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Home > Fact Sheets > Martin SM-68 Titan I


Posted 7/8/2009 Printable Fact Sheet

The two-stage Titan I, together with the Atlas, comprised our nation's first generation of liquid-fueled, strategic, intercontinental ballistic missiles. Operational Titan Is contained an all-inertial guidance system to direct the nuclear warhead to the target. Liquid propellants for the Titan I's Aerojet rocket engines were kerosene fuel and liquid oxygen. The HGM-25A (silo-stored, surfaced-launched, ground attack missile), formerly known as the SM-68 (Strategic Missile), was the first USAF ICBM to be placed in hardened underground silos for protection against enemy attack; however, they had to be lifted from their silos to the surface by elevator prior to launching.

The USAF launched its first test Titan I on Feb. 6, 1959, and in April 1962 the first Strategic Air Command squadron of nine Titan Is was declared operational. Eventually squadrons of Titan Is were deployed at five different bases in the western United States. By 1965, however, Titan Is were being phased out in favor of Titan IIs, which offered greater range and payload and were launched from within their silos. Modified Titan IIs also were used to launch the Gemini astronauts into space. The larger and more versatile Titan III, developed from the Titan II, became the third generation of Titan launch vehicles used by the USAF. The Titan III (and Titan 34D) had greatly increased payload lifting capacity provided by two strap-on solid rocket boosters, which combined with the LR-87 liquid-fueled first-stage engine, brought the total lift-off thrust to well over 1 million pounds.

The Titan IVB is the latest version in the Titan family of heavy lift vehicles in use by the USAF. It flew for the first time in February 1997.

The museum has a Martin Marietta SM-68A/HGM-25A Titan I on display in the Missile & Space Gallery.

Type Number built/
SM-68 - First generation ICBM

Note: The Martin B-68 Titan took over the designation after the Martin XB-68 bomber project was canceled. The B-68 Titan I was redesignated SM-68 and later changed to HGM-25A. The Titan I is easily distinguished from the Titan II by noting that the Titan I has a smaller diameter upper stage (the Titan II is constant diameter first and second stages).

Armament: Nuclear warhead
Engines: First stage powered by Aerojet LR87 two chamber liquid propellant rocket fueled by Kerosene and liquid oxygen (oxidizer) of 300,000 lbs. thrust; note that later versions of the LR87 were much more powerful and fueled by Aerozine-50 (fuel) that ignites on contact with nitrogen tetroxide (oxidizer); second stage powered by Aerojet-General LR91 rocket engine of 80,000 lbs. thrust
Maximum speed: 15,000 mph / 13,904 knots
Maximum range: 6,300 statute miles / 5,475 nautical miles
Maximum altitude: 620 statute miles / 538 nautical miles
Length: 98 ft. 4 in. (ICBM configuration)
Diameter: 10 ft. (first stage) and 8 ft. second stage (ICBM configuration)
Weight: 201,500 lbs. at launch

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