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History of the Delta Launch Vehicle

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To Reach the High Frontier: A History of U.S. Launch Vehicles

"A valuable contribution to the field of aerospace literature," this book includes an extensive overview of Delta history and development along with chapters on Atlas, Titan, Scout, Space Shuttle, and much more.

Order the book today


Many other excellent books about spaceflight are recommended here.



What about Delta IV?

(a note from the author)

After much hand-wringing, vacillation, and rationalization, I have made an editorial decision not to include Boeing's new Delta IV on this web site. This is not to imply that I am not excited by this vehicle, as I followed its development with great interest and it has proved itself with dozens of successful launches.

Delta IV has been designed for low cost and reliability, two touchstones of the Delta program since its inception. Its manufacture utilizes many of the techniques perfected by Douglas, McDonnell Douglas, and Boeing over four decades, and in flight the vehicle is guided by the same high-precision RIFCA avionics system used by Delta II and III. Boeing marketing images even depict Delta IV in the same light blue paint scheme that has become a virtual trademark of Delta (though so far the Common Booster Cores have all been orange).

However, I will contend that Delta IV is a Delta in name only, for a number of reasons:


    Delta II, and the oxidizer tank of Delta III, continued to use the same 8-foot-diameter dimension of the original Thor-Delta (though the tanks were considerably longer). Delta IV's Common Booster Core is 16.25 feet in diameter, more than twice that of a Thor.

    Main Engine and Fuel

    Though its lineage is somewhat convoluted, the Rocketdyne RS-27A is a direct descendant of the original MB-3 main engine, and continues to use the same fuel/oxidizer combination of kerosene (RP-1) and oxygen. Rocketdyne's RS-68 is a brand-new engine that owes much of its design philosophy to the Space Shuttle Main Engine, and like that engine, it burns hydrogen and oxygen.

    Erection process

    Same as ever, Delta II and III were assembled upright at the pad using cranes, a process that admittedly consumes a great deal of on-pad time. Delta IV is assembled in its Horizontal Integration Facility, then trucked to the pad to be raised to vertical by a hydraulic lift. Boeing expects this to reduce on-pad time by a factor of 2 to 3.

    Launch Sites

    SLC-17 at Cape Canaveral and SLC-2 at Vandenberg were both originally built as test pads for the Thor IRBM, and were converted for use by Thor-Delta. For Delta IV, two sites have been brought out of mothballs: Canaveral's Pad 37, which hosted eight unmanned Saturn I and IB rockets before it was mothballed in 1972; and Vandenberg's SLC-6, a site first built for the Air Force's Manned Orbiting Laboratory that was later intended to support polar-orbiting Space Shuttle launches.

Therefore, with its new tankage, main engine, choice of fuel, erection process and launch sites, Delta IV should be considered a separate family from Delta II and III. As a result, I have chosen to keep this site focussed on the small-to-medium capacity vehicles that were justifiably known as "the workhorse of space."

Last update 21 March 2016.

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History of the Delta Launch Vehicle by Kevin S. Forsyth