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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.



Frequently Asked Questions

What about Delta IV?
Boeing's new Delta IV rocket is not included on this site. This page explains the reasons why.

Do you have, or know of, similar websites for the Titan and the Atlas launch vehicles?
My research has only focussed on Delta, and I am not aware of any other active sites with similar specialization. For spaceflight in general, these sites are those I use regularly; all are run by contributors to this site:

I found your site during a search but can't find the information it quoted. Where is it?
Chances are, the search engine returned an item in "Current Delta News" that is no longer current. Since the news page is now RSS-enabled and searchable, this is no longer an issue.

Do you have more information of interest to model rocketeers?
Lots, but read on for the basics.

Do you have dimensions, measurements, etc.?
My first recommendation would be to check out Rockets of the World by Peter Alway, which is an excellent source and contains several different Delta models from representative phases in its development through Delta II. Unfortunately, it is out of print (and used copies are mindlessly expensive).

What colour is the Delta II?
The light blue paint of Delta II is Federal Standard 595 color 25193. (This info, plus other good notes on insignia, were provided by Marc "Moose" Lavigne in the Sept/Oct 1998 issue of Sport Rocketry.) "Delta Blue" was introduced with the 2000-series vehicles, starting with Delta 100. Two subsequent 1000-series flights, Delta 109 and Delta 112, wore white; though Delta 112 is unique in that it had a blue interstage—likely because they ran out of white interstages during the transition.

Can you explain how the stars in the Delta triangle insignia are determined?
A 2003 discussion on addressed this question, and came up with the following answer, which was confirmed by a Boeing PR person.

    The number of stars represents the highest number of consecutive launch successes attained by the Thor-Delta series (not including Delta III and Delta IV). Note that Boeing doesn't always get the number right every time. Part of the problem is that vehicles sometimes slip out of their planned launch sequence.

    As of 25 June 2003, the Thor-Delta series is on its best ever winning streak, having performed its 52nd consecutive launch success with Delta 298 (MER-A). Delta 298 correctly carried 51 stars. Unfortunately, Delta 297 (which orbited GPS IIR-9 in March 2003) also had 51 stars, but should have had 50. This may have been because the SIRTF launch, originally planned to go before GPS IIR-9, slipped.

    Here is a list of the Delta consecutive success streaks that seem to have determined the number of stars:

      Delta 2-24, 1960-64, 22 successes
      Delta 34-58, 1965-68, 25 successes
      Delta 101-129, 1974-77, 29 successes
      Delta 135-177, 1977-84, 43 successes
      Delta 180-227, 1986-94, 49 successes
      Delta 242-298, 1997-03, 52 successes and counting*

      *excludes 3 Delta III and 2 Delta IV launches

    I think you'll find that many launch vehicle insignias were consistent with this list. For example, I've counted 49 stars on Deltas 239, 264, 271, 286, 291, 292, 294, and 295. I found 43 stars on Delta 210, etc.

    As near as I can determine, the Delta star insignia first appeared sometime around 1966-67. Delta 51, for example, had 22 stars. Once the stars appeared, they were applied inside the triangle until sometime in 1982 when the number of successes exceeded 30 or so and stars began to be applied outside the triangle. By the time Delta 166 was launched in 1983, the number of stars inside the triangle had been fixed at 27 (it still is today). Delta 166 also had 4 additional stars outside the triangle, for a total of 31.

    Thus ends the Delta insignia star mystery!

Many thanks to Tim Johnson for writing this excellent summary of the newsgroup discussion. In 2006, as the United Launch Alliance took over launch services from Boeing, the stars were discontinued; Delta 322 (the first ULA-directed launch) was the last to bear them.

As is apparent from Tim's research, given the occasional inconsistency in the insignia, your best bet for modelling a specific Delta flight—as in all scale modelling—continues to be to get lots of photo documentation. For flights from the eastern range, a good place to start is the NASA/KSC Multimedia Gallery.

How are the boosters on the Delta II numbered?
Close observers have noted that each of the GEM strap-on boosters has a large number stenciled near its base (as well as a much smaller number just below each nose cone). These numbers are not in sequence. They go in threes, 1–3, 4–6, 7–9, equilaterally spaced. In other words, boosters 1, 2 and 3 mark the points of an equilateral triangle, as do 4–6 and 7–9. Boosters 4–6 are the air-lit boosters, and have larger nozzles for improved efficiency at altitude. On Delta III, which used the larger GEM-46 motors, boosters 7–9 had TVC nozzles. (Delta II-Heavy also uses GEM-46 motors, but this author speculates that TVC is not employed.)

Here are two videocaps of a Delta II for illustration:


Booster 1 is centered on the downrange axis of the vehicle, as shown in the left-hand image. Boosters 8 and 6 flank the uprange axis, and the turbine exhaust pipe from the main engine is between them on the axis, though it's difficult to see in the right-hand image. (Also, the mission logo is always on the uprange side.) Therefore, the boosters go in this order, starting at the downrange axis and proceeding clockwise when viewed from above: 1, 4, 9, 3, 6, 8, 2, 5, 7.

I found this object (or piece of debris) and think it's part of a rocket. Do you know what it is?
Probably not, but I enjoy seeing the pictures folks send. My standard warning on this subject is this: the space agencies tend to be pretty covetous of their hardware, even when they're done using it. For example, in 2001 the USAF demanded the return of three pieces from a Delta second stage that had reentered over South Africa and had wound up in a Cape Town science museum (which this author thinks is a good place for them). Spherical pressure bottles, of which AJ10s carry several, are especially frequent survivors of reentry. Don't try putting them on eBay because Uncle Sam will hammer you hard—ie., felony charges. Your best bet is probably to write to NASA and hope for a pat on the back.

How did you become interested in Delta?
My interest in Delta—and subsequently this web site—got started in 1996, when Mars Global Surveyor and Mars Pathfinder were preparing for launch. The press packages mentioned that these would be flights 239 and 240 for Delta. My first thought was this: with so many flights, why have I never heard of this launch vehicle? Looking into its flight record, I realized: Echo, Telstar, Relay, TIROS—these were the satellites that graced the pages of every book about space that I avidly read in grade school (in the 1970s), and they all flew on Deltas.

From there, my interest quickly turned into a for-fun research project that took on a life of its own, aided substantially by excellent government documents and engineering libraries at Michigan State University. (Perhaps I also had a subconscious desire to crusade for a rocket that I feel deserves a great deal of the credit for success in the Space Age.) More recently, this site was the impetus for an invitation from NASA's then-Chief Historian to contribute to a book on U.S. launch vehicle development, which was published by the University Press of Kentucky in 2002 as To Reach the High Frontier: A History of U.S. Launch Vehicles.

Last update: 14 December 2009 CST

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History of the Delta Launch Vehicle by Kevin S. Forsyth