The Lockheed C-130 Hercules is an American, four-engined, turboprop, military transport aircraft designed and built by Lockheed (now Lockheed Martin). Capable of using unprepared runways for takeoffs and landings, the C-130 was designed as a troop, medical evacuation, and cargo transport aircraft. Its versatile airframe has found other uses, including as a gunship (AC-130), 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 (USAF). The C-130 is the longest continuously produced military aircraft, having achieved 70 years of production in 2024.
The Korean War showed that World War II-era piston-engined 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 (USAF) 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 was to have a capacity of 92 passengers, 72 combat troops, or 64 paratroopers in a cargo compartment that was about 41 ft (12 m) long, 9 ft (2.7 m) high, and 10 ft (3.0 m) 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.
The Hercules resembles a larger, four-engined 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 driving vehicles onto the airplane possible (also possible with the forward ramp on a C-124). 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 1,100 nmi (1,270 mi; 2,040 km), and it could operate from short and unprepared strips.
Fairchild, North American, Martin, and Northrop declined to participate in the competition. The remaining five companies submitted 10 design proposals: Lockheed presented two, Boeing one, Chase three, Douglas three, and Airlifts Inc. one. The competition ultimately narrowed to a close contest between the lighter of Lockheed's two submissions, designated the preliminary L-206 project, and a four-turboprop aircraft design proposed by Douglas.
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-bladed 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 redesignated 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 6,000 pounds (2,700 kg) of fuel capacity for a total capacity of 40,000 pounds (18,000 kg).
The C-130 was named "Hercules" by its manufacturer, Lockheed, after the Greek mythological hero known for his strength, courage, and perseverance. Hercules is also the name of a constellation, which fits the company's tradition of naming aircraft after celestial constellations, along with the P-2V Neptune and P-3 Orion.
Among the U.S. Armed Forces personnel, the C-130 is nicknamed in military slang as the "Herk" or "Herky Bird".
Due to its versatile airframe and multiple variants designed for diverse military applications and missions, on which it has served from the 1950s to the present day, its name has also been described as fitting for its achievements in military history, with the Royal Australian Air Force (RAAF) comparing it to the legendary feats and labours of Hercules.
As an homage to the feats of the aircraft and of its namesake, the Hellenic Air Force painted one of its C-130 aircraft with a livery depicting Hercules in the style of Ancient Greek vase painting, with the inscription, "Expanding the legendary feats of Hercules".
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-bladed propellers that distinguished the earlier A-models. The C-130B had ailerons operated by hydraulic pressure that was increased from 2,050 to 3,000 psi (14.1 to 20.7 MPa), as well as uprated engines and four-bladed 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. In total, 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 tails of these aircraft were regularly changed to confuse observers and disguise their true mission.