Rocket-Powered C-130

Operation Credible Sport

Over the years the C-130 Hercules has been the subject of many experiments. From landing on aircraft carriers to retrieving falling film canisters from spy satellites. However, one of the more prominent experiments was around a rocket powered concept, which was to be used in a hostage rescue operation in the 1980s.

OPERATION CREDIBLE SPORT

The story begins in 1980. During the Iranian hostage crisis, the US had attempted a rescue mission known as Eagle Claw. This mission was to use a variety of transport aircraft and, most importantly, large utility helicopters (RH-53s) to extract the hostages. These helicopters would have flown into Tehran, taken hostages, and then flown back over the border. Technically the operation did enter an early phase, however several issues began to arise while the helicopters were in the Iranian desert. This culminated in one of the helicopters experiencing technical problems before crashing into a parked C-130, killing eight commandos. The plan was called off.

A new task force was set up. The US military still wanted to retrieve the hostages, but this time without the heavy lift helicopters, which they saw as a weak link in the plan. Focus was shifted towards transport aircraft. An aircraft would be modified with a short take-off and landing configuration, capable of landing on a soccer field in Iran, and then taking off again from the same field.

Codenamed Credible Sport, the concept got under way immediately, led by the newly formed Joint Test Directorate, or JTD. The first plan of action was picking a reliable aircraft which could be modified quickly, given the nature of the situation. The decision was made to use the C-130 Hercules. The mission would be strenuous; three modified Hercules would be produced. Two of these would be kept on the ready; one for the mission, and one as backup. These two aircraft would take off from the US, fly across to Iran aided by five in flight refuellings, and then head towards Tehran at low level in the dark. The mission aircraft would then land in the Amjadien Stadium, situated across the street from the US Embassy where the hostages were kept. A Delta Force team would then extract the hostages, before the aircraft took off again from the field. Heading out to sea, the Hercules would finally make a risky carrier landing - a feat which had been done once in the 1960s - to treat the wounded.

Three Hercules crews were selected from the 463^rd Tactical Airlift Wing. All were veterans of Eagle Claw, and all were trained on Lockheed’s latest MC-130 Combat Talon - a C-130 modified for special forces use.

The JTD selected four aircraft for the project; three testbed aircraft known as XFC-130H, and an EC-130ABCCC. The latter was to be used to mock-up cockpit setups, while one of the XFCs was to be used to test a variety of rocket systems. The remaining two were to be the mission aircraft. Designers had 90 days to research, and then modify these aircraft into something workable. Rocket assisted take-off and landing would be the most viable option. The C-130 had already been tested with rocket take-off tech, most notably put to use from 1975 to 2009 in the Blue Angels C-130, which used rocket take-offs as a performance trick, although even before this, the LC-130 had been using small rocket boosters to achieve rapid take-off.

The project would see twenty US Navy, fifty Air Force, and over 1000 civilians taking part.

Lockheed began work on structurally reinforcing these airframes to handle the shock of what would be a rough landing and take-off. A restraint system would also need to be developed for the 150 passengers. New tech was also loaded from the Combat Talon; a terrain following radar, GPS, new ailerons, flaps, ventral and dorsal fins, and a tail hook.

The most important element would be the rocket power, which would both stop the aircraft on landing, and aid take-off. Lockheed realised that the existing JATO method - which had been tested for decades - would be insufficient; the aircraft would require 58 JATO bottles, or roughly 7 times more than normal to stop it at the required distance, and arresting equipment wasn’t going to do the job either.

The USN Naval Air Weapons Station China Lake, was then bought in to come up with other solutions. The result was a Hercules strapped with 30 rockets, taken from various missile systems. To land, eight downward facing Shrike rockets were placed underneath to soften the landing, whilst eight forward facing Anti-Submarine Rockets (or ASROCs) would be used to slow down the aircraft. To take off, a further eight backward facing MK-56 rockets would rapidly propel the aircraft forward and up, whilst two Shrike rockets mounted wing pylons corrected yaw, and two ASROCs on the tail prevented over rotation.

Just three weeks after the beginning of the project, the aircraft were ready for testing. They were sent to Eglin Air Base, and over the following week a variety of tests were done. The take-off system worked well, setting record times for short take-offs. Meanwhile the aircrafts new avionics systems allowed it to fly at 85 knots on final approach. During one test, the aircrafts front wheel lifted off after 10 feet, and by 150 feet the aircraft had taken off. The final test would be using the landing rockets as well. Before this, Lockheed engineers calibrated the onboard computer system manually, and the test got underway.

As the aircraft approached the runway, the first pair of the forward-facing deceleration rockets fired. These would slow the aircraft significantly, but the other six deceleration rockets could only be fired once on the ground. However, the computer system malfunctioned and fired the downward facing rockets at the wrong time. Blinded by the rockets, the pilot assumed they were already on the runway, and fired the rest of the deceleration rockets. This caused the aircraft to immediately reach a near-zero speed, before dropping hard onto the runway. One of the wings broke off, and fires started.

Fire teams extinguished the flames in seconds, and the crew escaped, but for the airframe, it was over. The aircraft was stripped of its rocket components and, for security reasons, was buried on site. It was claimed that a computer error may have resulted in the timing error, and this may have occurred during the manual calibration before the final test. Regardless, the project was more or less over. It was not long before Ronald Reagan replaced Jimmy Carter as president, and the Algiers Accords of January 19^th, 1981, opened the way for the peaceful release of the hostages.

The remaining test aircraft - stripped of its rocket components - would keep its new avionics systems, be re-designated YHC-130H, and be used as Lockheed’s testbed for the Combat Talon II.

FURTHER EXPERIMENTS

Beyond this ambitious project, the C-130 would have other uses for rocket tech. The most well-known is the use of two conformal banks of rockets used by the Blue Angels during performances. The Blue Angels C-130 - known as Fat Albert - would continue to use a smaller rocket system up until 2009, at which point it had expended the last stockpiles of the Vietnam-era JATO bottles.

Another situation for rocket assisted take-off was in snow. The LC-130 had been designed for use in the Arctic and Antarctic. Equipped with skis and improved landing gear, it could land on both prepared and in some cases ill prepared snowfields or ice. Given that the aircraft may land on sticky or rough snow, or in some cases on unprepared snow surfaces, it would also require a system to launch it off the snow. To achieve this, two sets of four rockets would be used; one on either side of the fuselage. These rockets would provide sufficient thrust to not only overcome any increased friction, but also launch the aircraft within a far shorter distance.

Initially these rockets could be jettisoned after launch, however this would change after several incidents. The first was in Antarctica during 1971. A Hercules had been taking-off when one of the rocket clusters jettisoned improperly, hitting one of the propellers. A second LC-130 was dispatched to take repair parts to the first aircraft, when another accident occurred, resulting in a crash and two fatalities. From then on, the mounting of the rocket clusters were changed so that the expended rocket bottles could not be released in the air. Today, the remaining 10 LC-130s are all in service with the New York Air National Guard.

These projects showed that rocket assisted take-offs could yield impressive results. Based on testimonies, the hostage rescue aircraft would have been able to take-off and likely land within the specific field, if the mission had gone ahead, and then landing on an aircraft carrier. These stories exemplify the variety of roles, and the versatility of the Hercules, a 70-year-old design with no end to its service in sight.