Mike Gerzanics/NAS LEMOORE, CALIFORNIA
While most fighters mature into multi-role machines, Boeing's F/A-18 qualified for its dual-role designator from day one. That tradition continues with the latest iteration of the design - the F/A-18E/F Super Hornet. This upgrade of the proven Hornet lays the foundation for avionics and systems improvements that will maintain the aircraft's position as the centrepiece of US naval aviation.
More than just a photographic enlargement of the F/A-18C/D, the F/A-18E/F Super Hornet promises significant improvements over the basic Hornet. With an 860mm (34in) longer fuselage and 25% larger wing, the E/F can carry 33% more internal fuel - overcoming the range deficiency that has dogged the carrier-based F/A-18 since it was introduced.
Two General Electric F414 afterburning turbofans increase thrust by 25% over the F404s powering late model C/Ds, to handle the 18% higher maximum take-off weight of 29,900kg (66,000lb). With its 46m² (500ft²) wing, the E/F lands 10kt (18km/h) slower than the C/D despite being 30% heavier, and can bring back a 1,600kg heavier payload, returning up to 4,100kg of valuable unexpended ordnance and unused fuel to the carrier deck.
Improvements in survivability have also played a big role in the Super Hornet's development. The quadruplex-redundant digital fly-by-wire flight control system can reconfigure itself to compensate for battle-damaged control surfaces. The designers also incorporated low-observability features into the E/F. To reduce frontal aspect radar cross-section (RCS), the engine intakes are reshaped while inlet devices block radar energy backscatter from the engine fans. For self-protection, the E/F will carry towed decoys as well as chaff and flare dispensers.
Use of the proven F/A-18C/D avionics kept down E/F development costs, but Boeing and the US Navy are now developing a series of upgrades that will introduce an active-array radar, third-generation targeting pod, new mission computers and cockpit displays, helmet-mounted cueing system and independent aft crew station into the aircraft. This configuration will be the baseline for the export Super Hornet, which Boeing expects to be available for first deliveries around 2005.
Evolutionary cockpit
Flight International flew the US Navy's newest strike fighter with VFA-122 at NAS Lemoore in California's San Joaquin valley, the squadron responsible for training all Super Hornet aircrew. Lt Cdr Matt Tysler, a former F/A-18C/D operational pilot and F/A-18E/F test pilot, was safety pilot for the flight. First, we spent an hour in a fixed-base simulator while I familiarised myself with the front cockpit and normal operational procedures.
The front cockpit is dominated by a large, 20° field-of-view head-up display (HUD). Directly below the HUD is a touchscreen liquid-crystal display (LCD). This upfront control/display (UFCD) is activated by the pilot's finger breaking infrared beams just above the screen, and not by touching the glass.
The 75 x 130mm monochrome UFCD is truly multifunctional, and can present any of the displays available to the pilot apart from the colour moving map. On either side of the UFCD are two 130mm-square LCD digital display indicators (DDIs), while below is a 130mm-square LCD multipurpose colour display (MPCD), used mainly for the moving map. These displays are not touchscreens and each has 20 buttons around its perimeter.
The HUD is the Super Hornet's primary flight display, presenting all the information the pilot needs to fly in instrument weather conditions. A complete set of standby instruments is to the right of the MPCD. To the left is an LCD engine/fuel display (EFD). The upper half of this presents fuel status in either of two formats: one showing external tanks; the other each individual internal fuel tank. A nice feature is the ability to set a "Bingo" fuel level via a rotary knob on the display's left-hand side.
Autonomous operation
Simulator familiarisation complete, Tysler and I prepared for the flight. Most of VFA-122's F/A-18F two-seaters have missionised rear cockpits. The Super Hornet we would be flying had fully functional stick and throttles in the rear cockpit, which I would occupy. I could not help but notice how similar the Super Hornet looks to the basic Hornet. The only obvious difference, apart from overall size, is the enlarged, angular intakes, which appear more menacing than the basic Hornet's round inlets.
I followed Tysler as he quickly performed the straightforward walk around, checking such things as reservoir levels and accumulator pressures. The aircraft was clean except for weapon pylons on underwing stations 4 and 8 (the Super Hornet has 11 stores stations, two more than the Hornet). Zero fuel weight was 14,500kg and the aircraft held 6,250kg of fuel. The single-seat E model holds 6,675kg of fuel.
