Lockheed C-130 Hercules
The Lockheed C-130 Hercules is an American four-engine turboprop military transport aircraft designed and built by Lockheed. Capable of using unprepared runways for takeoffs and landings, the C-130 was designed as a troop, medevac, and cargo transport aircraft. The versatile airframe has found uses in other roles, including as a gunship, for airborne assault, search and rescue, scientific research support, weather reconnaissance, aerial refueling, maritime patrol, and aerial firefighting. It is the main tactical airlifter for many military forces worldwide. More than 40 variants of the Hercules, including civilian versions marketed as the Lockheed L-100, operate in more than 60 nations.
The C-130 entered service with the U.S. in 1956, followed by Australia and many other nations. During its years of service, the Hercules has participated in numerous military, civilian and humanitarian aid operations. In 2007, the transport became the fifth aircraft to mark 50 years of continuous service with its original primary customer, which for the C-130 is the United States Air Force. The C-130 is the longest continuously produced military aircraft, having achieved 70 years of production in 2024.
Design and development
Background and requirements
The Korean War showed that World War II-era piston-engine transports—Fairchild C-119 Flying Boxcars, Douglas C-47 Skytrains and Curtiss C-46 Commandos—were no longer adequate. On 2 February 1951, the United States Air Force issued a General Operating Requirement for a new transport to Boeing, Douglas, Fairchild, Lockheed, Martin, Chase Aircraft, North American, Northrop, and Airlifts Inc.The new transport would have a capacity of 92 passengers, 72 combat troops or 64 paratroopers in a cargo compartment that was approximately long, high, and wide. Unlike transports derived from passenger airliners, it was to be designed specifically as a combat transport with loading from a hinged loading ramp at the rear of the fuselage. A notable advance for large aircraft was the introduction of a turboprop powerplant, the Allison T56 which was developed for the C-130. It gave the aircraft greater range than a turbojet engine as it used less fuel. Turboprop engines also produced much more power for their weight than piston engines. However, the turboprop configuration chosen for the T56, with the propeller connected to the compressor, had the potential to cause structural failure of the aircraft if an engine failed. Safety devices had to be incorporated to reduce the excessive drag from a windmilling propeller.
Design phase
The Hercules resembles a larger, four-engine version of the Fairchild C-123 Provider with a similar wing and cargo ramp layout. The C-123 had evolved from the Chase XCG-20 Avitruc first flown in 1950. The Boeing C-97 Stratofreighter had rear ramps, which made it possible to drive vehicles onto the airplane. The ramp on the Hercules was also used to airdrop cargo, which included a low-altitude parachute-extraction system for Sheridan tanks and even dropping large improvised "daisy cutter" bombs. The new Lockheed cargo plane had a range of and it could operate from short and unprepared strips.Fairchild, North American, Martin, and Northrop declined to participate. The remaining five companies tendered a total of ten designs: Lockheed two, Boeing one, Chase three, Douglas three, and Airlifts Inc. one. The contest was a close affair between the lighter of the two Lockheed proposals and a four-turboprop Douglas design.
The Lockheed design team was led by Willis Hawkins, starting with a 130-page proposal for the Lockheed L-206. Hall Hibbard, Lockheed vice president and chief engineer, saw the proposal and directed it to Kelly Johnson, who did not care for the low-speed, unarmed aircraft, and remarked, "If you sign that letter, you will destroy the Lockheed Company." Both Hibbard and Johnson signed the proposal and the company won the contract for the now-designated Model 82 on 2 July 1951.
The first flight of the YC-130 prototype was made on 23 August 1954 from the Lockheed plant in Burbank, California. The aircraft, serial number 53-3397, was the second prototype, but the first of the two to fly. The YC-130 was piloted by Stanley Beltz and Roy Wimmer on its 61-minute flight to Edwards Air Force Base; Jack Real and Dick Stanton served as flight engineers. Kelly Johnson flew chase in a Lockheed P2V Neptune.
After the two prototypes were completed, production began in Marietta, Georgia, where over 2,300 C-130s have been built through 2009.
The initial production model, the C-130A, was powered by Allison T56-A-9 turboprops with three-blade propellers and originally equipped with the blunt nose of the prototypes. Deliveries began in December 1956, continuing until the introduction of the C-130B model in 1959. Some A-models were equipped with skis and re-designated C-130D. As the C-130A became operational with Tactical Air Command, the C-130's lack of range became apparent and additional fuel capacity was added with wing pylon-mounted tanks outboard of the engines; this added of fuel capacity for a total capacity of.
