Practice English Speaking&Listening with: Spitfire Mk V – Electrical Installations

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Hello, Im Bryan Atkinson and

welcome to UK Aircraft Explored.

In this video, we shall cover the

Spitfire Mk.Vs Electrical Installations

and their general function.

As we work our way through the various items of equipment,

I shall give you extracts from the 1942

Air Ministry Manual

along with wartime Electrical Circuit AP. diagrams,

that Ive re-worked into colour.

I hope you find this interesting.

We shall go in turn, through the Spitfire Mk.Vs

electrical equipment,

starting with the Generator.

Electrical power is supplied from a 750-watt

shunt wound engine driven generator,

Type L.X.,

which is mounted on the port side of the Merlin engine.

Here is a view of the Generators air cooling intake

located on the port cowling panel.

During flight, the generator charges the 12-volt, 40-Ah. accumulator, Type D,

which is mounted on the starboard side

at the rear of the pilot's seat,

power passes through a suppressor, Type W,

which prevents interference with the aircrafts radio equipment.

A carbon-pile voltage regulator,

mounted behind the pilot's headrest

is included in the circuit to maintain a

constant voltage, irrespective of engine speeds and load fluctuations.

A voltmeter is mounted on the instrument panel

in the top starboard corner,

and is connected across the accumulator.

The electrical system comprises

17 fused circuits,

allocated in the following manner.

Ten fuses for electrical services,

four fuses for the radio,

two for the undercarriage indicators

and one for engine starting.

These fuses are contained in

two 8-way fuse boxes and one 4-way

as shown here.

The generator control along

with either the T.R.9D,


or T.R.1143 radio fuses

being in single unit fuse boxes

mounted on the port side of the cockpit.

One 8-way fuse box together with

the 4-way box is

mounted on the port side of the cockpit

below the door.

The other 8-way fuse box is

mounted above the bottom longeron

on the port side of the cockpit.

Connection to the main planes

is made through 10-way plugs and sockets

mounted in the wing roots.

Marked 3 on these AP. Diagrams,

here is the port wing root.

And here is the Starboard wing root.

A 3-pin socket is mounted on the port side

of the fuselage aft of frame 11,

under the fillet,

for testing the electrical services or radio installation.

A door cut in the fillet

gives access to the socket,

as you can see here.

In Spitfires not fitted with a fuel pressure gauge,

a Fuel Pressure Warning Lamp

is fitted in its place on the pilot's instrument panel

to attract his attention should the

fuel pressure fall below a safe working value.

The lamp is fitted to a diaphragm switch

fitted on the engine in the fuel system.

The switch controlling the Navigation Lamps

is fitted at the top port corner

of the instrument panel.

The port and starboard wing tip navigation lamps

consist of lamps covered by standard

coloured glass domes.

The lamps are inserted in holders

attached to the face of the spar at the wing tips

and the domes are held in position by detachable shields

shaped to conform to the contour of the aerofoil

and to give the required cut-off angle.

This last set of navigation lamps

belong to the low flying clipped wing variant


The tail navigation lamp is inserted

in a holder inset in the trailing edge of the rudder,

and is covered by a streamlined screw-on dome.

The upward Identification Lamp

is located aft of the Aerial Mast

and the downward identification Lamp

is located on the centreline of the Main Plane.

Their purpose is to send a morse code

identification signal or steady beam

from the aircraft.

Here is a view of the Upward ID Lamp

and here,

the internal mounting point.

The Lower ID Lamp in this case,

has an orange lens,

and here is a view of the internal mounting point

for the lamp,

made visible by removing the Pilots seat.

The upward and downward Identification Lamps

are controlled from a Signalling Switchbox

on the starboard side of the cockpit.

This switchbox has a switch for each lamp

and a morsing key

and provides for steady illumination

or morse signalling from each lamp or both.

The switch lever has three positions,




The spring pressure on the morsing key

can be adjusted by turning the

small ring at the top left-hand corner

of the switchbox,

the adjustment being maintained

by a latch engaging one of a number of notches

in the ring.

The range of movement of the key

can be adjusted to suit the pilot by

opening the cover and adjusting the

screw and locknut at the centre of the cover.

