R4
R4, R04, R.4, R-4, or R/4 may refer to: == Military == === Aircraft === Caudron R.4, World War I French reconnaissance aircraft, first flown in 1915 Curtiss R-4, air ambulance version of the American Curtiss Model R utility aircraft, first flown in 1915 Sikorsky R-4, American helicopter, first flown in 1942 === Ships === HMCS Cayuga (R04), Royal Canadian Navy destroyer USS R-4 (SS-81), U.S. Navy submarine === Weapons === R4 assault rifle, produced by South African manufacturer Vektor Remington R4 carbine, assault rifle used by the Philippine Marine Corps Bisnovat R-4, Soviet missile === Other military === Plan R 4, the World War II British plan for an invasion of the neutral state of Norway in April 1940 == Science == R4, designation of risk phrase "Forms very sensitive explosive metallic compounds" R4 nuclear reactor, the fourth nuclear reactor built in Sweden Exotic R4, in mathematics, a differentiable manifold == Transportation == === Cars === R4, abbreviation for rear-engine, four-wheel drive layout R4, a sub-class of Group R rally cars Jaguar R4, Jaguar Racing's car for the 2003 Formula One season McRae R4, a rally car designed in part by Colin McRae Renault R4, alternative name for the Renault 4 Suzuki GSX-R/4, a concept car made by Suzuki in 2001 === Roads === R4 ring road in Ghent, Belgium R4 expressway (Czech Republic) R4 expressway (Slovakia) R-4 motorway (Spain) R4 road (Zimbabwe), a road connecting Harare and Nyamapanda Radial Road 4 or R-4, an arterial road of Manila, Philippines === Other transportation === R4 (Canberra), a bus route in Canberra, Australia R4 (New York City Subway car) R4 (RER Vaud), an S-Bahn line in the canton of Vaud R4 (Rodalies de Catalunya), a commuter rail line in Barcelona, Catalonia, Spain R4 41st Avenue RapidBus, an express bus service in Vancouver, BC, Canada == Video games == R4: Ridge Racer Type 4, a racing game for Sony PlayStation, developed by Namco Rush Rush Rally Racing, a racing game for Sega Dreamcast, developed by Senile Team R4 cartridge, a Nintendo DS flash cartridge == Other uses == BBC Radio 4 the premier BBC speech radio station R4, a building in the Norwegian Government quarter (Norw.