Improved versions
The C-130B model was developed to complement the A-models that had previously been delivered, and incorporated new features, particularly increased fuel capacity in the form of auxiliary tanks built into the center wing section and an AC electrical system. Four-bladed Hamilton Standard propellers replaced the Aero Products' three-blade propellers that distinguished the earlier A-models. The C-130B had ailerons operated by hydraulic pressure that was increased from, as well as uprated engines and four-blade propellers that were standard until the J-model.The B model was originally intended to have "blown controls", a system that blows high-pressure air over the control surfaces to improve their effectiveness during slow flight. It was tested on an NC-130B prototype aircraft with a pair of T-56 turbines providing high-pressure air through a duct system to the control surfaces and flaps during landing. This greatly reduced landing speed to just 63 knots and cut landing distance in half. The system never entered service because it did not improve takeoff performance by the same margin, making the landing performance pointless if the aircraft could not also take off from where it had landed.
An electronic reconnaissance variant of the C-130B was designated C-130B-II. A total of 13 aircraft were converted. The C-130B-II was distinguished by its false external wing fuel tanks, which were disguised signals intelligence receiver antennas. These pods were slightly larger than the standard wing tanks found on other C-130Bs. Most aircraft featured a swept blade antenna on the upper fuselage, as well as extra wire antennas between the vertical fin and upper fuselage not found on other C-130s. Radio call numbers on the tail of these aircraft were regularly changed to confuse observers and disguise their true mission.
The extended-range C-130E model entered service in 1962 after it was developed as an interim long-range transport for the Military Air Transport Service. Essentially a B-model, the new designation was the result of the installation of Sargent Fletcher external fuel tanks under each wing's midsection and more powerful Allison T56-A-7A turboprops. The hydraulic boost pressure to the ailerons was reduced back to as a consequence of the external tanks' weight in the middle of the wingspan. The E model also featured structural improvements, avionics upgrades, and a higher gross weight. Australia took delivery of 12 C130E Hercules during 1966–67 to supplement the 12 C-130A models already in service with the RAAF. Sweden and Spain fly the TP-84T version of the C-130E fitted for aerial refueling capability.
The KC-130 tankers, originally C-130F procured for the US Marine Corps in 1958 are equipped with a removable stainless steel fuel tank carried inside the cargo compartment. The two wing-mounted hose and drogue aerial refueling pods each transfer up to to two aircraft simultaneously, allowing for rapid cycle times of multiple-receiver aircraft formations,. The US Navy's C-130G has increased structural strength allowing higher gross weight operation.
Further developments
The C-130H model has updated Allison T56-A-15 turboprops, a redesigned outer wing, updated avionics, and other minor improvements. Later H models had a new, fatigue-life-improved, center wing that was retrofitted to many earlier H-models. For structural reasons, some models are required to land with reduced amounts of fuel when carrying heavy cargo, reducing usable range.The H model remains in widespread use with the United States Air Force and many foreign air forces. Initial deliveries began in 1964, remaining in production until 1996. An improved C-130H was introduced in 1974, with Australia purchasing 12 of the type in 1978 to replace the original 12 C-130A models, which had first entered Royal Australian Air Force service in 1958. The U.S. Coast Guard employs the HC-130H for long-range search and rescue, drug interdiction, illegal migrant patrols, homeland security, and logistics.
C-130H models produced from 1992 to 1996 were designated as C-130H3 by the USAF, with the "3" denoting the third variation in design for the H series. Improvements included ring laser gyros for the INUs, GPS receivers, a partial glass cockpit, a more capable APN-241 color radar, night vision device compatible instrument lighting, and an integrated radar and missile warning system. The electrical system upgrade included Generator Control Units and Bus Switching units to provide stable power to the more sensitive upgraded components.
The equivalent model for export to the UK is the C-130K, known by the Royal Air Force as the Hercules C.1. The C-130H-30 is a stretched version of the original Hercules, achieved by inserting a plug aft of the cockpit and an plug at the rear of the fuselage. A single C-130K was purchased by the Met Office for use by its Meteorological Research Flight, where it was classified as the Hercules W.2. This aircraft was heavily modified, with its most prominent feature being the long red and white striped atmospheric probe on the nose and the move of the weather radar into a pod above the forward fuselage. This aircraft, named Snoopy, was withdrawn in 2001 and was then modified by Marshall of Cambridge Aerospace as a flight testbed for the A400M turbine engine, the TP400. The C-130K is used by the RAF Falcons for parachute drops. Three C-130Ks were upgraded and sold to the Austrian Air Force in 2002.