CONVAIR B-36
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(Redirected from RB-36)
The 'Convair B-36' was a strategic bomber built by Convair for the United States Air Force, the first operational bomber to truly have intercontinental range. Unofficially nicknamed the ' “Peacemaker,â€'[2] the B-36 was the first thermonuclear weapon delivery vehicle. It was the largest piston engined aircraft ever to be mass-produced. The B-36 was also the largest combat aircraft ever built, although there have been larger military transports. With a range of over 6,000 miles and a maximum payload over 72,000 lbs, it set the benchmark for subsequent US long range bombers still in service such as the B-52 Stratofortress and B-1 Lancer.
The genesis of the B-36 can be traced to early 1941, prior to the entry of the US into World War II. At that time it appeared that there was a very real chance that Britain could fall, making a strategic bombing effort by the US against Germany impossible.[3] A new class of bomber would be needed to fill this role, one that offered trans-Atlantic range so that it could bomb targets in Europe from bases inside the continental USA.[4] The United States Army Air Corps opened up a design competition for the ''very long-range bomber'' on 11 April 1941, asking for a 450 mph top speed, a 275 mph cruising speed, a service ceiling of 45,000 feet, and a maximum range of 12,000 miles at 25,000 feet.[5] These proved too demanding for any short-term design, so on August 19, 1941 they were reduced to a maximum range of 10,000 miles, an effective combat radius of 4,000 miles with a 10,000 pound bombload, a cruising speed between 240 and 300 mph, and a service ceiling of 40,000 feet.[4]
After the Cold War began in earnest with the 1948 Berlin airlift and the 1949 atmospheric test of the first Soviet atomic bomb, American military planners sought bombers capable of delivering the very large and heavy first-generation nuclear bombs. The B-36 was the only American aircraft with the range and payload to carry such bombs from airfields on American soil to targets in the USSR (storing nuclear weapons in foreign countries was, and remains, diplomatically sensitive).
The B-36 was arguably obsolete from the outset, being piston-powered in a world of jet interceptors.[7][8] But its jet rival, the B-47 Stratojet, which did not become fully operational until 1953, lacked the range to attack the Soviet homeland from North America and could not carry the huge first-generation hydrogen bomb (and neither could the other American piston bombers of the day, the B-29 Superfortress and its later revision the B-50).[9] Intercontinental ballistic missiles (ICBMs) did not become effective deterrents until the 1960s. Until the B-52 Stratofortress became operational in the late 1950s, the B-36, as the only truly intercontinental bomber, was the mainstay of the Strategic Air Command (SAC).[8]
Convair touted the B-36 as an "aluminum overcast", a "long rifle" to give SAC a global reach.[8] When General Curtis LeMay headed SAC (1949-57) and turned it into an effective nuclear delivery force, the B-36 formed the heart of his command. Its maximum payload was more than four times that of the B-29, even exceeding that of the B-52. The B-36 was slow and could not refuel in the air, but could fly missions to targets 3,400 miles (5,500 km) away and stay aloft as long as 40 hours.[8] Moreover, the B-36 was believed to have an ace up its sleeve: a high cruising altitude, made possible by its huge wing area, that put it out of reach of all piston fighters and early jet interceptors.[8]
Nevertheless, the B-36 was difficult to operate, prone in its early service years to catastrophic engine fires and other costly malfunctions. To its critics, these problems made it a "billion-dollar blunder". In particular, the United States Navy saw it as a costly bungle that diverted funding and interest from their pet project, aircraft carrier–based nuclear bombers. In 1947, the Navy attacked Congressional funding for the B-36, alleging that the aircraft failed to meet Pentagon requirements. The Navy believed that the dominance of the aircraft carrier in the Pacific during World War II proved that carrier-based air strikes would be decisive in future wars. To this end, the Navy designed ''United States'', a "supercarrier" capable of launching huge fleets of aircraft — or nuclear bombers. It then pushed to have funding transferred from the B-36 to the ''United States''. The Air Force successfully defended the B-36 project, and the ''United States'' was officially cancelled by Secretary of Defense Louis A. Johnson. Several high-level Navy officials questioned the government's decision, alleging a conflict of interest because Johnson had once served on Convair's Board of Directors. The uproar following the cancellation of ''United States'' was nicknamed the "Revolt of the Admirals".[14] The furor resulted in the immediately following ''Forrestal'' class of supercarriers, with very similar specifications.
