General Dynamics Soars Ahead

The first delivery of an F-16A to an operational wing, the 388th TFW at Hill AFB, Utah, took place on 6 January 1979. Deliveries to the Belgian Air Force started in the same month, followed by that to the Netherlands in June 1979, Norway and Denmark in January 1980, Israel in December 1979 (accelerated by Iran cancelling its order), Egypt in March 1982, and Pakistan in December. Venezuela is scheduled to receive its first F-16 in October 1983, and South Korea in February 1986, although USAF F-16s have been in the latter country since May 1981.

Initial operational capability (IOC) was first declared by one squadron of the 388th TFW in October 1980. The F-16A now equips five USAF Wings, i. e. , the 388th at Hill AFB, the 56th TFW at MacDill AFB, Florida, the 474th TFW at Nellis AFB, Nevada the 8th TFW at Kunsan AB, South Korea, and the 50th TFW at Hahn AB in West Germany. Future plans call for the F-16 to be issued to USAF units at Shaw AFB, South Carolina, and Luke AFB in Arizona, Ramstein in West Germany, Torrejon in Spain, Osan in South Korea, and Clark AB in the Philippines. In addition to these regular units, the F-16 will be flown by ANG and Reserve squadrons, the aircraft going to the 169th TFG of South Carolina ANG at the middle of next year, and the 466th TFS (an AFRES unit) at Hill AFB in 1984.

In the Belgian Air Force, the F-16 equips the 1st Wing at Beavechain and the 10th at Kleine Brogel. In the case of the Netherlands, it is already with Nos 322 and 323 Sqn at Leeuwarden and is re-equipping Nos 311, 312 and 306 Sqn at Volkel. In Norway, the F-16 is with No 332 Sqn at Rygge and 331 at Bodo, and will later replace the F-5 with 336 at Rygge and 338 at Orland. In Denmark, it is with Nos 727 and 730 Sqn at Skrydstrup, and may later go to 723 at Aalborg.

At the end of 1982 the production delivery schedule called for 503 F-16s to have been handed over to the USAF, and 235 to the EPG air forces. In terms of exports, at that stage Israel will have received all 75 F-16s (final delivery was due in late 1981), Egypt will have received 21, and Pakistan 8, giving a worldwide total of 840 aircraft, which will have risen to 1097 by the end of 1983, an increase of 257.

The F-16 programme has been characterised by a very rapid production buildup, with deliveries shooting up from five aircraft at the end of 1978 to 90 by the end of 1979, 311 at the end of 1980, and 587 at the end of 1981. No less than six air forces initiated operations within a period of 15 months, and there was originally some concern that operations would be hampered by spares shortages. Judging by USAF statistics this has not been the case, with sorties running well ahead of projected figures, monthly MTBFs running at over 3 hr (better than the mature goal, and almost twice the F-15 figure for 1981), and missioncapable rates running in the 70-75 per cent band.

However, the early years of service are usually a time when many modifications are introduced, which can cause problems in a programme that quickly accelerates to a high production rate. To minimise the effects of modifications, changes are being made in a series of stages, the first of which will make provisions for equipment that will be available at a later stage.

The ultimate aims of this Multinational Staged Improvement Plan (MSIP) are to expand the F-16’s air-air capability, to take its air-ground performance into the all-weather category, and to provide jam-proof communications. The principal means by which these aims are to be achieved are an improved standard of Westinghouse APG-66 radar, the Hughes AMRAAM giving beyond-visual-range firings and multi-target engagement capability, the Martin-Marietta LANTIRN infra-red navigation and targeting system, displaying via a Marconi Avionics wideangle HUD, and operating in conjunction with the IR-imaging Hughes Maverick AGM-65D, together with a GPS (global positioning system) giving all-weather accurate navigation, ALQ-165 airborne self-protection jammer (ASPJ), and Seek Talk secure voice communications.

