The MGR-1 Honest John rocket was the first nuclear-capable surface-to-surface missile in the US arsenal.[notes 1] Designated Artillery Rocket XM31, the first such rocket was tested 29 June 1951 and the first production rounds were delivered in January 1953. The designator was changed to M31 in September 1953. The first Army units received their rockets by year’s end and Honest John battalions were deployed in Europe in the Spring of 1954. Alternatively, the rocket was designed to be capable of carrying an ordinary high-explosive warhead weighing 1500 pounds, even though that was not the primary purpose for which it was originally envisioned.
Developed at Redstone Arsenal, Alabama, Honest John was a large but simple fin-stabilized, unguided artillery rocket weighing 5820 pounds in its initial M-31 nuclear-armed version. Mounted on the back of a truck, HJ was aimed in much the same way as a cannon and then fired up an elevated ramp, igniting four small spin rockets as it cleared the end of the ramp. The M-31 had a range of 15.4 miles (24.8 km) with a 20 kiloton nuclear warhead but was also capable of carrying a 1,500 pounds (680 kg) conventional warhead. Early tests exhibited more scatter on target than was acceptable when HJ was conventionally armed. Development of an upgraded Honest John, M-50, was undertaken to improve accuracy and extend range. The size of the fins was greatly reduced to eliminate “weathercocking” (the tendency of crosswinds to turn a rocket to face into the wind). Increased spin was applied to restore the positive stability margin that was lost when fin size was reduced. The improved M-50, with the smaller fins and more “rifling”, had a maximum range of 30+ miles with a scatter on target of only 250 yards (230 m), demonstrating an accuracy approaching that of tube artillery. Honest John was manufactured by the Douglas Airplane Company of Santa Monica, California.
The M31 consisted of a truck-mounted, unguided, solid-fueled rocket transported in three separate parts. Before launch they were assembled in the field, mounted on an M289 launcher and aimed and fired in about 5 minutes. The rocket was originally outfitted with a W7 variable yield nuclear warhead with a yield of up to 20 kilotons of TNT (84 TJ) and later a W31 warhead with three variants was deployed with yields of 2 kt (8.4 TJ), 10 kt (42 TJ), or 30 kt (130 TJ) in 1959. There was a W31 variant of 20 kt (84 TJ) used in the Nike Hercules antiaircraft system exclusively. M-31 had a range between 5.5 and 24.8 km (3.4 and 15.4 mi).
Honest John warhead cutaway, showing M139 Sarin bomblets (photo c. 1960)
In the 1960s Sarin nerve gas cluster munitions were also available for Honest John launch.
The two basic versions of Honest John were:
MGR-1A (M31) was 27 feet 3 inches (8.31 m) long, had an engine diameter of 22.875 inches (58.10 cm), a warhead diameter of 30in (762mm), a span of 104 inches (2.6 m), weighed 5,820 pounds (2,640 kg) (nuclear), and had a maximum range of 15.4 miles. The Hercules Powder Company X-202 rocket motor was 197.44 inches (5.015 m) long, weighed 3,937 pounds (1,786 kg), and had 90,325 pounds-force (401.79 kN) average thrust.
MGR-1B (M50) was 24 feet 10.53 inches (7.5827 m) long, had an engine diameter of 22.8 inches (58 cm), a warhead diameter of 30 inches (76 cm), a span of 56 inches (140 cm), weighed 4,332 pounds (1,965 kg) (nuclear), and had twice the range of the M31. The Thiokol composite propellant solid rocket motor had 150,000 pounds-force (670 kN) thrust.
Production of the MGR-1 variants finished in 1965 with a total production run of more than 7,000 rockets. Honest John’s bulbous nose and distinctive truck-mounted launch ramp made it an easily recognized symbol of the Cold War at Army bases world-wide and National Guard armories at home. Even though HJ was unguided and the first U.S. nuclear ballistic missile, it had a longer service life than all other U.S. ballistic missiles except Minuteman. The system was replaced with the MGM-52 Lance missile in 1973, but was deployed with NATO units in Europe until 1985 and National Guard units in the United States as late as 1982. Conventionally armed Honest John remained in the arsenals of Greece, Turkey and South Korea until at least the late 1990s.
By the time the last Honest Johns were withdrawn from Europe in 1985, the rocket had served with the military forces of Belgium, Britain, Canada, Denmark (non-nuclear), France, Germany, Greece, Italy, the Netherlands, Norway (non-nuclear), South Korea, Taiwan (non-nuclear), and Turkey.