[1.0] F-16 Origins

v1.3.0 / chapter 1 of 4 / 01 jan 20 / greg goebel

* The F-16 began life largely as an experiment. At the time, the US Air Force did not realize that the type would become one of the most significant aircraft in the service's inventory.

[1.1] F-16 ORIGINS: LWF / YF-16 / FSD F-16
[1.2] F-16A & F-16B DESCRIBED

[1.1] F-16 ORIGINS: LWF / YF-16 / FSD F-16

* In the 1950s and early 1960s, the US military had emphasized speed over maneuverability in fighter design. The general belief was that air-to-air missiles (AAMs) had made dogfighting obsolete. Fighters would hit each other from long distance, well before they could close to get into a turning fight. However, American experience in Vietnam showed that reports of the death of dogfighting were premature. The new AAMs were not the miracles that they had seemed on paper, and operational realities, such as the need to confirm the identity of a target before engaging it, also limited the usefulness of AAMs.

By the mid-1960s, the US Air Force (USAF) was considering next-generation fighters to follow existing frontline aircraft, such as the McDonnell F-4 Phantom. The service envisioned a heavy fighter, the "Fighter Experimental (FX)", and a lightweight fighter, the "Advanced Day Fighter (ADF)". The plans went back and forth for several years as the Air Force took stock of new Soviet threat aircraft and the realities of air combat in Vietnam.

By 1969, the FX heavy-fighter concept had evolved into a requirement for an "F-15", with McDonnell Douglas receiving a development contract in December of that year. The ADF might have been forgotten except for the lobbying efforts of a "Fighter Mafia" in the Pentagon, the primary players being the legendary USAF fighter pilot Major John Boyd and a civilian analyst, Pierre Sprey. The Fighter Mafia managed to push through the "lightweight fighter (LWF)" program, which was formally initiated in January 1972.

The LWF program was formally set up as an experimental effort to evaluate design concepts, with no assurance that any of the designs would go into production. Specifications defined a fighter with Mach 2 performance, high maneuverability, and good range. Traditionally small fighters had short range, but the development of afterburning bypass turbojets with high power-to-weight ratios promised to change that.

Five companies submitted LWF proposals. On 13 April 1972, two of the proposals were selected for evaluation, with General Dynamics (GD) receiving a contract for two "Model 401" or "YF-16" prototypes and Northrop receiving a contract for two "Model P-600" or "YF-17" prototypes. These were to be pure demonstrators, lacking weapons and other operational kit.

* The first of the two YF-16 prototypes, designed by a GD team under Harry Hillaker, was rolled out in patriotic red-white-&-blue colors on 13 December 1973, only 21 months after award of the contract. Initial flight of the YF-16 was from Edwards Air Force Base (AFB) in California on 20 January 1974, with GD test pilot Phil Oestricher at the controls. He actually hadn't meant to take off; he was performing high-speed taxi trials when the aircraft became unstable, and as the instability began to get worse with the wingtips kicking sparks off the runway, Oestricher decided the safest thing to do was get off the ground. He did a circuit and came back down. The oscillation problem turned out to be due to the YF-16's electronic "fly by wire (FBW)" flight control system, which was too sensitive. It was straightforward to damp it down to correct the problem. The formal first flight of the YF-16 was on 2 February 1974. A 30% scale flying model, built of fiberglass with an aluminum frame, also joined the test program in 1975 to perform preliminary spin tests.

Even before the flight of the second YF-16 prototype in May 1974, the program had expanded beyond its original experimental charter. In April 1974, US Defense Secretary James Schlesinger announced that the winner of the LWF competition would go on to full development and production under the "Air Combat Fighter (ACF)" program. The ACF was defined as a no-frills, clear-weather, daylight air combat / strike fighter that could be purchased in large numbers -- or at least, that was the original idea.

The YF-16 and YF-17 "fought it out" through 1974, with the tests including flights by USAF and US Navy pilots, as well as "dogfights" with the Cessna A-37B Dragonfly, the Convair F-106 Delta Dart, the F-4 Phantom, and the Soviet MiG-17 and MiG-21; the MiGs were operated by the secret USAF "Red Hats" squadron. For whatever reason, the two LWF designs did not actually perform air combat tests against each other.

The YF-16 proved clearly superior to everything thrown at it. During a furball with the powerful but less-than-agile F-4E Phantom, the YF-16 scored three mock "kills" on its adversary. The Phantom ran low on fuel and had to land, another Phantom was sent up to take its place, and the YF-16 outlasted it as well. Tests for the strike role were also thrown into the program.