Following the production for the USAF of 43 aircraft in Block 1 (including 22 F-16Bs), 116 in Block 5 (including 27 F-16Bs), and 170 in Block 10, Stage I of MSIP began with the 330th aircraft, delivered in November 1981 as the first of Block 15, and thus officially designated an F-16A-GD-15 (although later Stage I aircraft will be -20s). Less formally, the Stage I aircraft are known as the F-16A + and F-16B +. This modification standard will be applied to 456 USAF aircraft, and consists of:

a) structural, wiring, and cooling provisions for AMRAAM, ASPJ, and for E-O/FLIR pod and terrain-following radar on inlet hardpoints;

b) cockpit modifications to take the wide-angle HUD and multi-function displays;

c) modifications to pylons Nos 3 and 7 to permit loads of 1587 kg;

d) strengthening of the aft equipment bay;

e) provision for braking parachute, as on Norwegian aircraft;

f) relocation of radio equipment, and provision for radar altimeter;

g) modifications to wiring to suit expanded core avionics.

At the same time as MSIP Stage I was introduced, GD also brought in the enlarged tailplane (ECP 425) with a revised structure. Early tailplanes have a honeycomb structure with a titanium pivot shaft, but the new design will have graphite-epoxy skins riveted to a full-depth corrugated aluminium sheet substructure. The larger tail enables satisfactory stability to be maintained despite the larger CG range associated with new external loads, and provides much more powerful control (e. g. at unstick).

A total of 456 aircraft is being produced to Stage I standard, the last being delivered early in 1985. Overlapping with the tail end of this batch (Blocks 15 and 20) is the start of Stage II, which applies to 603 aircraft of Block 25, designated F-16C and F-16D, beginning with the 741st production F-16 for the USAF, to be delivered in July 1984. These aircraft will introduce the improved APG-66 radar with the programmable signal processor and dual-mode transmitter, and a Delco computer with a 600,000-word programmable memory store. They will also have the wide-angle HUD and two multi-function displays, a radar altimeter, and increased equipment cooling. Maximum take-off weight will be increased to 17,000 kg, and the aircraft will be stressed for 9 g manoeuvres at up to 11,475 kg. Essential mission data such as target and checkpoint coordinates will be pre-prepared on a cassette that is plugged into a cockpit socket just prior to takeoff, this same cassette records mission performance for subsequent analysis.

Stage III, consisting of the introduction of the key items of equipment and armament, will be applied to later Block 25 aircraft for the USAF. Export aircraft delivered from 1982 onward have Stage I modifications, but the application of Stages II and Ill will depend on the individual operator’s requirements and US Government approval. The time for Stage Ill is not yet finalised, but GD anticipates that AMRAAM and Seek Talk will be introduced late in 1985, followed by LANTIRN at mid-1986 and ASPJ and GPS/PLSS later in the year.

CCV and AFTI

In addition to this mainstream of F-16 development, trials programmes have been carried out to investigate a wide range of possible improvements. In 1976 GD flew the first prototype (72-01567) with canard fins below the intake duct, using the designation CCV (control-configured vehicle). Late in 1977 an F-16 fired two AIM-7F Sparrow missiles over China Lake, California, from launchers mounted on the aircraft’s main undercarriage doors. In the following year an F-16 equipped with a helmet-mounted sight and Martin-Marietta ATLIS (automatic tracking laser illumination system) pod mounted on the lower starboard side of the inlet, demonstrated autonomous LGB delivery using GBU-10 and -16s.

On 29 October 1979 a modified pre-production two-seater (75-0752) flew with the J79-GE-119 engine of 8080 kg as a demonstrator for the Intermediate Export Fighter Aircraft F-16/79 programme, and on 19 December of the same year a pre-production single-seater (75-0745) flew with the General Electric F101 DFE of approximately 12,500 kg thrust as a possible future alternative to the standard Pratt & Whitney F100-PW-200 of 20,860 kg.

Of all these F-16 variations, the one with the greatest technological interest was arguably the CCV, with duct-mounted fins set at 15 degrees to the vertical and capable of generating both lateral and vertical forces. Although the aircraft lacked the sophistication of a flying control system to exploit the concept fully, in principle it was capable of six new control modes. In azimuth, the forward fins could be used either in harmony with or against the rudder, producing either an increased yawing moment or a pure side force (DSFC = direct side-force control). The aircraft could thus be flown through a flat turn (i. e. a change of heading with no sideslip), make an unbanked translation (a lateral change of flight path with no change of heading), or make use of fuselage pointing (lateral changes of heading with no change of flight path). In the vertical plane, the forward fins could be used in combination with the leading edge flaps and the tailplane, producing either an increased pitching moment or changes in lift at constant angle of attack.

