World War II Searchlight Battery
Accessories and how they all
An Anti-Aircraft Searchlight Battery was used for
detection, location and illumination of enemy aircraft during darkness
enabling Gun Batteries to fire at enemy aircraft efficiently. The
battery was made up of 2 transport trucks, Searchlight, Control
Sound Locator, Power plant, and interconnecting cables.
It took a team of 12 men to operate ONE
The Sound Locator Squad was made up of 5 men.
Chief of Section (Sergeant), Azimuth Listener, Elevation Listener,
Acoustic Correction Operator,
The Searchlight Squad was made up of 7 men.
Searchlight Commander ( Corporal) Azimuth Controller, Elevation
Controller, Light operator, Power Plant Operator /Truck Driver, Truck
A Basic (spare man)
The Sound Locator
Acoustic location was used from mid-WW1 to the early years of WW2
the passive detection of aircraft by picking up the noise of the
It was rendered obsolete before and during WW2 by the introduction of
which was far more effective.
Before Radar, the Sound Locator was the first practical means of
detecting enemy airplanes at a distance in the night sky by listening
their engines with the aid of listening sound horns. The size of the
served to gather in and acoustically amplify more of the sound, and
increased the range of detection. The spacing of the horns aided the
binaural sense in determining the plane's direction.
Below is a photo of one of the last Sound Locator unit that was
used during World War II, Model M-1, made by Sperry Corp. The azimuth
listened to the left and right horn for direction information, and the
elevation operator listened to the top and bottom horns for elevation
There was also the Acoustic Correction Operator to compensate for sound
delay. As the operators pointed this large hearing device, their
direction and elevation movement would generate electric signals
that would be sent to the searchlight control station, or to the
searchlight directly, using a selsyn system. During the
of the war, radar was invented and during the war eventually replaced
sound locators to detect aircraft. When replaced by radar, Sound
Locators were then placed in the field as decoys to let the enemy think
sound locators were still being used instead of radar.
Sound locators were built by the Sperry Corp. Sperry's wartime
was significant. By1943, the company was manufacturing 300 different
for the war effort, two-thirds of which had been developed within the
ten years. The sound locator picks up approaching planes before
are visible and determines their exact position, speed, and direction
flight. Simultaneously, the anti-aircraft director, functioning as a
mechanism, determines the direction, elevation, and setting required to
aim the anti-aircraft gun at the approaching airplane and transmits
information automatically to the guns through a remote control system.
Not only did Sperry invent and manufacture these products during
the six-year period from 1939 to 1945, Sperry also ran in-house schools
where they housed, fed, and trained over 77,000 military and naval
in the use and maintenance of Sperry equipment.
1941 Sperry Searchlight and Model M1 Sound Locator
Note the very large hoses going to the operators
The sound was not electrically amplified to the operator, but
coupled to the operators ears using hoses like the stethoscope a doctor
uses to listen to your heart.
Below are early 1927-1935-model sound locators .
had 4 horns. One operator listened to the left and right
for direction information, and the other operator listened to the top
bottom horns for elevation information. These units were used
the early 20's
Below are Sound Locators used by other Countries
Other Locating Devices that were used in place of
the Sound Locator in aiming the Searchlight
Heat Detecting Locator
Heat detectors were used to locate enemy aircraft. Looking like a
this device swept the sky to detect heat from the engines of enemy
Thermopiles and control equipment designed by the Signal Corps
were mounted in a mechanical structure previously built by the
Electric Company on an Engineer Contract. As operated in 1937, the
detector received directional data from the radio equipment and
turn controlled the pointing of a searchlight.
As the war, and technology progressed, the new invention of
was added to the list of Locator devices used to point the Searchlight
to light up enemy aircraft targets. It was Radar that eventually
made the searchlight battery obsolete in tracking enemy aircraft.
Searchlight Control Station
Once enemy aircraft was located by the Sound Locator, the Control
Station was used to aim the searchlight visually by remote control. The
control station was placed several hundred feet away the searchlight in
order to see illuminated aircraft better. The beam was so bright,
if you were right next to the searchlight, you would mostly see
atmosphere in the path of the beam. This distance was also
for safety. You do not want to be next to a searchlight pointed into
sky full of enemy aircraft as these lights also make great targets.
Electric signals from the Sound locator was sent to the
control station using a selsyn type system to send control signals to
zero locator meters that were on top of the station. Two of
the operators, looking at zero locator meters, one for direction and
for elevation, would watch these meters and keep the meters on a zero
using hand cranks on the side of the unit. Keeping these meters set at
zero would keep the control station and searchlight in sync with
the same direction and elevation as the locator device tracked enemy
The Commander was the third man on this station, and wass
the observer. With the observers head in a harness, and using
attached to the station, as the station was aimed by the other two men
following the zero locator meters, the observer was forced to visually
look at the same direction and elevation that the locators were aimed
Once the observer was able to spot the enemy aircraft, he would then
full control of the station using the crank controls located in front
him. These controls were directly connected to the same crank controls
the two other operators used to aim the station. Using the
station, he would now send Selsyn signals to the searchlight so it
track the observers actions. The observer could also throw a
on the control station so the searchlight could take Selsyn control
directly from the locator device whether it be a sound, heat, or radar
Finally, the signals from the control station or sound locator are
to the searchlight. Here, the searchlight operator maintains the light
mechanism. He assures that the carbons are burning correctly, the beam
is focused, and is the one who throws the switch to start the arc
on command given by the control station Commander..
In the event of a communication failure, he may also control the
aim of the light by hand control. This is done by using a long,
foot rod with a wheel on the end. With this rod he can walk the
in the direction he wants and turn the wheel to the elevation he wants.
The 10 foot distance give him a better view of the object away from the
After the War
After W.W. II, Radar had taken over the job the searchlight once had
in spotting and tracking enemy planes. The military kept some
that were used as spotlights through the Korean War, but most of the
were scrapped and sold to the public to be used for the next 60 years
searchlights in the outdoor advertising industry for the promotion of
Openings, sales, and special events..
to see my restored GE Searchlight ......