerbearings/tapered-roller-bearings/singlerow/index.html?prodid=1310002008&imperial=false&[email protected]
Spherical top of shock - http://www.skf.com/uk/products/bearings-units-housings/sphericalplain-bearings-bushings-rod-ends/radial-spherical-plain-bearings-requiringmaintenance/steel-onsteel/index.html?prodid=183011012&imperial=false&[email protected]
5 in a row -KP49BS – bottom and top of shock to trailing arm link - http://www.aircraftbearing.com/kpbsseries.html
For all static retraction loads - http://www.skf.com/uk/products/bearings-unitshousings/roller-bearings/carb-toroidal-roller-bearings/cylindrical-and-taperedbore/index.html?prodid=1580076908&imperial=false&[email protected]
Main strut to fuselage bearings - http://www.skf.com/uk/products/bearings-unitshousings/roller-bearings/tapered-roller-bearings/singlerow/index.html?prodid=1310002920&imperial=false&[email protected]#

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12.3 APPENDIX 3: ENGINEERING DRAWINGS

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PROJECTION

Drawing No: 1a

3.2

C

0.025 A

1740
80

R50

80

3.2

120

40
85

3.2

0.025 A

0.025 A

100

170

A

5

205

100
50

11

DETAIL C
SCALE 1 : 5

0
62 -0.013

0.2

50

25

0.2

0
140 -0.018

0.025 A

R20

40

B

0.2

0

DETAIL E
SCALE 1 : 5

0.025 A

180
FACULTY OF TECHNOLOGY

3.2

25

DETAIL D
SCALE 1 : 5

3.2

70
°

SolidWorks Student Edition.
For Academic Use Only.

55

0
99.75 -0.018

55

200

0.025 A

3.2

200

0.025 A

Unspecified Radii = 40mm

43°

D

3.2

783.5

40

3.2

20

795
145

E

0
62 -0.013

0.025 B

25
55

R51

25

3.2

SCALE: 1:10

Drawn by: MS

DIMENSIONS IN mm Date: 27/04/2013
TOLERANCE UNLESS
STATED
0 0.5
0.0 0.25
0.00 0.10

OXFORD BROOKES UNIVERSITY
TITLE: Main Strut

Checked by: SG
Approved by: JL
MATERIAL: Aluminium - AL7175
FINISH: Shot Peened

A3
Part No. AS13-MLG-01
Sheet 1 of 25

PROJECTION

Drawing No: 1b

R65

0

20

0
20

R40

R65

3.2

200

200

0.025 A
150mm Loft between sketches

180, 1732.5mm deep

M

200

DETAIL B
SCALE 1 : 5

100mm Loft between sketches

DETAIL C
SCALE 1 : 5

400

B
C

290

SolidWorks Student Edition.
For Academic Use Only.

Unspecified Radii = 40mm

FACULTY OF TECHNOLOGY

40
3.2

0.025 C

Perpendicular to Break-out Section M

40

290

3.2

60

80

3.2

200

0.025 A

R60

C

Parrallel to Break-out Section M

SCALE: 1:10

Drawn by: MS

DIMENSIONS IN mm Date: 27/04/2013
TOLERANCE UNLESS
STATED
0 0.5
0.0 0.25
0.00 0.10

OXFORD BROOKES UNIVERSITY
TITLE: Main Strut

Checked by: JLA
Approved by: SF
MATERIAL: Aluminium - AL7175
FINISH: Shot Peened

A3
Part No. AS13-MLG-01
Sheet 2 of 25

PROJECTION

70

Drawing No: 2a

40

135

0.025 A

80

170

3.2

40

3.2

2X

20

0.025 A

0.025 A

120

0.025 A

3.2

3.2

R20

40

0
77.788 -0.013

30

290

R60

2 X R30

0.025 A

2 X R10

0.025 A

221.11
75

30

0.2

72

78°

165.58

65.58

47.

30

A
R108

DETAIL A
SCALE 1 : 2

0.025 A

R60
0.2

0.025 A

0
80
0.015Student
SolidWorks

Edition.
For Academic Use Only.

