The GTR-18A, commonly known as the Smokey Sam, is a small unguided rocket developed by Naval Air Warfare Center Weapons Division (NAWCWD) in China Lake, California as a threat simulator for use during military exercises.

The GTR-18 was conceived in the late 1970s by Robert A. McLellan, a Weapons Range Scientist working with Exercise Red Flag at Nellis Air Force Base.

It quickly became apparent that no commercial product would perform adequately, so the development of the GTR-18 was undertaken by the Naval Weapons Center (NWC) during the early 1980s, with the intent of developing Mr. McLellan's idea of a simple and inexpensive rocket for visually simulating the launch of surface-to-air missiles (SAMs) during training exercises.

[6][5] The fuselage and fins are joined to the nose cone by the motor tube which contains 499 grams (17.6 oz) of X-60 solid fuel propellant.

[8] While the ordinary GTR-18A has a simple, model rocket type motor, an improved "Dual Thrust Smokey Sam" tested in the early 2000s featured a modified rocket motor, providing a 1.5 second boost period, followed by a lower-thrust sustainer burn with burnout occurring at 7.1 seconds after launch.