I boarded the aircraft via an integral ladder, which stows in the left-hand wing leading-edge extension (LEX). I sat first in the front cockpit to evaluate the field of view through the large canopy and was able to look back between the twin tails to check my six o'clock. The LEXs, although much larger than those on the C/D, are set further back, which should allow a better view in the lower forward quadrant.
Moving to the rear cockpit, I strapped myself into the Martin-Baker NACES zero/zero ejection seat, which as well as the four-point torso harness, has upper and lower leg restraints. Tysler settled into the front cockpit and turned on the aircraft battery ready for engine start. Using only internal battery power, he started the auxiliary power unit, which was up to speed in less than 30s. Placing the "engine crank" switch to the right-hand position spooled that engine up. At 10% N2, Tysler put the throttle over the idle stop. At 61% N2, the right generator automatically came on line. Exhaust gas temperature peaked at 475°C, against a limit of 871°C, with the engine reaching an idle rpm of 66% N2 in about 35s.
Before starting the left engine, Tysler initiated inertial navigation system (INS) alignment by entering position, elevation and magnetic variation via the MPCD. The INS can be augmented by the global positioning system (GPS), which allows rapid ground and in-flight alignment and precision navigation. Our aircraft did not have a GPS receiver, but the entire alignment took only 7min.
Once the left engine was started, it took 73% N2 to get the aircraft rolling as we taxied for take-off. Tysler engaged the nosewheel steering (NWS) in the low mode, ±22.5°, via a pinkie switch on the base of the stick. Once rolling, he allowed me to evaluate the NWS and brakes. At all times I was able to track the taxiway centreline accurately. Tysler, meanwhile, selected flaps to their "half" take-off position. Approaching runway 32R, I selected the high NWS mode, ±75°, to make the 90° turn for runway line-up. Once established on centreline, I pumped up the brakes in preparation for engine run-up.
Short field performer
With an 8kt head wind, the tower cleared us for take-off. I rapidly advanced both throttles to the military power position. Once both engines had stabilised, I jammed the throttles to the maximum afterburner position and released the brakes. The 16,000kg aircraft accelerated briskly down the runway. At the rotation speed of 120kt, I pulled the stick about 60mm aft. At about 125kt, and 13s after brake release, the aircraft left the runway after a ground roll of only 365m (1,200ft).
The climb attitude was maintained easily, with landing gear and flap retraction causing little, if any, pitch change. We maintained 350kt as we climbed to 19,000ft for our transition to the working area. Throughout the climb, I found the aircraft highly responsive in both pitch and roll. Less than 3min after lift-off, we were level at 19,000ft, having used only 680kg of fuel.
En route to the operating area, encompassing Mount Whitney to the west and Death Valley to the east, I engaged the autopilot in the "balt" - altitude and roll attitude hold - mode at 21,000ft. The autothrottles were engaged to hold 300kt indicated airspeed, to approximate a maximum range cruise angle-of-attack of 3°. At 415kt true airspeed, the total fuel flow was 2,180kg/h. Once cleared by air traffic control, I coupled the autopilot to the INS, via the UFCD, and the aircraft rolled smoothly on to a wind-corrected track directly to the working area. I found the autopilot - which can be disengaged by a paddle switch at the base of the stick - to be a good relief aid, allowing me to record in-flight observations. Tactical aviators will find it useful during the long missions typical of today's peacekeeping operations.
Once east of Mount Whitney, we descended into the Owens Valley for several low-level ingress legs to a simulated target. During our descent, we performed a g warm-up exercise to prepare us for the rigours of high-speed, low-altitude flight. At about 380kt indicated, I banked 90° left and pulled smoothly to 4g. Feeling the reassuring inflation of my g-suit, I unloaded, rolled right and pulled to 5.5g. There was light buffet as we tracked through 4.8g. The nose tracked smoothly across the horizon, displaying none of the wing drop that occurred early in Super Hornet development. A porous plate over the wing fold has cured this problem.
