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Delta 3
Delta 3 - Delta 3 on the pad before its first launch attempt.

Credit: Boeing. 12,783 bytes. 122 x 374 pixels.


The Delta space launch family had its roots in the Thor IRBM. Thor was a 2400 km range missile with essentially the same characteristics as the Army’s Jupiter. It was developed by Douglas Aircraft in one of the most accelerated crash programs in history. ‘Chief Designer’ of the Thor was Jack Bromberg. He was not educated formally as an engineer, but was smart and dynamic. Company owner Donald Douglas had hired him back in the 1930’s. He was a major influence in Douglas’ winning response to the USAF request for proposal, which emanated from USAF Missile Czar General Bernard Schriever.

The Air Force requirement was to build an IRBM around a discarded rocket motor design. The engine had been developed as the sustainer engine for the Atlas missile when the requirement was to launch a 2700 kg thermonuclear warhead over an intercontinental range. When it became apparent that the warhead could be reduced to less than half that weight, the Atlas was downsized, and the 68 tonne thrust sustainer motor was no longer required.

Douglas flew a first prototype only thirteen months after go-ahead. Sixty Thors were deployed to missile sites in Great Britain under Project Emily. Philip Payne worked for Rocketdyne as their manager in England. He recalls:

Those days I worked for Rocketdyne as the manager in England of Project Emily. Our mission: get 60 Thors aimed at Khrushchev’s privates. Things were going badly for lots of reasons, many of them lack of earnest concentration by many Americans in corporations as well as USAF. I was p....d and often loudly said so.

One day a dignified, little American man came to me at Feltwell, Cambridgeshire, England, site of the first squadron (if we could ever get it installed and checked out) and told me he heard I was the one to talk to find out what was wrong. I was bad on names then, in my youth and so for hours as I laid it on him, I did not realize until late in the day I was talking to the American Secretary of Defense, Charlie Wilson.

I was so unpolitical an engineer turned executive, that I did not bother to tell my company of this until, receiving a muted blast vis á vis Douglas, they told me. Douglas sent over Bill Duval to replace Earl Neff.....

Thereafter things improved. After a few years the Thors were withdrawn from Britain (and the Jupiters from Turkey) as part of the secret codicil of Kennedy’s deal to end the Cuban Missile Crisis. A few continued in an offensive military role as a nuclear-tipped anti-satellite system, based on Johnson Atoll in the Pacific, until the end of the early 1970’s. Surplus Thors were used for a variety of suborbital reentry vehicle tests.

Equipped with upper stages, stretched, and augmented with small solid propellant strap-on booster rockets, the Thor developed into the standard American medium-lift launcher. Through a myriad of versions it emerged as the reliable and economical Delta commercial satellite launch vehicle by the mid-1960’s. Improved Delta versions continued in production into the next millennium, with over 700 airframes completed, and no end of production in sight.


Launch Vehicle: Thor. Thor IRBM with no upper stage.

Launch Vehicle: Thor Able. Thor with Able stage derived from Vanguard second stage.

Launch Vehicle: Thor Agena A.

Launch Vehicle: Thor Able-Star.

Launch Vehicle: Thor Agena B.

Launch Vehicle: Delta. Commercial name for the military's Thor-Delta. The name of the Delta second stage eventually was applied to subsequent commercial follow-ons.

Launch Vehicle: Delta A.

Launch Vehicle: Delta B.

Launch Vehicle: Thor Agena D.

Launch Vehicle: Delta C.

Launch Vehicle: TA Thor Agena B. Thor Agena B upgraded with addition of three Castor 1 strap-on motors.

Launch Vehicle: TA Thor Agena D. Thor Agena upgraded with addition of three Castor 1 strap-on motors.

Launch Vehicle: Delta D.

Launch Vehicle: Delta E.

Launch Vehicle: Thor Burner.

Launch Vehicle: Delta G.

Launch Vehicle: LT Thor Agena D. Thor Agena upgraded with Long Tank Thor stage. Variant with straight tank from Delta was Thorad (Long Tank Augmented Thrust Thor Delta)

Launch Vehicle: Thorad Agena. Thor Agena upgraded with Extended Length Tank Thor stage,

Launch Vehicle: Delta J.

Launch Vehicle: Delta M.

Launch Vehicle: Delta N.

Launch Vehicle: Delta L.

Launch Vehicle: Delta 100.

Launch Vehicle: Delta 1914.

Launch Vehicle: Delta 2914.

Launch Vehicle: Delta 3914.

Launch Vehicle: N. Licensed version of Delta built in Japan using both US and Japanese components.

Launch Vehicle: N-2. Licensed version of Delta built in Japan using both US and Japanese components.

Launch Vehicle: Delta 3925.

Launch Vehicle: Barbarian MDD.

Proposed launch vehicle for large SDI 'Star Wars' payloads. Expected to cost $ 400-500 million, the Barbarian could place the Zenith-Star chemical laser into low earth orbit. It would consist of 3 Shuttle SRM's, attached around a ring of six Delta RS-27 first stage boosters, which in turn clustered around a single Delta first stage booster that was the last stage of the launch vehicle.


Launch Vehicle: Delta 4920.

Launch Vehicle: Delta 5920.

Launch Vehicle: Delta 6925.

Launch Vehicle: Delta 7925.

Launch Vehicle: Delta 3.

Launch Vehicle: Delta IV Large. 5 m diameter payload fairing.

Launch Vehicle: Delta IV Medium. 4 m diameter payload fairing.

Launch Vehicle: Delta IV Medium+ (4, 2). 4 m diameter payload fairing.

Launch Vehicle: Delta IV Medium+ (5, 2). 5 m diameter payload fairing.

Launch Vehicle: Delta IV Medium+ (5, 4). 5 m diameter payload fairing.

Launch Vehicle: Delta IV Small. 2 m diameter payload fairing.

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Last update 3 May 2001.
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© Mark Wade, 2001 .