Directory of U.S. Military Rockets and Missiles
Appendix 1: Early Missiles and Drones
SWOD Series
Copyright © 2004 Andreas Parsch

SWOD Series

At some time in World War 2, the U.S. Navy's Bureau of Ordnance (BuOrd) began to designate guided weapons in a new SWOD (Special Weapons Ordnance Device) series. Only a few members of this series are known, and the ones which survived until 1947 were then redesignated as guided missiles.

Early BuOrd guided weapons

Several early BuOrd guided bomb programs were managed by the National Defense Research Committee (NDRC). The first was project Dryden (some sources say "Dragon"), a TV-equipped glide bomb in the 900 kg (2000 lb) class with a wingspan of 3.6 m (12 ft), which was begun in January 1941. The bomb was to be steered into the target by a remote operator watching the TV image of the weapon's camera. For test purposes, a 2/3-scale model called Robin was designed by the National Bureau of Standards (NBS), but initial flight tests of the TV guidance system showed that the method was not (yet) good enough for the task.

In April 1942, the attention turned towards radar guidance, and in June that year the development of a semi-active radar homing glide bomb based on the Robin airframe was begun. This became the Pelican missile, q.v. below under SWOD MK 7.

Parallel to Pelican, the NDRC also studied three other radar-guided missiles. The Moth was a passive radar guided rocket to home on enemy radar emitters (what is today called an "anti-radiation missile"). It was eventually turned over to the Army, but did apparently not result in flying hardware. Falcon was either an anti-aircraft missile or a ship-to-ship rocket-powered Pelican derivative (there are conflicting sources), but no actual missiles were built anyway. Finally, there was the active radar guided Bat, which used a larger airframe of the Pelican configuration. It eventually became the SWOD MK 9 and later the ASM-N-2 guided missile.

SWOD MK 1 through MK 6

The first six members of the SWOD series are unknown. However, some of the guided weapon projects described in the previous section have no known designation (Robin, Moth and Falcon) and may have used one or more of the first six SWOD numbers.

SWOD MK 7 Pelican

In 1942 the NDRC began the development of radar-guided anti-shipping glide bombs for the U.S. Navy. One of the first such projects was called Pelican, and consisted of an airframe developed by the NBS (National Bureau of Standards) which could be fitted in the fuselage with bombs of various sizes. Pelican used a semi-active radar seeker, homing on radar reflections from the target which was illuminated by the AN/APS-2 radar of specially converted PV-1P patrol aircraft. The PV-1P could carry either two 450 kg (1000 lb) Pelican MK II or a single 680 kg (1500 lb) Pelican MK III bomb. Pelican was originally designated Bomb MK 55, but the 1500 lb MK III version was later redesignated as SWOD MK 7. No other SWOD designations for Pelican are known, but it's not unlikely that the 1000 lb MK II variant received one of the earlier SWOD numbers.

Photo: U.S. Navy
SWOD MK 7 Pelican

Drop tests of Pelican began in December 1942, and although these were moderately successful, the project was terminated in 1944. The reason was that the range of the PV-1P with Pelican was too short, and that there were not enough PV-1 aircraft available for conversion. In place of Pelican, the similar but more promising active-radar guided SWOD MK 9/ASM-N-2 Bat missile was further developed.

An interesting side note to Pelican is the pigeon-guided(!) missile. In early 1942, behavioral scientist B.F. Skinner studied the use of trained pigeons to guide weapons. The idea was to show the birds photos of the planned target on a screen, and train them to peck on it. In the actual missile, a lens system in the weapon's nose would project the target image to three birds' screens. Using an electrically conductive screen to translate off-center pecks to an error signal, the guidance logic could correct the flight path of the missile. The NDRC actually funded the effort on a small scale as "Project Pigeon". Skinner was able to demonstrate the basic principle successfully in simulations on the ground, and wanted to install a pigeon guidance system in Pelican glide bombs for actual flight tests. However, Navy officials eventually dismissed the whole idea as impractical, and therefore the pigeon-guided missile remained an obscure anecdote in the history of weapons development in World War 2.


The Bomb MK 56 was redesignated as a SWOD. No MK number is available, but given the redesignations of Bombs MK 55 and 57 to SWOD MK 7 and 9, respectively, it's not unlikely that the MK 56 bomb became SWOD MK 8. However, no further information is available on the MK 56.


The SWOD MK 9 Bat was originally designated as Bomb MK 57, and is described under its final designation ASM-N-2.


The SWOD MK 10 was a guided bomb originally designated as Bomb MK 69. No further information is available.

SWOD MK 11 Kingfisher A

In August 1944, BuOrd defined the Kingfisher series of radar-guided torpedo-carrying weapons. The SWOD MK 11 Kingfisher A was a glide-bomb with a MK 21 torpedo. It was to be an interim weapon for use against ships not defended by fighter aircraft, but it seems that no Kingfisher A missiles were built.

Other Kingfisher projects were SWOD MK 21 Kingfisher B (q.v. below), Kingfisher C (became AUM-N-2 Petrel), Kingfisher D (became AUM-N-4 Diver), Kingfisher E (became SUM-N-2 Grebe) and Kingfisher F (became AUM-N-6 Puffin).

SWOD MK 15 Kingfisher C

SWOD MK 15 was the initial designation for what eventually became the AUM-N-2 Petrel torpedo-carrying missile.

SWOD MK 21 Kingfisher B

Kingfisher B was to be a light-weight torpedo-carrying glide bomb with about 2/3 the weight of the SWOD MK 9/ASM-N-2 Bat. It was to replace the interim Kingfisher A as an anti-surface shipping weapon. However, it appears that the Kingfisher B missile was not built, either.

Source [1] mentions the designation SWOD MK 21 for Kingfisher B. The number 21 seems to be out of place, and it's possible that the identification is erroneous (e.g. a type for SWOD MK 12).

Main Sources

[1] Norman Friedman: "US Naval Weapons", Conway Maritime Press, 1983
[2] Greg Goebel: Dumb Bombs & Smart Munitions

Back to Directory of U.S. Military Rockets and Missiles, Appendix 1

Last Updated: 16 June 2004