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Navy Upgrading Sea-Mine Sweeper Helicopters 


by Frank Colucci 

The U.S. Navy intends to deploy the first MH-60S Knighthawk helicopters equipped with organic airborne mine countermeasures with carrier battle groups in 2005.

Although the service has not yet designated which carriers will receive the countermine equipment, planners expect forward-deployed helicopter sea combat squadrons with Sikorsky Knighthawks to replace dedicated helicopter mine countermeasures squadrons flying the MH-53E Sea Dragon. It takes 72 hours to airlift the big Sea Dragons and their minesweeping equipment to a combat theater. Multi-mission Knighthawks routinely operate from ships of many types.

“The beauty of the organic construct is that they’re already in theater,” observes Capt. James Rennie, the mine warfare branch head in the Expeditionary Warfare Directorate of the chief of naval operations.

The Navy will put new detection and neutralization technology on surface ships, submarines and aircraft. Seven new organic mine countermeasure programs are in development, five of which are helicopter based.

Helicopters have swept mines since the mid-1960s. The Sikorsky M-53Es can be airlifted on Air Force C-5 jet transports or self-deployed with aerial refueling.

In February, HM-15 filled six C-5s to deploy four Sea Dragons, 135 people and 200 tons of equipment to Bahrain in support of Operation Iraqi Freedom. The helicopters used side-looking sonar, noisemakers and magnetic sleds to sweep the shallow Khor Abd Allah waterway feeding the key Iraqi port of Umm Qasr.

Four more MH-53Es deployed soon afterwards to Sicily to provide countermine capability around the Suez Canal. The heavy-lift helicopters also serve as cargo carriers.

Once in-theater, Sea Dragons operate from shore bases, mine warfare command ships or amphibious ships. The three-engine MH-53E can tow the 8,000-pound Mk 105 magnetic/acoustic minesweeping sled through high seas, and it can deploy AQS-14 or 20 sonar bodies and Mk 103 cutter arrays from its rear cargo ramp. The 70,000-pound helicopter sustains 25,000-pound tow tension and absorbs surges near 40,000 pounds in high sea states.

The Sea Dragon nevertheless is costly to operate and dependent on strategic airlift or sealift, said Capt. Peter Wheeler, section head for maritime surveillance.

The 23,000-pound Knighthawk blends the utility airframe of the Army Black Hawk with the maritime features of the Navy Seahawk and shares a common cockpit with the Navy’s multi-sensor MH-60R. Sikorsky Aircraft delivered the first production MH-60S configured for mine countermeasures in August 2003. The mine-sweeping Knighthawk incorporates a tow point in the lower fuselage, hookups for a mine countermeasures operator console, and a 400-gallon auxiliary internal fuel tank.

The plan is to field up to 271 Knighthawks to fly vertical replenishment (underway resupply), strike, rescue, medevac and other missions from ships at sea. The 51st production MH-60S and all subsequent Knighthawks will be adapted for mine countermeasure kits. “We’re now planning to buy 44 kits,” says Rennie. “That is probably going to be the lowest number.” Each kit will ultimately include five new organic minesweeping systems.

Initial operational capability is scheduled for 2005, but the helicopter squadrons will introduce a series of mine detection and neutralization systems between 2005 and 2008. Under a 2001 contract, Lockheed Martin is integrating Block A mine countermeasure systems into the MH-60S aircraft.

The mine countermeasures console interfaces with sensors and with the GPS-assisted inertial navigator in the helicopter. It has a single large display that shows multiple views for each sensor and a smaller navigation display identical to those in the Knighthawk cockpit. According to Lockheed Martin director of multi-mission helicopter programs, Paul Monseur, “It’s one console for all sensors, one common look and feel for all of them.” Much of the console hardware is shared with the MH-60S/R common cockpit to facilitate maintenance, support and upgrades.

Block A systems operational on the Knighthawk in 2005 include the Raytheon AN/AQS-20 mine-hunting sonar and the Northrop Grumman Airborne Laser Mine Detection System (ALMDS).

The towed AQS-20 fish uses multiple sonars to scan large volumes of ocean quickly, and has an electro-optical imaging capability to detect and classify mines in one pass. ALMDS uses an aircraft-mounted LIDAR (light detection and ranging) sensor to detect floating mines and moored mines down to the keel depth of ships.