Unspecified Radii = 10mm

FACULTY OF TECHNOLOGY

515

A
0.2

0
79.75 -0.013

SCALE: 1:5

Drawn by: MS

DIMENSIONS IN mm Date: 27/04/2013
TOLERANCE UNLESS
STATED
0 0.5
0.0 0.25
0.00 0.10

OXFORD BROOKES UNIVERSITY
TITLE: Trailing Arm

Checked by: SF
Approved by: JLA
MATERIAL: Aluminium - AL7175
FINISH: Shot Peened

A3
Part No. AS13-MLG-02
Sheet 3 of 25

PROJECTION

Drawing No: 2b

160
120

25

12

0

25

R10

B

3.2

0.025 A

220

40mm Loft between the two sketches.

78

DETAIL B
SCALE 2 : 5

SCALE: 1:5

Drawn by: MS

DIMENSIONS IN mm Date: 27/04/2013

SolidWorks Student Edition.
For Academic Use Only.
FACULTY OF TECHNOLOGY

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OXFORD BROOKES UNIVERSITY
TITLE: Trailing Arm

Checked by: BS
Approved by: SG
MATERIAL: Aluminium - AL7175
FINISH: Shot Peened

A3
Part No. AS13-MLG-02
Sheet 4 of 25

PROJECTION

Drawing No: 3

Lofted Section - Weld Fillet to
disperse stress concentrations

90

SECTION A-A
SCALE 1 : 10

150
9.00°

DETAIL C
SCALE 1 : 5

C

6.31°

A

A

100

B

112.30

R10

B

22.50
107.50

SCALE 1:5
Detail View

60

55

SolidWorks Student Edition.
For Academic Use Only. SECTION B-B

SCALE 1 : 10

FACULTY OF TECHNOLOGY

SCALE: 1:10

Drawn by: JL

DIMENSIONS IN mm Date: 27/04/2013
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0 0.5
0.0 0.25
0.00 0.10

OXFORD BROOKES UNIVERSITY
TITLE: Side Strut

Checked by: MS
Approved by: BS
MATERIAL: Aluminium - AL7175
FINISH: Shot Peened

A4
Part No. AS13-MLG-03
Sheet 5 of 25

PROJECTION

70

+.013
80 0

Drawing No: 4

620
0.2

10.0
5.0

0.025

SCALE: 1:5

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For Academic Use Only.
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TOLERANCE UNLESS
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0.0 0.25
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OXFORD BROOKES UNIVERSITY

Drawn by: SF

DIMENSIONS IN mm Date: 27/04/13

TITLE: Trailing Arm Axle

Checked by: SG
Approved by: JL
MATERIAL: Steel - 300M
FINISH: As Machined

A4
Part No. AS13-MLG-04
Sheet 6 of 25

PROJECTION

70

+.013
100 0

Drawing No: 5

620
0.2

65.0

SCALE: 1:51:1

FACULTY OF TECHNOLOGY

TOLERANCE UNLESS
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0 0.5
0.0 0.25
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OXFORD BROOKES UNIVERSITY

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DIMENSIONS IN mm Date: 27/04/13

SolidWorks Student Edition.
For Academic Use Only.

20.0

0.025

TITLE: Main Strut Axle

Checked by: SG
Approved by:
MATERIAL: Steel - 300M
FINISH: As Machined

A4
Part No. AS13-MLG-05
Sheet 7 of 25

PROJECTION

Drawing No: 6

A

R4

0

B

0.025 A

100

0.025 B

80.0

0
80 -.013

0
68 -.013

45.2

0.025 A

0.025 A

B

214
3.2

A

115.8

119.00

0.025 C

C

A

120

75.0

B

79.0

0.025 A

R4

0

20

0.025

89.8

46
0.2

56

0.025

0.2

22
SECTION B-B
SECTION A-A

SCALE: 1:5

Drawn by: SG

DIMENSIONS IN mm Date: 26/04/13

All unspecified
Chamfers
are 55 Edition.
Deg
SolidWorks
Student
All unspecified Radiuses are 10 mm

For Academic Use Only.

FACULTY OF TECHNOLOGY

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OXFORD BROOKES UNIVERSITY
TITLE: Main Strut to Trailing Arm Link

Checked by: MS
Approved by: SG
MATERIAL: Titanium - Ti-6AL-6V-2Sn
FINISH: Shot Peened

A4
Part No. AS13-MLG-06
Sheet 8 of 25

PROJECTION

Drawing No: 7

0
107.95 -.013

65.91

B

3.2

0.2

175.0

0.025 A

75

0.025 B

0.025 A

0.025 C

175

A

0.2
C

0
77.788 -.013

67.50
150

150

0.025 A

SCALE: 1:5

Drawn by: SG

DIMENSIONS IN mm Date: 26/04/13

SolidWorks Student Edition.
For Academic Use Only.
All unspecified radiuses are 10mm

