The Lockheed F-104 Starfighter was an American high-performance supersonic interceptor aircraft, capable of high speeds and climb rates. The Starfighter entered service with the US Air Force in 1958 and was phased out by 1967 by the USAF and in the 1970s by the U.S. Air National Guard. An updated Starfighter sold well among the NATO air forces of Germany, Canada and Italy, where high-speed fighter-bomber versions continued in service until the mid-1980s. The last Italian Air Force examples were retired in 2004.
The later model Starfighter versions gained a reputation for being challenging to fly. Many air forces using F-104s eventually replaced them with the F-16 Fighting Falcon.
\"Kelly\" Johnson, chief engineer at Lockheed's Skunk Works, visited Korea in December 1951 and talked to fighter pilots about what sort of plane they wanted. At the time the US pilots were meeting the MiG-15 'Fagot' in their F-86 Sabres, and many of the American pilots felt that the MiGs were superior to the larger and more complex American design. The pilots requested a small and simple aircraft with excellent performance.
On his return to the US, Johnson immediately started the design of just such an aircraft. In March his team was assembled, and they studied several aircraft designs, ranging from small designs at 8,000 lb (3.6 t), to fairly large ones at 50,000 lb (23 t). In November 1952, a follow-on study started, the lessons learned from the earlier designs being used to eventually result in the Lockheed L-246, of about 12,000 lb (5.4 t). The L-246 remained essentially identical to the L-083 Starfighter as eventually delivered.
The design was presented to the Air Force in November 1952, and they were interested enough to create a new proposal and to invite several companies to participate. Three additional designs were received: the Republic AP-55, an improved version of its prototype XF-91 Thunderceptor, the North American NA-212 which would eventually evolve into the F-107, and the Northrop N-102 Fang, a new General Electric J79-powered design. Although all were interesting, Lockheed had an insurmountable lead, and was granted a development contract in March 1953.
Work progressed quickly, with a mock-up ready for inspection at the end of April, and work starting on two prototypes late in May. At the time, the J-79 engine was not ready; so, both prototypes were designed to use the Wright J-65 engine instead, a licensed version of the Armstrong Siddeley Sapphire. The first prototype was completed by early 1954, and started flying in March. The total time from design to first flight was about two years, a very short time even then, and unheard of today, when ten to fifteen years is more typical.
In order to achieve the desired performance, Lockheed chose a minimalist approach: a design that would achieve high performance by wrapping the lightest, most aerodynamically efficient airframe possible around a single powerful engine. The emphasis was on minimizing drag and mass.
Wing and fuselage
The F-104 had a radical wing design. Most jet fighters of the period (and to this day) used a swept-wing or delta-wing planform. This allowed a reasonable balance between aerodynamic performance, lift, and internal space for fuel and equipment. Lockheed's tests, however, determined that the most efficient shape for high-speed, supersonic flight was a very small, straight, mid-mounted, trapezoidal wing. The wing was extremely thin, with a thickness-to-chord ratio of only 3.36%. Its aspect ratio was 2.45. The wing's leading edges were so thin (0.016 in / 0.41 mm) and so sharp that they presented a hazard to ground crews, and protective guards had to be installed during ground operations. The thinness of the wings meant that fuel tanks and landing gear had to be contained in the fuselage. The motors driving the control surfaces had to be only one inch (25 mm) thick to fit.
The stabilator (horizontal tail surface) was mounted atop the fin to reduce inertia coupling. Because the vertical tailfin was only slightly shorter than the length of each wing and nearly as aerodynamically effective, it could act as a wing on rudder application (a phenomenon known as Dutch roll). To offset this effect, the wings were canted downward, given 10° anhedral. The wings had both leading- and trailing-edge flaps. Later Starfighter marks incorporated a system that allowed the flaps to be extended during combat maneuvering, reducing turn radius and generally improving sustained turn rate.
