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U.S. Army aviation is initiating a program to evaluate, demonstrate, and field countermeasures against optically-aimed, unguided air defense weapons. The largely-classified initiative includes visual-threat cuing sensors to locate threats on the ground within less than 5 degrees and vision disrupter technology to blind air defenders temporarily. The technologies could be applied to Army aircraft starting in 2007 and 2008.

Though Man Portable Air Defense Systems (MANPADS) remain the principal threat to US Army helicopters in Iraq and elsewhere, the Army Aviation Advanced Technology Directorate (AATD) and various Army laboratories are evaluating countermeasures to small arms, Rocket Propelled Grenades (RPGs), and improvised mortars, mines, and rockets. In an address before the Helicopter Military Operations Technology Specialists' Meeting, in Williamsburg, Virginia, AATD Associate Director of Operations Gene Birocco described on-going efforts to counter such low-technology threats.

The low-altitudes and low speeds typically used to counter more sophisticated infrared and radio-frequency threats force Army aircraft down into the low-technology threat envelope. A rapid study of such threats and possible countermeasures was initiated in 2003 and a final report was submitted to Army leadership in June. Continuing work aims at rapid demonstration and application of promising technologies.

Though Army survivability doctrine teaches aircrews to avoid detection, engagement, damage, and destruction, highly mobile, optically sighted threats without in-flight guidance are difficult to detect from the air. Countermeasures are most likely to be effective in the terminal phases of an engagement to avoid damage or destruction.

In the near term, better survivability tactics, techniques, and procedures combat low-technology threats. Improved base security perimeters, more night flying, judicious hovering and low flying, and shoot-on-the-run tactics can all deny enemy forces on the ground targeting opportunities. Significantly, all the fatal Army helicopter shoot-downs in Iraq so far have occurred in daylight. In addition, more liberal battle damage repair criteria may get aircraft back into the fight quickly. Some of the Apaches damaged in the abortive attack near Karbala, Iraq in March 2003 were downed for lengthy repairs. A Black Hawk with relatively minor small-arms damage had to be returned to the US for authorized repairs.

In the mid- to far-term, the AATD report concluded "perfect" sensors are needed to detect and identify enemy personnel at ranges from 1 to 1.5 km. "Equally "perfect weapons are needed to engage threat personnel reliably while reducing or eliminating collateral damage. Ultimately, Army aviation needs wide-area assisted target recognition and weapons. Active close-in protection systems for aircraft may be like those now under development for ground vehicles. In addition, non-lethal weapons may blind the threat operators.

After about 40 flight hours logged with a safety pilot aboard since first flight on September 8, the Boeing Unmanned Little Bird has already cleared most of the MD530F helicopter flight envelope. Flights of the optionally-manned helicopter so far have achieved speeds to 113 kt and altitudes to 5,000 ft. Boeing expects the demonstrator to clear the entire MD530F flight envelope, including altitudes to 10,000 ft, around its Mesa, Arizona facility by November. Live-fire demonstrations are planned at Yuma Proving Grounds early next year. At Yuma, the Unmanned Little Bird will fire Hellfire laser-designated missiles, unguided rockets, and the GAU-19 .50 caliber gun already integrated with the US Army Special Operations AH-6M.

Boeing Ideas sponsors the independent research and development initiative to demonstrate Level 5 UAV control (autonomous flight with the payload controlled from a forward location) on an existing US Army air vehicle. Boeing bought the MD-530F from MD Helicopters in March, took delivery in April, and flew the aircraft with a removable control package in September. "We looked at what was out there and saw some white space," says Waldo Carmona, Boeing director and general manager of Advanced Army Systems. "We got the company to fund this to show the art-of-the-possible right now."

Boeing chose the MD530F to model the Class IV UAV planned for the Army's Future Combat System. The Unmanned Little Bird also offers the service a UAV that fits the existing support and training infrastructure. The AH-6M with auxiliary fuel can potentially carry 1,000 lb for 10 hours. The company's broader objective is to develop a flight control package compatible with any UAV up to the 5,500 lb gross weight of the Little Bird.

The commercial MD530F with Rolls Royce Allison 250-C30R3 engine is the basis of the manned AH-6M Mission Enhanced Little Bird (MELB) in the 160th Special Operations Aviation Regiment. The MD530F provides 6 to 7 hours' endurance with a 300 lb payload or 4.7 hours with 750 lb. The MD530F demonstrator carries a WESCAM MX-15D sensor gimbal with television and infrared sensors, laser rangefinder/designator, and auto-tracker.

