Flying The Electric Jet

This article was first published in Air Clues October 1981, by Dim Jones

I have always wanted to fly an aircraft so new that the sticky price tag was still on it; when that price tag is attached to an F-16, the experience is well worth the effort. Much has been said, and written, about whether the F-16 is the right aircraft to do the job required of it by the USAF and the European Purchasing Nations, particularly in the Central European theatre. This article may not answer that question, but it should provide a pilot's eye view on which to base an opinion.

The F-16 is not just the latest in a long line of American fighter aircraft. It embodies many design features and operating concepts which are entirely new, and owes much of this originality to the manner in which the design was conceived. The participants in the Lightweight Fighter competition of the early 1970s were encouraged to try new ideas and to use state-of- the-art technology; General Dynamics did just that. Indeed, I have heard it whispered in the dark corridors of the Fort Worth plant that, had it been known that a vast government contract would be forthcoming as a result of the fly-oft, it is highly probable that the risk of building the aircraft around a revolutionary and untried fly-by-wire control system would have been too great to contemplate. Although the first flight of the F-16 was the unplanned result of an over-enthusiastic taxi test, the programme never encountered any serious problems, and was always ahead of schedule. The success of the original design is borne out by the fact that the production aeroplane is basically the same as the YF-16.

The combination of two major factors makes the F-16 what it is - firstly, its performance and handling qualities and, secondly, the avionic capability. From first contact) it is apparent that the aircraft really has been built around the pilot. The cockpit, although necessarily small, is well designed, and the 3o deg reclined seat with a console-mounted side stick controller affords a very comfortable sitting position. AII the data panels, instruments and switches required during flight are well positioned; those less accessible are generally preset or programmed before take-off, and do not require further attention.

For those accustomed to spending their aviating Iives peering at the outside world from the depths of a dimly lit greenhouse, through a mass of ironmongery, the visibility through the single mould canopy is exceptional. It is possible, when checking 6 o'clock, to see well to the other side of the tail-fin (although doing so under 7 or 89 without risking a broken neck is an acquired art). Last, but not least in the quest for the ideal environment, is the cabin conditioning. This may not be high on the list of priorities in a temperate climate, but it certainly grows in importance in the heat and humidity of a Florida summer. While our less fortunate counterparts here achieve near sonic velocity down the taxiways in an attempt to get some cooling airflow through the cockpits, the F-16 canopy comes down prior to engine start, and the cabin temperature can be easily and effectively controlled.

On taking the runway, it is immediately apparent that the stick is in a funny place, and that it doesn't move. It does not, however, take very long to get used to this; subsequent reversion to a standard stick position is very much more traumatic. The flight control system in the F-16 is quadruplex fly-by-wire, and has no manual reversion; there is, therefore, no mechanical link between the stick and the control surfaces. Control inputs are detected by pressure sensors in the controller, and transmitted to the multi-redundant flight control computer. The computer analyses the input and sends the processed signals to the integrated servo-actuators on each control surface, which then position as required.

Computerised fly-by-wire offers many benefits. First of all is a large weight saving through the absence of bulky and heavy control rods. Secondly, the elimination of the need to route such rods through all the aircraft bulkheads makes the airframe inherently stronger. It should be emphasised that a manual back-up system would all but negate these advantages. Lastly, the computer can be programmed to produce whatever control response or limitation is desired. For instance, the controls are programmed to g demand; if the aircraft is trimmed to 1g at 200 knots and then accelerated to 600 knots, it will still be trimmed to 1g. The same stick input also produces the same g demand at any speed. The computer will limit the flight control response according to aircraft structural or aerodynamic limits; this allows the pilot to manoeuvre the aircraft to its limits without reference to the performance instruments and, more importantly, allows him to achieve maximum performance instantly without fear of overstress or departure. This gives the F-r6 pilot a significant edge over opponents in other aircraft not thus equipped.

The fly-by-wire system also contributes to the turning performance of the F-16 by allowing it to be statically unstable in subsonic flight, in that the Centre of Lift is forward of the Centre of Gravity. Thus, the moment imparted by the tailplane is upward, and adds to the total lift of the airframe. Two other factors enhance the excellent turning performance; one is the variable leading edge flap system, which is programmed continuously to produce optimum wing performance throughout the flight envelope. The second is the forward fuselage strake, which produces an extra 1.6g capability during maximum manoeuvring. While the computer does not provide all the answers, particularly when the aircraft is configured with heavy external stores, the potential for improvement is vast, and many modifications are already in the pipeline.

