| GTR-18 | |
| Origin: | United States |
| Type: | SAM simulator rocket |
| Is Missile: | yes |
| Service: | 1980s-present |
| Used By: | United States military |
| Designer: | Naval Air Warfare Center Weapons Division (NAWCWD) |
| Design Date: | early 1980s |
| Weight: | 1.43lb |
| Length: | 394mm |
| Engine: | Solid fuel rocket |
| Engine Power: | 15abbr=onNaNabbr=on (66.72 N) of thrust[1] |
| Speed: | 165m/s[2] |
| Guidance: | None |
| Steering: | None |
| Wingspan: | 152mm |
| Propellant: | X-60[3] |
| Ceiling: | to [4] |
| Boost: | 6 seconds at 70° |
| Launch Platform: | single-bay LMU-23/E or four-bay LMU-24/E[5] |
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.
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 of X-60 solid fuel propellant.[3] Because of its very light construction, the Smokey Sam will only cause minimal damage even if it accidentally strikes a low-flying aircraft.[6] [3] [5]
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 GTR-18A received the altered designation DGTR-18A in the early 1990s, despite the use of the D ("Dummy") prefix usually being limited to non-flying rockets/missiles used for ground handling training only.[5] The Smokey Sam remains in production and operational service, and is extensively used by the U.S. military.[6]