In 1941, the fall of Britain to a German invasion seemed imminent. This would have left the United States Army Air Corps (AAC) with no bases in Europe from which to bomb Germany. American bombers would have had to reach Europe from bases in North America, necessitating a combat range of at least 5700 miles, the length of a Gander, Newfoundland–Berlin round trip. The AAC therefore sought a bomber of truly intercontinental range.[15][16]
On 11 April 1941, the AAC announced a design competition for an aircraft with a 275 mph (445 km/h) cruising speed, a service ceiling of 45,000 ft (14,000 m), capable of delivering 10,000 lb (4,500 kg) of bombs to targets 10,000 miles (16,000 km) away. These requirements far exceeded the technology of the day. The B-36 concept began with a proposal by Consolidated Vultee Aircraft Corporation (later CONVAIR) to meet this requirement; the same design request led to the Northrop YB-35. Though the need to bomb Germany from North American bases never arose, the project was not canceled because the B-36 was seen as playing a possible eventual role in the Pacific war.[15]
The B-36 took shape as an aircraft of immense proportions,[18] two-thirds longer than the previous superbomber, the B-29 Superfortress. The wingspan and tail height of the B-36 exceeded those of the Antonov An-22, the largest ever mass-produced propeller-driven aircraft. Only with the advent of the Boeing 747 and the C-5 Galaxy, both designed two decades later, did aircraft capable of lifting a heavier payload than the B-36 become routine.
The wings of the B-36 were large even when compared with present-day aircraft, exceeding, for example, those of the C-5 Galaxy, and enabled the B-36 to carry enough fuel to fly very long missions without refueling. The wing area permitted cruising altitudes above the operating ceiling of 1940s-era fighters, jet as well as piston. All versions of the B-36 could cruise at over 40,000 feet (12,000 m). B-36 mission logs commonly recorded mock attacks against US cities while flying at 49,000. In 1954, the gun turrets and other nonessential equipment were removed, resulting in a "featherweight" configuration that is believed to have had a top speed of 423 mph (700km/hour) [19], and to have been capable of cruising at 50,000 feet (15,000m), perhaps even higher. [20]
The large wing area and the option of starting the jet engines gave the B-36 a wide margin between Stall speed (VS)] and maximum speed (VNE) at these altitudes. This made the B-36 more maneuverable at high altitude than the USAF jet interceptors of the day, which either could not fly above 40,000 feet, or if they did, were likely to stall out when trying to maneuver or fire their guns (see Jacobson and Meyer, "The Big Stick"). However, the US Navy argued that their F2H Banshee fighter could intercept the B-36, thanks to its ability to operate at more than 50,000 feet.[1] The Air Force declined the Navy's invitation to a fly-off between the Banshee and the B-36. Later, the Secretary of Defense, Louis A. Johnson [2], who considered the US Navy obsolete and favored the US Air Force, forbade putting the Navy's claim to the test.
The propulsion system alone made the B-36 a very unusual aircraft. All B-36s featured six Pratt & Whitney R-4360 Wasp Major radial piston engines, each with 28 cylinders displacing 4,360 in³ (71.4 L). Even though the prototype R-4360 engines delivered a total of 18,000 hp (13.4 MW), early B-36s were slow and required long takeoff runs. The situation improved with later versions of the R-4360, delivering 3,800 hp (2.8 MW) apiece for a total 22,800 hp.[21] Each engine drove an immense three-bladed propeller, 19 ft (5.8 m) in diameter, mounted in the pusher configuration. Although rarely employed, this configuration prevents propeller turbulence from interfering with airflow over the wing.
Beginning with the B-36D, Convair suspended a pair of General Electric J47-19 jet engines from each wing; these engines were also retrofitted to all extant B-36Bs. The jet pods greatly improved takeoff performance and dash speed over the target. In normal cruising flight, the jet engines were shut down to conserve fuel.
