It was as though the Pentagon knew what was coming — and had prepared.
On Christmas Day, Chinese government censors allowed the first photos of a new stealth warplane prototype to surface on the Internet. For two weeks, a cascade of increasingly detailed snapshots and videos dispelled early assertions that the fighter might be a mock-up or a digital fake, the product of a misinformation campaign.
On Jan. 11, the black-painted fighter made its first, short test flight. By then, the consensus among foreign observers was that the large warplane with the angular nose and canards was in fact the long-awaited J-20, one of two low-observable next-generation fighters in development for the People’s Liberation Army Air Force.
By the time of the J-20’s debut, the Pentagon was already investing in methods of countering the Chinese stealth fighter.
Perhaps unsurprising in light of flattening budgets, the Pentagon’s plan does not rely on prolonging production of Lockheed Martin’s $130-million-a-copy F-22A Raptor beyond the currently-programmed 187 examples. “The Air Force has to make do with what it has,” Lockheed consultant Loren Thompson said. “That’s mainly the F-15 for many missions.”
To that end, most of the Air Force’s 250 1980s-vintage Boeing F-15C/D Eagles are getting new sensors and other improvements. The result is a “new” F-15 that will retain the old designation, but boast potentially decisive counter-stealth capabilities.
What’s Past is Prologue
In tapping the F-15 for counter-stealth duty, the Air Force is acknowledging the limitations of low-observability … and the inherent strengths of the Eagle’s now-classic design.
True, the F-22 has a miniscule frontal radar cross-section compared to the completely non-stealthy F-15C/D, which is often described as having the radar cross-section of a barn door. But to achieve its low observability, the F-22 designs trades volume and payload for shape and clean lines. To remain stealthy, the angular F-22 cannot carry missiles or fuel tanks underwing; this limits it to internal fuel plus six AIM-120 radar-guided missiles and two of the infrared-homing AIM-9s, all carried in enclosed bays.
By contrast, the F-15′s design emphasizes internal volume and heavy external payload. The Eagle can carries up to eight AIM-120s plus drop tanks, equating to a longer range and greater combat endurance in a beyond-visual-range missile battle.
Moreover, the Eagle has a more capacious nosecone than the F-22 and can carry a larger radar antenna. The larger the radar, the more power it can generate and the more likely it is to detect stealthy targets such as the J-20 at long range. The latest Airborne Electronically Scanned Array radars, which feature many independently radiating modules inside a single nosecone, further increase a fighter’s ability to spot and track small targets.
The F-22 already carries Northrop Grumman’s APG-77 AESA radar. Beginning in 2000, the Air Force installed the larger APG-63(V)2 AESA, built by Raytheon, on 18 F-15Cs belonging to the 3rd Wing in Alaska. Those 18 jets, which in 2007 moved to the 18thWing at Kadena Air Force Base in Okinawa, Japan, represented operational prototypes for a fleet-wide upgrade beginning last year.
In April 2010, the Florida Air National Guard received its first F-15C fitted with Raytheon’s APG-63(V)3 AESA; in December, four similarly-equipped F-15s joined the V2 jets already at Kadena. The Air Force plans to have 54 AESA F-15s in Okinawa by 2013, against a total fleet of 176 F-15C/Ds fitted new radars over the next decade.
In January, Gates announced he would accelerate by several years the installation of the new radars, using funds saved by eliminating redundant Air Force headquarters and staffs. The radars and other upgrades would keep the F-15s “viable well into the future,” Gates said.
In essence, the upgraded F-15s will pack on missiles and fuel and fly with radars blaring, spotting opponents through sheer, electronic brute force, while F-22s shut down their sensors and, perhaps guided by the Eagle pilots, circle around the enemy’s flanks. “Our objective is to fly in front with the F-22s, and have the persistence to stay there while the [F-22s] are conducting their [low-observable] attack,” Giggy said.
It’s a surprising and potentially risky plan — but one that, with its relatively low cost (just $8 million per new AESA radar), could protect the financing for America’s planned fleet of 2,400 F-35 fighter-bombers, due to begin entering service in 2016. Transforming F-15s in to stealth-killers hinges on the 1970s- and ‘80s-vintage Eagles lasting for decades longer than original planned.
When purchased, the F-15 was intended to last just 4,000 flight hours — in other words, until the early 1990s. With fatigue testing, the Air Force extended this deadline several times — first to 8,000 hours, then to 12,000. At today’s flying rates, most of the roughly 250 surviving F-15C/Ds will expire around 2025.
Most of the hard work of upgrading the Eagle’s systems and sustaining its airframe for at least another 15 years falls to the Eagle Division of the Aerospace Sustainment Directorate at Robins Air Force Base in Georgia. A team of around 125 engineers at Wright-Patterson Air Force Base in Ohio design the upgrades; the 212 workers at Robins’ Eagle Division, commanded by Col. Gerald Swift, do all the actual installation work, while another 650 technicians at Robins perform depot maintenance on as many as 70 USAF F-15 C-, D- and E-model Eagles every year.
“On the modernization side, our dollars specifically for F-15Cs and Ds are going into radar upgrades with the APG-63(V)3 AESA, an improved operational flight program to complement that radar capability, a new computer and displays in the light grays [F-15Cs and Ds, as opposed to the dark gray-painted F-15Es] and we’re also upgrading the communications suite,” Swift told Combat Aircraft.
The V3 radar is a recent addition to the Eagle and Swift’s people still haven’t perfected procedures for installing and maintaining the new sensor. At the moment, Raytheon contractors do most of that work. “AESAs? Not yet,” Swift admitted. “Today, we have lines primarily to support the V0 and V1 versions of the APG-63.”
“But,” he added, “we are upgrading our facilities in anticipation of being able to take on that work half a decade from now.”
On the strictly structural side, Swift’s people provide comprehensive services. “We have probably the Air Force’s best aircraft structural improvement program today,” Swift boasted. “We put a great deal of effort into understanding the critical structural points, tracking component throughout the fleet on a tail-by-tail basis, tracking flight hours … we’re doing one full aircraft tear-down on a C- and E-model, and we’re investing in two full-scale test fatigue rigs [at Boeing's facility] in St. Louis.”
The result of that attention to detail is a structurally healthy F-15 fleet — a state of affairs that might have seemed impossible just four years ago, when a Missouri Air National Guard F-15C disintegrated in mid-air, nearly killing the pilot.
After that incident, the Air Force grounded the F-15 fleet, fearing that the jet had simply become too old to fly safely. But a subsequent investigation proved that manufacturing errors related to the jet’s longerons caused the loss of structural integrity: it wasn’t a fatigue-life issue. The Eagles returned to the air.
“Right now, there is nothing life-limiting on the F-15,” Swift said. “It is a very well-designed platform.” For planning purposes, the Air Force foresees retiring the F-15C/D in 2025 and the E-model a decade later. “But those are just planning factors,” Swift stressed.
With the F-22 fleet constrained to fewer than 200 aircraft, the Air Force has little choice but to rely on upgraded and carefully maintained F-15s for decades to come. But the Eagle’s enormous fuel capacity and weapons payload, and its ability to fit a large AESA radar, make it more than a mere stopgap. Despite its age, the upgraded F-15 is arguably the most potent counter-measure to the J-20 and other stealthy rivals — especially when working in concert with F-22s.
“We know that we may not be the sexiest fighter platform out there,” Swift said. “But we certainly are the backbone of the USAF fleet for a long time to come.”