Editing UGM-27 Polaris (section)

== Polaris A-1 ==
[[File:Polaris AX (AX-1) on pad LC-25A CCAFS - 1958-09-24.jpg|thumb|Polaris AX-1 on pad [[Cape Canaveral Space Force Station|CC]]&nbsp;LC-25A before its maiden flight, September 24, 1958]]

The initial test model of the Polaris was referred to as the AX series and made its maiden flight from Cape Canaveral on September 24, 1958. The missile failed to perform its pitch and roll maneuver and instead just flew straight up, however the flight was considered a partial success (at that time, "partial success" was used for any missile test that returned usable data). The next flight on October 15 failed spectacularly when the second stage ignited on the pad and took off by itself. Range Safety blew up the errant rocket while the first stage sat on the pad and burned. The third and fourth tests (December 30 and January 9) had problems due to overheating in the boattail section. This necessitated adding extra shielding and insulation to wiring and other components. When the final AX flight was conducted a year after the program began, 17 Polaris missiles had been flown of which five met all of their test objectives.

The first operational version, the Polaris A-1, had a range of {{convert|1400|nmi|km|abbr=off}} and a single Mk 1 re-entry vehicle, carrying a single W-47-Y1 600&nbsp;kt nuclear warhead, with an [[inertial guidance]] system which provided a [[circular error probable]] (CEP) of {{convert|1800|m|ft|abbr=off|sp=us}}. The [[two-stage]] [[solid propellant]] missile had a length of {{convert|28.5|ft|m|abbr=on}}, a body diameter of {{convert|54|in|m}}, and a launch weight of {{convert|28800|lb|kg}}.<ref>{{Cite web|url=https://academic.eb.com/levels/collegiate/article/Polaris-missile/60595|title = Britannica Academic}}</ref>

<!--A test launch from a U.S. Navy submarine on July 20, 1960, was the first submerged guided-missile launch (apart from German experiments during World War 2). (Not the first; the Russian Scud naval version had been launched from a submarine in September 1956, see http://www.astronautix.com/lvs/r11.htm )--><!---(Russian Scud launch was surfaced)-->
{{USS|George Washington|SSBN-598|6}} was the first fleet ballistic missile submarine ([[Ballistic missile submarine|SSBN]] in U.S. naval terminology) and she and all other Polaris submarines carried 16 missiles. [[41 for Freedom|Forty more SSBNs]] were launched in 1960 to 1966.

Work on its [[W47]] [[nuclear warhead]] began in 1957 at the facility that is now called the [[Lawrence Livermore National Laboratory]] by a team headed by [[John S. Foster, Jr.|John Foster]] and [[Harold Brown (Secretary of Defense)|Harold Brown]].<ref>{{cite journal|date=January–February 2002|title=Fifty Years of Innovation through Nuclear Weapon Design|journal=Science & Technology Review|pages=5–6|url=https://www.llnl.gov/str/JanFeb02/JanFeb50th.html|access-date=2008-11-17|quote=Livermore designers, led by physicists Harold Brown and John Foster ... the assignment in 1957 of developing the warhead for the Navy's Polaris missile ...|archive-url=https://web.archive.org/web/20081115183157/https://www.llnl.gov/str/JanFeb02/JanFeb50th.html|archive-date=2008-11-15|url-status=dead}}</ref> The Navy accepted delivery of the first 16 warheads in July 1960. On May 6, 1962, a Polaris A-2 missile with a live W47 warhead was tested in the "Frigate Bird" test of [[Operation Dominic I and II|Operation Dominic]] by {{USS|Ethan Allen|SSBN-608|6}} in the central [[Pacific Ocean]], the only American test of a live strategic nuclear missile.

The two stages were both steered by [[thrust vectoring]]. Inertial navigation guided the missile to about a 900&nbsp;m (3,000-foot) CEP, insufficient for use against hardened targets. They were mostly useful for attacking dispersed military surface targets (airfields or radar sites), clearing a pathway for heavy bombers, although in the general public perception Polaris was a strategic second-strike retaliatory weapon.{{citation needed|date=June 2009}}