Two Instrument Lamps are fitted on the

port and starboard of the cockpit coaming.

The starboard lamp is mounted

so that it can be moved vertically

up or down,

and the port lamp is mounted on a universal joint,

so that it can be extended and

turned to suit the instrument panel when the T.R.1133

remote controller is fitted.

Both lamps are shielded with

an orange cover to prevent glare,

and are operated by two dimmer switches, Type A,

mounted in the centre of the instrument panel,

as shown here.

The Reflector Gun-sight (type G.M.2)

is mounted on a bracket above the instrument panel.

A main switch and dimmer switch

are fitted below the mounting bracket.

The dimmer switch has three positions,



Three spare lamps for the sight are stowed in holders

on the starboard side of the cockpit.

The Fuel Contents Gauge on the

starboard side of the instrument panel

indicates the contents of the bottom fuel tank.

The gauge indicates only when the pushbutton inboard of it is pressed.

A double scale is provided on the gauge

to give a correct reading for both

"tail on ground" and "flight" attitudes.

The electrically-operated visual Undercarriage Indicator

is fitted on the port side of the instrument panel

and has two semi-transparent windows

on which the words UP on a red background

and DOWN on a green background

are engraved.

These words are illuminated according to the position of the undercarriage units.

UP when both units are fully retracted and locked and

DOWN when both units are fully lowered and locked.

The switch for the DOWN circuit of the indicator

is mounted on the inboard side of the throttle quadrant

and is moved to the ON position by

means of a striker on the throttle lever

and should be returned to the OFF position by hand when

the aircraft is left standing for any length of time.

The UP circuit is not controlled by this switch.

The lamps behind the windows of the Undercarriage Indicator

are duplicated and wired in parallel.

The Undercarriage Warning Horn

for audible warning is mounted

behind the pilot, close to his head,

and sounds when the throttle is less than one- third open

if the wheels are not locked down.

The push switch controlling the horn

is mounted on the throttle quadrant

and is operated by a striker on the throttle lever.

When it is desired to stop the horn from sounding,

even though the wheels are retracted

and the engine is throttled back,

the pilot may do so by depressing the pushbutton

on the side of the throttle switch.

As soon as the throttle is again advanced

beyond about one-quarter of its travel

the pushbutton is automatically released and

the horn will sound again on the return.

On later Spitfires, the pushbutton used for silencing the

horn is not installed.

Moving on, the G.42B

or the later G.45 camera gun

is mounted on a bracket attached to a rib on the port wing,

exposures being made through a hole in the

leading edge fillet.

We shall be covering the G.45 Camera Gun installation

and operation in another video.

However, from an electrical point of view,

the multi-core cable is enclosed

in a tubular conduit which extends

forward and above the main spar

to the back of the camera.

When the camera is removed,

the socket end of the cable should be

placed in the stowage bracket.

A combined footage indicator and aperture control

is mounted on a wedge plate in the cockpit

above the throttle quadrant

and is connected to the electrical circuit

by means of the adjacent socket.

The master switch is situated on the

side of the fuselage,

forward of the fuse panel.

A push-button for operating the camera

independently is fitted to the control column.

The heating element in the A.S.I. pressure head

is controlled from a switch below the

trimming tab hand wheels.

To prevent the undue discharge of the accumulator

the element should be switched off on landing.

An Oil Dilution Valve, to

assist starting in cold weather,

is fitted to the engine on the port side

and is controlled by a push-switch

with a guard attached on the port side of the cockpit.

The socket for the pilots heated gloves and boots

supply is fitted in the starboard side

of the cockpit at the top of frame 10,

in such a manner that the connection will automatically

break if the pilot omits to disconnect

when leaving the aircraft.

The space between the oxygen pipe and the aft side of frame 10 forms a stowage

for the socket, when the latter is not in use.

The Engine Starter Motor is

fitted to the starboard side of the engine

and a boost coil is mounted on the starboard side of the fireproof bulkhead.

These are controlled by two push-switches

mounted in the centre of the instrument panel,

connection to the starter motor being

made through a magnetic relay.

The main magneto switches

are mounted on the bottom left of the instrument panel.