The combination provided extremely low drag except at high angle of attack (alpha), at which point induced drag became very high. As a result the Starfighter had superb acceleration, rate of climb, and potential top speed, but its sustained turn performance was very poor, described by some as more like a milk truck than a fighter. It was sensitive to control input, and extremely unforgiving of pilot error.
The small, highly-loaded wing resulted in an unacceptably high take-off and landing speed, so a boundary layer control system (BLCS) of blown flaps was incorporated, bleeding engine air over the trailing edge flaps to improve their lift. The system was a boon to safe landings, although it proved to be a maintenance problem in service, and landing without the BLCS could be harrowing.
NACA wind tunnel tested a model of the F-104, to evaluate its stability, and found it became increasingly unstable at higher angles of attack, to the point that it was recommended to limit the servo-control power to generate those higher angles and shake the stick to warn the pilot. In the same report, NACA stated that the wingtip tanks, possibly because of their stabilizing fins, reduced somewhat the model's instability problems at high angles of attack.
A research version called Lancer, fitted with a bigger, higher aspect ratio wing and a rocket engine, was employed to develop rocket controls for yaw, pitch and roll, to be used at extremely high altitudes, where conventional aerodynamic control surfaces lost much of their effectiveness. The few pilots to have flown the Lancer used to say that, due to its bigger wing, it was extremely nimble and a better dogfighter than any other plane. Later, those same rocket controls were installed on the X-15 rocket plane for use in its record-breaking high-altitude flights.
The Starfighter's fuselage had a high fineness ratio, i.e., tapering sharply towards the nose, and small frontal area. The fuselage was tightly packed, containing the radar, cockpit, cannon, all fuel, landing gear, and engine.
Several two-seat training versions of the Starfighter were produced. They were generally similar to the comparable single-seater, but the additional cockpit required removing the cannon and some internal fuel. Two-seaters were combat-capable, and, despite a slightly larger vertical fin and increased weight, have similar performance to the single-seater.
The F-104 was built around the General Electric J79 turbojet engine, fed by side-mounted intakes with fixed inlet scoops and a conical ramp optimized for supersonic speeds. (Unlike some supersonic aircraft, the F-104 does not have variable-geometry inlets.) Its thrust-to-drag ratio was superb, allowing a maximum speed well in excess of Mach 2: the top speed of the Starfighter is limited more by the aluminum structure and the temperature limits of the engine than by thrust or drag (which gives an aerodynamic maximum speed of Mach 2.2). Later models used uprated marks of the J79, improving thrust by almost 30%.
Equipment and armament
Early Starfighters used a downward-firing ejection seat (the Lockheed C-1), out of concern over the ability of an upward-firing seat to clear the tailplane. This presented obvious problems in low-altitude escapes, and some 21 USAF pilots failed to escape their stricken aircraft in low-level emergencies because of it. The downward-firing seat was soon replaced by a Lockheed C-2 upward-firing seat, which was capable of clearing the tail, although it still had a minimum speed limitation of 90 knots (170 km/h). Most export Starfighters were fitted with Martin-Baker zero-zero ejection seats (having the ability to successfully eject the pilot from the aircraft even if the aircraft was at zero altitude and zero airspeed).
The initial USAF Starfighters had basic AN/ASG-14T ranging radar, TACAN, and radio. The later international fighter-bomber aircraft had much more advanced Aeroneutics NASARR radar, a simple infrared sight, Litton LN-3 inertial navigation system, and an air data computer.
In the late 1960s, the Italian Air Force developed a more advanced version of the Starfighter, the F-104S, for use as an all-weather interceptor. The F-104S received a NASAAR R21-G with moving-target indicator (for some ability against low-level targets) and a continuous-wave illuminator for semi-active radar homing missiles, including AIM-7 Sparrow and Selenia Aspide. The missile-guidance avionics forced the deletion of the Starfighter's internal cannon. In the mid-1980s surviving F-104S aircraft were updated to ASA standard (Aggiornamento Sistemi d'Arma, or Weapon Systems Update), with a much improved, more compact Fiat R21G/M1 radar.
