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Wednesday, January 1, 2014

Stretching the ‘16

Combat Avionics Programmed Extension Suite integrates U.S. Air Force F-16s with an active electronically scanned array radar and the computing power and display space to use it.

by Frank Colucci

The F-16 Original Equipment Manufacturer (OEM) in Fort Worth, Texas is modernizing the federated architecture of the F-16C/D Block 40/42 and 50/52 Viper around Northrop Grumman’s new Scalable Agile Beam Radar (SABR). “I don’t want to imply that it’s a piece of cake, but it’s stuff that we’re very familiar with,” explained Bill McHenry, Lockheed Martin director of Integrated Fighter Group business development. He nevertheless acknowledged, “Replacing a radar is not an insignificant thing. The radar interacts with every other system on the damn airplane.”


Even with the U.S. Air Force expected to achieve Initial Operational Capability (IOC) with the so-called fifth-generation F-35A in 2016, fourth-generation Block 40/42 and 50/52 F-16C/D fighters will remain valuable assets. The Air Force plans a Service Life Extension Program (SLEP) to stretch the structural life of select Vipers from the current 8,000 flight hours to more than 10,000 — enough for six to eight more years of typical operations. The structural SLEP is to be coordinated with the avionics CAPES. The actual date of F-16 CAPES Initial Operational Capability will be determined by the Air Force Air Combat Command, but the F-16 System Program Office (SPO) at Hill Air Force Base, Utah plans to deliver assets to upgrade 24 aircraft by March 2020.


The AESA radar is likely to be the most significant of current modifications on the F-16 that can provide meaningful improvements in combat capability, according to the SPO. The ability of the new sensor to build a Synthetic Aperture Radar (SAR) map and use Automatic Target Recognition (ATR) and Automatic Target Cueing (ATC) against ground threats in bad weather fixes deficiencies in Suppression of Enemy Air Defenses (SEAD) and Destruction of Enemy Air Defenses (DEAD) capabilities. 


The U.S. Air Force plans to upgrade more
than 300 F-16C/D Block 40 to 52 fighters
with coordinated Service Life Extension
Program and the CAPES upgrade.
Photo: U.S. Air Force
Compared to the APG-68(V)9 radar now in front-line F-16C/Ds, the high-resolution SAR mapping, ATR, ATC and advanced Electronic Protection (EP) functions in the SABR promise to increase lethality and targeting precision, enhance pilot situational awareness and improve survivability. 


The Lockheed Martin F-16 Systems Integration Laboratory overlooking Dallas Fort Worth International Airport hosts working radars from every F-16 variant. Included are Northrop Grumman’s own APG-68(V)9 mechanically scanned radar on the Block 50/52 F-16C/D and the AN/APG-80 AESA now on the Block 60 F-16E/Fs of the United Arab Emirates. The Block 60 and the CAPES Block 40/42 and 50/52 Fighting Falcons are nevertheless different aircraft.


“When we incorporated the Block 60 AESA radar, we had to change the ECS [Environmental Control System] system on the airplane. We had to change the electrical system on the airplane.  You just don’t put a bigger fan on it; you’ve got a lot of tubing, etc. That was one of the reasons that drove us to a Block 60 — because of the infrastructure,” McHenry says.


In contrast, the Northrop Grumman SABR and competing Raytheon Advanced Combat Radar (RACR) evaluated for the CAPES both fit the existing Block 40-to-52 cooling and power infrastructure. “That’s the magic that the SABR and the RACR brought to the table,” said McHenry. The Northrop Grumman AESA has been selected by the Republic of China to upgrade Block 20 F-16 A/B fighters and the Raytheon set by the Republic of Korea for F-16K modernization. Lockheed Martin introduced a generic F-16V upgrade for US and international Vipers in 2012 but refuses to discuss specific customer configurations and schedules.


“Nobody goes off and buys a V,”  McHenry says. “They buy elements of the upgrade program and adapt it to their operations. CAPES is what the US Air Force comes out of the V-program with.”


Agile Beams


Northrop Grumman Combat Avionics Systems’ Intelligence, Surveillance, Reconnaissance and Targeting (ISR&T) division outside Baltimore, Md. built the mechanically scanned AN/APG-66 and APG-68 radars on F-16s flying around the world. The company has advanced through 13 different Viper radars with progressively more capability and greater reliability. It also built the AESA radars now on the F-22 air dominance fighter and F-35 Joint Strike Fighter.


