Monday, February 20, 2012

ICBM transport

In the course of writing the book, there has been some discussion about whether transporting ICBMs was a primary design criterion for the C-133. In going through some Douglas material, I found the following:

A Douglas historical background, DAC-67975, states that the tentative initial configuration of what became the C-133 had the basic design mission to carry 50,000 pounds of cargo 1,500 NM with a takeoff distance of 5,000'. This was as of 8 Oct 1952. The final configuration was Douglas Model 1333, weighing 275,000 pounds, a mission radius of 1,500 NM at 260 knots with a 60,300 pound payload. A range mission would transport 42,000 poounds 3,500 NM at 360 knots.

The first mention of ICBMs was in connection with Letter Contract AF33(600)-32817, dated 31 Oct 56 (seven months after the C-133's first flight), in which the major change was the redesign of the aft fuselage for Atlas loading capability. The redesign gave increased loading clearances. The Douglas material makes no mention of ICBM transport as a mission requirement associated with any of the various contracts prior to 31 Oct 56.

An article in Aircraft and Missiles Magazine, written by Philip Geddes in August 1959, discusses the aft fuselage modifications. He notes that the three-door design of the C-133A was changed to "the four-door clamshell design of the C-133B. This modification gives nearly 13 ft headroom at the loading ramp wth 12 ft width; sufficient to ingest an Atlas ICBM."

Another document is "Background History of the C-133 Aircraft," prepared by the Directorate of Aerospace Safety, Norton AFB, CA, dated 20 Jan 65. It comments that "AMC studied the C-133's capability of transporting missiles, such as : the SM-65 and the intercontinental ballistic missile (ICBM) of the Atlas program." AF approval of the final shape of the Atlas occurred on 14 Jan 55. A major development and test contract was awarded to Convair on 14 January 1955 for a 10 foot diameter missile. Empty weight was 8,750 pounds. This configuration represented a smaller, lighter missile than first designed by Convair in 1953.

Given that the Formal Specification DS-1333 was submitted to AMC for approval on 1 Jun 53, while Convair was still working on the final Atlas configuration, in addition to the Douglas material cited above, I am convinced and comfortable with the conclusion that the C-133 WAS NOT originally designed to transport ICBMs, of which Atlas was the first. Such employment came later, after the capabilities of the C-133 became clear.

It is more likely that over-the-road requirements and the C-133's cargo envelope resulted in final ICBM dimensions rather than the reverse!

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