The aircraft could thus be operated in a direct lift control (DLC) sense, or make a vertical translation without a change of pitch attitude, or use fuselage pointing (changing pitch attitude with no change in flight path). The CCV F-16 provided a potential for innovative flight control modes that was far beyond the capabilities of its systems, and hence it required highly skilled test pilots to fly the aircraft. It suffered an accident at Fort Worth in June 1976, due to a fuel system problem, and flight tests were not resumed until February 1977.

Despite its limitations, the CCV F-16 provided some useful indications regarding the application of the various new control modes, which were selected by push-button and then activated either via the trim switch on the sidestick controller, or alternatively (in the case of lateral manoeuvres) by use of the force-sensing rudder pedals. For example, unbanked turns (also known as wing-level steering or DSFC) were described by GD as ‘devastating’ in simulated attacks on nap-of-the-earth helicopters.

Lateral translation was limited in practice by the large fin area of the F-16, restricting sideways accelerations to around 0. 9 g, and sideslip component to 45 knots. As it happened, the lateral acceleration figure was roughly the most that could be accommodated in a conventional ejection seat: the much higher values (2 g-3 g) that would have been needed to give it significance in air-air evasion would have demanded lateral restraint for the upper torso. This mode of flight path control was seen as primarily useful in ground attacks, in cancelling out the effect of crosswinds or in tracking moving targets without the conventional ‘pipper pendulosity’ problem involved in rolling corrections.

Fuselage pointing in pitch and yaw (flight path unchanged) was useful in air-air gunnery, although the CCV F-16 lacked the fire control system to make full use of the concept. In dive attacks on ground targets the ability to point the nose three degrees below the flight vector gave a longer firing time, or a higher pull-up altitude.

Manoeuvre enhancement by DLC also appeared to be useful in air combat, since it gave the aircraft a faster response in pitch. Direct force control in both planes was felt to have application in formation flying and in-flight refuelling, although tanker hookups were not made because of safety considerations (the CCV aircraft having only a ‘single-thread’ flying control system with no redundancy).

In summary, the CCV tests were a quick preliminary investigation, which produced sufficient evidence to justify a more thorough exploration into potential benefits, such as survivability, air-air gun firing kill probability, and air-surface weapon delivery accuracy. For the new programme, the aircraft in use is the last of the pre-production single-seaters (75-0750), which now differs externally from the CCV F-16 in having a large dorsal. fairing to house a triple-redundant digital flight control system (DFCS). It also has a more advanced cockpit with TVtype displays, provisions for a voice-command system and an ejection seat that can be reclined from the normal 30 degrees back to 64 degrees.

The resulting AFTI/F-16 (advanced fighter technology integration) programme began with a first flight on 1 0 July 1982 at Fort Worth. The aircraft is now undergoing a 275-flight trials programme at Edwards AFB, California, under joint NASA/USAF/ USN sponsorship. The first phase of the tests is planned to check the DFCS and the aircraft’s aerodynamics, while the second will link the flying controls directly to the radar and other target-tracking sensors (IFFC = integrated flight/fire control), and thus investigate the future role of automation in fighter aircraft. At this stage the AFTI/F-16 will be fitted with a Westinghouse FUR/laser sensor in the leading edge, this combined sensor being pointed by a Honeywell helmet-mounted sight. In the air-air mode, it is anticipated that IFFC will provide 360-degree gun attacks with high sightline spin rates, perhaps trebling firing opportunities, while in air-surface attacks the automated manoeuvring attack system (AMAS) will make possible weapon release at considerable standoff distance and with minimum exposure time. Ordnance delivery modes will include low-level attacks with accurate release in high-rate turns.