Basic armament of the F-104 was the M61 Vulcan 20 mm Gatling gun. The Starfighter was the first aircraft to carry the new weapon, which had a phenomenal rate of fire of 6,000 rounds per minute. The cannon, mounted in the lower part of the port fuselage, was fed by a 725-round drum behind the pilot's seat. It was deleted in two-seat models and some single-seat models, including reconnaissance versions and the early Italian F-104S models (the gun bay and ammunition tank could be replaced by an additional fuel tank). Two AIM-9 Sidewinder air-to-air missiles could be carried on the wingtip stations, which could also be used for fuel tanks or other stores. F-104C and later models added a centerline pylon and two underwing pylons under each wing for bombs, nuclear weapons, rocket pods, or tanks. The centerline pylon could carry a \"catamaran\" launcher for two additional Sidewinders, although the installation had minimal ground clearance and made the seeker heads of the missiles vulnerable to ground debris. The
F-104S and some F-104G and F-104J models added a pair of fuselage pylons beneath the intakes, usually used for Sidewinders (providing better ground clearance than the catamaran launcher and leaving the centerline available for other stores). The Italian F-104S had still another pylon under each wing, for a maximum of nine. The F-104S was cleared for a higher maximum take-off weight, allowing it to carry up to 7,500 lb (3,400 kg) of stores; other Starfighters had a maximum external load of 4,000 lb (1,814 kg).
The initial F-104A served briefly with the USAF Air Defense Command as an interceptor, although neither its range or armament were well-suited for that role. Its status was nonetheless enhanced when, on May 18, 1958, an F-104A set a world speed record of 1,404.19 mph (2,259.82 km/h), and on December 14, 1959, an F-104C set a world altitude record of 103,395 ft (31.5 km). The Starfighter was the first aircraft to hold simultaneous official world records for speed, altitude, and time-to-climb.
The subsequent F-104C entered service with Tactical Air Command as a multi-role fighter and fighter-bomber. It saw service in the Vietnam War, both in the air-superiority role (although it saw little aerial combat and scored no air-to-air kills) and in the air support mission.
The USAF procured only 296 Starfighters in one- and two-seat versions. The USAF was less than satisfied with the Starfighter. At the time USAF doctrine placed little importance on air superiority (the \"pure\" fighter mission), and the Starfighter was deemed inadequate for either the interceptor or tactical fighter-bomber role, lacking both payload and endurance compared to other USAF aircraft. Its U.S. service quickly wound down after 1965.
At the same time as the F-104 was falling out of US favor, the Federal German Airforce was looking for a multi-role aircraft. The Starfighter was presented and reworked to convert it from a fair-weather fighter into an all-weather ground attack and interceptor aircraft the F104G. This brought it a new market with other NATO countries, and 2,578 F-104s were built in the U.S. and abroad for various nations, including Canada, West Germany, Italy, the Netherlands, Belgium, Pakistan, the Republic of China (Taiwan) and Japan. Norway, Denmark, Greece, Jordan, Turkey and Spain received theirs under the military aid program. The American engine was retained but built under license in Europe. The Lockheed ejector seats were also retained at first but were replaced later by the superior Martin-Baker zero-zero ejection seat.
The so-called \"Deal of the Century\" produced considerable income for Lockheed, but considerable political controversy in Europe, particularly in Germany, where minister of defense Franz Josef Strauß was almost forced to resign over the issue. Prince Bernhard of the Netherlands later confessed to having received more than 1 million USD in bribes. In the 1970s it was revealed that Lockheed had engaged in an extensive campaign of bribery of foreign officials to obtain sales, a scandal that nearly led to the ailing corporation's downfall.
The F-104 in international service began to wind down in the late 1970s, replaced in many cases by the F-16 Fighting Falcon, but it remained in service with some air forces for another two decades. The last frontline Starfighters were with the Italian AMI, which retired in mid-2004.
A total of 2,578 F-104s were produced by Lockheed and under license by various foreign manufacturers. Principal variants included: