Air Weapons: Digital Rocket Launcher

Archives

April 30, 2014:   In record time (less than two years) the U.S. Navy developed a launcher and fire control system that enables its shipboard MH-60S helicopters to fire APKWS guided missiles. The LAU-61 DRL (Digital Rocket Launcher) weighs about 220 kg (484 pounds) loaded with nineteen 70mm APKWS laser guided missiles. The APKWS is a 13.6 kg (30 pound) 70mm rocket, with a laser seeker, a 2.7 kg (six pound) warhead, and a range of about six kilometers. Laser designators on the helicopter, other aircraft, or with troops on the ground, are pointed at the target and the laser seeker in the front of the 70mm missile homes in on the reflected laser light. LAU-61 can carry unguided 70mm rockets as well, but the DLR was designed with the APKWS in mind because you need far fewer guided rockets than unguided ones to destroy a target.

The MH-60S entered in 2002 and the U.S. Navy is has over 200 them in service. The MH-60S was designed to replace the 11 ton, 1960s era, CH-46D helicopters. The ten ton MH-60S is superior to the older CH-46D in most ways (load, range, speed, reliability), but is smaller, so it can use the landing pads on destroyers and frigates. It can carry 1.9 tons internally. The navalized versions of the UH-60 are more expensive because of anti-corrosion features (salt water rusts unprotected metal and damages other components), more powerful engines, folding blades, a hoist system, more advanced electronics and numerous other changes.

The U.S. Marine Corps has been using APKWS II since 2010 on its helicopter gunships and SOCOM has used it on its slow moving AC-130 gunships. The marines were so pleased with it that they bought APKWS II kits to convert some of their 100,000 70mm unguided rockets to laser guided ones. All this began when the marines bought fifty APKWS II missiles for testing and that proved successful. There followed the first sale for 70mm guided rockets after more than a decade of trying to get anyone to buy more than a few evaluation missiles or upgrade kits. The marines armed their AH-1W helicopter gunships with the guided 70mm rockets. Since then marine AH-1Ws have fired over a hundred APKWS II in Afghanistan, and none of them missed. That led to modifications for use on fast movers and the recent successful tests.

The guided 70mm rocket is used against targets that don't require a larger (49 kg/108 pound), and more expensive (over $100,000), Hellfire missile but still needs some targeting precision. In tests the APKWS hit within a meter (a few feet) of the aiming point, about what other laser guided missiles are capable of. The 70mm missile makes an excellent weapon for UAVs, especially since you can carry more of them. The launcher for carrying these missiles is designed to replace the one for Hellfire but can carry four missiles instead of one.

A pair of LAU-61 DRLs on a MH-60S turns the transport and anti-submarine helicopters into a potent gunship armed with 38 laser guided missiles. The MH-60 has already been modified to carry Hellfire missiles, but can only carry sixteen of them, compared to 38 APKWS. 

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 a similar and very successful weapon (the R4M). Before long it was noted that neither the Japanese nor the Germans had any heavy bombers, so the U.S. 70mm rocket 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 108-138m cm (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 are many variations in terms of warheads and rocket motors. Some versions can go over ten kilometers.