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Fifty-two years ago this month, the United States successfully tested a USAF/Douglas Thor missile for the first time.   Thor Vehicle 105, launched from Launch Complex 17 at Cape Canaveral, flew 1,100 miles down the Eastern Test Range (ETR) on Saturday, 21 September 1957.

Named after the Norse god of thunder, the Thor (PGM-17A) was designed as a nuclear-armed Intermediate Range Ballistic Missle (IRBM).  Operational Thor missiles were armed with a single W49 nuclear warhead having an explosive yield equivalent to 1.44 megatons of TNT.

The Thor measured 65 feet in length and had a maximum diameter of 8 feet.  Weighing 110,000 pounds at lift-off, the test vehicle climbed-out on 150,000 pounds of thrust generated by its single Rocketdyne LR79-NA-9 first stage rocket motor.  The powerplant used LOX/Kerosene propellants and had a nominal burn time of 165 seconds.  Specific impulse was around 280 seconds.

Following development flight testing, the Thor would become the first operational ballistic missile deployed by the United States.  Sixty Thor missiles were tended by twenty RAF missile squadrons scattered throughout the United Kingdom from 1958 through 1963.

Although its tour of duty was brief, the Thor served as an effective deterent to Soviet agression until the arrival of the first true Intercontinental Ballistic Missiles (ICBM).  Interestingly, the Thor IRBM would become the basis for the first Delta launch vehicles, descendants of which remain in active service up to the current day.

Posted in Aerospace, History

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