The Titan IIID or Titan 3D was an American expendable launch system, part of the Titan rocket family. Titan IIID was flown 22 times with KH-9 and KH-11 satellites between 1971 and 1982, all successful launches. Essentially a Titan IIIC with the Transtage removed, it was designed for heavy LEO payloads.
The rocket had two UA1205 solid fuel boosters, the first stage was equipped with two LR-87-AJ11 engines and the second stage had a single LR-91-AJ11 engine.
Part of the Titan rocket family, the Titan IIID first flew on 15 June 1971, launching the first KH-9 satellite. It was retired from service in 1982, and replaced by the uprated Titan 34D. All launches occurred from Space Launch Complex 4E at Vandenberg Air Force Base.