Power is supplied by the Pratt and Whitney F-100 turbofan engine, rated in the 25,000 lb thrust class. The problems which beset this engine in the early days of the F-15 have largely been eliminated by modification (to the relief of those astute aviators who realise that they now only have one of them!) This gives the clean aircraft a better than 1 : 1 power to weight ratio on take-off, and a ground roll, under ICAO standard conditions, of about 1100 ft.

After lift-off, the trailing edge flaps retract automatically with the gear. The flight controls provide smooth and crisp response throughout the flight envelope. Once in the air, the rudder pedals are relegated to footrest status, since co-ordinated rudder commands for all manoeuvres are automatically transmitted by the flight control computer. Roll response is more than adequate, and there is a tendency, under high roll demand, to 'roll- ratchet'. This is best described as the fastest hesitation roll on record, and explains the flat bits on the sides of F-16 students' helmets. A modified stick which allows a very small amount of movement for 'feel' has largely eliminated this phenomenon, and also makes the aeroplane very much more pleasant to fly in formation.

So much for the airframe; equally important is the avionics fit. The heart of the system is the Fire Control Computer (FCC). This receives inputs from the Fire Control and Navigation Panel (FCNP), the Stores Management Set (SMS), the Inertial Navigation System (INS) and the radar. It then displays weapons release and navigational data on the Radar Electro- Optic (REO), and the Head-up-Display (HUD). The SMS and FCNP are programmed on the ground, but can be amended in the air.

The INS holds ten destinations, plus targets of opportunity. The system is very accurate, terminal errors of less than a mile after a combat mission being common. If required, the present position can be updated by using the HUD, the radar, the TACAN or by overflight.

The computer provides several cruise functions, compensated for weight and drag. Relative position from a preset destination is monitored, and an optimum climb and cruise programme to the overhead can be displayed with the predicted fuel on landing. If this is ever less than normal landing fuel, a warning will appear in the HUD. This warning is also activated at a preset Bingo fuel. Range and endurance speeds at current altitude are available, plus a readout of the maximum range cruising altitude which updates as fuel weight reduces.

The SMS is a memory bank into which the pilot enters, by type and number, all the ordnance, tanks, racks and pylons which are loaded on the aircraft. A readout appears on a digital display (located on the left of the instrument panel), and indicates to the pilot which stores he has selected, how many he has left, and what delivery mode is selected. The SMS holds release parameters, ballistics and drag data for all weapons and stores, and supplies these to the FCC. For air-to-ground weapons delivery, the pilot can pre-select a number of bombing programmes which include weapon type, delivery mode, impact pattern and fusing. Each programme can then be recalled in the air at the touch of a single button. This reduces time-consuming weapons selection in the air, and can provide flexibility on missions where the target is unknown such as armed reconnaissance. Those who have spent time on the range groping between their knees for switches while trying to control the aircraft, copy down the last score, call for a fuel check and monitor what No 4 is doing, may appreciate the significance of this.

The radar is an advanced pulse-doppler and has three primary modes - air-to-air, ground mapping and air-to- ground ranging. The controls are divided between a radar control panel on the left console, the throttle grip and the side-stick. The way in which the need to touch the control panel during an intercept has been all but eliminated is a good example of how the avionics are being constantly modified to reduce pilot workload and increase efficiency. Early models required the pilot to select the range scale on the control panel; this was soon recognised as being less than ideal. As soon as a target is locked, the REO automatically presents the shortest range scale on which that target will appear. As the target range closes, the scale automatically changes down. If the pilot needs to change the scale while in search mode, he has only to move the acquisition symbol to the top or bottom of the scope) and the REO will change scale.

The scope is located between the pilot's knees, unobscured by a control column. The presentation is synthetically generated, and contacts appear as small squares. A variable target history function also displays the contact position on previous sweeps, thus producing a 'blip track'. Locking on is very quick and easy, the accuracy required in positioning the acquisition symbol being very much less than for a conventional AI scope. In search, there is a readout of the height band being swept at the range of the symbol; after lock-on, the readout is of target height. Additionally the target heading, speed, aspect angle and direction of pass are presented. There is a symbol to indicate collision course and another to mark the INS destination, should that be within the area covered by the scope. This is very useful for quick reference to a CAP or 'Bullseye' position.