FACULTY OF TECHNOLOGY

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OXFORD BROOKES UNIVERSITY
TITLE: Shock Link

Checked by: MS
Approved by: SG
MATERIAL: Titanium - Ti-6AL-6V-2Sn
FINISH: Shot Peened

A4
Part No. AS13-MLG-07
Sheet 9 of 25

PROJECTION

Drawing No: 8

50.00

0
62 -.013

0.025 B
B

104.00

0.2

49

0.025 A

90

A

C
0.2

0.025 C

50.00

0
40 -.012

0.025 A

100
0.025 A

70

3.2

SCALE: 1:5

Drawn by: SG

DIMENSIONS IN mm Date: 27/04/13

SolidWorks Student Edition.
For Academic Use Only.

All unspecified radiuses are 10 mm

FACULTY OF TECHNOLOGY

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OXFORD BROOKES UNIVERSITY
TITLE: Actuator Mounting Link

Checked by: MS
Approved by: SG
MATERIAL: Titanium - Ti-6AL-6V-2Sn
FINISH: Shot Peened

A4
Part No. AS13-MLG-08
Sheet 10 of 25

PROJECTION

Drawing No: 9

200
10

40

0.025 A

20.00

3.2

51.7

150

95

13°

0.2

98.5
20
0.025 A

65

40

10

64.0

A

A

5

R4

R10

.
94
10



81.6
VIEW A

SCALE: 1:5
0.025 A

SolidWorks Student Edition.
For Academic
All unspecified
radiuses are Use
5 mm Only.
FACULTY OF TECHNOLOGY

Drawn by: SG

DIMENSIONS IN mm Date: 27/04/13
TOLERANCE UNLESS
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0 0.5
0.0 0.25
0.00 0.10

OXFORD BROOKES UNIVERSITY
TITLE: Retraction Piston Mount

Checked by: MS
Approved by: SG
MATERIAL: Aluminium - AL 7175
FINISH: Shot Peened

A4
Part No. AS13-MLG-09
Sheet 11 of 25

PROJECTION

Drawing No: 10

72

50

300

R56

50

SCALE: 1:5

Drawn by: SF

DIMENSIONS IN mm Date: 25/04/2013

SolidWorks Student Edition.
For Academic Use Only.

All unspecified radii 10mm

FACULTY OF TECHNOLOGY

TOLERANCE UNLESS
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0.0 0.25
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OXFORD BROOKES UNIVERSITY
TITLE: Side Strut Pin

Checked by: MS
Approved by: JL
MATERIAL: Titanium - Ti-6AL-6V-2Sn
FINISH: As Machined

A4
Part No. AS13-MLG-10
Sheet 12 of 25

PROJECTION

Drawing No: 11

0.025 A

45.0

R5

1

A

190

+.013
40 0

0.025 A

0.025 A

3.2

0.2

0
62 -.013

SCALE: 1:2

Drawn by: SG

DIMENSIONS IN mm Date: 27/04/13

SolidWorks Student Edition.
For Academic
Use Only.
All unspecifiec
radiuses are 10 mm
FACULTY OF TECHNOLOGY

TOLERANCE UNLESS
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0 0.5
0.0 0.25
0.00 0.10

OXFORD BROOKES UNIVERSITY
TITLE: Retraction Strut Pin

Checked by: MS
Approved by: SG
MATERIAL: Titanium - Ti-6AL-6V-2Sn
FINISH: As Machined

A4
Part No. AS13-MLG-11
Sheet 13 of 25

PROJECTION

Drawing No: 0
14
5

11
9

8
3

12
13

ITEM NO.

PART NUMBER

DESCRIPTION

QTY.

