Airborne Awesomosity

Don’t Be a Spoil-Sport

The prototype YMC-130H Credible Sport 1, firing its forward-facing retrorockets in a test of its STOL capabilities at Wagner Field in 1980.

Have you ever gone to a soccer match, and as you gazed out over the field to the surrounding stadium, wondered how hard it might be to land a C-130 in there? Okay, I will admit, our American readers are probably like me, and glazed over as soon as I said the word soccer. So for us, let’s do a thought experiment, and instead of the word soccer we’ll say football. Actually, that’s probably a better way to go, since then everyone will be roughly on the same page, as the word soccer probably doesn’t mean much elsewhere anyhow.

Back to the question at hand, landing inside a stadium turns out to be not all that hard, nor is taking off, given the quantity of rockets at hand is high enough. Many off us are probably familiar with JATO rockets used for very short takeoffs (the Blue Angels’ Fat Albert used them in shows up until a couple of years ago), but did you know that similar rockets could be used to stop the plane as well?

In 1980, after the failure of the first Iranian hostage crisis rescue mission (Operation Eagle Claw, previously referenced by yours truly in a post about sand filtration), the US government began planning an alternate rescue mission, focusing on eliminating the perceived weak link in the first mission, the helicopters. Under the Joint Test Directorate, a program named Honey Badger conducted projects to develop and validate a variety of capabilities that would be available to special forces units, and one of the projects within Honey Badger was Credible Sport, a joint venture between the Air Force, Navy, and Lockheed to create a ‘super short take-off and landing’ fixed wing aircraft that would be capable of inserting a resuce team and then extracting the team and hostages.

Aerial image showing the relation of the stadium to the embassy building.

The Credible Sport concept called for a modified C-130 Hercules cargo plane to land in the Amjadien Stadium (soccer) across the street from the American Embassy and airlift outDelta Force and the rescued hostages. The aircraft would then be flown to and landed on an aircraft carrier for immediate medical treatment of an expected 50 wounded. (A US Marine Corps KC-130 on loan to the US Navy had been previously landed on the aircraft carrier USS Forrestal (CVA-59) in November 1963 as part of a Naval Air Systems Command demonstration.) Three MC-130 Combat Talon crews (all Eagle Claw veterans) were assigned to fly the three aircraft, drawn from the 463rd Tactical Airlift Wing, with the concept plan calling for the mission of two aircraft (one primary and one spare) to originate in the United States, reaching Iran by five in flight refuelings, and penetrate at low altitude in the dark to evade Iranian air defenses. (Wikipedia)

YMC-130H Credible Sport 1, firing its take-off rockets in a test of its STOL capabilities at Wagner Field.

The aircraft were modified with fully-powered flight controls along with a 35% increase in the control surface areas. The flaps were modified to be double-slotted to increase their lift and the leading edge roots of the horizontal stabilizer were increased along with a corresponding increase in the leading edge dorsal root fin to provide more stability at low speeds. An extended nose section housed the additional avionics for the mission, the nose section coming from a DC-130 drone controller aircraft. The radar from a Vought A-7 Corsair II attack jet was housed in the extreme nose and an under-nose FLIR package would allow night operations. To provide flight path guidance on the approach into the stadium, a laser altimeter and laser range finder were also fitted. As the mission would be flown directly from the United States, the aircraft were modified with the inflight refueling receptacle from a Lockheed C-141 Starlifter. Five inflight refuelings would be needed to reach Tehran. The inflight refueling system reached back to the wings and was plumbed into the wing tanks. Under the fuselage just forward of the aft cargo ramp was an arresting hook- the plan called for the Credible Sport aircraft to recover on an aircraft carrier in case any hostages or personnel needed medical attention. (aviationtrivia)

Another major modification was the rockets sets required for the take-off and the landing, and the controls neccessary to fire them in the proper sequence:

For the landing, eight retrorockets were housed in pairs in sponson fairings on the forward fuselage. Another four rockets on each side of the fuselage were mounted by the main landing gear fairings and were pointed downward. It’s believed that the downward rockets were from US Navy ASROC missiles and the retrorockets were from AGM-45 Shrike anti-radar missiles. On approach, speed would be maintained at 85 knots but at 85% engine power to remain at least 5 knots above the stall speed. At height of 50 feet, the downward firing rockets were activated by the navigator for 3 seconds to arrest the descent rate and at touch down, the eight retrorockets deployed out of their fairings and fired with a thrust of 80,000 lbs, bringing the Hercules to a rapid halt.