Thus the B-36 came to have ten engines, more than any other mass-produced aircraft. If all engines functioned normally at full power during the pre-takeoff warm up, the lead flight engineer would say to the captain "six [engines] turning and four [engines] burning". Erratic reliability led to the wisecrack "two turning, two burning, two joking and two smoking," with two engines not accounted for.[23]
The B-36 required a standard crew of 15. As in the B-29, 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, one rode through the tunnel on a wheeled trolley, by pulling oneself on a rope. The rear compartment led to the rear gun turret, and featured six bunks and a galley.
The XB-36 featured single-wheel landing gear whose tires were the largest ever manufactured up to that time, 9 ft, 2 in (2.7 m) tall, 3 ft (1 m) thick, and weighing 1,320 lb (600 kg), with enough rubber for 60 automobile tires.[24] These tires placed so much weight per unit area on runways that the XB-36 was restricted to the Fort Worth airfield next to where it was manufactured, and to a mere two USAF bases. At the suggestion of General 'Hap' Arnold the single-wheel landing gear was soon replaced by a more conventional four-wheel bogie.An image of the four-wheel landing gear may be found here. At one point a tanklike tracked landing gear[25] was also tried on the XB-36, but proved heavy and noisy and was quickly abandoned.
The four bomb bays could carry up to 86,000 pounds of bombs, more than ten times the load carried by the WWII workhorse, the B-17 Flying Fortress - roughly equal to the B17s all-up weight. The B-36 was not designed with nuclear weaponry in mind, because the mere existence of such weapons was top secret during most of the period when the B-36 was engineered (1941-46), and their mode of delivery had yet to be determined. Nevertheless, the B-36 stepped into a nuclear delivery role immediately upon becoming operational. In all respects but speed, the B-36 could match what was arguably its Soviet counterpart, the Tu-95 (still in service).[26] Until the B-52 came on line, the B-36 was the only means of delivering the first generation Mark-17 hydrogen bomb,[27] 25 feet (7.5 m) long, 5 ft (1.5 m) in diameter, and weighing 42,000 lb (19,000 kg), the heaviest and bulkiest American nuclear weapon ever. Carrying this massive weapon required merging two adjacent bomb bays.
The defensive armament consisted of six remote-controlled retractable gun turrets, and fixed tail and nose turrets. Each turret was fitted with two 20 mm cannon, for a total of 16 cannons, the greatest defensive firepower ever carried by a bomber. Recoil from gunnery practice could cause the on-board electronics to malfunction, solid state then being unknown. This contributed to the crash of B-36B 44-92035 on 22 November 1950.[28]
The Convair B-36 was the only plane designed to carry the T12 Cloud Maker, a gravity bomb weighing 43,600 lb and designed to produce an Earth quake bomb effect. The T12 still remains the heaviest conventional bomb to have been employed by the United States.
The first prototype XB-36 flew on 8 August 1946. The speed and range of the prototype failed to meet the standards set out by the Army Air Corps in 1941. As is often the case with aircraft pushing the size envelope, the XB-36 experienced a number of problems. (For instance, the B-29 Superfortress was plagued by engine problems, and available engines were too weak to afford the Boeing XB-15 a useful top speed.) Many problems with the XB-36 stemmed from its "placeholder" engines, weaker engines used until the intended powerplant became available.
A second aircraft, the YB-36, flew on 4 December 1947. It featured a redesigned high-visibility "bubble" canopy, which was later adopted for production. Altogether, the YB-36 was much closer to the production aircraft. Additionally, the engines used on the YB-36 were a good deal more powerful and more efficient. The YB-36 was actually beaten to the air by the first production model: a single B-36A was built with enough equipment to fly to Wright Field, where its airframe was subjected to a battery of physical tests.
The first of 21 B-36As were delivered in 1948. They were admitted interim airframes, intended for crew training and later conversion. No defensive armament was fitted as none was ready. Once later models were available, all B-36As were converted to RB-36E reconnaissance models. The first B-36 variant meant for normal operation was the B-36B, delivered beginning in November 1948. This aircraft met all the 1941 requirements, but had serious problems with engine reliability, and with the availability of armaments and spare parts. Later models featured more powerful variants of the R-4360 engine, improved radar, and redesigned crew compartments.[29]
The four jet engines raised fuel consumption, thus reducing range. Meanwhile, new air-to-air missiles made hand-aimed guns mounted in heavy turrets obsolete; they were also unreliable. In February of 1954, the USAF awarded Convair a contract to reduce the weight of the entire B-36 fleet by implementing a new "Featherweight" design in three configurations:
★ I removed the 6 movable gun turrets and other defensive hardware.
