CHRYSLER-BELL VICTORY SIREN SIMPLE IN FUNDAMENTAL PRINCIPLES;
The Chrysler-Bell Victory Siren, which produces the loudest continuous noise ever created by mechanical means.

SINCE the sole purpose of a siren is to produce sound by creating variations in the atmospheric pressure, the basic principle of the Chrysler-Bell Victory model is simple. This siren was achieved and is being produced by the Industrial Division of Chrysler Corporation, with the Bell Laboratories of New York collaborating on the basic design.

The apparatus comprises the siren proper or modulator unit, a blower to supply compressed air and a Chrysler automobile engine of 140 horsepower to drive both. It is mounted on a turntable platform that may be placed on top of a building or in any other elevated position where the sound waves will have a clear channel. This turntable has an arc of 360 degrees, giving maximum coverage in any given area.

The noise is created by a high-frequency disturbance of air, achieved by means of a "chopper" 25 inches in diameter, revolving with the minimum possible clearance across the openings of six rectangular throats. These in turn connect with the horn. Compressed air, under five pounds pressure at the rate of 2,500 cubic feet per minute, is introduced behind the "chopper." As the compressed air rushes towards the six vents, it is "chopped" off by the revolving blades, thus setting up the variations in pressure that cause the noise. The "chopper" revolves at the rate of 4,400 r.p.m. producing a frequency of 440 cycles per second in the interruptions of the air's escape.

Operating at full throttle, the siren produces 170 decibels of sound at the throat, diminishing relatively slightly to approximately 140 at 100 feet. Scientists estimate that 190 decibels of sound are the maximum that ever could be produced by any mechanical means, which would moan the continuing instantaneous reduction of full atmospheric pressure to zero. Thus the Chrysler siren with 170 decibels is close to "par." 

The engine operating blower, siren and turntable, is of the standard Chrysler eight-cylinder type with a bore of 3¼ inches and a stroke of 4-7/8 inches, giving 323.5 cubic inches piston displacement. The engine top operating speed is 3,400 r.p.m. but a planetary step-up type transmission raises this to 4,400 r.p.m, for the blower and modulator drive. Radiator, fuel tank, ignition system, starting motor and battery are complete with the engine.

Engine and transmission are connected by a Chrysler Fluid Drive unit of the same type used to transfer power from the engine to the drive train in Chrysler cars.