In tests so far, the flying payload has been controlled from the front cockpit the AMUST (Airborne Manned/Unmanned System Technology) AH-64D Longbow Apache on the ground. Cooperative weapons trials at Yuma from March to May 2005 will team the Unmanned Little Bird and Longbow Apache. Another demonstration in the spring of 2005 will transfer Level 5 UAV control between an Apache, a Chinook, and a Stryker fighting vehicle, and exercise Level 2 sensor control through a solder's Personal Data Assistant.

Flights planned from February to April 2005 will use the UAV as a wideband communications relay for ground forces. Boeing is also clearing the Unmanned Little Bird for external cargo delivery with up to 2,000 lb sling loads. To date, the MD530F has picked up and delivered 500 lb cargo loads with precision.

The Unmanned Little Bird now uses the Tactical Common Data Link (TCDL) supplied by L3 Communications. Interfaced with the existing MD530F flight controls and instrumentation, the Boeing UAV control package integrates an off-the-shelf Astronautics autopilot and enhanced four-axis servo actuator with a Power PC processor and Boeing VITAL software. The open system architecture is potentially compatible with the DARPA-sponsored Boeing A160 Hummingbird unmanned helicopter and other unmanned platforms. "We designed the kit from the get-go so we could take something already in the inventory and make it optionally manned, or buy a new UAV," says Mr. Carmona.

The removable package can be loaded with up to 99 mission profiles using the standard SOF mission planning station. The Joint Mission Planning System from the Joint Unmanned Combat Aircraft System may be evaluated in the future. Mission programs can be modified in flight via the TCDL uplink.

The presence of a safety pilot with control override authority in the MD50F has accelerated envelope expansion with the optionally-manned air vehicle and provided opportunities for dual-mode flight assessments. With the autonomous flight controls off-line, the pilot can still engage the digital Automatic Flight Control System as a four-axis stability augmentation system to evaluate flying qualities. The optionally-manned Little Bird can potentially serve as a software development platform for the Hummingbird, to supplement the Maverick surrogate already used in the A160 program.

Boeing program managers plan a cooperative demonstration with the Unmanned Little Bird and AH-64D at Fort Campbell in 2005 and may offer the Unmanned Little Bird to complement the Hunter UAV in the Defense Advanced Research Projects Agency AMUST-D and HSKT (Hunter Standoff Killer) demonstrations. "Next year's going to be a busy time for this demonstrator," concludes Mr. Carmona.

Responding to the continuing threat of infrared-guided, shoulder-fired missiles in Iraq, the US Army has fielded a modified version of the veteran ALQ-144 infrared countermeasures set with an integrated dust filter and more powerful cooling fan. The base of the new ALQ-144C contains a two-stage polyurethane foam filter to keep dust from contaminating the mechanical and optical components of the omnidirectional jammer.

More than 3,000 ALQ-144 omnidirectional IR jammers are in service with the US military and foreign operators. Fine, pervasive desert dust caused bearing and motor failures in US Army systems during Operation Desert Storm, but the service took no action on the legacy Aircraft Survivability Equipment until the problem re-emerged in Operation Iraqi Freedom. In the dense dust environment of Iraq, jammers on Black Hawks, Apaches, and Kiowa Warriors clogged after just one hour of operation.

The US Army Communications and Electronics Command (CECOM) issued a rapid response contract for an air filtration application kit in September 2003 and has so far fielded more than 200 modified ALQ-144Cs. Units fielded on the UH-60 Black Hawk and AH-64 Apache operating in the worst dust conditions have required cleaning every 100 flight hours. Those installed behind the sooty exhaust of the OH-58D typically go 80 hours between filter replacements. Filter changes and cleaning take about 30 minutes. Modification of the earlier ALQ-144A jammer to ALQ-144C standards takes about 3.5 hours.

CECOM has also mobilized ASE Field Assistance Support Teams (FAST) to make repairs, expedite spares, and conduct operator/maintainer training in-theater.

To counter the threat posed by more sophisticated Man-Portable Air Defense Systems (MANPADS), the Army has accelerated fielding of the AN/ALE-47 integrated countermeasures dispenser with its three-flare 'cocktail,' and the AN/AAR-57 Common Missile Warning System (CMWS). Fleet installations on CH-47s, UH-60s, AH-64s and fixed-wing aircraft begin in 2005. The Army has already achieved Initial Operational Capability with the BAE AN/ALQ-212 Advanced Threat Infrared Countermeasures suite (including the CMWS) on the MH-47 and MH-60 Special Operations helicopters and will apply ATIRCM to the AH-64 Apache. The directional jammer currently uses cesium flash-lamp technology to focus powerful jamming energy on incoming missile seekers, but a modulated laser for more advanced threats will be introduced in 2006.