ISR&T Director of Strategy and International Business Development Skip Wagner notes that the F-35 at the beginning of its systems evolution provides technology for what may be the last big F-16 upgrade. “The formal testing qualification in the SIL [System Integration Labs] and on the customer aircraft is what remains for SABR,” he says. “SABR is unusually mature and capable for entering a development program.”


Northrop Grumman will supply the Scalable Agile
Beam Radar (SABR) to Lockheed Martin for the
U.S. Air Force F-16 Combat Avionics Programmed
Extension Suite (CAPES).
Photo: Northrop Grumman
The F-35 Joint Strike Fighter also has to keep pace with evolving Air Force, Navy and Marine Corps requirements, plus those of international F-35 customers and will feed developments to the F-16 SABR. “That collective team we would expect to have frequent upgrades with robust funding to keep that radar growing,” says Wagner, also noting the happy coincidence of US and international F-16 upgrade programs. “The timing of the US AF CAPES program and the Taiwan program could not be better.”


Northrop Grumman transplanted some fifth-generation F-35 capabilities into the new F-16 sensor — about 95 percent of the SABR software was “ported over” from the F-35. “That’s reduced the cost of that development, the schedule of that development, the risk of that development,” says Wagner. The radar maker built the first SABR in 2006. It subsequently took the AESA radar to the Lockheed Martin SIL and then flew it on a Block 50 F-16 at Edwards Air Force Base about two years ago. 


Fifth-generation radar technology brings big benefits to a fourth-generation fighter. The new, electronically scanned radar with its fixed, dense Receiver/Transmitter (R/T) array provides a sharper target picture with new processing opportunities. Mechanically scanned radars generate only low-resolution Synthetic Aperture Radar (SAR) imagery with a narrow field of view.


“The pilot has to hunt and peck to build a SAR map and hope he has the right field of view.  What SABR does is build a very large SAR map, and then with Automatic Target Recognition, the pilot can be multi-tasking while the radar will build a very large SAR map and recognize targets for the pilot to address,” says Wagner. The SABR achieve its highest resolution in a 1-square-mile map. “High-resolution SAR is one of the many key criteria that enables Automatic Target Cuing in the radar,” says Wagner.


 Wagner could not disclose comparative performance figures but acknowledges the SABR increases range significantly over the APG-68. In air-to-air engagements compared to legacy radars, the SABR tracks many more targets with greater fire control accuracy at longer ranges, all the while searching a much larger volume of sky. “Mechanically scanned arrays don’t see as far, and when you track a target, you’re limited in the field of view,” says Wagner.


“Mechanically scanned arrays generally do one task at a time. SABR does multiple functions, assessing data and reporting real information, not data for the pilot to sift through,” says Wagner.


Electronic Protection (EP) built into the new radar promises to maintain AESA performance advantages despite countermeasures. “In the past, radars have performed well in a nice, clean, friendly environment. Recently, there are advanced, very advanced and robust electronic jammers employed by our adversaries. They will effectively reduce the radars’ range and ability to detect anything at all very significantly. Radar must be measured and is only effective in a combat environment,” says Wagner.


The APG-81 AESA of the F-35 demonstrated its EP performance on Northrop Grumman’s BAC 111 airliner platform in a countermeasures environment during Northern Edge exercises in 2009 and 2011. The F-16 SABR on another BAC 111 was itself tested against the same threats in 2011. Northrop Grumman will not comment on SABR potential Electronic Attack (EA) capability.


For all the carry-over from F-35 to F-16, radar hardware on the later-generation fighter is still different from that in the F-16 CAPES. “We have not, literally, a box full of circuit boards,” says Wagner. “We have building blocks. There’s commonality in the building blocks, the SRUs [Shop Replaceable Units], but we don’t take the LRUs [Line Replaceable Units] from one aircraft to another,” he says.


The mechanically scanned APG-66 and -68 radars in F-16s have four LRUs. The SABR AESA antenna eliminates a dedicated transmitter LRU, and a single supporting Receiver/Transmitter Processor replaces today’s discrete receiver and processor LRUs. Wagner could not disclose actual weight and volume savings but says, “Four major LRUs are eliminated from the aircraft and replaced by only two LRUs. … We’ve eliminated federated boxes around the aircraft. We have everything on a single backplane with a lot more processing power and memory for better test.”