Once the pilot has assimilated the information on the REO, he will then concentrate on the HUD, referring back to the REO occasionally. The HUD presents target range and closure, and also highlights the target in a designator box when it is within the HUD field of view. If this is not the case, a target locator line will appear, indicating in which direction the target lies and how many degrees off boresight it is. All this information is designed to get the F-16 pilot to a position of tactical advantage from which he can see the target. Weapons release parameters are presented for the AIM-9J/P or AIM-9L. The gun, an internally mounted six-barrel 20mm cannon, has two sighting options, lead computing or snapshoot. For short range lock on, there are several auto-lock modes - boresight, 20 deg by 20 deg scan, 10 deg by 40 deg vertical scan or a slewable auto-lock.

Although it possesses a front-quarter missile capability in the AIM-9L, the F-16 is essentially a close-range fighter and, in this arena, there is very little that can touch it. Unqualified comparisons with other aircraft types rarely tell the whole story; suffice it to say that, in my experience, those opponents who have chosen to indulge in a knife-fight with an F-16 have generally gone away wiser and sadder men.

Although the F-16 can sustain a 9g turn, even at the medium altitudes where we train, the pilot's little pink body (and more particularly his little red eyeballs) can not. I believe there are some Hawk pilots who will support this opinion. However, there are times when the capability is useful. Offensively, judicious use of the 'square corner' can turn what would, in an F-4, be a high deflection gun shot into a very comfortable tracking solution. On the defence, the ability to turn, and meet head-on, a bandit detected 9000 ft at 6 o'clock, will very probably water the eyes of all but the most determined aggressor.

Handling characteristics are excellent at all speeds, as is nose authority. There is very little buffet, and the aerodynamic configuration renders the transonic region undetectable. However, the airframe can always dissipate more thrust than Pratt and Whitney can generate, and the lack of cues to a decreasing energy state can easily catch the unwary pilot out. For those with PhDs, of course, the HUD displays energy manoeuvrability data to obviate this possibility. A final, but not inconsiderable weapon in the F-16's arsenal is its small size. It has a very small frontal area, and, when it is pointing at you (which is a lot of the time), it can be very difficult to see, both on radar and visually.

So much for air-to-air. The primary role of the F-16 at the present time is air-to-ground, in which it is no less capable. The primary navigation aid is the INS, which is an excellent system. Other means of navigation, including DR, are only used to monitor and verify INS performance. The HUD displays time-to-go to destination at present groundspeed; this will soon be augmented by a command groundspeed required to make good a preset TOT. The ground mapping radar is also outstanding - the cursors are ground stabilised and preset on the INS target position, thus requiring only a small adjustment in most cases. Antenna elevation is automatically adjusted to scan the target as the range closes; gain levels are set manually. Highlighting of a radar return can be achieved by use of an expand mode, which takes the area surrounding the cursors and magnifies it. The cursors are then presented in the centre of the REO regardless of aircraft manoeuvring. Two offset aim points can be programmed for each destination.

Delivery steering is projected in both the REO and the HUD for Lay-Down or LADD deliveries. Both options have visual modes, but the accuracy of the radar deliveries is such that we are faced with the first case of a pilot trying to win money on the range by saying he dropped a bomb visually, when actually it was done on radar.

It is in conventional weapons delivery, however, that the F-16 shows its true worth. Dive bombing is accomplished using either a Continuously Computing Impact Point (CCIP), or a Dive Toss method. CCIP gives a continuous display of where a bomb would fall if released instantly, compensated for variations in airspeed, dive angle, bank angle and g, and a bomb fall line to aid the pilot in tracking the pipper to the target. Accuracy is spectacular - CEAs of 10 metres are not uncommon, and this can be achieved by a relatively inexperienced pilot. Furthermore, provided the target can be illuminated, accuracy is in no way degraded at night. Gone are the days when the criterion for a successful night GA mission was that all the bombs hit the ground. It should be emphasised, however, that the F-16 does not at present have the capability to operate at low level in the dark or in IMC.

For those concerned about getting to the target at all, the aircraft can carry an ECM pod, has integral programmed chaff and flare dispensers and a very good RHAW system. If worse comes to worst, a jab on the jettison button will release all the iron while retaining the missiles; selection of the Dogfight mode will select guns and missiles irrespective of what was previously selected on the SMS. Thus, in the space of a couple of seconds, your trash-hauler converts to a formidable air superiority fighter.

