Twilight of the Mighty Hunter

I had posted back in December about one of the obscure roles performed by the BAe Nimrod during the 1982 Falklands War. More often with ongoing commitments in Iraq and Afghanistan, maritime patrol aircraft like the Nimrod and the Lockheed P-3 Orion are finding themselves performing missions they were not initially designed to perform. During Operation Enduring Freedom in Afghanistan, the onboard high fidelity EO systems of the Orion proved valuable to US Special Forces teams fighting the Taliban. With long endurance, extensive sensor and communication suites and larger crews able to handle multiple tasks, maritime patrol aircraft became ideal in the role of overland ISR (Intelligence, Surveillance, and Reconnaissance).

In 2003 the RAF issued an Urgent Operational Requirement (UOR) to equip several Nimrods with a late-generation EO sensor system, the Wescam MX-15. Four aircraft had the sensor turret mounted in a fairing installed under the starboard wing just inboard of the pinion tank and deployed to Saudi Arabia to assist joint UK-US-Australian special forces teams in scouring the western deserts of Iraq for Scud missile launchers. After the fall of the Iraqi regime, the Nimrods returned to their home base of RAF Kinloss, but were soon recalled to Iraq in the summer of that year to assist in the fight against the insurgency under Operation Paradoxical. Since the RAF didn't yet have any UAVs in the same class as the MQ-1 Predator, the Nimrods with the MX-15 EO system provided high-fidelity overhead real-time ISR for the coalition forces involved. At the time, an early version of the ROVER (Remote Optical Video Enhanced Receiver) called Longhorn was in use that allowed, with much effort and technical issues, troops on the ground to see what the Nimrod overhead was seeing. The current ROVER system is much more user friendly.

In the spring of 2004 British forces in Basra found themselves battling the militia fighters of Shiite cleric Muqtada al-Sadr and once again the MX-15 equipped Nimrods provided overhead ISR for the troops on the ground. At the culmination of the effort against the Sadr Militia, an overhead Nimrod provided targeting information to an orbiting AC-130 Spectre gunship. As Sadr Militia units dispersed throughout the back streets of the city of Al Amarah, the Nimrod crew used the MX-15 system to identify the militia and then hand off the coordinates to the Spectre for destruction.

In the latter half of that year following the stabilization of the Shiite south, the Nimrods shifted their attention to Baghdad in an effort to combat the increase in Sunni insurgent bombings there. A Nimrod would forward deploy from Oman to Basra International Airport with a British army liason officer aboard. Flying almost nightly from Basra, the small Nimrod force was flying over 200 hours a month.

In the overland mission, the Nimrod's three acoustic sensor operators rotated shifts operating the MX-15 turret. The ESM and Searchwater radar operators were in charge of deconfliction over the crowded airspace over Baghdad. Army liason officers worked with the mission commander at the master display to coordinate and disseminate the information from the EO operators on the nine-hour missions. The MX-15 had three cameras- one narrow band, one wide band and one in infrared that were selectable by the operators. The best image is then displayed on a larger monitor over a moving map display that allowed ground units to easily relay to the operators where to look.

In July 2006 the MX-15-equipped Nimrod force switched its attention to Afghanistan in the intensifying effort against the Taliban. With a grueling schedule divided between Iraq and Afghanistan, the Nimrod force finally gave way with the loss of XV230 in September in 2006 with all of its 15 crew being lost. The cause was traced to persistent problems with the Nimrod's air-refueling plumbing system adjacent to hot air ducting. With 11 aircraft remaining in the overall fleet, the UK Ministry of Defense put those aircraft through a modification project that was completed in 2009, but the Nimrods never returned to Afghanistan, their role being taken up by a trio of new RAF aircraft, the General Atomics MQ-9 Reaper, Beechcraft Shadow R.1 ISR (based on the Beech King Air) and the new Bombardier Sentinel R.1 SAR surveillance aircraft (based on the Global Express business jet). In March 2010 the Nimrod MR.2 aircraft were official retired, ending some 30 years' service which began in the icy waters of the North Atlantic hunting Soviet subs and ended over the harsh terrain of Afghanistan hunting insurgents. It's replacement, the Nimrod MRA.4, won't be due to enter service until 2012 at the earliest.

Source: Air Forces Monthly, July 2010. "Secrets of the Nimrod at War", by Tim Ripley, p38-42.