Eliminating conventional transmitter and travelling wave tube hardware from the SABR eliminates the most failure-prone parts of today’s radars. Reliability of the next-greatest-failure item — the receiver-exciter — is also enhanced with fewer boards providing more processing power. The AESA array is inherently more reliable than a mechanically scanned antenna.


“There are no moving parts. You don’t have motors, slip rings. When you have motion, that creates reliability issues,” says Wagner. Estimates of three-to-five-times better reliability for the SABR radar depend on comparisons with the APG-68 and earlier APG-66, but the greater reliability of the new AESA radar can move the Air Force from common three-level maintenance schemes to just two levels — organizational and depot.


Fourth- and fifth-generation fighters naturally differ in available power, aperture size and cooling accommodations — all determinants of AESA radar range. However, Northrop Grumman is confident it can integrate the AESA advantages into the F-16. “We know how to do this; we’ve done it 13 times before,” says Wagner.
Computing CAPES


The F-16 CAPES also includes the Terma AN/ALQ-213(V) electronic warfare management system to integrate existing radar and missile warning receivers, active jammers and countermeasures dispensers. Lockheed Martin would not address specifics of the suite, but Bill McHenry acknowledged, “All customers are just generally looking for more capability against state-of-the-art air-to-surface to air- and-air-to-air weapons systems.”


CAPES will simultaneously give the F-16 pilot access to off-board threat data through the Intelligence Broadcast Receiver (IBR) that brings networked data into the Viper cockpit. The big, sharp radar picture, new threat displays and access to off-board intelligence resources drive the CAPES requirement for a new F-16 cockpit display. The F-35 instrument panel is built around a 20- by 8-inch touch display to show aircraft systems data and targeting imagery. The legacy F-16 cockpit imposes size constraints.
“It would be a huge disruption in the cockpit to have that big panoramic display,” says Bill McHenry at Lockheed Martin. “We’re putting a big display between the pilot’s legs. We did that on the Block 60,” says McHenry. Lockheed Martin will not discuss display specifics, but McHenry says, “That will allow the very high-resolution SAR maps and all the other data to be effectively displayed to the pilot.”


CAPES configurations are still to be finalized, but the F-16 SPO expects the new 6- by 8-inch center display unit to replace the existing horizontal situation indicator, air speed Mach indicator, altimeter, vertical velocity indicator, angle of attack indicator and attitude direction indicator. The new 1024x768 pixel display will show symbology and imagery with three times the resolution of the existing 4-inch square displays now in the F-16 cockpit. Elbit Systems of America recently won a contract to provide a 6- by 8-inch center pedestal display to Lockheed Martin for an F-16 Foreign Military Sales customer. The multifunction display replaces electromechanical flight instruments. Raytheon Intelligence and Information Services provided a similar display upgrade for U.S. Air Force F-16s.


With the Air Force deciding not to field the Night Vision Cuing and Display (NVCD) system, an analysis is underway to find a night-capable helmet mounted cuing system to replace the VSI Joint Helmet Mounted Cuing System now on some F-16s. “There are integrated helmets that are coming down the pipe,” says McLean. “There are some customers that have more advanced and some that have less advanced. We’re looking at the state of the art.”


To integrate the SABR radar and other enhancements into the CAPES F-16, Lockheed Martin plans an upgrade to the aircraft Modular Mission Computer (MMC) and Operational Flight Program (OFP). OFP updates routinely add new weapons, targeting pods and subsystems to the Viper menu of options. The OFP also adds new capability to the F-16 digital flight control system. Some Viper customers now want the Ground Collision Avoidance System (GCAS) integrated into their aircraft, and later F-16 blocks incorporate a pilot disorientation switch that puts the aircraft wings-level and nose-up to help a dangerously confused aviator get home.


More data and a new OFP drive the introduction of a more powerful F-16 Modular Mission Computer (MMC). “We are expanding on that for the CAPES configuration to provide speed and memory improvement for the bus traffic on the airplane,” says McHenry. Raytheon Space and Airborne Systems introduced the first-generation MMC in 1997 and replaced three processor boxes with a single LRU having 30 times the throughput/speed and memory. A subsequent Common Configuration Implementation Program (CCIP) kit added even more processing power.


Raytheon refuses to discuss further MMC expansions for CAPES, but McHenry says, “The core computer and the architecture are likewise a derivative and an improvement on the MMC in a thousand F-16s, and I mean literally a thousand F-16s.” 
 

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