Externally, the most striking feature of the Lockheed Martin F-16E/F Block 60 is the two shoulder-mounted conformal fuel tanks. The removable tanks add about 1,360kg (3,000lb) of internal fuel, while increasing empty weight by 450kg, but with little adverse impact on flying qualities. Otherwise, the aircraft closely resembles the latest Block 50/52 F-16s.
But further examination reveals the forward-looking infrared (FLIR) turret on the nose, forward of the cockpit, and the targeting "mini-pod" attached to the inlet, both unique to the Block 60. These external differences hint at greater changes inside the aircraft, where the avionics are substantially different from those in previous F-16s.
Northrop Grumman's APG-80 agile beam radar (ABR), integrated FLIR and targeting system (IFTS) and Falcon Edge electronic-warfare (EW) suite are all new to the Block 60. The core avionics and digital flight control system use new commercial processors. And the cockpit has been improved to provide enhance situational awareness, with several features added to enhance operational safety.
Flight International was invited to preview the Block 60's capability by "flying" the simulator at Lockheed Martin's Fort Worth, Texas plant. The cockpit layout will be familiar to pilots of other late-model F-16s, particularly the hands-on-throttle-and-stick (HOTAS) control philosophy. The Block 60 cockpit features three 125 x 180mm (5 x 7in) head-down colour liquid-crystal multifunction displays (MFDs) and a 25º x 25º field-of-view head-up display (HUD). The HUD has been certificated as a primary flight reference, allowing flight in instrument conditions solely by reference to this display. A Smiths standby flight instrument, mounted below the centre MFD, is available in the unlikely event the HUD and all three MFDs fail.
Each MFD has 26 bezel buttons around its perimeter, allowing ready access to non-HOTAS functions. The MFDs can be configured in any one of three formats: a single 125 x 180mm window; a 125mm-square window on top of a single 55mm-high window, or a 125mm-square window on top of two side-by-side 55mm-high windows. Selected displays can be rotated through the several windows on each MFD via HOTAS actuation.
The entire cockpit is night-vision-goggle compatible, allowing the seasoned F-16 pilot to leave the previously required masking tape at home. Rounding out notable changes to the Block 60 cockpit is the addition of an onboard oxygen generation system (OBOGS) control panel on the right side console.
Superior sensors
The nose of the Block 60 houses the APG-80 ABR active electronically scanned array radar. To improve radar performance, the nose-mounted pitot tube, found on all previous F-16s, has been removed. Air data is now provided by three fuselage-mounted multifunction probes. An upgraded environmental control system (ECS), designed for harsh desert conditions, provides cooling air to the cockpit and avionics. The radar array has a dedicated liquid cooling system housed in the enlarged vertical tail fairing on single-seat aircraft and in the dorsal spine on two-seaters.
Digital radar information is displayed to the pilot either on a dedicated radar display or a fused tactical situation display (TSD). The standalone radar display can present a vertical situation display (VSD), which shows air-to-air target elevation information in an easy to interpret graphical format.
The IFTS system is comprised of separate navigation and targeting sensors. The navigation sensor is housed in a ball forward of the canopy just to the left of the fuselage centreline, and presents a lower drag profile than the Lockheed Martin Lantirn navigation pod on earlier F-16s. Navigation sensor images are presented in the HUD and give the Block 60 a night visual attack capability independent of night-vision goggles. The targeting pod is mounted on the left inlet hardpoint. The mini-pod incorporates a laser designator and allows the aircraft to guide its own weapons as well those from other platforms.
An internal electronic-warfare system rounds out the Block 60's combat sensor suite. The EW system has three major components: passive receivers, active emitters and dispensable countermeasures. Threat information collected by the passive sensors can be displayed on a dedicated display and/or as part of the fused TSD. If threats are unavoidable, active emitters can be used to degrade or defeat many possible threat systems. Should this fail a large payload of chaff and flares is available to decoy incoming missiles in the end game.
Display fusion
The aerial combat arena places many demands on the single-seat fast jet pilot. With the Block 60, Lockheed Martin has taken big strides to reduce the pilot workload. The TSD is the centrepiece of the Block 60's cockpit, presenting a god's-eye view of the tactical environment with the pilot's own ship centred on the display or positioned about fourth-fifths of the way down from the top. Additionally, a second TSD can be presented to the pilot with its reference centre being another tactically significant point. While air refuelling, for example, a second TSD allows the pilot to monitor both his current position and the future target area.
Information on the TSD is gathered from a number of sources: pre-flight input, own-ship sensors or via datalink. Data displayed on the TSD is from individual sensors, and is not the product of a sensor-fusion algorithm. While not as powerful as the technology promised for the F/A-22 or F-35 Joint Strike Fighter, the TSD is a valuable resource for the pilot. The display builds the tactical picture for the pilot, freeing him from having to assemble a mental picture. With fewer mental gymnastics needed to see the battlefield, the pilot can concentrate more on tactics than he could in previous generation F-16s.
As with all F-16s since the Block 15, the Block 60 has a programmable data transfer cartridge (DTC). While the physical size of the DTC has not changed over the years, its memory capacity has increased dramatically. In addition to communications and route information, for example, it can also hold a digital terrain elevation database (DTED). The DTED for an operational area is a powerful tool that provides terrain elevation and resultant ground clearance when combined with aircraft altitude.
