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
starting with the Generator.
Electrical power is supplied from a 750-watt
shunt wound engine driven generator,
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
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,
NIGHT and DAY.
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
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
or generator fuse are open-circuited.
Radio equipment provided with a Spitfire Mk.V
consists of the following installations:
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