Block III Apache Takes Control of UAVs
Feb 15, 2009
By Graham Warwick and Bettina H. Chavanne
Hovering above Boeing's Mesa, Ariz., facility, the Little Bird is playing a key role in developing the latest Block III version of the AH-64D Apache. The light helicopter is acting as a surrogate for the U.S. Army's MQ-1C Warrior as Boeing tests the capability to control the unmanned aircraft from the Apache cockpit.
Level 4 control of the UAV, its sensors and weapons is one part of the Block III upgrade that Army officials believe will change helicopter combat operations completely. The ability to receive UAV video in the cockpit - Level 2 - is already fielded in Iraq and credited with transforming the fight against insurgents.
The Level 2 capability, called VUIT-2, has been added as a kit to the Apache and only allows the crew to view incoming video. Level 4 is integrated into the Block III avionics, allowing use of the existing cockpit controls and displays to manage the UAV's flight path, control its payload, and launch its weapons.
"Level 2 is video receipt only - if a UAV is transmitting, the Apache can tune into the frequency and receive the video," says Lt. Col. Rob Johnston, the Army's Apache product manager. "Level 4 is the next step. You receive video, but now you control the flight path of the UAV and its payload - not joystick control, but by putting in a flight plan."
The Army is pursuing plans to field Level 2 capability across its Apache fleet. "We have one battalion fielded with a prototype system," says Johnston. "All 24 aircraft have the A-kit, which allows the aircraft to transmit what it sees, sending MTADS [modernized target acquisition and designation system] sensor video to the ground. Nine of the 24 aircraft have a B-kit that allows them to see UAV video." The requirement is to equip up to 10 battalions, and VUIT may be deployed on other platforms including the UH-60 Black Hawk. "We know there will be huge demand for it because the operational capability is phenomenal."
It is against this backdrop that the next version of the Apache is being developed. The Block III program will involve 634 aircraft: 230 Block Is will be upgraded from 2011-16, followed by 404 Block IIs from 2016-30. Some AH-64As may be upgraded directly to Block IIIs, domestically and internationally.
The main elements of the new upgrade include composite main rotor blades, uprated drive system and digitally controlled General Electric T700-701D engines; open-system architecture avionics, enhanced sensors and radios, and UAV connectivity.
The composite main rotor blade and enhanced rotor drive system combine to provide an increased payload capability of 3,400 lb., says Boeing's Block III program manager Scott Rudy. This change restores some of the performance lost when the original AH-64A was upgraded to the heavier AH-64D Apache Longbow. Now flying on a test aircraft, the new blade is 6 in. longer and has different aerofoils, allowing more of the available power to be used and increasing performance at higher altitudes and temperatures.
The new main transmission splits torque from the two engines between upper and lower face gears, allowing more power to be transmitted within the same space. This boosts capacity to 3,400 shp., from 2,800 shp., with growth capability to 4,200 shp. Using that extra power would require a new tailrotor, changes to the main rotor hub and a new 3,000-shp.-class engine, but these are on the cards beyond Block III.
Performance improvements aside, the avionics architecture constitutes the biggest change to the Apache. An outgrowth of the Army's Manned/Unmanned Common Architecture Program (MCAP), the upgrade replaces three processors with one that has eight times the throughput, 20 times the memory capacity and 100 times the network bandwidth.
Two of these common mission processors replace three pairs of system, display and weapons computers in Block II, each with its custom hardware. There are 19 PowerPC processors in each of the two boxes, plus graphics processors and image compressors, but the system is cheaper and lighter, says Bob Spier, MCAP program manager. The cost is reduced 40% and weight by 85 lb., and reliability is improved 50%, mainly by removing wiring and using easily replaceable data concentrators at six locations where there are airframe splices.
"We wanted a nonproprietary architecture using the best commercial standards and components," says Spier. The open-system software architecture is called Ncore, and is compatible with the Soscoe operating environment developed for the Army's Future Combat Systems (FCS). Where a 1553B databus links the processors in today's Apache, Block III uses Ethernet networks and Internet Protocol-based communications.
