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:
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.
- 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
- 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
- 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.
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 Parrot was also the term for an admiral's barge, traditionally with a green-painted hull.
- 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.
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