četvrtak, 24. siječnja 2008.

Flying the F-104
Chuck Yeager in the cockpit of an NF-104, 4 December 1963.

The Starfighter was generally considered a rewarding, if very demanding, "sports car" of a fighter. It was the first combat aircraft capable of sustained Mach 2 flight and its speed and climb performance remain impressive even by modern standards. If used appropriately, with high-speed surprise attacks and good use of its exceptional thrust-to-weight ratio, it could be a formidable opponent, although being lured into a turning contest with a slower, more maneuverable opponent (as Pakistani pilots were with Indian Hunters in 1965) was perilous. The F-104's large turn radius was mainly due to the high speeds involved and its high-alpha stalling and pitch-up behavior was known to command respect.

Takeoff speeds were in the region of 190 knots, with the pilot needing to swiftly raise the landing gear to avoid exceeding the limit speed of 260 knots. Climb and cruise performance were outstanding; unusually, a "slow" light illuminated on the instrument panel at around Mach 2 to indicate that the engine compressor was nearing its limiting temperature and the pilot needed to throttle back to decelerate. Returning to the circuit, the downwind leg could be flown at 210 knots with "land" flap selected, while long flat final approaches were typically flown at speeds around 180 knots depending on the weight of fuel remaining. High engine power had to be maintained on the final approach to ensure adequate airflow for the BLC system; consequently pilots were warned not to cut the throttle until the aircraft was actually on the ground. A drag chute and effective brakes shortened the Starfighter's landing roll.[9]

[edit] Safety record

The safety record of the F-104 Starfighter became high profile news especially in Germany in the mid 1960s and lingers in the minds of the public even to this day. Some operators lost nearly one third of their aircraft through accidents, although the accident rate varied widely depending on the user and operating conditions; the Spanish Air Force, for example, lost none. The Starfighter was a particular favorite of the Aeronautica Militare Italiana (Italian Air Force), although the AMI's accident rate was far from the lowest of Starfighter users.

Notable U.S. Air Force pilots who lost their lives in F-104 accidents include Major Robert H. Lawrence, Jr. and Captain Iven Kincheloe. Civilian (retired USAAF) pilot Joe Walker died in a mid-air collision with an XB-70 Valkyrie while flying an F-104. Chuck Yeager was nearly killed when he lost control of an NF-104A during a high-altitude record-breaking attempt. He lost the tips of two fingers and was hospitalized for a long period with severe burns after the flight.

To understand the aircraft's safety record the causes of many accidents need to be examined in detail:

* Aircraft general characteristics

The F-104 series all had a very high wing loading (made even higher when carrying external stores) which demanded that sufficient airspeed be maintained at all times. The high angle of attack area of flight was protected by a stick shaker system to warn the pilot of an approaching stall, and if this was ignored a stick kicker system would pitch the aircraft's nose down to a safer angle of attack but this was often overridden by the pilot. At extreme high angles of attack the F-104 was known to "pitch-up" and enter a spin which in most cases was impossible to recover from. Unlike the twin-engined F-4 Phantom II for example, the F-104 with its single engine lacked the safety margin in the case of an engine failure, and had a very poor glide ratio without thrust.

* Early problems

The J79 was a new engine which continued to be developed during the YF-104A test phase and in service with the F-104A. The engine featured variable incidence compressor stator blades which was a design feature that altered the angle of the stator blades automatically with altitude and temperature. A condition known as "T-2 reset" (a normal function which made large stator blade angle changes) caused several engine failures on takeoff. It was discovered that large and sudden temperature changes (from being parked in the sun to getting airborne) were falsely causing the engine stator blades to close and choke the compressor. The dangers presented by these engine failures were compounded by the downward ejection seat which gave the pilot little chance of a safe exit. The engine systems were subsequently modified and the ejection seat changed to the more conventional upward type. Uncontrolled tip-tank oscillations sheared one wing off of an F-104B; this problem was apparent during testing of the XF-104 prototype and was eventually resolved by filling the tank compartments in a specific order.[10]

* Later problems

A further engine problem was that of "uncommanded" opening of the variable thrust nozzle (usually through loss of engine oil); when, although the engine would be running normally at high power, the opening of the nozzle resulted in a drastic loss of thrust. A modification program installed a manual nozzle closure control which reduced the problem. The engine was also known to suffer from afterburner blow out on takeoff or even non-ignition resulting in a major lost of thrust, which could be detected by the pilot, the recommended action was to abandon the takeoff. The first fatal accident in German service was caused by this. Some aircrews experienced uncommanded "stick kicker" activation at low level when flying straight and level, so F-104 crews often flew with the system de-activated removing the protection it offered. Asymmetric flap deployment was another common cause of accidents, as was a persistent problem with severe nosewheel "shimmy" on landing which usually resulted in the aircraft leaving the runway and in some cases even flipping over onto its back.[11]

