Launch complex 18 is another dual pad complex supported by a single blockhouse. Built in the mid 1950s it was used mainly for launching the Vanguard satellites along with testing of the Thor rocket (on pad 18B).
Launch pad 18A saw 24 launches, mainly of the Vanguard rocket with Vanguard spacecraft. The first launch on December 8th 1956 was a Viking rocket with the Vanguard TV0 payload.
This was followed by a second Viking then the launch vehicle switched to the Vanguard for 11 flights. The climax of the Vanguard was an attempt to launch the first US satellite, the Vanguard TV3, on December 6th 1957. Unfortunately this was a dramatic failure with the rocket losing thrust and exploding after 2 seconds into the flight.
The final launches from Launch Pad 18a were Blue Scout Jr. launch vehicles with mostly magnetospheric satellite payloads. The final flight being June 9th 1965.
Launch Pad 18B witnessed its first launch on June 4th 1958, clocking up 23 launches before the last flight on April 12 1962. The main launch vehicle from this pad was the Thor DM-18 a rocket modified from the Thor ICBM to lift spacecraft into orbit. This was mainly a test phase in the development of the Thor as a viable launch vehicle. The Thor is a predecessor of the Delta II and Delta IV rockets that are currently in service.
As with launch pad 18A the final 6 flights from pad 18B were Blue Scout rockets with plasma radio astronomy payloads.
Launch complex 18 was deactivated on February 1st 1967.