The S-IVB had earlier also been used as the second stage of the smaller Saturn IB rocket, such as the one used to launch Apollo 7. The Centaur upper stage was first designed and developed for launching the Surveyor lunar landers, beginning in 1966, to augment the delta-V of the Atlas rockets and give them enough payload capability to deliver the required mass of the Surveyors to the Moon. More than 100 Convair-produced Atlas-Centaur rockets (including those with their successor designations) were used to successfully launch over 100 satellites, and among their many other outer-space missions, they launched the Pioneer 10 and Pioneer 11 space probes, the first two to be launched on trajectories that carried them out of the Solar System. In addition to aircraft, missiles, and space vehicles, Convair developed the large Charactron vacuum tubes, a form of cathode ray tube (CRT) computer display with a shaped mask to form characters, and to give an example of a minor product, the CORDIC algorithms, which is widely used today to calculate trigonometric functions in calculators, field-programmable gate arrays, and other small electronic systems. General Dynamics announced the sale of the Missile Systems segment of Convair to Hughes Aircraft Company in May 1992 and the Space Segment to Martin Marietta in 1994. In July 1994, General Dynamics and McDonnell Douglas mutually agreed to terminate Convair's contract to provide fuselages for the 300-seat MD-11 airliner. Manufacturing responsibility was to be transferred to McDonnell Douglas, which said it would not preserve the operation in San Diego. General Dynamics had tried for two years to sell the aircraft structures segment of Convair unit, but the effort ultimately failed. The termination of the contract meant the end of the Convair Division and of General Dynamics' presence in San Diego, as well as the city's long aircraft-building tradition. The defense contractor once employed 18,000 people there but after selling its divisions, that number is now zero. General Dynamics closed its complex in Kearny Mesa, demolishing the facility between 1994 and 1996. Homes and offices now occupy the site. The Lindbergh Field plant that produced B-24s during WWII was also demolished and the consolidated rental car facility now occupies this space. The Fort Worth, Texas factory, constructed to build the B-24 Liberator bomber, and its associated engineering locations and laboratories—all previously used to make hundreds of Consolidated B-24 bombers, General Dynamics F-111 Aardvark fighter-bombers and General Dynamics F-16 Fighting Falcon fighters, along with dozens of smaller projects—were sold, along with all intellectual property and the legal rights to the products designed and built within, to the Lockheed Corporation.