The YF-16 was declared the winner on 13 January 1975. The Air Force concluded that the YF-16 had generally superior performance, though the YF-17 was better in some areas. While twin-engine fighters are generally regarded as more survivable, GD managed to sell the single-engine YF-16 design on the fact that a single-engine aircraft was lighter than a twin-engine aircraft with the same thrust, and produced convincing statistics that single engines did not seriously degrade aircraft survivability.

The Air Force may have had another agenda in being persuaded that a single engine was best. The fact that the YF-16 was powered by the Pratt & Whitney (P&W) F100 engine, essentially the same powerplant as used on the twin-engine F-15 Eagle, was apparently a big selling point. The mainstream Air Force bureaucracy remained lukewarm on the ACF concept and felt that as long as they were stuck with a lightweight fighter, they might build up purchase volumes on the F100 and cut the price to help support the fighter the USAF really wanted, the F-15.

The losing YF-17 didn't die out. McDonnell Douglas refined the design as a response to a US Navy / Marine Corps requirement, with the redesigned aircraft emerging as the highly successful "F/A-18 Hornet", which would become a competitor of sorts with the F-16 in international sales.


* The Air Force ordered an initial evaluation batch of eight "full scale development (FSD)" machines, including six "F-16A" single-seaters plus two "F-16B" tandem-seat conversion trainers. The first FSD single-seat F-16A performed its initial flight on 8 December 1976, with test pilot Neil Anderson at the controls.

Another, very strong, influence on the program was the fact that a four-nation European group consisting of Belgium, Denmark, the Netherlands, and Norway had been looking for a replacement for their Lockheed F-104 Starfighters. The group had been tracking the American LWF effort closely as their prime candidate. In June 1975, following flight displays of the YF-16 at the Paris Air Show where Neil Anderson wowed the crowd, the group had decided to buy the F-16, with the aircraft to be locally assembled. More is said about European F-16 production later.

Even with the order for the FSD machines in hand, there was still some doubt that the Air Force would acquire the F-16 in quantity, but the USAF ordered 738 more F-16s in early 1977. The first two-seat FSD F-16B performed its initial flight on 8 August 1977. Many of the FSD F-16s would have interesting careers as test and evaluation machines; the two YF-16 prototypes similarly remained in service as test aircraft, with these matters also discussed in more detail later.

Production lines opened on both sides of the Atlantic in early 1978. The first production F-16, rolled out from the GD plant in Fort Worth, Texas, performed its initial flight on 7 August 1978. Service deliveries to the USAF began in early 1979. A "Multinational Operational Test & Evaluation (MOTE)" program was conducted in 1980 to bring the new fighter up to full service.

Outside of the four-member European group, the only export customer for the F-16 at the time was Israel, which was high on the priority list for deliveries. Export restrictions imposed during the Carter Administration prevented deliveries to other countries. These restrictions were later relaxed significantly by the Reagan Administration, making the F-16 a "must have" fighter in the export market.

At the outset, unit flyaway cost of an F-16A was $10.2 million USD in contemporary dollars. That was about twice as much in strict dollar terms as anticipated in 1975, but the US had undergone a burst of high inflation in the late 1970s, and the cost in real dollars was actually under target.

There was still the problem of giving the new fighter a name. "Falcon" was proposed, but the Dassault company of France was already selling a business jet with that name and objected. "Mustang II" was another suggestion, but Ford was selling a sports car with that name. On 21 July 1980, the Air Force announced the name "Fighting Falcon". In practice, the F-16 would often be referred to by the more sinister name of "Viper".


[1.2] F-16A & F-16B DESCRIBED

* The F-16A that emerged from this development process was a neat, sleek, dartlike aircraft with swept wings; a degree of wing-body blending; a conventional tail assembly, with all-moving horizontal tailplanes; and twin ventral fins. The wing-body blending allowed the aircraft's body to provide lift. The wing had a leading-edge sweep of 40 degrees and a straight trailing edge, with full-span leading-edge flaps and large "flaperons" on the trailing edge to provide improved landing performance and combat maneuverability. Airbrakes were fitted between the tailplane and the engine exhaust, with the airbrakes opening top and bottom.

The F-16A's appearance was very similar to that of the YF-16 prototypes, but there were clear differences. The YF-16 was about 30 centimeters (a foot) shorter, with a smaller nose since the original plan wasn't to fit a sophisticated radar; had a slightly shorter tailfin, smaller ventral fins, slightly smaller wings and fuel tankage, and a more complicated nosewheel door arrangement; and, lacking operational kit, weighed only about 75% as much.

The F-16A was of conventional construction, with about 80% of the airframe built with aircraft aluminum alloys, 8% with steel, 3% with composites, and 1.5% with titanium. There were 228 access panels over the entire aircraft, simplifying maintenance. About 80% of the aircraft could be reached without work stands, and the number of lubrication points, fuel-line connections, and replaceable modules was greatly reduced compared to fighters of an earlier generation.

