Tyre Construction - Wheels & Tyres - Airframes & Aircraft Systems #20
Summary
TLDRThis educational video script delves into the construction of aircraft tires, focusing on radial and cross ply types. It explains the function of tire components like the crown, shoulder, and sidewall, and the significance of tire inflation with nitrogen. The script distinguishes between radial ply and bias tires based on cord arrangement. It also covers tire ratings, bead construction, and the importance of correct tire pressure for aircraft safety. Additionally, it touches on special features like breaker strips and chines for water dispersion, emphasizing the need for various tire sizes and pressures to accommodate different aircraft landing speeds and surfaces.
Takeaways
- đ« Aircraft tires are crucial for absorbing shocks and supporting the weight of the aircraft during landing and takeoff.
- đ There are two main types of aircraft tires: radial and cross ply (bias) tires, differing in their construction methods.
- đ Modern aircraft mostly use tubeless tires, while some light and older aircraft may use tires with inner tubes.
- đ Tires are inflated with nitrogen to enhance their performance and durability.
- đ© The tire is divided into sections: crown, shoulder, sidewall, and bead, each playing a specific role in the tire's function.
- đ Radial tires have cords that run from bead to bead at approximately 90 degrees to the centerline, enhancing their strength and performance.
- đ Bias or cross ply tires have cords arranged at 90 degrees to one another in adjacent plies, providing a different structural integrity.
- đ· The ply rating on a tire indicates its strength and is displayed on the sidewall, but it does not directly correspond to the number of plies.
- đ© Tire beads, made of high tensile wire strands, are crucial for holding the tire onto the wheel and maintaining a gas-tight seal if tubeless.
- đ§ Tread patterns, such as ribbed types with circumferential grooves, aid in water dispersion and prevent aquaplaning, improving grip on runway surfaces.
- âïž Special breaker strips in some tires provide additional strength and support, especially under heavy loads or high-speed operations.
Q & A
What are the two types of tires fitted to aircraft?
-The two types of tires fitted to aircraft are radial and cross ply or bias tires.
What type of tires are most modern aircraft equipped with?
-Most modern aircraft are equipped with tubeless tires.
What gas is commonly used to inflate aircraft tires and why?
-Nitrogen is commonly used to inflate aircraft tires because it absorbs shocks and supports the weight of the aircraft.
What is the function of the tire cover in an aircraft tire?
-The tire cover maintains the shape of the tire, transmits braking, and provides a wearing surface.
What are the two main sections of a tire and what are their roles?
-The two main sections of a tire are the crown and the shoulder section. The crown bears the load and provides a contact surface with the ground, while the shoulder section provides additional support and helps maintain tire shape.
How are the cords in bias or cross ply tires arranged during tire construction?
-In bias or cross ply tires, the cords of adjacent plies are arranged at 90 degrees to one another and from bead to bead at approximately 90 degrees to the centerline of the tire.
What does the ply rating of a tire indicate?
-The ply rating of a tire does not directly relate to the number of plies but is an index of the tire's strength.
What is the purpose of the rubber lining applied to the inner surface of a tubeless tire?
-The rubber lining in a tubeless tire retains the gas pressure and forms a gas-tight seal on the wheel rim.
What is the function of breaker strips in aircraft tires?
-Breaker strips are narrow plies embedded in thick layers of rubber between the casing and the tread to provide additional strength and protection against damage.
Why are chines molded onto the shoulder of nosewheel tires?
-Chines are rubber extensions designed to direct water away from engine intakes, preventing flameouts due to water ingestion.
What is the importance of checking tire inflation pressure in aircraft?
-Checking tire inflation pressure is crucial as incorrect pressure can lead to tire failures. Under-inflated tires may cause excessive shoulder wear and creep, while over-inflated tires can cause excessive wear to the crown of the tires.
Outlines
đ« Aircraft Tire Construction and Types
This paragraph introduces the two types of tires used in aircraft: radial and cross ply or bias. It explains the function of pneumatic tires, which are either tubeless or have an inner tube, with modern aircraft typically using tubeless tires. The paragraph details the various parts of a tire, including the crown, shoulder, tread, sidewall, and bead. It also discusses the construction of tires, highlighting the arrangement of cords in the casing and the difference between radial ply and bias or cross ply tires. The importance of tire ratings, bead construction, and the use of rubber lining in tubeless tires are also covered. Additionally, the paragraph touches on the role of breaker strips and tread patterns, emphasizing the ribbed type for water dispersion and improved grip. Special features like chines on nosewheel tires are mentioned to prevent water ingestion and engine flameouts.
