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Thursday, February 1, 2007

Arrowhead’s Vision Enhancement

Descended from the sensor suite of the canceled RAH-66 Comanche, the Arrowhead system provides significant improvements over current Apache FLIRs

Ron Laurenzo

Nothing can wreck the plans of a pilot skimming the earth at 120 knots in pitch darkness like an unseen power line. Except maybe an insurgent with a rocket propelled grenade or the myriad other things that threaten low-flying helicopters.

One of the U.S. Army’s most fearsome weapons, the AH-64D Apache Longbow attack helicopter is really only as good as its ability to evade or destroy the dangers that lurk on nighttime battlefields. Now the Apache’s original Forward Looking Infrared (FLIR) system is being replaced with the most advanced technology available, Lockheed Martin’s Arrowhead Modernized Target Acquisition Designation Sight/Pilot Night Vision Sensor (M-TADS/PNVS), or simply Arrowhead.

In 2000, the Army awarded a $78.5 million development contract to Lockheed Martin and Apache manufacturer Boeing to begin the Arrowhead upgrade, and deliveries began in 2005. Last June, Lockheed Martin was awarded the Lot 3 follow-on production contract, valued at $385 million. Work is being performed by the company’s Missiles and Fire Control unit in Orlando and Ocala, Fla. As of this year, $925 million had been committed for the U.S. Arrowhead program, with a Lot 4 contract expected this month.

The Army requires 704 Arrowhead systems, which are being installed in theater. Four battalions are scheduled to be equipped by the end of 2008, and 10 by the end of 2010. Fielding will be completed to the Longbow Apache fleet by 2011, according to the Army.

The system will be installed on British AH Mk 1 Apaches beginning in 2009, and Arrowhead is the sensor of choice for the Apache Longbow Block III upgrade, slated to begin production in 2011.

Descended from the sensor suite of the canceled RAH-66 Comanche scout helicopter program, the Arrowhead M-TADS/PNVS provides significant improvements over the current Apache FLIR in all areas. It has received rave reviews from the first Arrowhead-equipped Apache battalion, which has been putting the system to the test in Iraq. The Army says Arrowhead is the number one requested upgrade from Apache users.

With Arrowhead, pilots can see better and further at night than ever before, more than double the range of the legacy system. In fact, Apache crews can finally see further at night than the range of their weapons, allowing them to strike from the same standoff distances they would enjoy during the day. Spotting wires and power lines or insurgents crouching in doorways is also much easier.

The whole of the improvement is greater than the sum of its parts because Arrowhead drastically reduces the intense pucker factor associated with maneuvering a helicopter in the dark while man and nature conspire to kill you.

"The crews are much more relaxed and they can stay in the seat for six or seven hours now, whereas with the first generation system, which was designed back in the 70s, you’d fly a two-hour mission and you were pretty much soaked through your flight suit just from the stress," said Bob Gunning, Lockheed Martin’s Apache Fire Control program director. In Iraq, he said, some Arrowhead-equipped Apache pilots are logging as many as 100 flying hours per month, more than most airline pilots.

Maintainers are as pleased with the new system as the pilots, says the Army. Arrowhead’s modularity and vastly improved reliability have taken the pressure off crew chiefs and eliminated one of three levels of maintenance, saving nearly $1 billion in operation and support costs over the system’s 20-year life, according to Lockheed Martin.

When Arrowhead components fail, which occurs less frequently than with the legacy system, maintainers quickly locate the problem with the system’s built-in diagnostics. They then replace the bad part right on the flight line. Broken modules are shipped back to Lockheed Martin for repair and returned to the unit in 15 days on average.

"They’re setting records for flying hours with the new systems because they can," Gunning said. "The pilots can handle it better and it’s a lot less maintenance and consequently it’s a lot less operational support cost for the Army."

Second generation

Widely used on a variety of ground vehicles, ships and aircraft, FLIRs work by sensing temperature differences. Everything radiates heat in the infrared spectrum, and FLIRs build images by comparing the objects’ heat to their background. The heart of the system is an array of detector elements which is cooled to 67 degrees Kelvin (-339 Fahrenheit). The focal array, made up of photon-gathering units called detectors or pixels, looks at the world through a set of optics similar to a telescope. Because the array is so cold, it is extremely sensitive to differences in temperature. The FLIR unit electronically takes data gathered by the detectors, runs it through an image processor and then displays it to the user.

First generation arrays, built in the 1980s, had one row of anywhere from 120 to 180 detectors. The system scanned across the detectors, picking up light from each one to build a picture. These first-generation systems operated in the 8-to-12 micron part of the electromagnetic spectrum, considered long-wave for infrared. Second-generation systems, also long-wave and scanning, came out in the 1990s with four sets of 480 detectors.

To illustrate the improvement, the first-generation Apache system had a one-by-180 array, which the scanner swept across as many times as necessary to build a composite picture. The second-generation system has a four-by-480 array (1920 pixels), which alone accounts for 20 times greater resolution without counting Arrowhead’s improved optics, image processing and other features.

Arrowhead’s detector assembly was originally designed by the Army’s Night Vision and Electronic Sensors Directorate to satisfy Comanche’s tough requirements. Gunning calls it the most advanced detector in production.

While night-vision experts dispute the exact definition of third generation, FLIRs have continued an evolutionary development since the second generation with more pixel-dense arrays (640 x 480 is becoming more common), mid-wave length light gathering and staring technology that gathers light like a video camera instead of scanning across the array.