* German service

The introduction of a highly technical aircraft type to a newly reformed airforce was fraught with problems. Many pilots and groundcrew had settled into civilian jobs after World War II and had not kept pace with developments, with pilots being sent on short "refresher" courses in slow and benign handling first generation jet aircraft. Groundcrew were similarly employed with minimal training and experience. Operating in poor North West European weather conditions (vastly unlike the fair weather training conditions at Luke AFB in Arizona) and flying at high speed and low level over hilly terrain, a great many accidents were attributed to CFIT or Controlled Flight Into Terrain (or water), which it is fair to say was no fault of the aircraft. Many Canadian losses were attributed to the same cause as both air forces were operating in the same country. An additional factor was that the aircraft were parked outside in adverse weather conditions (snow, rain etc) where the moisture affected the delicate avionic systems. It was further noted that the Lockheed C-2 ejection seat was no guarantee of a safe escape and the Luftwaffe retro-fitted the much more capable Martin Baker GQ-7A seat from 1967, and many operators quietly followed suit. In 1966 Johannes Steinhoff took over command of the Luftwaffe and grounded the entire F-104 fleet until he was satisfied that problems had been resolved or at least reduced. In later years the German safety record improved although a new problem of structural failure of the wings emerged. Original fatigue calculations had not taken into account the high number of g-force loading cycles that the German F-104 fleet was experiencing, and many airframes were returned for depot maintenance where their wings were replaced, while other aircraft were simply retired. Towards the end of Luftwaffe service, some aircraft were modified to carry an ADR or 'Black Box' which could give an indication of what might have caused the accident.[12]

* Normal operating hazards

The causes of a large number of aircraft losses were the same as for any other similar type. They included: birdstrikes (particularly to the engine), lightning strikes, pilot spatial disorientation, and mid-air collisions with other aircraft. A particularly notable and tragic accident occurred on 19 June 1962 when a formation of four F-104F aircraft practising for the type's introduction into service ceremony, crashed together after descending through a cloud bank. This accident was explained as probable spatial disorientation of the lead pilot, formation aerobatic teams were consequently banned by the Luftwaffe from that day on.[13]

* Comparison with other aircraft types.

A USAF study of the accident rate of all the Century Series fighters over 750,000 flying hours showed that the F-100 Super Sabre led the table with an accident rate over double that of the F-104 (which had the second highest rate), closely followed by the F-102 Delta Dagger.[3]

[edit] Operational history

[edit] USAF Air Defense Command
Lockheed F-104A-20-LO of the 83rd Fighter Interceptor Squadron at Taeyan Air Base, Taiwan, on 15 September 1958, during the Quemoy Crisis (Operation Jonah Able).
Lockheed F-104A-20-LO of the 83rd Fighter Interceptor Squadron at Taeyan Air Base, Taiwan, on 15 September 1958, during the Quemoy Crisis (Operation Jonah Able).

The F-104A initially served briefly with the USAF Air Defense Command as an interceptor, although neither its range nor armament were well-suited for that role. The first unit to become operational with the F-104A was the 83rd Fighter Interceptor Squadron on 20 February 1958 at Hamilton AFB in California. After just three months service, the unit was grounded after a series of engine-related accidents. The aircraft were then fitted with the J79-3B engine and another three ADC units equipped with the F-104A. After only one year of service these aircraft were handed over to the Air National Guard although it should be noted that the F-104 was intended as an interim solution while the ADC waited for delivery of the F-106 Delta Dart.[14]

[edit] USAF Tactical Air Command

The subsequent F-104C entered service with Tactical Air Command as a multi-role fighter and fighter-bomber. The 479th Tactical Fighter Squadron at George AFB, California was the first unit to equip with the type in September 1958. It saw service in the Vietnam War. Again in 1967 the TAC aircraft were transferred to the Air National Guard.

[edit] Vietnam War

Commencing with the Operation Rolling Thunder campaign, the Starfighter was used both in the air-superiority role (although it saw little aerial combat, and scored no air-to-air kills Starfighters were successful in deterring MiG interceptors[15]) and in the air support mission. Starfighter squadrons made two deployments to Vietnam, the first was from April 1965 to November 1965, flying 2,937 combat sorties. During that first deployment, two Starfighters were shot down by ground fire, one was shot down by a Chinese MiG-19 (Shenyang J-6) when the F-104 strayed over the border, and two F-104s were lost to a mid-air collision associated with that air-to-air battle. The 476th Tactical Fighter Squadron deployed to Vietnam in April 1965 through July 1965, losing one Starfighter; and the 436th Tactical Fighter Squadron deployed to Vietnam in July 1965 through October 1965, losing four.[16]

