The Rainbow Codes were a series of code names used to disguise the nature of various British military research projects. They were mainly used from after the Second World War until 1958, when they were replaced by an alphanumeric code system.
The Ministry of Supply (MoS) initiated the idea because, during World War II, the British realised that although the code-names of some German secret projects could be cryptic, they often provided useful clues as to their nature. For example, basic characteristics of a new German radio navigation device known as Wotan (which used a single radio beam) were inferred by the British before it entered service with the Luftwaffe. This was because the system was named after the one-eyed god of the same name, which offered British scientists a useful hint. The intention of rainbow codes was to clearly and uniquely identify British projects, whilst not providing any hints or clues regarding their characteristics.
Each rainbow code name was constructed from a randomly selected colour, plus an (often appropriate) noun taken from a list, for example:
"Blue" + "Steel" = Blue Steel, a nuclear-armed stand-off missile
"Green" + "Mace" = Green Mace, an anti-aircraft (AA) gun.
While most colour and noun combinations were meaningless, some were real names, although quite unrelated to the project they designated. For example, "Black Maria" is also a name for a police van and the "Red Duster" is a name for the Red Ensign, the flag flown by British merchant ships.
The names were mostly dropped with the end of the Ministry in 1959. Its functions were transferred to the War Office, the Air Ministry that handled military aviation, and the newly created Ministry of Aviation in charge of civil aviation. After the reorganization, projects were mostly named with randomly selected codes comprising two letters and three digits, e.g. BL755, WE.177. However, rainbow codes continue to be used with some modern systems; current examples include the Blue Vixen radar and the Orange Reaper Electronic Support Measures system.
Black Arrow - a satellite launch vehicle derived from Blue Streak/Black Knight
Black Knight - a launch vehicle used to test re-entry vehicles for Blue Streak
Black Maria - fighter IFF interrogator
Black Prince - proposed satellite launch vehicle based on Blue Streak/Black Knight — a.k.a. Blue Star
Black Rock - surface to surface guided missile
Blue Anchor - X-Band CW target illumination radar for Bristol Bloodhound
Blue Badger - truck-mounted nuclear land mine - later renamed Violet Mist
Blue Bishop - portable 2.5 MW nuclear-powered electrical generator - previously Green Janet
Blue Boar - TV-guided bomb
Blue Boy - VHF speech scrambling
Blue Bunny - ten-kiloton nuclear mine, see Blue Peacock
Blue Cat - nuclear warhead a.k.a. Tony - UK version of US W44, a.k.a. Tsetse
Blue Cedar - AA No. 3 Mk. 7 mobile anti-aircraft radar
Blue Danube - the first British nuclear weapon in service
Blue Devil - T4 optical bombsight - drift and ground speed from Green Satin
Blue Diamond - AA No. 7 anti-aircraft radar
Blue Diver - ARI (Airborne Radio Installation) 18075 airborne low-band VHF jammer - against metric frequency radar such as Tall King - fitted to Victor & Vulcan
Blue Dolphin - Blue Jay Mk V for Sea Vixen - see Hawker Siddeley Red Top
Blue Duck - Anti-Submarine Warfare missile, entered service as Ikara
Blue Envoy - surface-to-air missile to OR.1140
Blue Fox - kiloton range nuclear weapon, later renamed Indigo Hammer - not to be confused with the later Blue Fox radar
Blue Fox - airborne radar
Blue Jacket - ARI (Airborne Radio Installation) 5880 airborne Doppler navigation radar fitted to Hawker-Siddeley Buccaneer aircraft.
Blue Jay - air-to-air missile - entered service as de Havilland Firestreak
Blue Joker - balloon-borne Early Warning radar - a.k.a. AMES Type 87
Blue Lagoon - Infra-red air-to-air detector.
Blue Moon - nuclear-armed cruise missile project, replaced by Blue Streak
Blue Oak - AWRE Atlas 2 super-computer used for simulation of nuclear explosions
Blue Orchid - Marconi doppler navigation equipment for helicopters
Blue Parrot - ARI 5930 I band automatic contour-following radar for Buccaneer - also known as AIRPASS II (AIRPASS=Airborne Interception Radar & Pilot's Attack Sight System)
Blue Peacock - ten-kiloton nuclear land mine - also known as Blue Bunny and Brown Bunny; it used the Blue Danube physics package.
Blue Ranger - Delivery of Blue Steel to Australia
Blue Rapier - Red Rapier - missiles - see UB.109T
Blue Riband - large anti-jamming radar - cancelled 1958 and supplanted by smaller version as Blue Yeoman
Blue Rosette - short-case nuclear weapon bomb casing for reconnaissance bomber to spec R156T, including the Avro 730, Handley Page HP.100, English Electric P10, Vickers SP4 and others.
Blue Saga - ARI 18105 airborne radar warning receiver (RWR) - fitted to Victor & Vulcan
Blue Sapphire - astro-navigation system - see also Orange Tartan
Blue Shadow - navigation equipment for Canberra B.16, developed as Yellow Aster.