One of the possible dangers of providing control in six degrees of freedom is that the pilot workload may be increased, and the concept could therefore prove partly self-defeating. To reduce cockpit workload, the AFTI/F-16 is to be tested with a voice-command system that will eliminate the need for up to 50 push-button operations, using single-word commands initially to change nav/attack or flight control modes. The first voice recognition system to be tested will be supplied by Lear Siegler, to be followed by one from ITT Defense Communications. Work on such systems is being done by several other companies (including Marconi Avionics in the UK), but it is known that they currently have a very limited vocabulary (30-50 words) and have difficulty in following the pilot’s voice change under stress (e. g. in high-g manoeuvres).

F-16XL

The use of new control modes as in the AFTI/F-16 is one important line of fighter development. Another is the concept of a fighter that can cruise supersonically for a significant period, rather than being limited to a brief supersonic dash, as are the best of current fighters. Structural limits in the form of distortion (creep) or loss of strength at high temperatures only apply to really high speeds (over Mach 2. 2), and can be pushed to Mach 2. 5 or beyond by the use of special coatings or materials such as titanium. The more practical problem restricting the use of supersonic speeds is fuel consumption, associated with the comparatively high drag of conventional fighters (the Lockheed YF-12 was clearly an exception) and the resulting need for use of an afterburner. Fuel flow thus suffers both from the need to generate a high thrust and from the fact that afterburner SFC is well over twice that of a dry engine.

Conversely, if wave drag can be significantly reduced, then the fighter’s fuel consumption benefits directly from the drop in thrust required, and may also benefit in flight at low supersonic speeds from the fact that afterburner may not be required. The obvious way to reduce wave drag would be to adopt a delta wing in the manner of Concorde. However, if a fighter is to be operationally flexible, it needs a high sustained turn rate at subsonic speeds, which demands a moderate span loading. Combining the two ideas produced what is generally described as the cranked arrow platform, which was the approach adopted by GD in designing the F-16XL.

The first prototype of the F-16XL was based on another of the pre-production aircraft (75-0479), and flew in this modified form on 3 July 1982. It retains the standard F100 engine, while the second prototype, a two-seater, will be equipped with the more powerful F101 DFE. Aside from having this large-area cranked arrow wing with graphite composite skins, the F-16XL has two fuselage plugs, increasing its length by 142 cm, and allowing (in combination with the larger wing) an 82 per cent increase in internal fuel volume. It is claimed that the F-16XL retains approximately 80 per cent commonality with the existing production aircraft. Maximum take-off weight is increased to 21,770 kg to allow for the additional fuel and for external loads of up to 6800 kg. The aircraft is stated to have 17 store stations and a total of 29 hardpoints. One of the configurations illustrated shows the F-16XL with eight AMRAAM: two on the tips, two on short pylons at the wing kink, and four semi-recessed at the wing root.

The ‘semi-conformal’ carriage of external stores results in a supersonic strike penetration capability, although GD has not released details of the store configuration, penetration speed, or radius, nor whether a partial afterburner is required for the mission. The F-16XL thus fulfils the original aim of the SCAMP (supersonic cruise aircraft modification programme), but attention appears to have swung to the other benefits provided by its larger fuel volume, low-drag weapon carriage, and 121 per cent larger wing area. The manufacturer thus emphasises the fact that this new variant will provide up to 124 per cent more radius with the same warload, and up to 45 per cent more radius on internal fuel with twice the warload. Seen in the context of the aircraft that on 7 June 1981 and in its basic version flew a remarkable strike mission of almost a 1000 km radius to destroy the Iraqi nuclear reactor near Baghdad, the F-16XL is clearly a fighter with considerable potential, especially if this can be combined with a useful dogfight performance. It is also noteworthy that take-off and landing performance is claimed to be improved by roughly one-third.

Although the F-16XL began as a company-funded programme, the objective that GD has in mind is a USAF order for almost 400 such aircraft (designated F-16E), fitted with Stage Ill MSIP avionics and equipment. The alternative would be the much larger McDonnell Douglas F-15E, based on the company-funded Strike Eagle. The competition appears to be temporarily stalled, while the service finalises its requirements. Nonetheless, the outcome is obviously going to be well worth waiting for!