For low-altitude ingress, the aircraft has two terrain-following (TF) modes. One, database terrain following (DBTF), uses the DTED to assure terrain clearance. The other, radar terrain following (RTF), uses the APG-80 to establish terrain separation. The pilot can select which TF mode he wants to use, and altitudes from 100ft (30m) to 1,000ft can be selected and flown manually or hands off.
Of the two modes, DBTF has several advantages over RTF. First, it is not limited by the radar's physical look-angle capability. Even mildly aggressive manoeuvres at low altitude can move the aircraft's projected flight path outside the radar's field of view. DBTF "sees" all the terrain around the aircraft, allowing for more aggressive manoeuvring during terrain-following ingress to the target.
A reduced radio-frequency signature is another benefit of DBTF operations. Since the radar is not required to assure terrain clearance, the Block 60 is less likely to give away its position by its own radar emissions. But it should not be construed that DBTF will be the pilot's mode of choice. Database terrain following lives in a virtual world, where inaccurate or incomplete terrain data could cause real problems. One large advantage RTF has over DBTF is reality versus virtual reality. RTF uses the actual ground, as sensed by the radar, to compute terrain clearance. In some cases, pilots may be willing to be a bit less stealthy to be more assured of avoiding the ground.
One hallmark of the F-16 has been its carefree manoeuvre envelope. In general, the aircraft has few pilot-observed operating limitations. After deliberate mishandling with certain centre-of-gravity positions and stores configurations, however, the aircraft could stabilise at a stalled angle of attack (AoA) where there is insufficient nose-down pitch authority to recover the aircraft. This phenomenon is called a deep stall.
To effect a recovery in the past, the pilot activated a manual pitch override switch to give him direct control of the horizontal tail. In this manual mode, the pilot first pulls the nose up and then pushes it down to establish a pro-recovery pitch rate. This pilot-initiated pitch rocking will break the stalled AoA and allow recovery to controlled flight. In the Block 60 there is an automatic deep stall recovery (ADSR) mode built into the flight control laws. If a deep stall condition is entered, the ADSR will automatically pitch-rock the aircraft and recover it to controlled flight.
The ADSR provides another layer of safety, allowing the pilot to concentrate on the tactical situation and not how he has to fly his aircraft.
Further reducing pilot workload and enhancing safety in the tactical environment are the Block 60's capable autopilot (AP) and autothrottle (AT). The AP can follow mission profiles in both the lateral and vertical dimensions. As mentioned, it can even automatically terrain-follow at low altitude to minimise exposure to hostile radar. The back-driven AT maintains desired speed, and can be used to manage arrival times over specific points. At the end of the mission, the AP and AT combination will even fly an instrument landing system approach for the weary pilot.
Avoiding the ground
As with civil aviation, controlled flight into terrain (CFIT) is a recurring concern for the fast-jet pilot. The Block 60 has three embedded systems designed to significantly reduce the likelihood of flying into the ground. The first and perhaps simplest is the pilot activated recovery system (PARS). This is designed for the situation where the pilot realises he is disoriented. PARS is activated by a pushbutton on the upper right-hand side of the glareshield. Since the sidestick is flown with the right hand, the pilot will most likely release the stick before pushing the PARS button, preventing him from fighting the automatic recovery. Once engaged, PARS will roll the aircraft wings level and establish a 5¼ nose-high climb. The AT will also engage and command a target speed of 350kt (650km/h). For a disoriented pilot, PARS may be the ideal panic button.
The remaining two systems, the predictive ground-collision avoidance system (PGCAS) and automatic ground-collision avoidance system (AGCAS), use the mission-loadable DTED. Only one may be active at a time, but both can be selected off. A selectable minimum terrain clearance (MTC) level establishes the floor for aircraft operations.
Current aircraft position and flight conditions are used to calculate terrain closure rates. If the MTC level will be violated with PGCAS active, large "Break Xs" displayed on the MFDs and HUD as well as an aural warning will prompt the pilot to recover the aircraft before ground impact. With AGCAS active, the recovery will be initiated slightly after it would have with PGCAS, as pilot reaction time does not have to be allowed for. Once AGCAS engages, the pilot is taken out of the loop, and the system climbs the aircraft to safety. Once clear of the immediate terrain AGCAS will recover the aircraft to a 5¼ nose-high 350kt climb, just as PARS does.
The Block 60 iteration of Lockheed Martin's best-selling F-16 is a shining example of evolution improving the breed. Shoulder-mounted conformal fuel tanks increase combat radius with essentially no degradation of subsonic performance. Upgrades to the sensor suite are led by the APG-80 active-array radar. The collated tactical situation display, presented on a large-format MFD, should significantly increase situational awareness by building the tactical picture for the pilot.
Incorporation of digital terrain elevation data allows for terrain-following operations with no radar emissions, while significantly reducing the likelihood of controlled flight into terrain. While not incorporating any ground-breaking technological advances, the Block 60's capabilities close the gap between prior F-16s and the future promise of the F-35 JSF. Those nations needing a new multirole fighter in the near term may do well to follow the United Arab Emirates' lead and evaluate the F-16E/F Block 60.
Source: Flight International
