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 The Sikorsky R-4 is a two-seat light helicopter that was designed by Igor Sikorsky with a single, three-bladed main rotor and powered by a radial engine. The R-4 was the world's first large-scale mass production, mass-produced helicopter and the ...

, 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 Plan R 4 was an unrealised British plan to invade Norway and Sweden in April 1940, during the Second World War. As a result of competing plans for Norway and Operation Weserübung the German invasion of Norway the same month, it was not carrie ...

, 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 Ghent ( ; ; historically known as ''Gaunt'' in English) is a City status in Belgium, city and a Municipalities of Belgium, municipality in the Flemish Region of Belgium. It is the capital and largest city of the Provinces of Belgium, province ...

, Belgium * R4 expressway (Czech Republic) * R4 expressway (Slovakia) * R-4 motorway (Spain) *

R4 road (Zimbabwe) The A2 Highway (also known as the R4 Highway) is a primary road in Zimbabwe running from Harare to Nyamapanda at the border with Mozambique. The Mozambican side border post is called Cochemane. This is a busy entry point used by people travellin ...

, a road connecting Harare and Nyamapanda *

Radial Road 4 Radial Road 4 (R-4), informally known as the R-4 Road, is a network of roads and bridges which comprise the fourth arterial road of Metro Manila in the Philippines. Spanning some , it connects the cities and municipalities of Makati, Manila, and T ...

or R-4, an arterial road of Manila, Philippines

Other transportation

R4 (Canberra) Route R4 is a main cross-city bus route in Canberra, Australia operated by ACTION between Belconnen, City, Woden Town Centre and Tuggeranong.

, a bus route in Canberra, Australia *

R4 (New York City Subway car) The R4 was a New York City Subway car model built from 1932 to 1933 by the American Car and Foundry Company in Berwick, Pennsylvania. These subway cars were purchased for the IND Division. A total of 500 R4s were built, numbered 400–899, and ...

R4 (RER Vaud) The R4 is a railway service of RER Vaud that provides hourly service between and in the Swiss canton of Vaud. A limited number of trains continue from Bex to . On weekdays, a section of the train operates from to . Swiss Federal Railways ...

, an S-Bahn line in the canton of Vaud *

R4 (Rodalies de Catalunya) The R4 is a line of Rodalies de Catalunya's Barcelona commuter rail service, operated by Renfe Operadora. It runs northwards from the northern limits of the province of Tarragona to Barcelona, passing through the inland Alt Penedès region. The ...

, a commuter rail line in Barcelona, Catalonia, Spain *

R4 41st Avenue RapidBus The R4 41st Ave (designated the 91 B-Line during planning stages) is an express bus route with bus rapid transit elements in Metro Vancouver, British Columbia, Canada. Part of TransLink's RapidBus network, it replaced the 43 Express that tra ...

, 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 ''Rush Rush Rally Racing'', also known as ''R4'', is an independently developed, commercially released video game developed by Dutch studio Senile Team and published by RedSpotGames.

, a racing game for Sega Dreamcast, developed by Senile Team *

R4 cartridge R4 (also known as Revolution for DS) is an unlicensed flash cartridge for the Nintendo DS handheld system. It allows ROM image, ROMs and Homebrew (video games), homebrew to be booted on the Nintendo DS handheld system from a SD card, microSD ca ...

, a Nintendo DS flash cartridge

Other uses

BBC Radio 4 BBC Radio 4 is a British national radio station owned and operated by the BBC. The station replaced the BBC Home Service on 30 September 1967 and broadcasts a wide variety of spoken-word programmes from the BBC's headquarters at Broadcasti ...

the premier BBC speech radio station * R4, a building in the Norwegian Government quarter (''Norw. Regjeringskvartalet'') * Region 4, the

DVD region code DVD region codes are a digital rights management technique introduced in 1997. It is designed to allow rights holders to control the international distribution of a DVD release, including its content, release date, and price, all according to t ...

for most of Mexico, Central America, South America, Australia, New Zealand, Oceania