GTR-18 Smokey Sam

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. Widely used in training, the Smokey Sam remains in operational service with the United States military.

GTR-18
Two GTR-18 "Smokey Sams" on LMU-23/E single-bay launchers
Type	SAM simulator rocket
Place of origin	United States
Service history
In service	1980s-present
Used by	United States military
Production history
Designer	Naval Air Warfare Center Weapons Division (NAWCWD)
Designed	early 1980s
Specifications
Mass	1.430 pounds (649 g)[1]
Length	15.5 inches (394 mm)[2][3]
Diameter	2 inches (51 mm)
Wingspan	6.0 inches (152 mm)[2]
Engine	Solid fuel rocket 15 lbf (6.80 kgf) (66.72 N) of thrust[1]
Propellant	499 grams (17.6 oz) X-60[2]
Flight ceiling	1,800 feet (550 m) to 2,000 feet (610 m)[3][1][4]
Boost time	6 seconds at 70° [1]
Maximum speed	165 m/s (540 ft/s)[3]
Guidance system	None
Steering system	None
Launch platform	single-bay LMU-23/E or four-bay LMU-24/E[5]

Design and development

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. He first searched for a commercially available system that would perform as he envisioned. 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]

The design of the GTR-18A rocket is very simplistic and intended for minimal cost with the fuselage and nose cone being constructed from phenolic paper while the fins are constructed out of styrofoam.^[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.^[2] Because of its very light construction, the Smokey Sam will only cause minimal damage even if it accidentally strikes a low-flying aircraft.^[6][2][5]

Operational history

A GTR-18 is launched at the Crow Valley Range Complex, Philippines, 1984.

The complete launch system, known as the Smokey Sam Simulator, includes single-rail LMU-23/E and four-rail LMU-24/E launching pads, an AN/VPQ-1 radar set, the PVU-3A/E Igniter^[7] and the GTR-18A rockets themselves, making up the SMU-124/E system as a whole.^[6][5]

When launched, the GTR-18's rocket motor produces a distinctive white plume, providing a realistic simulation of the launch of a surface-to-air missile.^[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.^[9]

This motor was altered to use a two-part laminated grain propellant which utilized both the standard zinc based grain and a high thrust aluminium based grain as used by other US rockets. The new propellant allows the "Dual Thrust Smokey Sam" to have a boost and sustain signature to better imitate a surface-to-air missile and while thrust is initially low, the higher thrust for the majority of the motors burn time gives an improved trajectory.^[10]

The Smokey Sam remains in production and operational service, and is extensively used by the U.S. military.^[6]

Gallery

• 
  A GTR-18A Smokey Sam being set up during Exercise PATRIOT PEACH '86
• 
  A Smokey Sam being launched at an aircraft approaching the Crow Valley Electronic Warfare Tactical Range, Luzon, Philippines, during exercise "Cope Thunder '84-7"
• 
  Ordnancemen of VMGR-152 aim a Smokey Sam at pilots during threat reaction training