Titan IIIB

Titan IIIB was the collective name for five related American launch vehicles that put an Agena D upper stage on a Titan core: the Titan-3B Agena-D, the Titan 23B, the Titan 24B, the Titan 33B and the Titan 34B. The 3B Agena-D used a Titan IIIA core, the 23B a basic Titan III core, and the 24B and 34B the longer Titan IIIM core, while the 33B and 34B added an enlarged fairing that enclosed the Agena and its payload. All flew from Space Launch Complex 4W at Vandenberg Air Force Base, mainly carrying KH-8 Gambit 3 photo reconnaissance satellites, with Jumpseat signals intelligence satellites and military communications satellites also flown. The family was chosen over the Atlas used for the earlier KH-7 because it lifted more and its two-stage hypergolic design was simpler and more reliable. It suffered four outright failures and two partial failures over its run.