Electrical current is supplied to the

starter motor from the accumulator,

or alternatively by an external accumulator known

as a Trolley Acc

which can be connected through a socket mounted on the starboard engine

bearer, as shown here.

A Power Failure Warning Lamp is

fitted on the port side of the cockpit,

and consists of a lamp and rectifier unit.

The lamp will light if either the

accumulator cut-out

or generator fuse are open-circuited.

Radio equipment provided with a Spitfire Mk.V

consists of the following installations:

A.R.I. 5000

with either T.R1133,

TR.1143 with beam approach (if required)

or A.R.I. 5000 with T.R.9D,

which is fitted only as part of the tropical conversion set.

In this video, we shall cover just the

A.R.I. 5000 with the T.R.1143.

A.R.I. 5000.A.R.I. stands for Aircraft Radio Installation,

and A.R.I. 5000 was the installation number

for IFF Mk.II.

known as Identification Friend or Foe.

Basically, IFF was a transponder

used to create an enlarged blip

on the UK Chain Home Radar screen,

and thus confirm to the radar operator

that the Spitfires radar blip

was friendly and not an enemy aircraft.

The R.3002 (12 volt) IFF receiver

is mounted forward of the radio door

on the starboard side

and is controlled through a control panel

mounted adjacent to the receiver

by an ON/OFF switch mounted on a

panel on the starboard side of the cockpit.

Mounted on this panel are

R.3002 two push-switches which are covered by a

spring-loaded lid marked DANGER.

These two push switches,

connected in series, must be depressed

together by the pilot, and are in parallel with an

impact switch mounted on the port side

opposite the receiver.

Either the push switches or impact switch

operate the detonator

on the side of the receiver through

a 2-pin socket.

Aerials run from the outer leading edges

of the tail planes

and enter the fuselage

just aft of the radio door

through insulator eyelet points,

being fixed inside the fuselage

by means of two shock-absorber cords.

Connection to the receiver is made by means of two

single pole sockets.

Feed to the control unit is made through a 3-pin plug and socket.

And now for a look at the T.R.1143 system.

Wireless stowage access is gained

through a door fitted on the port side of the fuselage.

Here is a view of the wireless stowage tray.

The T.R.1143 Transmitter-receiver

is mounted on a tray which is

similar to and interchangeable with that of the T.R.9D unit.

The unit is attached to four shock-absorbers

by means of the bolts and check washers

which were used to secure it to the transit case.

A push-button electrical control unit

is mounted on a base plate which is

interchangeable with the plate for the

mechanical remote control of T.R.9D.

The aerial mast is fitted at its base

with a screened socket which

accommodates the aerial plug from the T.R.1143.

The mic-tel socket and the remote contactor

gear are the same as

those employed with the T.R.9D.

The junction box, which is a separate unit,

is attached to brackets on the port side

below the transmitter-receiver.

A special shorted socket is provided

in place of beam approach not being used with T.R.1143.

The harness consists of metal braided connectors

which are secured in roller type

spring clips that are provided

to enable the various flexible conduits

to be secured quickly in position ;

these clips are marked with red lines.

The motor generator is mounted

below the transmitter-receiver

mounting on two rails fitted with shock absorbers.

The generator is secured by

means of the nuts and check washers which were used to attach it to the transit

case. Finally, here are details and

positions of the various items of the Beam Approach equipment, which could be used with either T.R. 1133 or T.R. 1143.

The amplifier is mounted within the roof of the fuselage, aft of the radio bay, on a

mounting that contains stowage for the connectors.

The aerial is mounted on the underside of

the aeroplane directly under the T.R. 1133

or T.R. 1143 radio and is connected to the amplifier by a

screened socket which is incorporated in

the aerial mounting.

The switch unit controlling the amplifier

is mounted on a bracket

near the remote contactor

which is on the starboard side of the cockpit.

Before I finish this video,

here is the AP. circuit diagram

for the T.R.1133 system,

and here is the T.R.9D System.

Well thats it for this video.

I do hope youve found it interesting.

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Thanks as always for watching

and Ill see you again next time.

Bye for now

The Description of Spitfire Mk V – Electrical Installations