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Operation Credible Sport was a United States military aircraft modification plan in late 1980 to prepare for a second rescue attempt of the hostages held in Iran using C-130 cargo planes modified with rocket engines. Its followup project in 1981-82, Credible Sport II, used one of the original aircraft as the YMC-130 prototype for the MC-130H Combat Talon II.

Contents 1 Credible Sport 1.1 Concept 1.2 Development 1.3 Testing 2 Credible Sport II 3 Sources 4 References 5 External links

[edit] Credible Sport

[edit] Concept

The Credible Sport program was a developmental project to create capabilites for a "Super STOL" aircraft to use in rescuing the hostages after the dramatic failure of Operation Eagle Claw. Eagle Claw failed when a Sea Stallion helicopter crashed into a parked C-130 Hercules in the Iranian desert, killing 8 servicemen. Credible Sport was abandoned as unnecessary after the election of Ronald Reagan as President in November, 1980. The program was developed to be a quick strike, simplified plan when overall plans and military exercises developed for Project Honey Badger to implement a second rescue attempt grew to involve over a hundred primary aircraft and large numbers of ground troops.

The Credible Sport concept called for modified C-130 Hercules cargo planes to land in the Amjadien (soccer) Stadium across the street from the American Embassy in Tehran and airlift out the rescued hostages. The aircraft would then be flown to and landed on an aircraft carrier for immediate medical treatment of injured hostages. Three MC-130 Combat Talon crews (all Eagle Claw veterans) were assigned to fly the three aircraft drawn from the 463rd Military Airlift Wing, with the concept plan calling for the mission to originate in the United States, reaching Iran by five in flight refuelings.

[edit] Development

The three C-130s were modified under a top secret project at Eglin Air Force Base, Florida. The contract called for two to be modified to the proposed XFC-130H configuration within 90 days, and the third to be used as a test bed for various rocket packages blistered onto the forward and aft fuselage, which theoretically enabled the planes to land and take off within the confines of the sports arena.

The XFC-130H aircraft were modified by the installation of 30 rockets in multiple sets: eight forward-pointed ASROC rocket motors mounted around the forward fuselage to stop the aircraft, eight downward-pointed Shrike rockets fuselage-mounted above the wheel wells to brake its descent, eight rearward-pointed MK-56 rockets (from the US Navy's RIM-66 Standard Missile) mounted on the lower rear fuselage for takeoff assist, two Shrikes mounted in pairs on wing pylons to correct yaw during takeoff transition, and two ASROCs mounted at the rear of the tail to prevent it from striking the ground from over-rotation.

Other STOL features included a dorsal and two ventral fins on the rear fuselage, double-slotted flaps and extended ailerons, a new radome, a tailhook for landing aboard an aircraft carrier, and Combat Talon avionics, including a TF/TA radar, a defensive countermeasures suite, and a Doppler radar/GPS tie-in to the aircrafts inertial navigation system.^[1]

[edit] Testing

The test bed aircraft (74-2065) was ready for its first test flight on September 18, 1980, just three weeks after the project was initiated. The first fully modified aircraft, AF Serial No. 74-1683, was delivered on October 17 to TAB 1, a disused auxiliary airfield at Eglin Air Force Base, Florida. Between October 19 and October 28, numerous flights were made testing various aspects, including the double-slotted flaps system, which enabled the C-130 to fly at 85 knots on final approach at a very steep eight-degree glide slope. All aspects worked flawlessly, and a full profile test was scheduled for October 29.

During the test, the Lockheed crew determined that the computer used to command the firing of the rockets during the landing sequence needed further calibration to perform the crucial firing sequence during landing, and elected to manually input commands. The reverse-mounted (forward facing) eight ASROC rockets were situated in pairs on the upper curvature of the fuselage behind the cockpit, and at the mid-point of each side of the fuselage beneath the uppers. Testing had determined that the upper pairs, fired sequentially, could be ignited while still airborne (specifically, at 20 feet), the lower pairs could only be fired after the aircraft was on the ground. The flight engineer, blinded by the firing of the upper deceleration rockets, thought the aircraft was on the runway and fired the lower set early, while the descent-braking rockets did not fire at all. Later unofficial disclaimers alleged to have been made by some members of the Lockheed test crew asserted that the lower rockets fired themselves through an undetermined computer or electrical malfunction, which at the same time failed to fire the descent-braking rockets.

As a result, the aircraft's forward flight vector was reduced to zero, dropping it to the runway and tearing off the starboard wing between the third and fourth engines. During rollout the trailing wing ignited a fire, but crash response teams extinguished the fire within eight seconds of the aircraft stopping, enabling the crew to exit the aircraft without injury. 74-1683 was destroyed but most of its unique systems were salvaged.

74-1686 was nearly completed, but the defeat of Jimmy Carter by Ronald Reagan in the presidential election on November 4, 1980, and an Algerian-negotiated release plan led to the cancellation of this rescue mission plan. The hostages were subsequently released concurrent with Reagan's inauguration in January 1981. The program has been criticized after-the-fact as having been fatally handicapped by inadequate systems and flight testing due to haste caused by the political expediency to effect a rescue before the 1980 presidential elections.

[edit] Credible Sport II

The remaining airframes were stripped of their rocket modifications and 74-2065 returned to regular airlift duties. 74-1686, however, retained its other Credible Sport STOL modifications and was sent to Robins Air Force Base, Georgia. There in July 1981 it was designated YMC-130H as the test bed for development of the MC-130 Combat Talon II, under the project name Credible Sport II. Phase I was conducted between August 24 and November 11, 1981, to test minor modifications to improve aerodynamics, satisfy Combat Talon II prototype requirements on STOL performance, handling characteristics, and avionics, and to establish margins of safety. It also identified design deficiencies in the airframe and determined that the Credible Sport configuration was suitable only for its specific mission and did not have the safety margins necessary for peacetime operations.

Phase II testing began June 15, 1982, continued through October 1982, and determined that the final configuration resulted in significant improvements in design, avionics, and equipment, and that the Combat Talon II design was ready for production. The 1st SOW attempted to have the test bed transferred to operational duty as an interim Combat Talon II until production models became available, but TAC disagreed. The cost of demodifying the YMC-130H to airlift configuration was more than its value, and it never flew again.

In 1988 74-1686 was placed on display at the Museum of Aviation at Robins Air Force Base in Warner Robins, Georgia. As of February 2008, the other surviving Credible Sport aircraft, 74-2065, was assigned to the 317th Airlift Group, 15th Expeditionary Mobility Task Force, at Dyess Air Force Base, Texas, in grey scheme with blue tailband.

[edit] Sources

• Foreign Invaders - The Douglas Invader in foreign military and US clandestine service, by Dan Hagedorn and Leif Hellström, Midland Publishing Limited, Earl Shilton, Leicester, 1994 (Operation Millpond chapter, p.133, for CIA use of Duke Field) ISBN 1-85780-013-3

• The Praetorian Starship: The Untold Story of the Combat Talon. Jerry L. Thigpen, Air University Press, Maxwell Air Force Base, Alabama, December 2001.

• Lockheed-Martin Employee Association Flying Club quarterly newsletter, "FLYPAPER," August 2000.

[edit] References

[edit] External links

• Footage on YouTube
• More Footage on YouTube

• YMC-130H Page on Museum of Aviation Website