At higher speeds, the Super Hornet's pitch axis control is a g command system. Each g requires 1.6kg of stick force. At speeds above 320kt, about 10kg of force is required to generate the design load factor of 7.5g for gross weights below 19,140kg. For higher gross weights, the limit load decreases, but is never less than 5.5g for a maximum weight aircraft. The digital flight controls prevent the pilot inadvertently exceeding this, but depressing a control stick paddle switch allows the pilot to pull to 33% more than the design limit.
Low-level ingress
Using the HUD's radar altitude display, repeated on the left DDI in the rear cockpit, we proceeded north over the high desert floor of the Owens Valley at 500ft above ground level (4,500ft above mean sea level). En route to our first turn point at 480kt true airspeed, total fuel flow was 5,100kg/h. Tysler programmed a notional time over target into the mission computer, which displayed the wind-corrected speed required to achieve this in the HUD's lower left corner, and provided guidance to attain an on-time arrival. During our low-level ingress, the INS automatically sequenced from waypoint to waypoint, providing excellent guidance along our route.
Controlled flight into terrain is a concern for all aircraft operating at low altitude, and the Super Hornet has two features designed to increase the pilot's altitude awareness. The first is procedural, using the radar altimeter. Before descending to low altitude, the pilot sets an alert altitude 10% below the planned flight altitude - 450ft for my planned 500ft ingress. Descending below the set value triggers an aural tone and displays "altitude" in the HUD. The second, more innovative feature is a function of the ground proximity warning system (GPWS). It provides an aural "altitude" warning should the GPWS predict ground impact.
En route to our target at 450kt and 750ft, I initiated a 4,600ft/min (23.37m/s) dive into a valley. The low altitude and high rate of descent triggered the GPWS' "altitude" warning. Had I been distracted by another task, it would have provided ample warning to avoid ground impact. The current GPWS uses only radar altimeter information and may not provide adequate warning in steeply rising terrain. Future plans call for the integration of a digital terrain database and GPS to ensure timely and accurate warnings, even in mountainous areas.
The final low-level leg was our attack run. To bring up the air-to-ground symbology for our attack, we had simulated loading a 450kg (1,000lb) bomb on one of the weapon pylons. At 5km (2.8nm) from the target, I initiated a climbing left-hand turn for our pop-up delivery. Tysler slewed the HUD's target box visually over the target, an oasis in a small valley. At 2,000ft, I rolled inverted and initiated a 4g pull to the target. Aligning the aircraft with the HUD's target guidance, I rolled out in a 20° dive and depressed the stick's pickle button. At about 1,500ft, the computer released the "bomb" and we aggressively manoeuvred off target. I simulated dispensing chaff and flares using the countermeasures thumbswitch on the throttle.
Egressing the target area northbound at 430kt and 500ft, Tysler called a simulated launch of an infrared-guided surface-to-air missile from seven o'clock. I slammed the throttles to idle and dispensed simulated chaff and flares while initiating a 6g break to the left. After 180° of turn, I rolled out and jammed the throttles to military at 320kt indicated airspeed to preserve the aircraft's manoeuvring capability.
Wanting to leave the threat area as soon as possible, I selected maximum afterburner as we accelerated through 380kt. Maintaining level flight, we stopped accelerating 29s later, having reached 605kt indicated airspeed - Mach 0.95 - well short of the published 780kt limit. Low-level manoeuvring complete, I selected military power and started a climb in preparation for high angle-of-attack (AoA) manoeuvring.
Extraordinary at high AOA
At M0.84, we climbed at an average rate of 12,500ft/min, and quickly reached an altitude of 25,000ft over Death Valley. Once level, I pulled the throttles to idle to set up for slow flight. At 260kt indicated, I selected "speedbrake" to aid deceleration. Unlike most aircraft, the Super Hornet does not have a dedicated speedbrake. The speedbrake function is performed by deflection of various control surfaces, including spoilers and ailerons.
Although the system does not actively seek a constant deceleration rate, selected control surfaces are deflected more as airspeed decreases and hinge moment loads decrease. I found speedbrake operation to be totally transparent, at no time causing more than a slight variation in pitch attitude.
