The codenames for US nuclear devices are difficult to track. Usually, the primary and secondary stages have separate codenames and generally they are classified when associated with a specific weapon, but in some instances, they have been declassified and in others they have slipped through the cracks during declassification.
Hansen in Swords of Armageddon provides a list of many codenames which is far too long to list here, and in some cases has linked codenames to specific weapons, some of which I will list:
| Name | Type | Weapons | Lab | Notes |
| Boa | Primary | W30, W52 | LANL | |
| Fife | Secondary | W47Y2, W56 | LLNL | |
| Gnat | Primary | nil | LANL | Extensively tested but never used in a production weapon |
| Kinglet | Primary | W47, W55, W56 | LLNL | Replaced Robin in the W47, and Starling in the W56 |
| Piccolo | Secondary | W47Y1 | LLNL | |
| Python | Primary | B28, W34, W49 | LANL | |
| Robin | Primary | W38, W45, W47 | LLNL | |
| Starling | Primary | W56 | LLNL | LLNL modification of Tsetse. Used mechanical safing. |
| Swan | Primary | W45, W47 | LLNL | Replaced by Robin in production W47, was briefly considered as the XW45X1. |
| Tsetse | Primary | B43, W44, W50, W59, B57 | LANL |
I have some small disagreements with this list. For example, I believe Swan is the device replaced by Robin in the W47 and that the production W45 used Robin, and I believe that Python was only used in early B28 weapons before being replaced by Tsetse, but those are relatively minor disagreements.
As part of my work into researching Super Octopus, I have attempted to determine the device names of weapons I believe are multi-point systems. So far, I have tentatively identified the device ER-106 as being the Mound part number for Tsetse, Hedgehog as being the primary for the W68 warhead, and Kinglet as the primary of the W62 and W70 warheads. But, central to this discussion, I have proven that the device Cougar is the primary of the early (non-IHE) B61 bomb mods.
It begins with a report on production manpower requirements at Mound Laboratory. This document lists the product “ER-184 (ER-213 Cougar)”.[2, p. 34]
Mound made limited life components (LLCs) such as tritium reservoirs and neutron generators (both the tritium and Polonium-210 kind), and small explosive products like detonators, squibs, explosive actuators and explosive timers. The item ER-184 is listed alongside items that are definitely detonators and squibs.
Later in the same document is the item “ER-213 (TX-61)”.[2, p. 56] TX-61 was the name of the B61 bomb before it was formally accepted into service. The TX prefix was used for development bombs, while the XW prefix was used for development warheads.
Again in the same document, Cougar is described as “Cougar assy (ER-213)”, which presumably means Cougar assembly.[2, p. 49]
The next piece of evidence comes from the official history of the Defense Atomic Support Agency (DASA, now Defense Threat Reduction Agency or DTRA). The full document is classified, but the document indices is available on OpenNet with only minor redactions. In it is listed a “Cougar A” and “Cougar B” device. Cougar A is listed as being discussed in Part 8-1A page 80, while Cougar B is listed as being discussed in Parts 8-1A page 77 and 8-3 pages 127-128.[3, p. 41]
Further, in the same document (for some reason the indices are split up), it says “Cougar A (Red Hot Event)”.[3, p. 79] Red Hot was a nuclear test part of Operation Flintlock, fired 5 March 1966 with a official yield of less than 20 kt.[4, p. 6][5, p. 52] Wikipedia lists the yield as 2 kt, but I can’t find the number in the citations given.
Another document as part of the DASA history series lists reports published by the atmospheric studies division during the period of 1959 to 1969, one of which is VERA Calculations of Cougar B and Wildcat 10.[6, p. 163] VERA stands for Variable Eddington Radiation Approximation and appears to be a radiation transport code, presumably for modelling radiation transport from the primary to secondary stage in a weapon.[7]
From these documents it seems clear that the primary stage for the conventional high explosive B61 mods (i.e. the Mods 0, 1, 2 and 5) was Cougar, possibly Cougar B given the more attention the device was given in the DASA histories. From there, it’s reasonable to assume that Cougar was the primary for the W69 and W73, the warheads for the SRAM and Condor missiles respectively, as these warheads were B61 derived.