đ Tire Inflation, Pressure Groups, and Maintenance
The second paragraph delves into the specifics of tire inflation, emphasizing the use of nitrogen or inert gases with less than 5% oxygen content to maintain correct tire pressure. It categorizes tires into four pressure groups: low, medium, high, and extra high pressure, each designed for different types of runway surfaces. The paragraph underscores the importance of proper inflation to prevent tire failure, with 90% of failures attributed to incorrect gas pressure. It also mentions the potential for real-time tire pressure monitoring on modern aircraft and the manufacturer-specified maximum ground speed for tires. The summary concludes with a reminder of the significance of tire ply ratings as an indicator of strength rather than the number of plies and the effects of under and over inflation on tire performance and longevity.
Mindmap
Keywords
đĄAircraft Tires
đĄRadial Ply Tires
đĄCross Ply or Bias Tires
đĄTire Bead
đĄTire Cord
đĄTread
đĄSidewall
đĄInflation Pressure
đĄNitrogen Inflation
đĄTire Failure
đĄMax Ground Speed
Highlights
Aircraft tires come in two types: radial and cross ply or bias.
Aircraft wheels are fitted with pneumatic tires, which can be tubeless or have an inner tube.
Most modern aircraft use tubeless tires inflated with nitrogen for shock absorption and weight support.
The tire cover maintains the tire's shape, transmits braking, and provides a wearing surface.
Tires are divided into regions: crown, shoulder, sidewall, and bead.
The term 'tread' applies to both plain and block pattern rubber.
Bias or cross ply tires have cords arranged at 90 degrees to one another.
Radial tires have cords running from bead to bead at approximately 90 degrees to the centerline.
Tire ply rating is an index of tire strength, not directly related to the number of plies.
Tire beads are made of high tensile wire strands coated with rubber and spiral-wound into a coil.
For tubeless tires, a rubber lining is applied to the inner surface for a gas-tight seal.
Breaker strips are narrow plies embedded in rubber to protect the casing from damage.
Ribbed tread patterns are popular for water dispersion and to prevent aquaplaning.
Nosewheel tires may have chines to direct water away from engine intakes, preventing flameouts.
Inflation valves are required for both tubed and tubeless tires, with a non-return valve and valve cap for safety.
Tires are categorized into low, medium, high, and extra high-pressure groups based on inflation pressures.
Incorrect gas pressure is estimated to cause 90% of tire failures.
Real-time tire pressure monitoring is available on some modern aircraft.
Tire ply rating indicates strength, not the number of plies, and is marked on the sidewall.
Aircraft tires must be kept inflated to the correct pressure to prevent under or over-inflation issues.
Transcripts
in this the first of two lessons on
aircraft tires the construction of the
two types of tire fitted to aircraft
radial and cross ply or bias will be
described
aircraft wheels are fitted with
pneumatic tires which may be tubeless or
have an inner tube
tires fitted with inner tubes tend to be
used on some light aircraft and on older
aircraft most modern aircraft have two
'bless tires fitted
tires are usually inflated with nitrogen
which absorb shocks and supports the
weight of the aircraft while the tire
cover maintains the shape of the tire
transmits braking and provides a wearing
surface
if a tube is fitted the tire also
restrains the tube and protects it from
damage
you
the tire is divided into regions or
sections as illustrated here
the tire is situated in the crown and
shoulder section
it is worth noting that the term tread
is applied irrespective of whether the
rubber is plain and smooth or molded on
a block pattern
the sidewall allows the tire to be
flexible
and the bead is seated inside the flange
of the wheel
there are two types of tire in common
use these are known as radial ply and
bias or cross ply tires the names
originating from the way the tires are
constructed
the tire consists of a casing made of
plies of cotton rayon or nylon cords the
cords are not woven but arranged
parallel in single layers and held
together by a thin film of rubber which
prevents cords of adjacent plies from
cutting one another as the tire flexes
in use during construction of the tire
the plies are fitted in pairs and set
out so that the cords of adjacent plies
are at 90 degrees to one another in the
case of bias or cross ply tires
and from bead to bead at approximately
90 degrees to the centerline of the tire
in radial tires
the tire manufacturer gives each tire
apply rating
this rating does not relate directly to
the number of plies in the tire but is