Starfighters returned to Vietnam when the 435th Tactical Fighter Squadron deployed from June 1966 until July 1967, in which time they flew a further 2,269 combat sorties, for a total of 5,206 sorties. Nine more F-104s were lost; two F-104s to ground fire, three to surface-to-air missiles, and the final four losses were operational (engine failures). The Starfighters rotated and/or transitioned to F-4 Phantoms in July 1967, having lost a total of 14 F-104s to all causes in Vietnam.[17] F-104s operating in Vietnam were upgraded in service with APR-25/26 radar warning receiver equipment, and one example is on display in the Air Zoo in Kalamazoo, Michigan. The last USAF Starfighters left active service in 1969, but continued with the Puerto Rico ANG until 1975.[18]

The USAF was less than satisfied with the Starfighter and procured only 296 examples in single- and two-seat versions. 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 capability and endurance compared to other USAF aircraft. Its U.S. service was quickly wound down after 1965.

[edit] 1967 Taiwan Strait Conflict

On 13 January 1967, four Republic of China (Taiwan) Air Force F-104G aircraft engaged a formation of 12 MiG-19s of the People's Liberation Army Air Force over the disputed island of Quemoy. One MiG-19 was claimed shot down with one F-104 also lost.[19]

[edit] India-Pakistan Wars

Main articles: Indo-Pakistani wars and conflicts and Aerial warfare in 1965 India Pakistan War

At dawn on 6 September 1965, Flight Lieutenant Aftab Alam Khan in an F-104 claimed a Dassault Mystère IV destroyed over West Pakistan and another damaged, to mark the start of aerial combat in the Indo-Pakistani War of 1965. At that time it was claimed as the first combat kill by any Mach 2 aircraft, and the first missile kill for the Pakistan Air Force. Indian sources dispute this claim.[20] The PAF lost three F-104 Starfighters during the 1965 operations scoring two kills in return.[21]

The Starfighter is also believed to have been instrumental in intercepting an Indian Air Force Folland Gnat earlier, on 3 September 1965. F-104s were vectored to intercept the Gnat flying over Pakistan, returning to its home base. The F-104s, closing in at supersonic speed, caused the Gnat pilot to lower the undercarriage and land at a nearby disused Pakistani airfield to surrender. The Indian AF claims Squadron Leader Brij Pal Singh (who later rose to be an Air Marshal) made a navigation error that led him to land on the Pakistani airstrip. Singh was taken as a POW and later released.[21] The IAF Gnat is now displayed at the PAF Museum, Karachi.

[edit] International service

At the same time as the F-104 was falling out of U.S. favor, the Federal German Airforce was looking for a multi-role combat aircraft. The Starfighter was presented and reworked to convert it from a fair-weather fighter into an all-weather ground attack, reconnaissance and interceptor aircraft, as the F-104G. The aircraft found a new market with other NATO countries, and eventually a total of 2,578 of all variants of the F-104 were built in the U.S. and abroad for various nations. Several countries received their aircraft under the U.S.-funded Military Aid Program (MAP). The American engine was retained but built under license in Europe, Canada and Japan. The Lockheed ejector seats were also retained initially but were replaced later in some countries by the statistically safer Martin-Baker zero-zero ejection seat.

The so-called "Deal of the Century" produced considerable income for Lockheed. However, the resulting Lockheed bribery scandals caused considerable political controversy in Europe and Japan. In Germany, the Minister of Defence Franz Josef Strauss was accused of having received at least $10 million for West Germany's purchase of the F-104 Starfighter in 1961.[22] Prince Bernhard of the Netherlands later confessed to having received more than $1 million 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 downfall of the ailing corporation.

The international service of the F-104 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 operational Starfighters served with the Italian AMI, which retired them in mid-2004

Development contract

Clarence "Kelly" Johnson, chief engineer at Lockheed's Skunk Works, visited Korea in December 1951 and talked to fighter pilots about what sort of aircraft they wanted. At the time the U.S. pilots were confronting 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.[5]

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). The L-246 remained essentially identical to the L-083 Starfighter as eventually delivered.[5]

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. The prototype was given the designation XF-104.[6]

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 J79 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.

[edit] Wing design
Lockheed F-104A-10-LO.

The F-104 featured 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% and an aspect ratio of 2.45. The wing's leading edges were so thin (0.016 in / 0.41 mm) and 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 wings had both leading- and trailing-edge flaps. The small, highly-loaded wing resulted in an unacceptably high 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 a harrowing experience.[7]

[edit] Tail surfaces

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.[7]

[edit] Fuselage

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. This fuselage and wing 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 excellent 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.