     Marine Corps Outlines CH-53 Heavy Lift Replacement

With an Operational Requirements Document awaiting the signature of the Commander of Fleet Forces Command, the US Marine Corps is moving toward a Milestone B launch decision on the CH-53 Heavy Lift Replacement (HLR) program in early 2005. The program is now aimed at 154 new-build CH-53 helicopters with first flight in Fiscal 2011, full-rate production decision in Fiscal 2013, and Initial Operational Capability in Fiscal 2015.

Separate from the Army-led Joint Heavy Lift concept studies, the Marine HLR has a threshold requirement to carry 27,000 lb over 110 nm unrefueled with a 3,000 ft, 91.5 F density altitude; the objective load is 30,000 lb over the same distance. The payload is equivalent to two heavy High Mobility Multi-Purpose Wheeled Vehicles or the latest configurations of the Light Amphibious Vehicle. The totally new HLR will increase current CH-53 gross weight from 74,000 lb to 82,000 lb. At the same time, it provides an opportunity to roll back the high operating and support costs of the CH-53E with new technology.

The CH-53 HLR is now envisioned with a totally new fuselage 12 in. wider than that of the CH-53E to accommodate C-130-size cargo pallets without repacking. Longer, higher sponsons will eliminate the jettisonable tanks usually carried by CH-53Es and give the new helicopter the same fuel capacity with no increase in shipboard footprint. Fly-by-wire flight controls promise to reduce empty weight and enhance survivability. An integrated "glass" cockpit is meant to reduce crew workload and provide joint-service digital interconnectivity.

The conceptual CH-53 HLR will have three new 6,000 shp-class turboshafts driving a new split-torque gearbox. Constrained by the dimensions of existing LHA and LHD amphibious assault ships, the CH-53 HLR will have the same main and tail rotor diameters of the CH-53E, but it will exploit broader-chord rotor blades with advanced airfoils to hike performance. The current concept has a 79 ft diameter main rotor with 6% greater blade chord and a 20 ft diameter tail rotor with 5% greater chord. A new rotorhead with dry elastomeric bearings is expected to cut maintenance costs and last the life of the aircraft.

The Marines have considered mid-life upgrades for the CH-53E since 1992 and with the extraordinary operational tempo in Iraq, Afghanistan, and elsewhere face both high operating and support costs and the impending retirement of Super Stallion airframes. A comprehensive Analysis of Alternatives completed in 2003 considered the cost and schedule history of US Department of Defense aircraft remanufacturing programs. It concluded a new-build HLR program provides least risk. The Marine Corps recently found the cost of remanufacturing UH-1Ns to UH-1Ys comes within 1% of the cost of a totally new helicopter and removes needed aircraft from the fleet for two to three years.

   More Hummingbirds Join Program

The first of three new Boeing A160 Hummingbird Unmanned Aerial Vehicles (UAVs) will be delivered to the Defense Advanced Research Projects Agency (DARPA) in November. Two more of the long-endurance rigid rotor helicopters are scheduled for delivery at three-month intervals to continue the Phase I Advanced Concept Technology Demonstration (ACTD) through 2007. The new A160s will have the same four-bladed Optimum Speed Rotor (OSR) system now flying but share various air vehicle improvements. The turbocharged Subaru four-cylinder gasoline engine currently flying gives way to a six-cylinder powerplant in the new aircraft. Plans call for the introduction of a turboshaft in 2006, and a fuel-efficient diesel powerplant under separate development remains under consideration.

Since January 2002, the long-endurance helicopter UAV has accumulated some 400 flight hours in 150 flights. Of the three original Hummingbirds, only the second Air Vehicle (AV02) and the Robinson R22 Maverick demonstrator now fly. Due to software limitations, the three-bladed AV01 autorotated into the ground after a bearing failure. AV03 with a WESCAM optical payload crashed after a tail rotor failure. AV02 resumed test flights in October and recently demonstrated 45 degree banks at speeds from 60 to 80 kt. Maximum speed attained so far is 130 kt.

Hummingbird AV02 has accumulated 7.5 hours in 14 flights during which it has varied rotor speed from 55 to 85% maximum. The A160 OSR turns at 200 to 400 rpm for maximum efficiency throughout the flight envelope. Low rotor speeds are used at airspeeds from hover 80 kt. High rotor speeds provide cruising speeds to 135 kt. Each sailplane-like main rotor blade incorporates seven airfoils along the span, and the rigid rotor hub provides an expanded maneuvering environment with a wide center of gravity range. Future configurations may add a compound wing.

The Hummingbird helicopter has a 50 to 60% fuel fraction, and with the high-efficiency OSR and an efficient heavy-fuel engine is meant to loiter for 24 hours 500 km from base with a 300 lb payload. A productionized vehicle may compete with the Northrop Grumman Firescout unmanned helicopter for the Army FCS Class IV UAV and the Marine Corps VUAV programs.