★ II removed the rear compartment crew comfort features, and all hardware accommodating the XF-85 parasite fighter.
★ III incorporated both I and II.
The six turrets eliminated by I reduced the crew from 15 to nine. III enabled a longer range and an operating ceiling of at least 47,000 feet (14,000 m), features especially valuable for reconnaissance missions. The B-36J-III configuration (the last 14 made) featured a single radar-aimed tail turret, extra fuel tanks in the outer wings, and landing gear allowing the maximum gross weight to rise to 410,000 pounds (190,000 kg). Production of the B-36 ceased in 1954.
More than a third of all B-36 models were reconnaissance models, designated RB-36. Before the development of the Lockheed U-2, the RB-36 was the mainstay of American photo reconnaissance over hostile territory. It was the only American aircraft having range enough to fly into Asia from bases in the USA, and size enough to carry the bulky high-resolution cameras of the day. The RB-36 performed a number of rarely acknowledged reconnaissance missions and is suspected of having carried out numerous penetrations of Chinese (and possibly Soviet) airspace.
The RB-36 was well-suited for such reconnaissance missions. Its high cruising altitude made it difficult to intercept, and its fuel capacity enabled missions up to 50 hours long. The RB-36 featured a pressurized camera compartment staffed by a crew of seven, in place of a forward bomb bay. The aft bomb bay contained tanks for extra fuel. The RB-36 cameras could produce very high resolution photographs: pictures of a golf course taken from 40,000 ft (12,000 m) show recognizable golf balls. RB-36s were distinguished by the bright aluminum of the camera compartment (contrasting with the dull magnesium of the rest of the fuselage) and by a series of radar domes under the aft fuselage, varying in number and placement.
The B-36, including its RGB-36, RB-36, and XC-99 variants, was in service as part of the USAF Strategic Air Command from 1948 through 1958.
Unlike the B-52, which has seen action in the Vietnam War and the two Gulf Wars, no B-36 ever dropped a bomb or fired a shot at an enemy. The closest the B-36 came to seeing action was during the 1956 Hungarian Revolution and the Suez Crisis, when nuclear-armed B-36s were dispatched to Turkey and Morocco.
Though the B-36 had a better than average overall safety record, ten crashed between 1949 and 1954 (three 36Bs, three 36Ds, and four 36Hs). Goleta Air and Space Museum maintains a web site with photographs and lengthy excerpts from the official crash reports.[30]
A B-36 was also involved in two "Broken Arrow" incidents. On 13 February 1950, a B-36, serial number 44-92075, crashed in an unpopulated region of British Columbia reputedly after ditching its bomb over the ocean (recovery teams also searched the crash site for its remains and accompanying "bird-cage"), resulting in the first loss of an American nuclear weapon.[31] On 22 May 1957, a B-36 accidentally dropped a Mark-17 hydrogen bomb on a deserted area while landing at Kirtland AFB in Albuquerque NM. Only the conventional trigger detonated, the bomb being unarmed. These incidents were classified for decades. See list of military nuclear accidents.[32][33]
The B-36 needed a great deal of maintenance between flights; although in an emergency an aircraft could be "turned" in a few hours for a ferry flight, it took much longer to get the airplane ready for an operational mission.[34] In January 1951, a B-36 amassed 200 hours of flight time (8.3 standard 24-hour missions), an apparent record.
The B-36 was too large to fit in most hangars. Moreover, even an aircraft with the range of the B-36 needed to be stationed as close to the enemy as possible, and this meant the northern USA, Alaska, and the Arctic. As a result, most "normal" maintenance, such as changing the 56 spark plugs (always at risk of fouling by the leaded fuel of the day) on each of its six engines, or replacing the dozens of bomb bay light bulbs shattered after a gunnery mission, was performed out of doors, in 100-degree summers and 60-below winters. Special shelters were built so that the maintenance crews could enjoy a modicum of protection while working on the engines. Often, ground crews risked slipping and falling from ice-covered wings, or being blown off by a propeller running in reverse pitch. Some procedures even required a mechanic to sit astride a running engine, a 19-foot diameter propeller at his feet, his hand near the 34-inch diameter cooling fan.
