Want a better, more informative version of this article? Check this out! The ACA Penetrator-50 is the largest of ACA's Penetrator series of sirens, and is a large rotating electromechanical siren. It later became known as the T-135AC after ACA became ASC.
The ACA P-50 is effectively an ACA Cyclone 120 flipped on its side with a rotator and projector attached, which allows the siren to boast an incredible 135db at 100ft. This makes the P-50 the loudest electromechanical siren ever made, and the second loudest in general. The siren came only in 8/12 port, is powered by a monstrous 50HP motor, and the entire projector is rotated by a large chain-driven rotator using a separate motor. The ACA P-50's controller causes it to stop rotating whenever it winds down, causing it to stop continually during the attack signal. The P-50 uses a directional rotor, so reverse wiring it harms sound output.
The P-50 was introduced with the rest of the Penetrator series in 1980, and was advertised as being large enough for an adult man to stand inside of. These advertisements proved effective, as many P-50s were produced and sold across the US, especially in Illinois and Wisconsin. In 1991, ACA went under and became ASC, and the P-50 was renamed to the Tempest-135AC and was sold again until 2007. There are no differences between the P-50 and the T-135AC other than the controller used and the decals placed on it. Due to their controller, T-135ACs often do not stop rotating upon winddown.
Early P-50s used a slightly different horn, with a different horn design. This was quickly changed to the design it used for the rest of its production run. P-50s are extremely huge, dwarfing any siren placed next to it. It is so large that an adult man can stand inside the horn without having to crouch.
An early production P-50. Note the different horn design compared to later units. Located in Morrison, IL.
Despite their age, P-50s continue to serve many cities as they are effective and reliable. The siren was finally discontinued in 2007 in favour of ASC's Tempest-135AC/DC, which allowed similar (although not as much) sound output while also boasting battery backup.