1
2
3
4

AS13-MLG-01
AS13-MLG-02
AS13-MLG-03
AS13-MLG-04

MLG Main Strut
MLG Trailing Arm
MLG Side Strut
MLG Trailing Arm Axle

1
1
1
1

5
6

AS13-MLG-05
AS13-MLG-06

MLG Main Strut Axle
MLG Trailing Arm Link

1
1

7
8
9

AS13-MLG-07
AS13-MLG-08
AS13-MLG-09

MLG Shock Link
MLG Retraction Strut Link
MLG Retraction Strut Bracket

1
2
2

10

AS13-MLG-10

MLG Trailing Arm Link Pin

1

11

AS13-MLG-11

MLG Retraction Strut Pin

2

12

N/A

MLG Shock Unit

1

13
14

N/A
N/A

MLG Retraction Strut
MLG Secondary Retraction Strut

1
1

1
7

4

6
2
10

SCALE: 1:10

TOLERANCE UNLESS
STATED

SolidWorks Educational License
Instructional
Use Only
FACULTY OF TECHNOLOGY

Drawn by: SG

DIMENSIONS IN mm Date: 27/04/13

0 0.5
0.0 0.25
0.00 0.10

OXFORD BROOKES UNIVERSITY
TITLE: MLG Assembly

Checked by: MS
Approved by: SG
MATERIAL: See component drawings
FINISH: See Component drawings

A3
Part No. AS13-MLG-00
Sheet 1 of 1

PROJECTION

780.00

20.00

X
°

25

60
15.00
50.00

Z

30.00

25

980.00
785.00

10.00

X

50.00

P
675.00

P

310.00

.21
21

+0.028
55 +0.012

30.00

80.00

0.2

SECTION X-X
SCALE 1 : 10

128.00

146.00

150.0
DETAIL Z
SCALE 1 : 5

3.2

100

185.00

X

SCALE: 1:10

100.00

Drawn by: BS

DIMENSIONS IN mm Date: 27/04/2013

SolidWorks Student Edition.
SECTION P-P
For Academic Use Only. SCALE 1 : 10
FACULTY OF TECHNOLOGY

130

1374.19

R40.0

°

10.00

20.00

110.0

52.00

DETAIL H
SCALE 1 : 5

135.00

38.79°

50.0

40.00

H

50.00

Y

Y
SECTION Y-Y
SCALE 1 : 10

R30.00

1140.00

+0.034
52 +0.013

Drawing No: 1

5 x M10 throu. holes
156mm on PCD

TOLERANCE UNLESS
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0 0.5
0.0 0.25
0.00 0.10

OXFORD BROOKES UNIVERSITY
TITLE: Trunnion

Checked by: JLA
Approved by: MS
MATERIAL: Aluminium - AL7175
FINISH: Shot Peened

A3
Part No. AS13-NLG-01
Sheet 14 of 25

PROJECTION

Drawing No: 2

141.0
99.0

30.00

0.025 X

10.0

0.025 X

2x

10

24.0
724

110.0

350.0

50.0

0.025 X

10.0

0.025 X

30.00

40

X

Note:
All Unspecified radii =
SCALE: 1:5

SolidWorks Student Edition.
For Academic Use Only.
FACULTY OF TECHNOLOGY

TOLERANCE UNLESS
STATED
0 0.5
0.0 0.25
0.00 0.10

OXFORD BROOKES UNIVERSITY

Drawn by: BS

DIMENSIONS IN mm Date: 27/04/2013

TITLE: Drag Strut Rod

Checked by: JL
Approved by: SF
MATERIAL: Steel - 300M
FINISH: As Machined

A4
Part No. AS13-NLG-02
Sheet 15 of 25

PROJECTION

X
3.20

+.034
52 +.013

40.00

Drawing No: 3

627.24

Y

60.00
0.025 X

K

614.31

DETAIL K
SCALE 1 : 5

30.00

L

30

31°

96.02

R100

66.

+.028
55 +.012

30.0

60.0

10.00

Y

0.2
0.025 X

SECTION Y-Y
30.00
DETAIL L
SCALE 1 : 5

50.00
SCALE: 1:10

SolidWorks Student Edition.
For Academic Use Only.
Unspecified Radii =

FACULTY OF TECHNOLOGY

TOLERANCE UNLESS
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0 0.5
0.0 0.25
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OXFORD BROOKES UNIVERSITY