The common cockpit displays of the MH-60S and MH-60R remain unchanged, but additional software gives minesweeping crews tow tension and skew indicators. Mission plans generated aboard the ship will be downloaded into the aircraft on PCMCIA cards.

There are concerns, however, about future funding for ALMDS. This fiscal year, Congress cut $11.4 million from the program. That will prevent the Navy from starting low-rate production, unless it can reprogram money, possibly from other mine countermeasure programs, said a Navy source. ALMDS was scheduled to go through Milestone C in January 2004.

If the funds are not restored, Northrop Grumman would continue development work, but would not produce any systems, said a company official.

Lockheed Martin received a contract in September 2003 to develop organic mine countermeasure systems on the MH-60S. The Block B capability in 2007 introduces the AN/AQS-232 AMNS (Airborne Mine Neutralization System) and RAMICS (the Rapid Airborne Mine Clearance System). The AN/ALQ-220 OASIS (the Organic Airborne and Surface Influence Sweep system) follows in 2008.

Derived from the German Seafox shipboard mine-neutralization system, the AMNS enables the MH-60S to relocate, identify and neutralize mines previously found by AQS-20 sonar, the ALMDS laser detector or other mine warfare platforms. The hovering helicopter deploys an expendable, self-propelled neutralizer steered to the suspected mine by the MH-60S operator. Sonar and video displays on the airborne console help identify a potential mine threat. Confirmed mines are destroyed or detonated with a shaped charge.

The RAMICS uses a laser-aimed 30 mm Bushmaster II cannon to neutralize near-surface, floating and shallow-bottom mines. The blue-green laser penetrates the water to target the mine for the stabilized, rapid-fire gun. Flat-nosed, super cavitating projectiles are designed to enhance range, speed and accuracy when entering the water. The high-velocity rounds penetrate the mine case and detonate the mine with a reactive charge.

The OASIS combines the acoustic and magnetic mine detonation functions now performed by noisemakers and magnetic sleds in a single towed body. Deployed from the helicopter, it emulates ship signatures in shallow water at speeds up to 40 knots.

The Navy’s helicopter master plan introduced the MH-60S (originally CH-60S) Knighthawk to replace the CH-46 Sea Knight, UH-3H Sea King and HH-60H Seahawk in a variety of roles. The MH-60S completed its first operational deployment with squadron HC-5 last May. The 14-helicopter squadron kept two aircraft at Guam and deployed six two aircraft detachments aboard ships at sea.

Current helicopter combat squadrons will be redesignated HSC when the Navy implements its helicopter consolidated operations plans in 2005. The goal is to have MH-60Ss equipped for airborne mine countermeasures on any aviation-capable ship. In carrier strike groups, the helicopters come from carrier-based MH-60S squadrons. In expeditionary strike groups, smaller ships will support HSC expeditionary detachments.

Notional plans call for four mine countermeasures-equipped helicopters in the expeditionary strike force. Each two-aircraft detachment has 26 people. HSC crews will train for mine warfare along with combat rescue and other missions. “The way we see it, every aircrew will have that skill,” says Wheeler.

Countermine missions nevertheless will make additional demands on HSC crews. Today’s dedicated mine-warfare squadrons emphasize crew coordination and specialized pilot training. Air taxiing through sliding turns low above the water with minesweeping gear in tow takes practice.

More responsive, less-costly organic systems put additional demands on the MH-60S helicopter. Towing minesweeping gear inevitably takes a toll on aircraft. Mine countermeasures add about 300 pounds to the empty weight of the MH-60S, compromising performance in cargo and other roles. Sikorsky is studying weight reduction options, including composite stabilizers and lightweight crew seats.

With around 6,000 pounds sustained and 9,000 pounds peak tow tension and a comparatively small cabin, the MH-60S cannot use the Mk 105 sled or Mk 103 cutter array deployed with the MH-53E. However, OASIS, RAMICS and AMNS should provide operational commanders with new capabilities, and eliminate the need for explosive ordnance disposal divers to deal with mines cut loose by mechanical cutters. “It’s our intent to deploy a capability equal to or greater than the -53 capability,” says Rennie.

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