Further, if we assume that Cougar was the workhorse primary for LANL at this time, we can assume that the W66 (Sprint ABM warhead) and W64 (LANL’s failed proposal for a Lance warhead) warheads used the same primary.
Which leads to the question of what Wildcat was. Given the device was simulated using VERA in conjunction with the Cougar primary, we can assume that Wildcat is a secondary stage. But, for what weapon?
One suggestion can be found in the name Wildcat 10 — presumably this is the 10th version of Wildcat. The question is if this means 10th minor design iteration, or 10th major design (such as a preproduction or production design). If the latter, it’s presumably a design with a long pedigree.
One hint comes from a list of documents available on OpenNet. In the early 1990s as part of the increased openness, the Defense Nuclear Agency published a printout of a search about radiation using DASIAC (I understand this is a document archiving system). The search includes document titles and abstracts where they are unclassified, and also includes device associations which in many cases were redacted by hand.
The document of interest is Some Radiation Environments Produced by a Wildcat Nuclear Weapon Detonated at High Altitude, Interim Report (December 1969).[8, p. 312] The way DASIAC presents the information includes one or more short descriptions of the report, the devices discussed, shots discussed and the nature of the shots. In this case, devices and shots are blank, but the description includes “Wildcat Test Readiness Program”, three more descriptions for gamma, x-ray and neutron spectrums, and that the shot was a high-altitude shot.
Of all of the high-altitude thermonuclear tests, only three devices were used: the W28, W38 and W50. But it could also mean a simulated high-altitude environment, such as an underground tunnel shot, fired in a vacuum. Excluding the W28 and W38 for being quite old and large at the time, the two most likely candidates for the Wildcat secondary are the W50 and W66.
The W50 came in three yield options: 60, 200 and 400 kt (The upper yield is sometimes described as 440 kt). If we assume that the B61 used Wildcat, then the different B61 Mods maximum yields of 50, 170 and 340 kt are quite close to the yields given for the W50 versions and we may be able to assume that they shared a secondary design. Reusing the secondary design fits if Hansen’s claim that the W78 used the W50’s secondary are to be believed,[9, p. 346] which is very believable given the W78’s yield of 335 to 350 kt is very close to that of the B61-7’s 340 kt.
This idea is also supported by the number of Wildcat versions. If we assume three versions for the W50, and three more similar but hardened versions for the B61 by 1969 when the report was written, it’s not inconceivable that another 4 versions were seriously considered by that point. One may have been for the Terminal Evasion/Accuracy MRV program[10, p. V–78] which LANL were working on by 1969 (which I believe evolved into the W78), another could have been slightly modified for the W69, and much later on, another version may have been developed for the W85 (80 kt maximum yield).
At the same time, 1969 was right in the middle of W66 development, and research into the various aspects of warhead prompt radiation at high altitude would be a large part of Sprint missile development. If we assume Wildcat 10 means the 10th minor design iteration (something easily achieved with computer simulation), then the idea of Wildcat being for the W66 seems credible. Given the W64 was also an enhanced radiation device, they may share a secondary design. This could be supported by Red Hot, which was a weapons effects tunnel shot, which may have tested hardening against enhanced radiation weapons.
To summarise:
- The B61-0,-1,-2,-5 (non-IHE mods) used the primary stage Cougar.
- The specific device may have been Cougar B.
- Cougar was almost certainly the primary for the W69 and W73 warheads.
- Cougar may have been used in the cancelled W64 Lance warhead and in the W66 Sprint warhead.
- A different primary with a different name is used in IHE B61 bomb mods and in the W81 and W85 warheads.
- Wildcat was a secondary device.