Drawn by: BS

DIMENSIONS IN mm Date: 27/04/2013

TITLE: Drag Strut Brace

Checked by: MS
Approved by: JLA
MATERIAL: Steel - 300M
FINISH: As Machined

A4
Part No. AS13-NLG-03
Sheet 16 of 25

PROJECTION

R10

13.9

2

0.025 X

17

15.20

30

.35

°

30.00

2 x R10

20.00
25.00

15.00

Y

15.20
0.025 X

0.2

DETAIL Y
SCALE 2 : 5

X

17.0

+.028
35 +.012

0.025 X

225.00

15.00

15.00

Drawing No: 4

45.00

50.00

0.025 X

100.00
130.0
SCALE: 1:5

SolidWorks Student Edition.
For Academic Use Only.
FACULTY OF TECHNOLOGY

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OXFORD BROOKES UNIVERSITY

Drawn by: BS

DIMENSIONS IN mm Date: 27/04/2013

TITLE: Torque Link

Checked by: SF
Approved by: JL
MATERIAL: Steel - 300M
FINISH: As Machined

A4
Part No. AS13-NLG-04
Sheet 17 of 25

PROJECTION

Drawing No: 5

210.0
105.0

30.0

Y

120

DETAIL Y
SCALE 2 : 5

2 x M48

2 x 45
Chamf

285.60

80.0

0.025 X

2 x R1.20

500.00

X

0.025 X

0.025 X

2 x R30

0.025 X
X

20.20
72.00

3.2

60.00

X

2x

0.025 X

0
30 0.00
0
100 0

145.0

+0.05
50 +0.03

0.025 X

R107.99

30.0

100.0

All Unspecified Radii = 5mm

0.2
3.2

0.2

Notes:

SECTION X-X

SCALE: 1:5

DIMENSIONS IN mm Date: 27/04/2013

SolidWorks Student Edition.
For Academic Use Only.
FACULTY OF TECHNOLOGY

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OXFORD BROOKES UNIVERSITY

Drawn by: JL

TITLE: Axle

Checked by: SG
Approved by: MS
MATERIAL: Steel - 300M
FINISH: Shot Peened

A3
Part No. AS13-NLG-05
Sheet 18 of 25

PROJECTION

Drawing No: 6

121.40

15.00

15.00

0.025 X

30.0

3.2

0
100 0

0.025 X

0
15 0

3.2

50.00

160

110.0

44°

23.

0.025 X

.27

X

138

15.00
250

SCALE: 1:5

SolidWorks Student Edition.
For Academic Use Only.
FACULTY OF TECHNOLOGY

TOLERANCE UNLESS
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0.0 0.25
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OXFORD BROOKES UNIVERSITY

Drawn by: BS

DIMENSIONS IN mm Date: 27/04/2013

TITLE: Towing Fixture

Checked by: MS
Approved by: JLA
MATERIAL: Steel - 300M
FINISH: As Machined

A4
Part No. AS13-NLG-06
Sheet 19 of 25

PROJECTION

Drawing No: 7

40
3.2

70

80

10

F

85

F

SECTION F-F
SCALE 1 : 5

25

0.2

65

20

100

150

0.025 A

52

3.2

10

60

8X

0.025 A

20

0.025 A

30

5

A

5

R1

5

85

3.2

200
SCALE: 1:5

SolidWorks Student Edition.
For Academic Use Only.
Unspecified Radii = 5mm

FACULTY OF TECHNOLOGY

TOLERANCE UNLESS
STATED
0 0.5
0.0 0.25
0.00 0.10

OXFORD BROOKES UNIVERSITY

Drawn by: MS

DIMENSIONS IN mm Date: 27/04/2013

TITLE: Actuator Mounting Plate

Checked by: SF
Approved by: JLA
MATERIAL: Steel - 300M
FINISH: As Machined

A4
Part No. AS13-NLG-07
Sheet 20 of 25

PROJECTION

Drawing No: 8

2.50 x 45

130

160

12.50

M 140.41

25
12.50

SCALE: 1:2

Drawn by: BS

DIMENSIONS IN mm Date: 27/04/2013

SolidWorks Student Edition.
For Academic Use Only.
FACULTY OF TECHNOLOGY

TOLERANCE UNLESS
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OXFORD BROOKES UNIVERSITY
TITLE: Steering Collar

Checked by: JLA
Approved by: MS
MATERIAL: Aluminium - AL7175
FINISH: As Machined

A4
Part No.AS13-NLG-08
Sheet 21 of 25

PROJECTION

Drawing No: 9

3.2

185.0

X

235.58

2X

+.04
35 +.02

0.025 X

135.00

I

I

15.00

2x

5.00

0.025 X

228.72

SECTION I-I
SCALE: 1:5

Drawn by: BS

DIMENSIONS IN mm Date: 27/04/2013

SolidWorks Student Edition.
For Academic Use Only.
FACULTY OF TECHNOLOGY

TOLERANCE UNLESS
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0.0 0.25
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OXFORD BROOKES UNIVERSITY
TITLE: Steering Retaining Upper Plate

