The Thunderbolt siren is a warning siren that was once manufactured in the United States by Federal Signal Corporation. The Thunderbolt siren consists of three major components: the blower, rotator and siren chopper. The blower, which is made up of a motor-driven Roots-type supercharger, supplies the large volume of air for the siren head. It is housed inside a large rectangular box typically found at the base of the siren head. The blower is connected to an air standpipe which pumps 250 cubic feet per minute of air at 6-7 psi up to the siren head. The rotator is a motor-driven gear unit which rotates the directional horn/projector to direct the sound in all directions. The chopper is located in the cylindrical housing that the horn/projector attaches to at the top of the siren. The siren chopper motor in the Thunderbolt siren is actually the same siren motor used in the Federal's Model 2 siren. The siren chopper in the Thunderbolt operates in the same manner as any conventional siren. As the chopper rotor spins air pulses are generated by the rapid opening and closing of the chopper openings. This generates the sound the siren makes. The primary difference in the Thunderbolt siren is that the air supplied by the blower is pumped through the siren resulting in a greatly increased sound volume and distinct sound generated by the Thunderbolt siren.
The Thunderbolt siren is operated by a control panel called an RCM Panel. This panel consists of the three relays that switch the three components of the siren on and off. The RCM panel also has a time delay relay and circuit. This time delay section keeps the blower and rotator operating in the attack signal while the siren chopper motor is switched on and off which produces the up-and-down pitch of the attack signal. With the blower and rotator operating as the siren motor is switched on and off the Thunderbolt maintains a high level of sound output. An additional important feature of the RCM panel is a transformer in the siren/chopper electrical circuit. This transformer has seven different voltage taps from 120 volts up to 240 volts. This allows the top pitch of the siren to be changed as desired when the siren is installed. A siren with the chopper connected to the 120volt transformer tap will sound at a lower top pitch than a siren connected at the 240volt transformer tap.
The Federal Thunderbolt was the siren of choice by many Civil Defense authorities and emergency management agencies from the early 1950s through the late 1970s. The main marketing point of the Thunderbolt by Federal Signal was the fact that the siren, since it uses a blower to move air through the siren rotor, maintains a high sound output at all siren pitches when the siren is in operation. Normally aspirated sirens lose sound output because of the reduced air flow through their rotors as the siren runs down during the coast down during the wail or attack signal. Since the Thunderbolt was introduced in 1952 during the beginning of Cold War tensions as primarily an attack warning siren the high volume during all phases of the attack signal was stressed in advertising the siren by Federal. The attack signal was a series of wailing tones to alert of immediate danger. One of the most distinguishing features of the Thunderbolt siren's sound is the dramatic volume in the down-pitch phase of the signal. It's usually this part of the signal that carries the farthest and is the most "attention-getting."
With the discontinuation of federal matching funds for civil defense equipment in the late 1970s-early 1980s the sales of the Thunderbolt siren declined. The Thunderbolt was a very expensive siren to purchase new. The January 1, 1979 Federal Signal Price List lists the price of a new 1000 Thunderbolt siren from $6684.25 up to $7716.75 depending on the model. In addition to that the necessary control panels to operate the siren were $837.00 for the main motor control panel and $236.00 for the additional control panel needed to operate the 1003 model of Thunderbolt.
Federal's development of new types of sirens also led to the end of the Thunderbolt. In Late 1988, Federal Signal introduced a new single-tone siren called the 2001 Series. This siren can utilize a DC (battery) backup power feature, enabling the siren to be operated during a power failure, operates on only 2 motors, and requires far less maintenance. As the Thunderbolt only operates on AC power, the introduction of the 2001 Series spelled the end of the Thunderbolt siren, and Federal Signal phased out the Thunderbolt series, as well as many other of its sirens, by 1990.
The Thunderbolt was first produced by Federal Enterprises (now Federal Signal Corporation) in 1952 and its use continued through the Cold War.
- Model 1000, a single-tone siren capable of two signals (alert and attack). (126dB at 100 feet)
- Model 1000T, a dual-tone version of the 1000.