For takeoff, four main RATO units that came from the Navy’s Standard RIM-66 surface-to-air missile were mounted on each side of the aft fuselage. In addition, six smaller rocket units were installed in three pairs- one pair under each wing mounted on the fuel tank pylon and one pair under the tail unit. The tail unit rockets prevented over-rotation and the wing-mounted units were to provide yaw stabilization should the main RATO units not shut down simultaneously. The ten rocket motors for takeoff provided 180,000 lbs of thrust! This was approximately twenty times the power provided by the C-130’s four T56 turboprops. (aviationtrivia)

The testing for the project was done at Wagner Field, an auxiliary field for Eglin Air Force Base in the Florida Panhandle, from September to October of 1980–just months after the failure of the initial rescue attempt. (Wagner Field was also used in training for the Doolittle Raid on Tokyo in 1942.) The short take-off portions of the flight test were very successful, with the modified C-130 able to take off after a ground roll of just 100 feet and attain an altitude of 300 feet after 200 feet of horizontal distance. With the new flap configurations, the aircraft was capable of an approach speed of 85 knots. However, when the landing and braking rockets were tested, issues arose that caused the rockets to fire in improper sequence. This resulted in the loss of one of the test aircraft, although sources differ on whether the rocket problems were the result of mechanical failure or human error.

The Lockheed test crew then assessed that the computer used to command the firing of the rockets during the landing sequence needed further calibration, and elected to manually input commands. The reverse-mounted (forward-facing) eight ASROC rockets for decelerating the aircraft’s forward speed 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), but that the lower pairs could only be fired after the aircraft was on the ground, with the descent-braking rockets also firing during the sequence.

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. 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 was immediately reduced to nearly zero, dropping it hard to the runway and breaking the starboard wing’s spar between the third and fourth engines. During rollout the trailing wing ignited a fire, but a medical evacuation helicopter dispersed the flame and crash response teams extinguished the fire within eight seconds of the aircraft stopping, enabling the crew to exit the aircraft without injury. (Wikipedia)

YouTube Preview Image

YMC-130H Credible Sport 1, firing its downward-facing rockets in a test of its STOL capabilities at Wagner Field.

The facilities at Wagner field used to test the prototype YMC-130H.

Wagner Field, also known as Eglin Auxiliary No. 1, in 1998.

YMC-130H Credible Sport 1, firing its forward-facing retrorockets in a test of its STOL capabilities at Wagner Field.

When Ronald Reagan won the election over Jimmy Carter in November of 1980, the Iranian revolutionary government indicated a desire for a resolution to the crisis, culminating with the release of the hostages concurrent with Reagan’s inauguration in January 1981. Of the three airframes modified for the program, one was a total loss in the crash at Wagner, one was de-modified and returned to service, and the last was donated to the Museum of Aviation at Warner-Robbins, Georgia.

Wreckage of the prototype YMC-130H Credible Sport 1, after its crash at Wagner Field caused by improper timing of the firing of its retro rockets.

YouTube Preview Image

Images, in order of appearance, from tripod/airfields_freeman, crediblesport, aviationtrivia, combatreform.org (Lockheed drawings x 5), tripod/airfields_freeman (Wagner Field and YMC-130), and crediblesport (crash diagram). Find out more about C-130s on aircraft carriers here.

 

Special thanks to Cavemanengineer for the great tip!

Spread The Word:
  • Print
  • Digg
  • Facebook
  • Twitter
  • Google Bookmarks
  • email
  • Tumblr
  • The Professor

    Nice article Hyco! I hadn't heard of this program before. There were all sorts of strange things going on in the military after the Eagle Claw disaster, lots of hand-wringing and head bashing. This project looks at least workable once the rocket firing sequence was worked out. Lots of thrust in those braking rockets, they really dropped that C-130 out of the air on that first test flight. It sure is an impressive fireball when it takes off and lands the way it's supposed to though. I'd bet it would scare the hell out of anyone on the ground nearby.

    • fodder650

      Right idea, wrong aircraft. They would have needed more of them but they should have used a group of true STOL aircraft to get them out. It wouldn't have carried their equipment but they wouldn't have needed to go this far.

      We did learn a lot of lessons from this but this would be one of the last times we would let the mad scientists plan this sort of thing out.

      • The Professor

        That's it, blame the mad scientists. Bah! Ingrates! You people have no vision!

  • Pingback: Hercules Goes For a Swim : Atomic Toasters()

  • CaptianNemo2001

    I think that with modern computers for timing we could put this thing to use.
    Besides if you didn't use the JATOs in takeoff you could always use them to change direction while in flight. =)

-->