Scanning allows Arrowhead to optimize the sensitivity of a scene for targeting application and the resolution of the scene for pilotage applications.

"The pilot at the controls needs to see wires, whereas the targeting guy needs to have higher sensitivity to pick out a man that’s hiding in the doorway of a building," Gunning said.

Arrowhead offers the co-pilot/gunner, who sits in the front seat of the Apache, a wide, medium and narrow field of view for finding, identifying and engaging targets. In the narrow field, there is an electronic zoom for zeroing in on human-sized targets, a plus in Iraq. The pilotage sensor has one-to-one magnification.

When moving into or out of a combat area, the co-pilot typically puts his M-TADS sensor in the wide field of view to help the flying pilot navigate and dodge obstacles. Each Arrowhead sensor is gimbaled to slew wherever its pilot is looking, so the crewmen can swivel their heads in opposite directions. Pilots have three options for viewing FLIR imagery: the Apache’s Multi-Function Display and Integrated Helmet Display Sighting System and Arrowhead’s new Target Acquisition Designation Sight Electronic Display and Control (TEDAC).

In contrast to the two older displays, TEDAC is a high-definition screen without which crews would be unable to receive the full benefit of Arrowhead’s vision. The Apache program office is upgrading the helmet display so it can optimally display the new imagery, an upgrade that should be fielded in a year.

Lockheed Martin also has completed the development of a low-light television camera that it has been evaluating with the Night Vision lab. The low-light camera, which looks in the visible spectrum, would pick up city lights, tower lights and other urban illumination that the FLIR, which only sees heat, might not see.

The low-light imagery will be blended with the FLIR so the pilot can simultaneously see both spectra, a big plus in an urban combat situation. The system has already been flight-tested, and Gunning said the Army was pleased with the results. If given the go ahead, he said the company can field the low-light camera as a spiral development in 18 to 20 months.

Lockheed Martin also wants to fuse the targeting imagery from Arrowhead with the Longbow fire-control radar, the cheese-shaped radome perched above the Apache’s main rotor hub, which the company also makes. Longbow can detect motion and identify targets. Currently, the radar cues the pilot if it finds a threat and the pilot looks for the threat. With image fusion, the system would help the pilot find things he might otherwise have missed.

For example, the radar would point out a threat to the FLIR, which automatically would slew to place the threat in the pilot’s crosshairs.

The night vision community now is pursuing 1000-by-1000 pixel arrays. That incredibly high level of resolution will pose tough image-processing challenges, but prototypes are already available, and Gunning said he expects to see these kinds of third-generation systems fielded in the next 10 years.

While the hardware improvements are impressive, they are worth little without the software to rapidly process the vast amounts of data they gather.

"The biggest and most dramatic improvements have come in the software algorithms that do the actual image processing," Gunning said. "We’ve got a team of guys who have probably half a dozen patents for things that are in the Arrowhead system."

The ultimate goal for FLIR is to completely break down the differences between night and day, and do it in living color. That day will come, say industry sources, with systems that are increasingly reliable without being heavier or bulkier.

"The pressure on cost and weight and size that we had on day one in the 1980s is every bit as intense today. That is the universal constant," said Jeff McConnell, business development manager with Raytheon. "And there are great reliability expectations with the product that are being fulfilled."

FLIR Use Spans Services

Although the AH-64D is the only helicopter in the U.S. Army’s conventional fleet with a Forward Looking Infrared (FLIR) system, the cameras are standard equipment for the 160th Special Operations Aviation Regiment.

The Air Force’s HH-60G Pave Hawk and MH-53 Pave Low III helicopters are equipped with FLIRs, as will be the service’s CV-22 Osprey tiltrotor. In the Navy and Marines, the MH-60R and S Seahawk, MV-22 Osprey and CH-53E Sea Dragon have FLIR cameras. FLIRs are proving their value in the Iraq theater, where the Marine Corps’ giant CH-53E cargo helicopters have been equipped with Raytheon’s AN/AAQ-29 system.

The systems are saving lives in Iraq because of the huge improvement they provide in situational awareness, said a spokesman at the Naval Air Systems Command in Patuxent River, Md.

People in industry see a rising demand for these systems considering the improvement of FLIR technologies, more affordable prices thanks to better manufacturing techniques, and the simple fact that having FLIR on board virtually eliminates the possibility of flying into terrain or wires.

"I think we’re going to see, certainly in the military area, there’s not going to be a platform out there that doesn’t have capability like this," said Jeff McConnell, business development manager with Raytheon Space and Airborne Systems.

McConnell said he sees the opportunity extending to even light utility helicopters that typically are not in harm’s way and traditionally have not been considered candidates for FLIR packages.

The Army has been so impressed with Arrowhead that Lockheed Martin is marketing a scaled-down version for the service’s cargo and utility helicopters, a system known as the Pathfinder Pilotage Sensor. Lockheed Martin developed the system from the Pilot Night Vision Sensor (PNVS) side of the Arrowhead program, said Bob Gunning, Lockheed Martin’s Apache Fire Control program director.

Chinook and Blackhawk helicopters are not getting any cheaper, and many of the accidents that destroy or damage them could be avoided with a pilotage FLIR, Gunning said.

Pathfinder is being marketed as an appliqué system that can be mounted easily without altering the system software or operational flight programs of the aircraft.

Lockheed Martin and the Army’s Night Vision and Electronic Sensors Directorate, stationed at Fort Belvoir, Va., planned to begin flight demonstrations in January with Pathfinder on a UH-1 Huey.

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