The 2.75 inch (70mm) rockets were developed during World War II as an air-to-air weapon for use against heavy bomber formations. The Germans had developed such a successful weapon (the R4M), but before long it was noted that neither the Japanese nor the Germans had any heavy bombers, and the weapon was switched to air-to-ground use. Actually, the 70mm rocket was retained for air-to-air use into the 1950s, but it was never successful in that role. The 70mm rocket became very popular in the 1960s, when it was discovered that the weapon worked very well when launched from multiple (7 or 19 tube) launchers mounted on helicopters. The 42-55 inch long rockets could be fired singly or in salvoes, and gave helicopter pilots some airborne artillery for supporting troops on the ground. There many variations in terms of warheads and rocket motors. Some versions can go over 10 kilometers.
Developing the APKWS took so long because the manufacturers underestimated the technical difficulties of getting the laser seeker and flight control mechanisms into that small a package, at a weight and price the army could afford. The price of the APKWS is supposed to get down to $20,000 each (about the cost of a smart bomb), but the manufacturers have been having problems doing that. As a result, Congress may cancel the APKWS before it enters mass production. The APKWS is to be used against targets that don’t require a larger (hundred pound), and more expensive (over $100,000) Hellfire missile, but still need some targeting precision. In tests, the APKWS hit within a few feet of the aiming point.
After nine years of effort, the U.S. Army has finally gotten a guided 70mm air-to-ground rocket that works, at least during tests. The APKWS (Advanced Precision Kill Weapons System) is a 25 pound rocket, with a laser seeker and a six pound warhead. It has a range of about six kilometers. The recent tests had one APKWS hit a stationary target 1.5 kilometers distant, while a second rocket hit a moving target 3.3 kilometers away. Laser designators on the helicopter, or with troops on the ground, is pointed at the target, and the laser seeker in the front of the APKWS homes on the reflected laser light.