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

  • , Royal Canadian Navy destroyer
  • , 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 R<sup>4</sup>, 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. Regjeringskvartalet)
  • Region 4, the DVD region code for most of Mexico, Central America, South America, Australia, New Zealand, Oceania

See also

  • 4R (disambiguation)