Blue Shield - see Armstrong Whitworth Sea Slug
Blue Silk - airborne Doppler navigation radar unit with lower speed range than Green Satin
Blue Sky - see Fairey Fireflash
Blue Slug - heavy ship-to-ship missile using Sea Slug launcher, nuclear or conventional
Blue Star - satellite launcher - see Black Prince
Blue Steel - an air-launched rocket propelled nuclear stand-off missile
Blue Stone - Unit 386D ENI (Electronic Neutron Initiator) - nuclear weapon component
Blue Streak - a medium-range ballistic missile
Blue Study - automatic blind bombing system for V-bombers
Blue Sugar - air-droppable target marking radio beacon developed by TRE.
Blue Vesta - a later version of the Blue Jay air-to-air missile
Blue Vixen - Pulse-Doppler radar for Sea Harrier FA2
Blue Warrior (EW) VHF/UHF Jammer countermeasure to use of Radar AA Shells
Blue Water - see Red Rose
Blue Yeoman - Early Warning radar, also known as AMES Type 85, a component Linesman
Brown Bunny - original, unofficial name for Blue Peacock
Green Apple - related to Window for measuring drift at sea
Green Archer - mortar-locating radar
Green Bamboo - nuclear weapon
Green Bottle - 1944 device for homing on U-boat radio signals (ARI.5574)
Green Cheese - nuclear anti-ship missile
Green Flash - Green Cheese’s replacement
Green Flax - Surface-to-Air Guided Weapon (SAGW) or surface-to-air missile (SAM); see Yellow Temple
Green Garland - infrared proximity fuze for Red Top
Green Garlic - Early Warning radar, also known as the AMES Type 80
Green Ginger - surveillance radars - combined installation of AMES Type 88 and AMES Type 89
Green Granite - thermonuclear warheads: Green Granite (small), and Green Granite (large), both tested at Operation Grapple
Green Grass - nuclear warhead for Violet Club and Yellow Sun Mark 1 bombs
Green Hammock - low-altitude bomber, Doppler navigation
Green Janet - portable, nuclear power plant; see Blue Bishop
Green Light - SAGW or SAM - see Short Sea Cat
Green Lizard - tube-launched SAM with variable geometry wings
Green Mace - 5-inch rapid firing anti-aircraft gun
Green Minnow - Radiometer imager
Green Palm - airborne VHF voice channel jammer with four pre-set channels, replaced in the Vulcan B2 by the I band jammer
Green Salad - Wide-band VHF Homing equipment for the Avro Shackleton.
Green Satin - airborne Doppler navigation radar unit
Green Sparkler - advanced SAM for the "Stage 2" program
Green Thistle - Infra-red homing
Green Walnut - blind bombing equipment
Green Water - pilotless interceptor/SAGW
Green Willow - EKCO AI Mk. 20 Fire Control radar, backup to ARI.5897 AI Mk. 23 Airborne Interception radar for the English Electric P.1 fighter
Green Wizard - instrument for calibrating anti-aircraft guns, by measuring their muzzle-velocity
Indigo Bracket - radar jamming system
Indigo Corkscrew - continuous wave radar, used with the Bristol Bloodhound and English Electric Thunderbird SAMs
Indigo Hammer - nuclear weapon
Jade River - continuous wave radar, developed from Indigo Corkscrew
Orange Blossom - Pod-mounted electronic support measures used on the Hercules.
Orange Cocktail - Experimental homing radar weapon from 1950s
Orange Crop - Racal MIR 2 ESM system for Royal Navy Lynx helicopters and some Royal Air Force Hercules aircraft.
Orange Harvest - S and X band warning receiver fitted to Shackletons
Orange Herald - nuclear weapon
Orange Nell - SAGW - surface-to-air missile
Orange Pippin - Ferranti, anti-aircraft, fire-control radar
Orange Poodle - low altitude, OTHR (Over-the-Horizon) early-warning radar - abandoned
Orange Putter - Tail Warning radar fitted to Canberra and Valiant
Orange Reaper - Electronic Support Measures system for Royal Navy Merlin helicopters
Orange Tartan - 'Auto-Astro' automated star navigation system (day) - see also Blue Sapphire (night).
Orange Toffee - radar for Blue Envoy
Orange William - Swingfire, anti-tank missile
Orange Yeoman - Early Warning radar & guidance for Bristol Bloodhound SAGW - a.k.a. AMES Type 82
Pink Hawk - early name for Fairey Fireflash missile. As this was a "reduced" version of the Red Hawk, it is a rare example of Rainbow Codes having some implied meaning, rather than their usual purely deliberately meaningless choice.
Purple Granite - nuclear weapon - see Green Granite
Purple Passion - Sub-kiloton demolition mine project related to Violet Mist.
Purple Possum - VX Nerve Agent.