F-16A with stores

The F-16A was originally powered by a single P&W F100-PW-200 bypass turbojet with 65.2 kN (6,655 kgp / 14,670 lbf) maximum dry thrust and 106 kN (10,810 kgp / 23,830 lbf) afterburning thrust. It was a modified version of the F100-PW-100 developed for the twin-engine F-15, adapted for single-engine operation with such features as a redundant fuel system to improve reliability. The kidney-shaped engine intake was fitted on the belly of the aircraft below the cockpit; the positioning of the intake permitted adequate airflow at high angles of attack. Surprisingly, the inlet geometry was fixed, not variable.

The engine was backed up by an "Emergency Power Unit (EPU)" to provide auxiliary electrical and hydraulic power. The EPU was not exactly the same as an aircraft "Auxiliary Power Unit (APU)", which is a small turbine engine run off jet fuel; the EPU was indeed a turbine unit, but it was run off a store of hydrazine fuel in the right wing strake. Hydrazine is a toxic, corrosive, unstable liquid; in the EPU, it was fed to a catalyst that converted it into a hot gas to drive the turbine. Unlike an APU, the EPU was only used in an emergency.

The F-16A's fuel capacity was surprisingly large for the aircraft's size and configuration, 31% of its fully-loaded weight, and gave the aircraft correspondingly long range. The large fuel capacity was one of the benefits of the wing-body blending, which along with aerodynamic efficiency provided additional volume that could be used for fuel tanks. There was a boom refueling socket in the center of the back, normally marked by a white "fishbone" pattern to guide a tanker boom operator. No production F-16s have ever been fitted with refueling probe for probe-and-drogue refueling.

The F-16A had tricycle landing gear, all with single wheels, the front gear retracting backward underneath the intake and the main gear retracting forward into the fuselage. The position of the nose gear behind the intake helped reduce the chance of foreign-object ingestion, a potential problem given the size and position of the intake. A distinctive drag-parachute compartment could be fitted behind the rear of the base of the tailfin, though the USAF and most other users did not specify this item. There was also a runway arresting hook under the tail behind the ventral fins.

The pilot sat under a single-piece polycarbonate bubble canopy on a McDonnell Douglas "Advanced Concept Ejection Seat (ACES) II" "zero-zero" (zero speed, zero altitude) ejection seat. The rocket-boosted ACES II ejection seat, designed for the F-15 Eagle, was reclined 30 degrees and the pilot's legs were raised, helping to help deal with high-gee maneuvers. It appears that the specific reason for slanting the seat in such a way was to allow it to fit in the slender nose of the aircraft, and the gee-resistance was just an unintended benefit. Incidentally, the two YF-16s used Escapac ejection seats, while the FSD F-16s used Stencel SIIIS ejection seats.

The canopy was hardened against birdstrikes and provided an excellent all-round view. The pilot held a throttle in the left hand and a sidestick controller in the other, both studded with "hands on throttle and stick (HOTAS)" controls. The sidestick controller was originally pressure-sensitive, not moveable like a joystick, but would later be modified to provide a slight "give" for pilot feedback.

   _____________________   _________________   _______________________
   spec                    metric              english
   _____________________   _________________   _______________________

   wingspan with AAMs      10.0 meters         32 feet 10 inches
   wing area               28.87 sq_meters     300 sq_feet
   length                  15.03 meters        49 feet 4 inches
   height                  5.09 meters         16 feet 8 inches
   empty weight            8,275 kilograms     18,220 pounds
   MTO weight              19,185 kilograms    42,300 pounds

   max speed               2,125 KPH           1,320 MPH / 1,145 KT 
   service ceiling         15,250 meters       50,000 feet
   combat radius           925 KM              575 MI / 500 NMI
   _____________________   _________________   _______________________

The aircraft featured a quadruplex (quadruple redundant) analog-electronic FBW flight control system. An FBW system was required because the F-16A was designed for "relaxed stability" or "dynamic instability", meaning it didn't tend to fly right if left to itself. This provided increased maneuverability, but also dictated an automatic flight-control system to keep the aircraft flying right. The FBW system featured built-in limiters to prevent stalls, with override capability for the pitch control if the pilot wanted it. The F-16 was one of the first relaxed-stability fighters to be put into production. The FBW system led pilots to call the F-16 the "Electric Jet" -- but it appears that this nickname fell out of use as FBW systems become more normal.