- Model 1003, a dual-tone version with the added capability of producing a High-Low signal with solenoid valves.
- Model 2000, A Single tone thunderbolt 1000 with a gasoline powered Roots Blower
The "System 7000" line  was a generator back up version of the Thunderbolt. These were available as 3 separate models:
- Model 7012, a single tone siren capable of two signals (alert and attack).
- Model 7022, is the same as Model 7012, but is dual tone.
- Model 7026, which uses a dual-tone Thunderbolt siren to produce six siren signals: wail, pulsed steady, steady, alternating steady, alternating wail, and pulsed wail.
The Jailbar thunderbolts were the earliest thunderbolts made, with bars in the horn to keep birds from nesting in the horn. They are rare to find because the horn design was changed in the mid to late 1950s from Jailbars to a screen instead. The most common type of Jailbar thunderbolt in original condition is the single tone 1000A, but they made few dual toned Jailbar 1000ATs. All Jailbars were fitted with either an A1 blower or a Gas powered blower. These were not specifically ordered models.
In popular culture
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- In 1959, Chicago Fire Commissioner Robert J. Quinn ordered his fire chief to sound the city's civil defense alert sirens (all Thunderbolts at the time) at the moment the White Sox won the pennant, prompting many unaware citizens to be alarmed of an air raid or nuclear attack.
- The siren was featured in many Civil Defense films including one from the early 1950s titled Let's Face It (a close up of a single tone 1000 painted black and yellow sounding the alert signal with an added in sound effect).
- In 2011, the History Channel show American Restoration featured a restoration of a Thunderbolt 1000T for a museum in Nevada.
A Thunderbolt 1000AT in Topeka, Kansas
Federal Thunderbolt 1003 Siren located at the Massie Township Fire Department in Harveysburg, Ohio.
Cities using the Thunderbolt Siren
Honolulu, HI Many standing, all operational 1000T Denver All have been removed as of Wednesday, July 24, 2013. 1000,1000T,1003 Scottsbluff, NE All In the process of being replaced. 3 still remain, operational 1003 Lake Odessa, MI 1 standing, Operational 1003 Glassport, PA Thunderbolts have been replaced 1000T Bayard, NE 1 standing, operational 1003 Willard, OH 2 standing, Operational 1003 Brush, CO At least one standing, operational. 1003 Constantine, MI 1 standing, Operational 1003 Cincinnati, OH Many Standing, All Operational. 1000,1000T,1003 Hamilton, OH 7 Standing, All operational 1000T Minneapolis Thunderbolts have been replaced. 1000,1000T Woodstock, OH 1 standing, Operational. 1003 Allegan, MI 1 standing, operational 1003 Sheboygan, WI 1 or more standing, operational 1000T Marshfield, WI Inactive, No Horn. 1003 Imperial, NE 1 standing, operational. 1003 Delphos, OH 2 standing, all operational. 1003 Shamrock, TX Still operational but broken rotator and never repainted and does not have a blower. 1003 Neola, IA 1 operational. 1000T Axtel, NE 1 standing, operational. 1003 Harrodsburg, KY 1 standing, operational, Hi-Lo used for tornado warnings. 1003 Mechanicsburg, OH 1 standing, operational. 1003 West Jefferson, OH 1 standing, operational 1003 Jonesville, MI 1 standing, operational 1003 Standish, MI 1 standing, operational 1003 Falls City, NE 1 standing, operational. 1003 Columbus, NE 1 standing, operational. 1003 Hastings, MI 1 standing, operational. Hi Lo used for Tornado warnings. 1003 Clarence Center, NY Thunderbolt removed and replaced with A Newer Siren Model. 1003 Alton, NY 1 standing, operational and always sounds Hi Lo For Tests and Severe Weather Warnings. 