Speedbrake deselected, we slowed down in level flight. Light airframe buffet was present at 17° AoA (130kt), but was gone as AoA increased past 25°. At 30° AoA, I selected military power and captured 35° AoA. I was able to control AoA to within 1° as we descended wings level at 6,000ft/min and 105kt indicated. I put in partial right rudder, and the aircraft smoothly entered a 30° banked turn. After a 60 ° heading change, I released the rudder and reversed the turn direction using left lateral stick - I hesitate to say "aileron", because the E/F's flight control system (FCS) can use a number of different surfaces to perform the "aileron" function. I found control responsiveness in all three axes (pitch, roll and yaw) to be excellent, with no wing rock or yaw wandering tendencies.
With wings level, in an effort to demonstrate the E/F's resistance to departure from controlled flight, I simultaneously put in full right lateral stick and full left rudder. This abrupt cross-control input had no discernible effect, the aircraft remained rock steady at 35° AoA.
Next, I reduced the AoA to 30°, with the aircraft in a 25° nose-high pitch attitude. I rapidly pulled the stick to the full aft stop and held it there. The aircraft pitched to 45° nose up, an increase of 20° from the stabilised value, as the AoA peaked at 59°. This large pitch reserve, available at such a low airspeed, will be useful should the Super Hornet pilot find himself in a close-range visual fight.
The aircraft stabilised wings level at 48° AoA and 70kt indicated, in a full aft stick stall. Aircraft heading tended to oscillate ±3° from the steady heading at about 2Hz. Seeking to prevent a departure in the yaw axis, the FCS actively uses yaw rate feedback to keep the aircraft pointing forward. One benefit of this control scheme has been the elimination of the "falling leaf" departure mode present in the basic Hornet.
A full left rudder input rolled the aircraft into a 45° banked turn, with AoA stabilised at 45°. A stabilised yaw rate of 6.25°/s was attained, and I was able to control aircraft heading accurately. After levelling the wings, I moved the stick to the full forward stop to recover from the stall. The aircraft pitched over to 40° nose low at an impressive rate of 17°/s.
Next, we performed a full forward stick inverted stall. As was the case with the aft stick stall, the aircraft was extremely stable, attaining a steady state AoA of -32° at -1g.
The final high AoA manoeuvre we performed was a vertical recovery. A military power 4g pull to a vertical attitude started the event. Heading straight up at 100kt indicated, I selected maximum power. At this extreme condition, the digitally controlled engines, which have no pilot-observed limits, responded by smoothly lighting both afterburners. I started the recovery by pulling aft stick to bring the nose toward the horizon. The nose tracked smoothly downward, and I released the stick when the aircraft was in an inverted, 20° nose-low attitude. Without any pilot inputs, the aircraft slowly rolled upright and stabilised in a wings level 30° dive. It was as if the Super Hornet knew how to complete a recovery from an extremely low-speed vertical attitude.
Pirouette manoeuvre
Finally, we performed a pirouette manoeuvre. This is essentially the Hornet equivalent of a hammerhead turn - a slow-speed, nose-high to nose-low, yaw rate turn in the near-vertical plane. When first developed, the E/F was unable to perform this stock Hornet manoeuvre, but modifications to the yaw rate feedback schedule put this back into the repertoire.
In military power, I started the manoeuvre at 210kt and 13,000ft altitude by pulling the nose up. At 150kt in a 65° nose high attitude, using slight aft stick pressure to keep the AoA above 25°, I put in full left rudder and left lateral stick. To my amazement, the aircraft yawed smoothly 180° to the left, ending up in a nose-low attitude on a reciprocal heading. Recovery to level flight and 200kt completed the manoeuvre. The entire operation took less than 25s, yielding a turn rate of about 8°/s.
Area work complete, we turned to the west for our recovery to Lemoore. Flight control laws limit maximum roll rate to 225°/s in an air-to-air configuration, and 150°/s with wing-mounted fuel tanks or air-to-ground munitions. At 15,000ft, I performed full lateral stick rolls at 240kt and 360kt indicated. At both speeds, a 360° roll was complete in less than 2s.
During our cruise home, I was able to reflect on the Super Hornet's manoeuvrability. The second leading cause of Hornet losses in the US Navy has been departure from controlled flight. At all conditions, the flight control system had allowed me to manoeuvre the aircraft predictably without regard to airspeed or AoA. The Super Hornet's demonstrated departure resistance is exactly what "carefree" manoeuvrability is all about.
