With the retirement of the Peacemaker, the US Air Force became an all jet bomber fleet.
On 12 February 1959, the last B-36J “Peacemaker” built, Air Force serial number 52-2827, departed Biggs Air Force Base, Texas, where it had been operational with the 95th Heavy Bombardment Wing. The aircraft was flown to Amon Carter Field in Fort Worth, Texas, where it was put on display. With the retirement of this last operational B-36J, the United States Air Force Strategic Air Command was henceforth equipped with an all-jet bomber force.
The United States Air Force operated several versions of the Convair B-36 “Peacemaker” from 1949 to 1959. Unique in design, size, capability, and configuration, the B-36 is still the largest mass-produced piston-engine aircraft ever built. With a wingspan of 230 feet (70.1 meters) the B-36 had the longest wingspan of any combat aircraft ever built. With a range of 10,000 miles (16,000 kilometers) and a maximum payload of 87,200 pounds (39,600 kilograms), the B-36 was capable of intercontinental flight without refueling. The B-36 had an unsurpassed cruising altitude for a piston-driven aircraft, over 40,000 feet (12,000 meters), made possible by its huge wing area and six 28-cylinder engines. The B-36 “featherweight’ configuration resulted in a top speed of 423 miles per hour (681 kilometers per hour) at 50,000 feet (15,000 meters) altitude with the ability to fly at 55,000 feet (17,000 meters) for short periods.
Until the B-52 became operational, the B-36 was the only means of delivering the first generation Mark-17 hydrogen bomb. The Mark-17 was 25 feet (7.6 meters) long, 5 feet (1.5 meters) in diameter, and weighed a whopping 42,000 pounds (19,000 kilograms), making it the heaviest and bulkiest American aerial thermonuclear device ever. Carrying this massive weapon required merging two adjacent bomb bays. The B-36 was the only aircraft designed to carry the T-12 “Cloudmaker,” a gravity bomb weighing 43,600 pounds (19,800 kilograms) and designed to produce an earthquake bomb effect. The B-36’s maximum payload was more than four times that of the World War II-developed B-29, and actually exceeded the payload of the B-52. The B-36’s four bomb bays could carry up to 86,000 pounds (39,000 kilograms) of bombs, more than 10 times the load carried by the Boeing B-17 Flying Fortress, and substantially more than the entire B-17’s gross weight. Only more than ten years after the B-36’s retirement were American aircraft capable of carrying larger payloads than the B-36 when the Boeing 747 and Lockheed C-5 Galaxy went into production
Each B-36 piston engine drove a 19 foot (5.8 meters) three-bladed propeller in a pusher configuration. These were the second-largest diameter propellers ever used to power a piston-engine aircraft. B-36 maintenance was as large an effort as the airplane itself. There were a total of 336 spark plugs in the six engines. At 7 feet (2.1 meters), the wing roots were thick enough for a flight engineer to access the engines and landing gear during flight by crawling through the wings. Similar to the B-29 and B-50, the pressurized flight deck and crew compartment were linked to the rear compartment by a pressurized tunnel through the bomb bay. In the B-36, movement through the tunnel was on a wheeled trolley, pulling on a rope. The rear compartment featured six bunks and a dining galley, aft of which was the tail turret.
The NB-36H was modified to carry a 1 megawatt air-cooled nuclear reactor in the aft bomb bay, with a four-ton lead disc shield installed in the middle of the aircraft between the reactor and the cockpit. The highly modified cockpit was encased in lead and rubber, with a 1 foot thick (30 centimeters) leaded glass windshield to protect the crew from radiation.
The lineage of the B-36 can be traced to early 1941. Concerned that the United States would be forced into the war and not have the ability to base aircraft in Europe, the United States Army Air Corps (USAAC) would need a new class of bomber which could reach Europe and return to bases in North America, necessitating a combat range of at least 5,700 miles (9,200 kilometers), equal to a Gander, Newfoundland to Berlin round-trip flight.
The Army Air Corps realized early in 1943 it needed a bomber capable of reaching Japan from its bases in Hawaii, and the development of the B-36 then resumed in earnest. The USAAF submitted a letter of intent to Convair, ordering an initial production run of 100 B-36s before the completion and testing of the two prototypes. The first delivery was planned for August 1945 and the last delivery in October 1946. Consolidated (by this time renamed Convair after merging with Vultee Aircraft in 1943) delayed the delivery schedule. The B-36 was rolled out on August 20th 1945, and flew for the first time on August 8th 1946.
After the United States Air Force was born in 1947, strategists sought bombers capable of delivering the very large and heavy first-generation atomic bombs. The B-36 was the only American aircraft with the range and payload to carry the bombs from airfields on American soil to targets in the USSR. The modification to allow the use of the larger atomic weapons on the B-36 was called the “Grand Slam Installation.”
Convair referred to the B-36 as the “aluminum overcast”. While General Curtis LeMay headed Strategic Air Command from 1949 to 1957, he turned the B-36 fleet into an effective nuclear weapon delivery force through intense training and development. The B-36 formed the heart of the Strategic Air Command as its so-called “long rifle.”
“Six turnin’, four burnin'”
Beginning with the B-36D, Convair added a total of four General Electric J47-19 jet engines. These were dual-mounted in pods outboard of the piston engines. The existing B-36 fleet was retrofitted to include the jet engines. Thus the classic B-36 slogan of “six turnin’ and four burnin’” was born. The B-36 had more engines than any other mass-produced aircraft. The jet engines were primarily used during takeoff and for added speed over the target.
The RB-36D was developed as a specialized photographic-reconnaissance version of the B-36D. The RB carried a crew of 22 rather than 15, the additional crew members flying along to operate and maintain the photographic reconnaissance equipment that was carried. The bomber’s forward bomb bay was replaced by a pressurized manned compartment carrying the cameras and a small darkroom. The second bomb bay contained photoflash bombs. The third bomb bay could carry an extra 3000 gallons (11,000 liters) of fuel in a droppable tank, which increased mission endurance to 50 hours. The fourth bomb bay carried electronic countermeasures (ECM) equipment.
The RB-36D had an operational ceiling of 50,000 feet (15,000 meters). Later, a lightweight version of this aircraft, the RB-36-III, could reach 58,000 feet (18,000 meters). When the RB-36 was developed, it was the only American aircraft having enough range to fly over the Eurasian land mass from bases in the United States, and size enough to carry the bulky high-resolution cameras in use at the time. More than a third of all B-36 models were reconnaissance models.
RB-36Ds began probing the boundaries of the Soviet Arctic in 1951. RB-36 aircraft operating from RAF Sculthorpe in England flew overflights of most of the Soviet Arctic bases, including the recently completed nuclear weapons test complex at Novaya Zemlya. RB-36s also performed a great number of rarely acknowledged (read SECRET) penetration reconnaissance missions into Chinese and Soviet airspace under the direct direction of Strategic Air Command General Curtis LeMay himself.
Even though no B-36 ever dropped a single bomb on an enemy target, the airplane set the stage for the development of the aircraft and weapons systems that were to come online and eventually replace it during the 50s and 60s.
Once the final B-36 was retired in 1959, Strategic Air Command utilized the Boeing B-47 Stratojet and B-52 Stratofortress. The Convair B-58 Hustler and the Rockwell B-1 Lancer were also Strategic Air Command jets when they came into service in 1960 and 1986 respectively