1003 Worthington, MN 2 Standing, Both operational. Hi Lo Used for Tornado Warnings. 1003 Hastings, NE Several Standing, Most Likely Operational. 1000,1000T,1003 Valentine, NE 1 standing, operational 1000T Westmont, NE 1 standing, operational 1000T St. Peter, WI 1 standing, operational 1000T Bellchester, MN 1 standing, operational 1003 White Bear Lake, MN 2 standing, Both operational. 1003 Bloomington, MN 1 standing, operational 1003 Mendon, MI 1 standing, operational but is sick. 1000T Beebe, AR 1 standing, operational. 1003 Moore, OK Several standing, all operational 1000T Dallas, TX Thunderbolts have been replaced. 1000,1000T Spearman, TX 1 standing, operational, Hi Lo used for tornado warnings. Siren 1st recorded in 1990. 1003 Hudson, MI 1 standing, operational 1003 Otsego, MI 1 standing, operational. 1003 Moores Hill, IN 1 standing, operational 1003 Lebanon, OH 1 standing, Inactive and next to a FS 2001. 1003 Napoleon, OH 2 standing, all operational 1000T Wapakoneta, OH 5 standing, all operational, Hi Lo used for tornado warnings. 1003 Creighton, NE 1 standing, operational 1003 Central City, NE 1 standing, operational and atop a Sentry 3V8. 1003 St. Paul, NE 1 standing, operational. 1003 Orange City, IA 1 standing, operational 1003 Walnut, IA 1 standing, operational 1000T Rosemont, MN Several standing, all operational 1000T Worthington, MN 2 standing, operational 1003 Defiance, OH Thunderbolts have been dismantled. 1000T Belding, MI 1 standing, operational. 1003 Albion, MI 1 standing, operational. 1003 Indianapolis, IN Thunderbolts have been dismantled. 1000T Elkhart, IN 5 standing, All operational. 1000, 1000T Melvindale, MI 1, in the process of being replaced. 1003 Redford, MI Thunderbolts have been replaced. 1000, 1000T Harper Woods, MI Thunderbolts have been replaced by FS-2001-130 sirens. 1000T Wisconsin Dells, WI Replaced with a ASC T-121 siren. 1003 La Crosse, WI In the process of being replaced. 1000,1000T Tinley Park, IL 8 standing, all operational 1000T,1003 Lebanon, IL 1 standing, operational 1003 Matteson, IL Thunderbolts have been replaced by FS-2001-130s. 1000T River Forest, IL Thunderbolts have been dismantled. 1000T Canton, MI Thunderbolts have been replaced with ASC-T-128 sirens. 1003 Carrollton, MI 2 standing, all operational but in the process of being replaced. 1003 Pawnee City, NE 1 standing, operational. 1003 Manchester, NY 1 standing, operational. 1000T Marmet, WV 1 standing, inactive. 1003 Christianburg, OH 1 standing, operational 1003 Centerville, OH Thunderbolts have been dismantled. 1000T Harveysburg, OH 2 standing, all operational 1000T,1003 Marlette, MI 1 standing, operational. 1003 Arthur, NE 1 standing, operational and right next to a Sterling M-5. 1000T Venedocia, OH 1 standing, operational 1000T Lapeer, MI 1 operational. 1003 Detroit 9 standing, all operational. 1000, 1000T Decatur, IN 1 standing, operational 1000T New Castle, IN 1 standing, operational 1000T Caledonia, NY 1 standing, operational 1003 Bremen, IN 1 standing, operational 1000T Eaton, OH Thunderbolts have been replaced. 1003 Batavia, OH 1 standing, operational 1000T Auburn, IN 4 standing, all operational 1003 Lansing, KS 1, replaced. 1003 Topeka, KS Thunderbolts have been dismantled 1000, 1000T Wichita, KS Several standing, all operational 1000,1000T Lenexa, KS 1 standing, operational 1000T Sterling, CO 1 operational 1003 Grand Island, NE Several Standing, All operational 1000,1000T,1003 Syracuse, NE 1 standing, operational but next to a FS-2001. 1003 Julesburg, CO 1 standing, operational 1003 Omaha, NE All have been replaced. 1000,1000T Belluvue, NE Replaced with FS 2001 sirens. 1003 Rosewood, OH 1 operational 1003 Bardstown, KY 1 standing, operational but next to a Whelen 4004. 