While air traffic control vectored us to Lemoore, I explored some of the air-to-air (AA) and air-to-ground (AG) modes of the current Raytheon APG-73 radar. As well as the normal "B scope" AA presentation (azimuth versus distance) on the right DDI, I placed the azimuth versus elevation AA display on the left DDI. Although you could glean the same information from a single B scope presentation, having both a "God's eye" view and relative elevation display at the same time made it much easier to interpret the air-to-air picture.
Radar capabilities
The Super Hornet's AG radar display was impressive. The synthetic aperture radar (SAR) ground-mapping mode had three different levels of expansion (EXP), each expanding a smaller area to a higher resolution. The moving map display on the MPCD greatly enhanced my ability to use the EXP modes. For gross target acquisition, I did not need to use the radar display. Rather, I could slew the cursor over the target area on the moving map, and get an SAR expanded picture by hitting one of the DDI's side buttons. Each radar sweep built a more detailed and refined picture. From over 37km away, the SAR clearly showed Lemoore's runways, taxiways and hangars. After several sweeps, we could even discern the point on the ramp where we had taxied from an hour earlier.
Boeing and Raytheon have already begun development of an active electronically scanned array (AESA) radar for the Super Hornet. This will provide increased range and resolution in near-simultaneous air-to-air and air-to-ground operation. Raytheon is also developing the E/F's ATFLIR (advanced tactical forward-looking infrared) pod, which will replace separate navigation and targeting sensors and provide increased range and resolution.
The F414s have proven extremely reliable, but to simulate an engine loss Tysler retarded the left throttle to idle. Single-engined combat aircraft are widely accepted, but some operators still prefer a twin-engined design for just this contingency. Half flaps were selected for the single-engined instrument landing system approach to Lemoore's Runway 32L. Final approach speed for the 16,340kg aircraft was only 132kt indicated.
The rudder trim easily took care of adverse yaw caused by the asymmetric thrust condition and I was able to track precisely both the localiser and glideslope during our approach. Even with only one engine, I was able to maintain the desired approach speed ±3kt. The view from the back seat enabled me to make the transition to a visual approach at 200ft above ground level. The smooth touchdown on runway centreline was a direct result of the Super Hornet's compliant gear, because the navy's "no-flare" carrier landing technique was used.
After the single-engined approach, we entered the visual circuit for several touch-and-goes. Pattern altitude was 600ft and the flaps were selected to "full". With the improved view from the rear cockpit, I was able to fly a reasonable visual circuit. Power responsiveness was excellent, especially on final approach, when I sought to maintain an approach AoA of 8.1°. Final approach speed for the full stop landing, with 1,090kg of fuel remaining, was 121kt. After an on-speed touchdown, I retarded the throttles to idle. As the aircraft slowed, I applied full anti-skid braking at 100kt. Total distance from touchdown to stop, with an 8kt head wind, was less than 610m (2,000ft). An even shorter landing roll could have been achieved if I had applied full brakes before touchdown, relying on the anti-skid system to prevent wheel lock-up.
Taxiing back to VFA-122's ramp was uneventful. The INS, even without GPS, had drifted only 0.37km during our 1h 44min block-to-block flight. Shutdown and post-flight procedures were accomplished easily. Fuel remaining at shutdown was 1,045kg, the aircraft having consumed a total of 5,200kg.
Best of a generation
My brief introduction to the Super Hornet convinced me it is one of the best strike fighters of its generation. Its only real deficiencies are in transonic acceleration and top speed. The Super Hornet, however, has extraordinary high-AoA manoeuvre capabilities, unmatched by any current Western strike fighter. Its avionics are world class, and the planned AESA radar will only increase its capabilities. The E/F's design provides room for further upgrades, helping to maintain its tactical edge for years.
The US Navy got exactly what it asked for from the Super Hornet programme: an affordable, capable strike fighter ready for operational deployment now. The question facing prospective export buyers of the Super Hornet is less easily answered, as the F/A-18E/F faces stiff competition on the international market.
But while aircraft still under development, such as the Eurofighter Typhoon, may promise better capabilities at competitive prices, the Super Hornet is fast becoming a known quantity - and some operators may be well served by choosing the sure thing.
Source: Flight International