the index of the strength of the tire
the ply rating is shown on the sidewall
of the tire
this tie for example has apply ratings
32 but it only has 18 plies
the tire beads hold the tire on its
wheel the beads are made of high tensile
wire strands
each wire strand is coated with rubber
compound and is spiral-wound into a coil
of the specified diameter for the tire
the plies are wrapped around the beads
and turned out back on to themselves
if the tire is designed to be used
without an inner tube a rubber lining is
applied to its inner surface and the
underside of the beads
this lining which retains the gas
pressure forms a gas tight seal on the
wheel rim
the cows seal depends on a wedge fit
between the underside of the tyre bead
and the taper of the wheel rim
to absorb and distribute load shocks and
protect the casing from concussion
damage some tires have to narrow plies
embedded in thick layers of rubber
between the casing and the tread
these special prize are termed breaker
strips
the most popular tread pattern is the
ribbed type it is formed from
circumferential grooves around the tire
to assist in water dispersion and to
help prevent aquaplaning or hydroplaning
the grooves also help to improve contact
grip between the tread and the runway
surface
nosewheel tires particularly those
fitted to aircraft with the engines
mounted on the rear fuselage may have a
chine or chines molded onto the shoulder
these a rubber extensions
designed to direct water away from the
engine intakes and so prevent flameouts
due to water ingestion
a nosewheel tire fitted to a single
wheel installation will have a chine
moulded onto both sides of the tire
whilst on a double nosewheel
installation the Chinese fitted only to
the outer edge of each tire
whether the chair is fitted with a tube
or is tubeless an inflation valve is
required
in the case of the tire with a tube the
vowel forms part of the tube
installation
on a tubeless tire it is fitted directly
onto the wheel rim with a rubber sealing
gasket
each inflation valve is fitted with a
non-return valve
the valve core is not considered to be a
perfect seal therefore the inflation
valve must always be fitted with the
valve cap
the valve cap also prevents dirt from
entering the valve
it is important when doing your external
check the aircraft that you check that
the valve caps which are normally
colored yellow are fitted
they will slow down the loss of pressure
in the event of a valve failure
the differences in landing speeds
loading landing gear surfaces and
landing gear construction of aircraft
make it necessary to provide a wide
range of tire sizes types of tire
construction and inflation pressures
in terms of inflation pressures ties a
split into four main groups identified
as low medium high and extra high
pressure tires
low pressure tires are designed to
operate at a pressure of 25 to 35 pounds
per square inch psi or 1.73
to 2.4 to bar
these are fitted to aircraft using grass
surfaces for takeoff and landing
medium pressure tires operate at a
pressure of 35 to 70 psi or 2.4 to 24.8
3 bar and are used on grass surfaces or
on medium firm surfaces without a
consolidated base
I pressure tires operated a pressure of
70 to 90 psi or four point eight three
to six point two one bar and is suitable
for concrete runways
extra high-pressure tires are fitted to
most large modern airliners
they operate at pressures of over 90 psi
with some ties of this type being
inflated to 350 psi or 24.2 bar
these tires are suitable for concrete
runways
tires in use must be kept inflated to
the correct pressure using nitrogen or
another inert gas with less than 5%
oxygen content as under inflated tires
may move or creep around the wheel and
overinflated tires will cause other
types of failure
it is estimated that 90% of all tire
failures can be attributed to incorrect
gas pressure over inflation will cause
excessive wear to the crown of the tires
whilst under inflation is the cause of
excessive shoulder wear and creep on
some modern aircraft real-time tire
pressures can be displayed on the flight
deck as shown here on this a320
electronic display screen
the manufacturer will set a maximum
ground speed to which a tire can be
subjected this will be marked on the
side of the tire
it is important that this speed is not
exceeded as damage including possible
tread separation may occur
you should now have an understanding of
how the two types of tire are
constructed
bear in mind that the prior rating of
attire is not necessarily an indication
of the number of plies it is an
indication of the ties strength
you also need to be aware of the effects
of both under and over inflation of
tires
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