The A-12CB (Carrier Based) was a minor study for a major change in operations for the Oxcart: flight to and from aircraft carriers.
The A-12 was the product of Project Oxcart, a secret military program to develop a high-speed, high-altitude reconnaissance aircraft. First flown in 1962, the A-12 was built by Lockheed’s Advanced Development Projects office, now known as Skunk Works. The A-12 was capable of performing sensitive intelligence-gathering missions while flying at speeds over Mach 3, or three times the speed of sound. The Central Intelligence Agency (CIA) used A-12s for surveillance missions until 1968. Later versions, known as the SR-71 Blackbird, served in reconnaissance and test missions for the US Air Force (USAF) and NASA through the 1990s.
The A-12CB was a minor study for a major change in operations for the A-12: flight to and from aircraft carriers. As told by Scott Lowther in his book Origins and Evolution Lockheed SR-71 Blackbird, the A-12 certainly seems an unlikely aircraft to operate at sea… big, finicky, fragile and with blistering takeoff and landing speeds. Numerous changes would have been required.
Known so far from only two similar, but not identical diagrams, the A-12CB (Carrier Based) would have had sizable solid rocket motors attached to the underside. The motors were Rocketdyne RS B-202s, used for the F-104G zero length launch system.
With a total thrust of 130,000lb and a burn time of 7.9 seconds, these jettisonable take-off units would, with the aircraft carriers catapult system, have done a good job of lofting the A-12 forwards into the air. The A-12 would have required substantial internal modification both to the underside of the wings and the forward fuselage to tie these new sources of thrust into the aircraft structure. For landing, an arrester hook was fitted, which also would have required tie-in to the main structure. Presumably the landing gear would also need reinforcement.
The available diagrams show that the A-12CB was to be catapult-launched using the now-obsolete system of a bridle cable attached to two hooks located on the underside of the fuselage, straddling the centerline just aft of the inlets. The bridle cable attached to a very large catapult shuttle that seemed to serve as a support for the forward fuselage, perhaps intended to hold the nose of the aircraft down during the catapult launch. With the large booster rockets firing, it’s likely that substantial forces would have been in play that could have thrown the aircraft all over the deck until aerodynamic flow held it on course.
Nothing is known about what aircraft carrier or li carriers the A-12CB was meant to operate from. Here it has been provisionally shown on the deck of CVAN-65 USS Enterprise. It can be seen that it would a have been a very large aircraft for the deck of that ship, though it appears that with some effort it could have been made to fit on the ship’s elevators. Whether it could have been shoved through the hangar doorway is unclear; it may have had to be partly disassembled to fit. Additionally, the deck of the carrier would likely need reinforcement, or at the very least protective coatings, to shield it from the booster rocket exhaust.
Operations would have been complex and difficult and their purpose is unclear. Presumably the A-12 would have remained a reconnaissance platform, but it is possible that the A-12 was to be a strike variant. One diagram of the A-12CB shows a crudely sketched something penciled in above the fuselage, but it’s impossible to determine what was intended.
In any event, nothing came of the design. Dimensions, weights and performance are not available, but would presumably have been much the same as for the standard A-12.
Origins and Evolution Lockheed SR-71 Blackbird is published by Mortons Books and is available to order here.
Photo credit: Gunnar Klack own work via Wikipedia and Scott Lowther via Mortons Books