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 there was a recommendation to limit the servo-control power that generated 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.

[edit] Engine
Detail of F-104G's J79 turbojet exhaust (the red coloring is artificial and has been added by the museum).
Detail of F-104G's J79 turbojet exhaust (the red coloring is artificial and has been added by the museum).

The F-104 was designed to use the General Electric J79 turbojet engine, fed by side-mounted intakes with fixed inlet cones optimized for supersonic speeds. Unlike some supersonic aircraft, the F-104 does not have variable-geometry inlets. Its thrust-to-drag ratio was excellent, allowing a maximum speed well in excess of Mach 2: the top speed of the Starfighter being limited more by the aluminium airframe structure and the temperature limits of the engine compressor than by thrust or drag (which gives an aerodynamic maximum speed of Mach 2.2). Later models used uprated marks of the J79, improving both thrust and fuel consumption significantly.

[edit] Equipment and armament

* Ejection seat

Early Starfighters used a downward-firing ejection seat (the Stanley 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 the 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 at zero altitude and zero airspeed).[8]

* Avionics

The initial USAF Starfighters had basic AN/ASG-14T ranging radar, TACAN, and the AN/ARC-34 UHF radio. The later international fighter-bomber aircraft had much more advanced Autonetics NASARR radar, a simple infrared sight, a Litton LN-3 inertial navigation system, and an air data computer.

In the late 1960s, Lockheed developed a more advanced version of the Starfighter, the F-104S, for use by the Italian Air Force as an all-weather interceptor. The F-104S received a NASARR R21-G with moving-target indicator and a continuous-wave illuminator for semi-active radar homing missiles, including the 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.
Lockheed F-104G showing full external stores load.
Lockheed F-104G showing full external stores load.

* Armament

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 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 all the two-seat models and some single-seat versions, including reconnaissance aircraft and the early Italian F-104S, the gun bay and ammunition tank were usually replaced by additional fuel tanks. Two AIM-9 Sidewinder air-to-air missiles could be carried on the wingtip stations, which could also be used for fuel tanks. F-104C and later models added a centerline pylon and two underwing pylons for bombs, rocket pods, or fuel tanks. The centerline pylon could carry a nuclear weapon; and a "catamaran" launcher for two additional Sidewinders could be fitted under the forward fuselage, although the installation had minimal ground clearance and made the seeker heads of the missiles vulnerable to ground debris. The F-104S models added a pair of fuselage pylons beneath the intakes available for conventional bomb carriage. The F-104S had an additional pylon under each wing, to give a maximum of nine.

[edit] Two-seat trainer

Several two-seat training versions of the Starfighter were produced. They were generally similar to the single-seater, but the additional cockpit required removing the cannon and some internal fuel (very early versions of the F-104B did have a cannon fitted but it became impractical for many reasons). The nose landing gear bay was repositioned and the strut retracted rearwards. Two-seaters were combat-capable with Sidewinder missiles, and, despite a slightly larger vertical fin and increased weight, had similar performance to the early model single-seat aircraft.

F-104 Starfighter

The Lockheed F-104 Starfighter was a single-engined, high-performance, supersonic interceptor aircraft that served with the United States Air Force (USAF) from 1958 until 1967. It continued in service with Air National Guard units until it was phased out in 1975. The National Aeronautics and Space Administration (NASA) flew a small mixed fleet of F-104 types in support of supersonic flight tests and spaceflight programs until they were retired in 1994.[2] Several two seat trainer versions were produced, the most numerous being the TF-104G.

The F-104C was used in combat with the USAF during the Vietnam War, and F-104A aircraft were deployed during the Indo-Pakistani wars. Republic of China Air Force F-104s also engaged MiG-19s of the People's Liberation Army Air Force over the disputed island of Quemoy.

The poor safety record of the F-104 Starfighter brought the aircraft in to the public eye, especially in Luftwaffe service, and the subsequent Lockheed bribery scandals surrounding the original purchase contracts caused considerable political controversy in Europe and Japan. A USAF study of other Century Series fighters revealed that the F-100 Super Sabre had an accident rate far worse than the F-104.[3]

The F-104G version sold well amongst NATO air forces where these high-speed fighter-bomber variants continued in service with most operators until the late 1980s. Lockheed developed the final and most advanced version of the Starfighter, the F-104S, for use by the Italian Air Force which was designed to carry AIM-7 Sparrow missiles, the Italian Air Force being the last remaining Starfighter operator on retiring their fleet in 2004. Many F-104 users eventually replaced them with the F-16 or Panavia Tornado. A projected, highly modified version of the F-104 known as the CL-1200 Lancer did not proceed and the project was cancelled at the mock-up stage. A civilian demonstration team based in Florida operates the last three airworthy Starfighters