Testing of the MCAP architecture began in 2005 with a mission processor mounted on a pallet in the ammunition bay of an Apache. During FCS experiments in 2006 and 2007, embedded interoperability services were demonstrated in which data went directly from the processor to the radio. Capabilities evaluated included downlinking imagery from the Apache's sensors and uplinking streaming video from a Honeywell micro air vehicle.
Under the Block III development program, two aircraft are testing the new avionics: production vehicles 27 and 203. Aircraft 27 has been used to test communications, navigation and the robustness of the baseline avionics. The helicopter recently began testing Level 4 UAV control, working with Boeing's Unmanned Little Bird demonstrator. Aircraft 203 is testing the upgraded, lighter fire-control radar (FCR).
Both helicopters will be used for limited user testing (LUT) of the Block III Apache in November. This will support a decision on low-rate initial production in April 2010. Following LUT, the two aircraft will return for installation of the -701D engines, face-gear transmission and composite rotor blades to test the complete Block III upgrade.
Fielding of the first Block III Apache is scheduled for June 2011. The 53 aircraft planned for low-rate initial production will be remanufactured; beginning with the 54th helicopter in April 2013, the upgrade program will switch to new-build airframes for full-rate production. Plans call for a third of the Block IIIs to be equipped with Level 4 UAV control and another third with radars.
Level 4 capability uses the Lockheed Martin-developed unmanned aerial systems tactical common data link assembly (UTA). A Ku-band TCDL antenna replaces the mast-mounted radar, but uses the same pedestal and radome, and cards are changed out in the radar electronics unit inside the aircraft.
The steerable mast-top antenna provides a high-capacity two-way data link for streaming video. A second omnidirectional mini-TCDL antenna under the fuselage provides a wider range of geometries for the aircraft-to-UAV link, as well as the ability to downlink imagery from the Apache's onboard sensors.
"VUIT-2 was a quick-reaction capability," says Greg Walker, Lockheed Martin business development manager. "The biggest distinction between the two systems is that VUIT-2 is federated - it does not interfere with the aircraft's operational flight program. Getting it fielded was of the utmost urgency and a federated system allowed us to do that." The UTA, in contrast, is fully integrated into the mission processors on Block III aircraft. "The UTA antenna is encased in the same housing as the fire-control radar and they are mutually exclusive," says Walker. "You can either put the UTA up there or the FCR, but you can switch between them in less than an hour."
Level 4 gives the Apache crew full control of the UAV's flight profile and payload, including steering the electro-optical sensor and firing its laser designator. "We treat the UAV as a remote sensor, using the existing controls, displays and the same procedures for operating the Flir and laser in the Apache's MTADS," says Paul Rannik, senior manager for system integration. The UAV's position, flight plan and sensor footprint are superimposed on a moving map on the Apache's tactical situation display.
The ground-station operator will launch the UAV and hand over control to the Apache. The copilot/gunner in the front cockpit will be able to modify the vehicle's flight plan by entering new waypoints. "UAV technology does a lot to reduce workload. It's not a remote-controlled aircraft," says Rannik. "You can set it up as a wingman."
Boeing is using its Little Bird for development testing because the Warrior UAS is not yet available. The helicopter is being flown unmanned, but with a safety pilot on board to allow operations in unrestricted airspace. The second pilot is acting as the UAS operator, using an onboard version of the Warrior's One System ground station.
Initial flights with the Block III Apache are focusing on data-link quality and reacquiring the UAV if the link is lost. "The challenge is keeping the link. We've been successful so far," Rannik says. If the link is lost, the UAV will return to ground-station control. The operator also monitors the vehicle's status at all times and can take back control if there is a problem or it is running low on fuel and needs to return to base.
The Little Bird is equipped with the Warrior UAV's electro-optical/infrared payload, and initial testing will focus on control of the remote sensor and laser. Warrior trials are to begin after limited user testing is complete. Remote control of the UAV's weapons is also a later step and will be introduced with a major software update in production Lot 4.
