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
Weapons
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
Roads
Other transportation
Video games
Other uses
See also
This
disambiguation page lists articles associated with the same title formed as a letter–number combination.
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