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AVIATION IN THE WEST OF
ENGLAND SINCE 1910
FLYING
FLYING
• People dreamed of be able to fly like the birds from
the beginning of time.
• Some people did more than just dream. They spent
years and years of research, experiments, trial and
error, learning all about flight.
• At last, in 1903, the Wright Brothers made the first
powered, controlled, aeroplane flight.
• By 1910 ‘Bristol’ aeroplanes the first were being built
at Filton.
• Today millions of people have had the chance to fly
thanks to those early experiments.
FORCES
One of the things that had to be understood
before humans had a chance to fly were the
four forces of flight. These are:
• LIFT – the upward force that comes from air
moving over and under the aeroplane’s wings.
•WEIGHT – the downward force that comes
from gravity.
•THRUST – the forward force that comes from
the aeroplane’s engine or propeller.
•DRAG – the backward force that comes from
the resistance caused by the air moving against
the aeroplane.
LIFT UP
THRUST
FORWARD
DRAG
BACK
DOWNWARD WEIGHT
BRISTOL FREIGHTER 1950s
CLIMBING
Thrust has to be greater than drag
if an aeroplane is to climb steadily.
BRISTOL BOMBAY 1936
DIVING
In a steady dive the weight of the aircraft is partly pulling it
forwards. If the dive is steep enough the aircraft will speed
up even if the engine is switched off and thrust is zero (like
freewheeling downhill on your bike).
BLACKBURN SKUA WITH ‘BRISTOL’ ENGINES, 1936
WINGS GIVE LIFT
When an aeroplane is flying, air is passing over and under its wings.
The air pushed over the top of the wing is moving faster than the air
below so is spread out more thinly. This creates lower air pressure
above the wing than below. The curve of the wing increases the speed at
which the air flows.
The difference in air pressure above and below the wing keeps the
aeroplane in the air until the pilot wants to land.
Sucked upwards
from above
o
Pushed upwards
from below
AIRBUS A350 2000s
SOME AEROPLANES GET THRUST FROM A PROPELLER
The propeller is usually turned by a piston engine. The power comes
from four separate actions taking place one after the other inside each
engine cylinder.
SUCK – the piston is pulled down, and air and fuel is sucked in through
the inlet valve at the top of the cylinder.
SQUEEZE – the inlet valve closes, the piston is pushed up and the air
inside the cylinder is squeezed (the technical word for this is
‘compressed’).
BANG – the fuel is set alight with a spark. This causes an explosion
inside the cylinder (this is called ‘combustion’). The piston is pushed
down strongly. This provides the power to turn a crankshaft. The
crankshaft then turns the aeroplane’s propeller.
BLOW – the exhaust valve opens at the top of the cylinder and hot gas
from the explosion is pushed out. The exhaust valve closes, the piston is
pushed up and the sequence begins again.
PISTON SEQUENCE
SUCK
SQUEEZE
BANG
BLOW
This is a famous ‘Bristol’ piston
engine built by the Bristol
Aeroplane Company. It has nine
cylinders.
‘BRISTOL’ JUPITER 1920s
PROPELLERS
All piston engines need propellers to generate thrust. The BANG of
the engine turns the propeller which then pulls or pushes the
aeroplane through the air.
SOME AEROPLANES GET THRUST FROM A JET
Like the piston engine, the jet engine SUCKS, SQUEEZES, BANGS and
BLOWS. The difference is that these actions are taking place
CONTINUOUSLY in different parts of the engine. If the engine can
continuously produce energy it can be more powerful and efficient.
SUCK – air is sucked into the engine by the rotating blades at the front
of the engine.
SQUEEZE – the air is driven through the engine by the compressor
blades which squeeze the air into a tighter and tighter space.
BANG – fuel is sprayed into the compressed air so it bursts into flames.
BLOW – the hot gases of the flames produce energy to turn the turbine
blades. The turbine produces the power to drive the compressor. The
gases blow out the back of the engine, thrusting the aeroplane forward.
SUCK
SQUEEZE
BANG
A JET ENGINE
BLOW
The Olympus used in Concorde was
a type of engine known as a
TURBOJET. In a turbojet, the
thrust only comes from the jet of
hot gases blown out the exhaust.
CONCORDE’S OLYMPUS ENGINE, 1970s
This cutaway picture is of the RB.211. The engine is assembled at RollsRoyce in Derby but some of the parts needed for it are made at RollsRoyce at Filton. This is a type of engine known as a TURBOFAN.
In a turbofan, the thrust comes from the jet of hot gas blown out the
exhaust and also from the cold air that the huge fan at the front pushes
around the sides of the core engine. An extra turbine is needed to drive
the fan. All modern airliners are powered by turbofans which can be
quieter and cheaper to run than turbojets.
TURBOFAN, 1980s
CONTROLS
Imagine three lines running through the aeroplane. Another word for
line is axis.
The LONGITUDINAL axis runs from the nose to the tail.
The VERTICAL axis runs from top to bottom.
The LATERAL axis runs from one side to the other.
The lines cross at the aeroplane’s centre of gravity. When the
aeroplane is flying forward, it can rotate around the centre of gravity
on each axis. On most aeroplanes, the pilot can control the movement
using three moveable flaps: the AILERONS, the RUDDER and the
ELEVATORS.
When these move, they change the flow of the air around the
aeroplane. By changing the flow of air, the direction in which the
aeroplane flies is also changed.
Controlled movement is SAFE, STABLE and PREDICTABLE. That’s just
what you want, when you are flying an aeroplane!
LATERAL
LONGITUDINAL
VERTICAL
‘BRISTOL’ BLENHEIM 1940s
AILERON
BRISTOL M1D MONOPLANE 1920s
RUDDER
BRISTOL BABE 1919
ELEVATOR
BRISTOL BULLDOG 1920s