Big Blue 82: The Commando Vault Bomb

Although the role of the Lockheed C-130 Hercules in Vietnam was primarily that of airlift, one of the most common non-airlift roles it flew was that of a bomber- dropping the large, 15,000-lb BLU-82/B "Big Blue 82" bombs. Following the end of the Second World War the United States did have some bombs in the 10,000-lb class and higher which were dropped by Convair B-36 Peacemaker. They weren't extensively deployed, let alone used, as the B-36's primary mission in the 1950s was that of nuclear deterrence. As the war in Vietnam intensified, the Air Force Systems Command returned to the idea of a large air dropped bomb not as a weapon, but as a rapid combat engineering tool to clear out a helicopter landing zone in the jungle. The B-36 was no longer in service and the B-52's pylons and bomb bay systems weren't designed for the type of weapon the AFSC was considering. One option looked at using the Army's Sikorsky CH-54 Tarhe skycrane helicopters, but the choice eventually settled on the C-130 Hercules due to its speed and range over the CH-54.

The project was designated Commando Vault with the first test drops being conducted in October 1968. The first Commando Vault bombs were the smaller M121 series which weighed in at 10,000 lbs. They were filled with what was called GSX- gelled slurry explosive, a mix of ammonium nitrate, aluminum powder and a liquid gelling agent. GSXs were standard explosives in the mining industry. They were cheap and easily handled, mixed prior to each mission as the mixture tended to be come unstable with time. There is a big misconception that these bombs were fuel-air explosive weapons and they weren't for the simple reason that GSX is a completely inappropriate explosive for FAE applications as it had the consistency of mud and couldn't be aerosolized for an FAE weapon.

The first combat drops were made in Vietnam in March 1969 from the C-130 Hercules. The bomb was carried on a pallet-mounted cradle in the cargo hold and an extraction parachute pulled the load out the rear ramp. The bomb then separated from the cradle and it's own parachute deployed to stabilize it. An extended fuse probe nicknamed the "Daisy Cutter" triggered the bomb before it hit the ground, thereby clearing the trees but not leaving a crater which would preclude the use of the site as a helicopter landing zone. In 1970 a larger version was put into use, this one designated BLU-82/B and it weighed in at 6.8 tons and was about 80% explosive by weight. Also filled with GSX, the BLU-82/B was also dropped by the C-130 and also had a 4-foot stand-off fuse probe that for whatever reason, got the bomb the nickname "Daisy Cutter" when in fact the term "Daisy Cutter" referred to any extended nose probe fuse used on bombs during the conflict.

Accurate drop of the Commando Vault weapons required precise navigation and some of the drops in Vietnam were made using radar guidance as well as the MSQ-77 Combat Skyspot beacon guidance method that was also used to control the B-52 Arc Light drops over South Vietnam. One minute before the drop, the extraction parachute on the cradle of the bomb was deployed into the airstream out the open ramp while the pallet was restrained by the locks in the cargo rails in the C-130's cargo hold. At the release point- usually from a navigator on the flight deck or a ground radar beacon operator in the case of Combat Skyspot- the loadmaster released the locks, dropping the weapon. This also had the unique distinction of making the Commando Vault loadmasters the only enlisted men in Vietnam to deploy aerial weapons!

The minimum altitude for a drop was about 6,000 to 7,000 feet and even at that height, it wasn't unusual for the Hercules to be buffeted by the shockwave of the explosion. In Vietnam, about 200 of the smaller M121 bombs were dropped and about 250 of the larger BLU-82/Bs were dropped. In Desert Storm, the BLU-82/Bs saw action again as being very useful for clearing out large swathes of desert where the Iraqis had placed minefields to stall the Coalition advance. They were also a useful psychological weapon that were typically accompanied by leaflet drops on Iraqi units in the area. On the first night of the ground offensive, the first BLU-82/B drop was mistaken for a tactical nuclear weapon by some of the Coalition units in the area! Eleven BLU-82/Bs were dropped during Desert Storm.

The BLU-82/B was used again in Operation Enduring Freedom in Afghanistan, approximately 3-4 of them being used to hit some of the cave complexes where the Tailban forces were holding out. The last BLU-82/B drop was a test drop in Utah in 2008, the bomb having been since replaced by the more accurate MOAB- GBU-43/B Massive Ordnance Air Blast weapon, also deployed by the C-130 Hercules.

Source: C-130 Hercules: Tactical Airlift Missions, 1956-1975 by Sam McGowan. Aero Publishers, 1988, p124-128.