The German
15 cm sFH 18 howitzer was the first artillery piece to make use of RAP rounds with the objective of replacing the
10 cm schwere Kanone 18 by making the howitzer range equal or superior to the 10 cm sK 18, freeing up production capacity for more important weapons. Issued in 1941, the 15cm R Gr 19 FES shell achieved a maximum range of , but it wasn't entirely successful and withdrawn from service shortly after. Ultimately, it proved to be a little more than an experimental design: the instruction manuals and warnings included did nothing to imbue the users with confidence in the new weapon, but provided valuable lessons for the designers, who would successfully develop a RAP round for the
Krupp K5. The German
Sturmtiger (1944) used a 380 mm (14.9-inch) Rocket Propelled Round as its main projectile. These rounds were high explosive shells or shaped charges with a maximum range of . The gun first accelerated the projectile to 45 m/s (150 ft/s), the 40 kg (88 lb) rocket charge then boosted this to about 250 m/s (820 ft/s). The Krupp K5 railway gun of used rocket-assisted projectiles in the later stages of
World War II, although it also used conventional artillery projectiles. In early 1943, the Germans worked on the development of a RAP round for the
38 cm Siegfried K (E) railway gun, but apparently it never reached production stage. The Germans also made experimental RAP rounds for the
10.5 cm Flak 38/39 and
12.8 cm FlaK 40 anti-aircraft guns in an attempt to increase their ceiling. The North Korean
M-1978 / M-1989 Koksan 170 mm (6.7-inch) self-propelled gun can use rocket-assisted projectiles to achieve a range of around ; at one time this was the world's longest-range tube field artillery piece. When
NATO standards required member armies to have corps-level artillery that could fire to a minimum range of , nearly all member nations solved the problem with RAP rounds in their 155 mm (6.1-inch) artillery. The
Belgian Army was the only NATO member army that did not require RAP, reaching the required range with a conventional round. The
XM1113 RAP round replaced the
M549A1 RAP round for the
M777 howitzer and other 155 mm (6.1-inch) artillery after 2016. The new round had a range of instead of the NATO standard. As of 2016, the XM1113 was scheduled for Limited Rate Initial Production in fiscal year 2022. A special variant of a RAP is the experimental
155MM HE-ExR artillery shell developed by
Nammo, which uses a
ramjet for propulsion. The shell is supposed to achieve a range of up to 150 km. ==See also==