Red Angel - air-launched anti-ship weapon or "special bomb"
Red Beard - nuclear weapon
Red Brick - Experimental continuous-wave target illuminating radar
Red Cabbage - Naval radar
Red Carpet - X-band radar jammer
Red Cat - Air-launched nuclear stand-off missile cancelled 11/54.
Red Cheeks - inertially guided bomb based on the work of Tubby Vielle
Red Dean - large air-to-air missile
Red Drover - airborne radar - see Avro 730
Red Duster - Bristol Bloodhound surface-to-air missile
Red Eye - An American general-purpose infra-red homing missile
Red Flag - free-fall nuclear bomb - 'Improved Kiloton Bomb' - WE.177
Red Flannel - experimental Q band H2S
Red Garter - Tail warning radar for the Vulcan, did not enter service
Red Hawk - large missile "downrated" to give Blue Sky
Red Heathen - early name for Red Shoes
Red Hebe - air-to-air missile, a replacement for Red Dean
Red Light (ECM) - X band jammer for V Bombers, entered service as ARI 18146
Red Neck - airborne side-looking radar (SLAR)
Red Queen - rapid fire 42 mm revolver cannon anti-aircraft gun
Red Rapier , Blue Rapier missiles - see UB.109T
Red Rose - short-range, battlefield nuclear missile for the British Army - English Electric - later known as Blue Water; cancelled 1962
Red Sea (AA) - the AA predictor designed for use with the Green Mace automatic AA gun
Red Setter - experimental side-looking radar for V bombers
Red Shoes - see English Electric Thunderbird
Red Shrimp - ARI 18076 airborne high-band jammer fitted to Victor & Vulcan
Red Snow - nuclear weapon physics package - fitted to Yellow Sun Mk2 and Blue Steel
Red Steer - EKCO ARI 5919/ARI 5952 airborne tail warning radar - development of AI 20 Green Willow - fitted to Victor & Vulcan
Red Ticket - associated with AI 17 radar
Red Top - air-to-air missile also known as Firestreak Mk 4
Red Tulip - phase coherent radar Moving Target Indicator (MTI)
Violet Banner - infrared seeker for Red Top
Violet Club - nuclear weapon
Violet Friend - simple ABM system
Violet Mist - truck-mounted nuclear land mine - formerly Blue Badger. Used the Red Beard physics package.
Violet Picture - UHF Homer, built by Plessey - Fitted to many RAF aircraft.
Violet Vision - nuclear warhead for Corporal missile - based on Red Beard
Yellow Anvil - nuclear artillery shell warhead
Yellow Aster - H2S Mk 9A bombing radar, fitted to Victor and Valiant aircraft
Yellow Barley - radar warning receiver
Yellow Duckling - infra-red submarine detector
Yellow Gate - Loral ESM for E-3D Sentry and Nimrod MR.2
Yellow Jack - Orange Pippin's radar component
Yellow Lemon - Doppler-navigation system for naval aircraft
Yellow River - mobile tactical control radar for Bristol Bloodhound - a.k.a. AMES Type 83
Yellow Sand - anti-ship missile, possibly a precursor to Green Cheese
Yellow Sun - nuclear weapon casing
Yellow Temple - nuclear-armed SAGW development of Red Shoes
Yellow Tiger - Target illuminating radar used with the Thunderbird missile.
Yellow Veil - ALQ-167 pod for Royal Navy Lynx.
Several British military related terms have a similar format to Rainbow Codes, but are not since they do not refer to classified research projects, and some names have been used unofficially. These include:
Black Banana - unofficial nickname for the Blackburn Buccaneer, originally named the Blackburn ANA (Blackburn Advanced Naval Aircraft).
Blue Circle - sardonic name for concrete ballast for Buccaneer while awaiting Blue Parrot radar. Also used for Sea Harrier ballast in place of Blue Fox radar, and Tornado F.2 ballast. From the Blue Circle cement company.
Blue Eric - improvised I band ECM jammer against the Fledermaus gun control radar during the Falklands War. Installed in the Harrier GR.3's starboard 30mm gun pod.
Blue Yeoman - unofficial name for an experimental radar made from components of the Blue Riband and Orange Yeoman
Green Goddess - colloquial name for Civil Defence fire pump
Green Meat - a 'spoof' SAM programme reported in the 1976 RAF Yearbook
Green Parrot - unconfirmed low yield nuclear weapon mentioned in a 1981 New Statesman article by Duncan Campbell who later claimed that it was "probably" a copy of the B57 nuclear bomb. The WE.177 has incorrectly been referred to as the Green Parrot by some authors. However Green Parrot was a NATO codename for the Soviet PFM-1 anti-infantry mine.
Green Porridge - RAF aircrew nickname for green-tinted H2S bombing radar display PPI image in Valiant, Victor & Vulcan
Red Arrows - RAF display team
Red Devils - Parachute Regiment display team
Red Slab - joke name for a large ballast weight replacing the nose radar in Avro Vulcan XH558 in its return to flight as a civil display aircraft.
Violet Fire - Ultraviolet light fire detection system for Concorde engine bays.