Checked by: SG
Approved by: MS
MATERIAL: Aluminium - AL7175
FINISH: As Machined

A4
Part No. AS13-NLG-09
Sheet 22 of 25

PROJECTION

15.00

135.00

8.08

3.2

0.025 X

Drawing No: 10

3.2

2x
SECTION Y-Y

15.00
25.0

15

Y

235.58

185

X

116.25

15.00

0.025 X

+.028
35 +.012

0.025 X

5.00

Y

25.00

228.72

SCALE: 1:5

Drawn by: BS

DIMENSIONS IN mm Date: 27/04/2013

SolidWorks Student Edition.
For Academic Use Only.
FACULTY OF TECHNOLOGY

TOLERANCE UNLESS
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0.0 0.25
0.00 0.10

OXFORD BROOKES UNIVERSITY
TITLE: Steering Retaining Upper Plate

Checked by: MS
Approved by: JLA
MATERIAL: Aluminium -AL7175
FINISH: As Machined

A4
Part No. AS13-NLG-10
Sheet 23 of 25

PROJECTION

X
80

X

M 30 x 50

Drawing No: 11

100
80

530

SECTION X-X
SCALE 1 : 5

SCALE: 1:5

Drawn by: BS

DIMENSIONS IN mm Date: 27/04/2013

SolidWorks Student Edition.
For Academic Use Only.
FACULTY OF TECHNOLOGY

TOLERANCE UNLESS
STATED
0 0.5
0.0 0.25
0.00 0.10

OXFORD BROOKES UNIVERSITY
TITLE: Shock Strut

Checked by: JLA
Approved by: JL
MATERIAL: Steel 300M
FINISH: As Machined

A4
Part No. AS13-NLG-11
Sheet 24 of 25

PROJECTION

Drawing No: 12

127.46
50.0

X

25.0
15.20

180.00

200.0

138.09

0.025 X

15.20
X
0.2

X

162.23

0.2

SECTION X-X

35.00

202.92
SCALE: 1:5

Drawn by: BS

DIMENSIONS IN mm Date: 27/04/2013

SolidWorks Student Edition.
For Academic Use Only.
FACULTY OF TECHNOLOGY

TOLERANCE UNLESS
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0 0.5
0.0 0.25
0.00 0.10

OXFORD BROOKES UNIVERSITY
TITLE: Steering Actuator Centre Plate

Checked by: JL
Approved by: JLA
MATERIAL: Aluminium - AL7175
FINISH: As Machined

A4
Part No. AS13-NLG-12
Sheet 25 of 25

PROJECTION

Drawing No: A2

7
Trunnion
Drag Strut Road
Drag Strut Brace
Torque Link
Axle
Towing Fitting
Actuator Mounting
Plate
Ateering Collar
Upper Steering
Actuator Plate
Lower Steering
Actuator PLate
Shock Strut
(Absorber)
Steering Actuator
Plate
Drag Strut Assembly
Actuator
Gear Actuation
Cylinder
Steering Actuator
Cylinder

1
2
3
4
5
6

3

14

7
8

2

9
10
11
12
13
14

13

15

9
1

12

8

15

4
6

10
SCALE: 1:10

11

SolidWorks Student Edition.
For Academic Use Only.
FACULTY OF TECHNOLOGY

5

DIMENSIONS IN mm Date: 27/04/2013
TOLERANCE UNLESS
STATED
0 0.5
0.0 0.25
0.00 0.10

OXFORD BROOKES UNIVERSITY

Drawn by: JLA

TITLE: Nose Landing Gear Assembly

Checked by: JL

Assembly Drawing

Approved by: SF
Steel
MATERIAL: (See Drawings)
FINISH: (See Drawings)

A3
Part No. AS13-NLG-AS.
Sheet 2 of 2

PROJECTION

Drawing No: EX

SCALE: 1:10

DIMENSIONS IN mm Date: 27/04/2013

SolidWorks Student Edition.
For Academic Use Only.
FACULTY OF TECHNOLOGY

TOLERANCE UNLESS
STATED
0 0.5
0.0 0.25
0.00 0.10

OXFORD BROOKES UNIVERSITY

Drawn by: JL

TITLE: Nose Landing Gear Exploded View

Checked by: SG
Approved by: BS
MATERIAL: (See Drawings)
FINISH: (See Drawings)

A3
Part No. AS13-NLG-EX
Sheet 1 of 1

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