Avionics for the F-16A included defensive countermeasures, UHF & VHF radios, identification friend or foe (IFF) unit, TACAN beacon navigation set, ILS landing set, and multimode radar. The backbone of the countermeasures system was the Itek AN/ALR-69 radar warning receiver (RWR), featuring antennas on the top and bottom of the rear of the tailfin, on each side of the nose, and under the engine intake. Warning was provided on cockpit displays and the pilot's headphones. Elements of the countermeasures suite varied between different nations that acquired the F-16, but all could carry a jamming pod on a centerline stores pylon.

Although the LWF competition was for a simple, clear-weather air-superiority fighter, of course the Air Force decided after selecting the F-16 for production that they wanted more capability, beginning a process of "mission creep" that continues with the F-16 to this day. It is a tribute to the fundamental soundness of the design that it has been able to take on such an increasing spectrum of roles.

In any case, instead of being a simple daylight air-combat fighter, the F-16A as built was basically an all-weather fighter-bomber. Although the YF-16 was designed with the idea that it would have a very simple radar for air combat, resulting the small nose, the F-16A featured a relatively sophisticated Westinghouse AN/APG-66 multimode radar providing "eyes" for both air combat and ground-attack in night or bad weather.

The AN/APG-66 was a medium-pulse-rate Doppler radar with a flat slotted antenna. The radar was designed to be compact enough to fit into the F-16's relatively small nose. It provided four operating modes for air-to-air combat and seven for air-to-ground combat, with a "videogame"-like digital display that provided text and symbology to make the radar easier to use.

Surprisingly, the AN/APG-66 did not provide guidance capability for the AIM-7 Sparrow medium-range semi-active radar homing (SARH) AAM. This omission had its roots in the original concept of the F-16 as a simple, cheap fighter. It would later be seen to be a serious error in judgement, since it meant that in principle the F-16 could be picked out of the sky with impunity by an adversary fighter carrying medium-range missiles.

Although there had been a tendency to delete gun armament in the previous generation of jet fighters such as the Phantom, this had been recognized as a blunder, and the F-16A had built-in armament consisting of a single General Electric (GE) 20-millimeter M61A1 six-barreled Gatling cannon, with 500 rounds of ammunition. The gun fired out a port on top of the left wing root extension, just behind the pilot's seat, with the ammunition drum behind the cockpit. The position of the cannon muzzle prevented gun gas ingestion into the air intake, and avoided blinding the pilot with muzzle flash.

The F-16A had a single centerline stores station; three stores stations on each wing; and wingtip launch rails for Sidewinder AAMs, for a total of nine stores stations. Maximum external load was 9,275 kilograms (20,450 pounds).

The two-seat F-16B had exactly the same dimensions as the single-seat F-16A, with the second seat in the F-16B obtained by removing a fuselage fuel tank, reducing internal fuel capacity by 17%. The F-16B was intended as a conversion trainer and of course had dual controls. Both variants were produced on the same production lines. The F-16B was fully combat-capable, allowing it to be used both for training and for operational missions where the workload required two aircrew. About one F-16B was acquired for every six F-16As.


* The P&W F100 turbojet was an impressive engine -- but the Air Force was not happy with it, claiming it didn't meet its longevity spec, and that it also suffered from a tendency to go into a violent oscillation under some conditions. There was a wearying cycle of finger-pointing between the USAF and P&W, with the Air Force publicly criticizing Pratt & Whitney, while P&W engineers insisted that the Air Force was not only failing to follow documented maintenance procedures, but was ignoring P&W's recommendations on how to deal with the problems.

In any case, the feud led the Air Force to work with General Electric to develop an alternate engine, based on the GE F101 bypass turbojet used on the Rockwell B-1 bomber. The first FSD F-16A was refitted with the GE F101 and performed its initial flight on 19 December 1980. The only visible distinction between the "F-16/101", as it was called, and a stock F-16 was that the sides of the engine exhaust were noticeably curved, not straight as they were for the P&W F100 engine. The F-16/101 made 58 test flights to July 1981. The GE powerplant was not adopted for the time being, but the wheels had been set in motion that would eventually see a GE engine fitted to the F-16.

* The Air Force's enthusiasm for the F-16 grew in time. It was a very hot machine; the F-16's thrust-to-weight ratio allowed it to accelerate while climbing straight up. One pilot commented: "I can take off and climb straight to 10,000 feet without crossing the fence around the airport."

Pilots quickly became confident in its capability for air-to-air combat and its ground attack capabilities. The lack of a medium-range AAM was troublesome, though that problem was eventually fixed. Some pilots were a little insecure about the single-engine configuration, though it didn't lead to real trouble in terms of loss rates. The F-16 does tend to be somewhat dodgy to land; like many aircraft that are very aerodynamically clean, it wants to stay in the air, and may dance around a bit on its wheels when it first makes contact with the runway.