1003 Muncie, IN Several standing, all operational. 1000,1000T Plymouth, MI Thunderbolts have been replaced 1000,1000T Temperace, MI 1 still operational 1003 Somerset, KY 1 standing, operational 1003 Paducah, KY 8 standing, all operational 1000T Brunswick MO 1 standing, operational 1003 Ninety Six, SC 1 operational. 1003 Newberry, SC One Standing, Operational. 1003 New Hope, MN 1 standing, operational 1003 St Paul, MN Thunderbolts have been replaced 1000 St. Cloud, MN Several standing, all operational 1000,1000T Fremont, NE 2 operational 1003 Wood River, NE Thunderbolt replaced with a ASC T-128. 1003 Kennesaw, NE 1 standing, Operational, Next to a Banshee. 1003 Shenandoah, IA 1 operational 1003 Kirkwood, MO 1 standing, operational 1000T Gary, IN 2 standing, all operational 1000T Holtsville, NY 1 standing, operational 1003 Copiague,NY 2 used for fire calls. 1003 Riverview, MI 1 standing, operational 1000 Grand Rapids, MI 1 standing, operational 1000T Grand Blanc, MI 1 operational 1000 Grosse Point Woods, MI 1 standing, operational 1000T Northville, MI 1 standing, operational 1000 Charlotte, MI 2 standing, both operational, 1 without blower. 1003 Tooele, UT 1 standing, operational 1003 Sandersville, MS 1 standing, operational 1003 Dickinson, ND All have been replaced 1003 Aitkin, MN 1 standing, operational 1003 Fostoria, OH Several standing, all operational 1000,1000T Newark, OH 1 standing, operational 1000 Fairfield, OH Thunderbolts have been replaced 1000T,1003 Georgetown KY 1 standing, operational, tested for over 8 minutes in April 2012. 1000T Ft Thomas, KY At least 1 standing, operational 1000T Lansing Township, MI 3 standing, all operational 1000,1000T,1003 Lansing, MI Several standing, all operational 1000,1000T Carbondale, IL 1 standing, operational 1000T Sandwich, IL 1 standing, operational 1000T Pontiac, IL Several standing, all operational 1000T Chicago Heights, IL 1 standing, In the process of being replaced. 1003 Waukegan, IL A few standing, status unknown. 1000T Nashville, TN All have been replaced. 1000 West Frankfort, IL 1 standing, operational 1000T Murraysville, PA At least 1 standing, all operational 1003 Somerset, PA 2 standing, all operational 1003 Palmyra, NY 1 standing, operational 1003 Laguardia Airport, NY 2 standing, all operational 1003 Holland, MI 2 standing, all operational 1000T Kalamazoo, MI 1 standing, operational 1000T Battle Creek MI 1 standing, operational 1000 Warren, MI 1 standing, operational 1000 Berlin, WI 2 standing, operational 1000,1003 Ames, IA 2 standing, operational 1000T Des Moines, IA Thunderbolts have been replaced. 1003 Cedar Rapids, IA All have been removed and replaced. 1000 Austin, MN Thunderbolts have been dismantled. 1000T Red Wing, MN Thunderbolts have been replaced. 1000T Burlington, KS 1, replaced with an ASC T-128. 1003 Boulder, CO 1, inactive. 1000 Amarillo, TX 2 standing, operational 1000 Little Rock,AR Many standing, All inactive. 1000,1000T,1003 Jonesboro, AR Several standing, all operational 1000,1000T Morris, IL Thunderbolts have been replaced. 1000 Murphysboro, IL All have been replaced with FS-Modulator sirens. 1003 Dickson, TN 1 standing, operational but privately owned. 1000T Memphis, TN Several standing, all operational 1000,1000T Champaign, IL Several standing, all operational 1000T Bloomington, MN 1 standing, operational 1003 White Bear Lake, MN 2 standing, both operational 1003 Lakeville, MN A few standing, operational 1000T Peoria, IL Thunderbolts have been replaced. Unknown model. Frankfort, KY 6 standing, all operational 1000T Louisville, KY 34 standing, All but one operational 1000,1000T
Civil Defense Siren