Further avionics include separate UHF and VHF radios, giving the pilot a significant anti-jam and tactical communications capability. There is an autopilot, fitted as an afterthought but nonetheless outstanding for that. It is both simple to use and well harmonised with the controls, the latter being borne out by the fact that pilots have been known to strafe with the autopilot inadvertently engaged - and qualify!

The mission complete, it only remains to find your way home and get the aeroplane on the ground. Instrument flying in the F-16 is very easy, especially using the HUD. For ILS approaches, deviation bars appear in the Attitude Indicator, the main compass and the HUD; a flight director bead also appears on the HUD. The aircraft is very stable in the approach configuration, and airspeed control is easy.

For those who like to make things more difficult for themselves, there is always the ARA (Airborne Radar Approach). This is, more accurately an airborne INS approach since the radar is only used to update the INS during recovery. This can be done using any natural or artificial radar return on the airfield. Should this not be on the threshold, use of an offset aim point will adjust the fix. In many cases, however, the need does not arise since the Doppler Beam Shift (DBS) mode of the radar can break out the concrete of the runway and the cursors are then positioned on the desired touchdown zone. Once the INS is updated, and the aircraft positioned on the extended centreline, the pilot waits until the target designator box appears in the HUD depressed by the required glideslope angle, and then flies the flight path marker down to it while monitoring the radar for any INS drift.

The game, however, is not yet over. The maximum AOA of the F-16 is 25 deg. In order to avoid leaving the back half of the airframe in the undershoot, the normal landing AOA is about 13 deg. Therefore, the pilot has generally finished flying before the aircraft has, and it requires some persuasion to stay on the ground. Once on the runway, the normal method of initial deceleration is aerobraking. To achieve this, the pilot must continue to 'fly' the aeroplane down the runway until Bernouill finally concedes the day. In a gusty crosswind, this can be entertaining.

Having won the fight, one still has to win the debrief. For this purpose, there is a video-cassette recorder which tapes voice plus either the REO or the HUD output. This tape can be played back through a TV with no processing. The TV sensor also allows the instructor in the back seat of the family model to see through his REO what the front seater is seeing through his HUD.

For the engineers, the onboard computer carries a Maintenance Fault List which records in code all malfunctions occurring during flight. Those of direct interest to the pilot are displayed in the FCNP. This greatly improves systems monitoring and debrief. Reliability is good for such a complex aircraft. Many components are Line Replacement Units (LRUs) which speed repair time.

That, then, is the F-16 in a rather large nutshell. If my enthusiasm has been slightly transparent, I never claimed to be an unbiased observer. Quite simply, it is the most exhilarating aircraft I have flown in, and the most capable I have flown against. It is not a perfect aeroplane. For instance, in contrast to the sophisticated computers of the flight control and weapons systems, the engine fuel control is still, amazingly, mechanical. Furthermore, while the canopy affords outstanding visibility, the prospect of losing it at high speed, or of indulging in mortal combat with a turkey buzzard, does not enthral me. It may not be the world's most sophisticated aircraft, but it has got to be one of the most capable, particularly at the relatively low unit cost.

As far as its ability to do the job is concerned, it is undeniably single seat, with all that that entails. However, the systems are constantly being modified to increase the capability and reduce the workload on the pilot. \With regard to its capacity to destroy targets at long range, I suspect that the recent Israeli raid on the Iraqi research plant has answered a few questions in that direction. Perhaps, also, the results of the recent Tactical Bombing Competition were not unimpressive. Significant improvements in both hardware and software are already in production or on GD's drawing boards, plus the acquisition, in the not-too-distant future, of both AMRAAM and LANTIRN capability.

Whatever your personal opinion may be, we are fortunate that it's on our side, not theirs!



Squadron Leader Jones, who did his flying training at Cranwell Valley and Chivenor, did two operational tours on Lightnings with No 29 Squadron, Wattisham, and No 92 Squadron, Gutersloh, and one tour on Phantoms with No 56 Squadron, Wattisham, before starting his American tour. For 18 months he was an Instructor Pilot with F-4s at MacDill AFB and then converted to the F-16 with the 56th TFW at MacDill.

© Dim Jones


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