SM-65 Atlas Inter-Continental Ballistic Missile System 1956-1965
Avco Corporation
Mark 4 Re-Entry Vehicle for Atlas E/F
The Mark 4 (Mk 4) re-entry vehicle was an early ablative design developed for U.S. intercontinental ballistic missiles (ICBMs) in the late 1950's and deployed in the early 1960's. It was primarily used on the Air Force's Titan I and Atlas E/F missiles to carry and protect a nuclear warhead during the high-heat phase of atmospheric re-entry after being launched into space. The vehicle housed the W-38 thermonuclear warhead, which had an explosive yield of about 3.75 megatons. Manufactured by AVCO Corporation, the Mk 4 featured an aluminum inner structure coated with an ablative material—likely a phenolic resin or similar composite—that vaporized during re-entry to dissipate extreme heat and prevent structural failure. This ablative approach was a significant advancement over earlier heat-sink designs (GE MK2), allowing the vehicle to survive temperatures exceeding thousands of degrees while decelerating from hypersonic speeds. The overall design was conical, approximately 10 feet long and 4 feet in diameter, with a weight around 3,465 pounds including the warhead.
Avco Mark 4 Re-Entry Vehicle
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