- Wildcat may have been used in the W50, B61, W69, W73, W78 and W85 bombs and warheads, or it was a small, enhanced radiation secondary for the W66 and possibly the W64 warheads.
Some other questions remain. For example, what are parts ER-184 and ER-213? I have also found evidence of a part ER-206 (which seems to include ER-206N and ER-206R, and was extensively test fired as part of the B61 program) which appears to be associated with ER-213. There is also evidence linking 1E30 with ER-213, and 1E30 is definitely a detonator.
30 June 2022: Some documents I received from Alex Wellerstein have reliably informed me that my assumption about Wildcat 10 is wrong. Wildcat 10 is a primary stage that is part of the Wildcat generation of primaries (as is Cougar). VERA Calculations of Cougar B and Wildcat 10 is likely a report examining the output of Wildcat 10 and comparing it to Cougar B (which was probably Los Alamos’ workhorse primary at the time).
References
[1] Chuck Hansen, Swords of Armageddon, vol. V, 7 vols. 2007.
[2] ‘Mound Laboratory Manpower Reports’, Mount Laboratory, MLM-CF-66-6–292, Jan. 1964. Accessed: Jun. 17, 2022. [Online]. Available: https://www.osti.gov/opennet/detail?osti-id=16137954
[3] ‘History of the Defense Atomic Support Agency 1959-1969, Indicies 1967-1969’, DEFENSE ATOMIC SUPPORT AGENCY WASHINGTON DC. Accessed: Jun. 09, 2021. [Online]. Available: https://www.osti.gov/opennet/detail?osti-id=16004116
[4] K. K. Horton, B. F. Eubank, and W. J. Brady, ‘Operations FLINTLOCK and LATCHKEY Events RED HOT, PIN STRIPE, DISCUS THROWER, PILE DRIVER, DOUBLE PLAY, NEWPOINT, MIDI MIST, 5 March 1966-26 June 1967’, REYNOLDS ELECTRICAL AND ENGINEERING CO INC LAS VEGAS NV, Oct. 1984. Accessed: Jun. 20, 2022. [Online]. Available: https://apps.dtic.mil/sti/citations/ADA148997
[5] ‘United States Nuclear Tests, July 1945 through September 1992, September 2015’, USDOE National Nuclear Security Administration, Las Vegas, NV (United States). Nevada Field Office, DOE/NV-209-Rev16, Sep. 2015. doi: 10.2172/1351809.
[6] ‘History of the Defense Atomic Support Agency 1959-1969, Part II Headquarters, Ch 8 Weapons Effects and Tests’, DEFENSE ATOMIC SUPPORT AGENCY WASHINGTON DC, DTL-070-024. Accessed: Jun. 21, 2022. [Online]. Available: https://www.osti.gov/opennet/detail?osti-id=16004614
[7] J. T. Palmer, B. E. Freeman, and J. H. Schaibly, ‘MODIFICATIONS AND APPLICATIONS OF THE VERA SYSTEM OF CODES. VOLUME I. MODIFICATIONS OF THE CODES.’, SYSTEMS SCIENCE AND SOFTWARE LA JOLLA CALIF, Dec. 1969. Accessed: Jun. 21, 2022. [Online]. Available: https://apps.dtic.mil/sti/citations/AD0705513
[8] ‘DASIAC PRINTOUT NO.5, 1967-1968, 857 CITATIONS (USING RADIATION OR RADIOLOGICAL)’, NV0754573, Jan. 1994. Accessed: Jun. 20, 2022. [Online]. Available: https://www.osti.gov/opennet/detail?osti-id=16388922
[9] Chuck Hansen, Swords of Armageddon, vol. VI, 7 vols. 2007.
[10] Betty L Perkins, Tracing the Origins of the W76: 1966-Spring 1973. Los Alamos National Labs, 2003. Accessed: Jul. 23, 2021. [Online]. Available: http://archive.org/details/DeclassifiedNuclearWeaponDevelopmentHistoryReports
Super Octopus 