The wing roots were thick enough, 7 ft (2.1 m), to enable a flight engineer to access the engines and landing gear by crawling through the wings. This was possible only at altitudes not requiring pressurization.
The Wasp Major engines also had a prodigious appetite for lubricating oil, each engine requiring a 100 gallon (380 L) tank. A former ground crewman has written: "[I don't recall] an oil change interval as I think the oil consumption factor handled that." It was not unusual for a mission to end because one or more engines ran out of oil. Though the B-36 could continue flying with as many as three inoperative engines, the extra stress on the remaining engines put them at risk of failing.
Like all large aircraft powered by piston engines, the B-36 was prone to engine fires, a problem exacerbated by the pusher configuration. When a crash occurred for any reason, the magnesium-rich airframe burned readily.
When thinking about these engine fires, keep in mind that:
★ The ambient temperatures typical of the B-36's cruising altitude and of the high latitude bases where it was often stationed, were usually far below freezing.
★ Radial aircraft engines like the R-4360 are air-cooled. Hence the large volume of air flowing past the cylinders during flight underwent substantial warming.
The design of the R-4360 engine tacitly assumed that it would be mounted in the conventional tractor configuration - propeller/air intake/28 cylinders/carburetor - with air flowing from left to right. In this configuration, the carburetor is bathed in air warmed by engine cooling and so is unlikely to ice up. However, the B-36 employed the R-4360 engine in the pusher configuration - air intake/carburetor/28 cylinders/propeller. Because the carburetor is now in front of the engine, it cannot benefit from engine heat. Hence when intake air was cold and humid, ice gradually obstructed the carburetor air intake, which in turn gradually increased the richness of the air/fuel mixture until the unburned fuel in the exhaust caught fire. Engine fires of this nature led to the first loss of an American nuclear weapon, described above. The later addition of electric heating to the carburetor intakes eliminated the problem.
Training missions were typically in two parts; first, a 40 hour flight - followed by some time on the ground for refueling and a bit of maintenance - then a 24 hour second flight. When thinking about missions of such great duration, two facts should be kept in mind:
★ Given a sufficiently light load, the B-36 could fly at least 10,000 miles (16,000 km) nonstop
★ The highest cruising speed of any version, the B-36J-III, was only 230 mph (380 km/h). Turning the jet engines on could raise the cruising speed to over 400 mph (650 km/h), but the resulting higher fuel consumption reduced the range.
Hence, a 40 hour mission, with the jets used only for takeoff and climbing, flew about 9200 miles (15000 km). Many missions were flown "around the flag pole", meaning they began and ended at the same base.
The B-36 was not a particularly enjoyable aircraft to fly. Its overall performance, in terms of speed and manuverablity, was never considered sprightly. Lieutenant General James Edmundson likened it to "...sitting on your front porch and flying your house around."[35] And despite its immense exterior size, the pressurized crew compartments were relatively cramped, especially when occupied for 24 hours by a crew of fifteen in full flight kit. Although the rear compartment included six bunks, and the radio compartment behind the flight deck included a couple of bunks, crewmen usually chose to sleep in their seats.
War missions would have been essentially one-way; taking off from forward bases in Alaska or Greenland, overflying the USSR, and landing in Europe or the Middle East. Ironically, recollections of crew veterans reveal that while crews were confident of their ability to complete a mission if called upon to do so, they were less confident of surviving the weapon delivery itself.[36] Their concerns were a function of the relatively low speed of the aircraft coupled with the extreme destructive power of the bombs they were carrying, resulting in the plane still being in harms way once the bombs were released and detonated on target. These concerns were borne out by the 1954 Operation Castle tests, in which B-36s flew near detonations in the 15 megaton range, at distances believed typical of wartime delivery, and experiencing serious heat and blast damage.
The B-36 was employed in a variety of aeronautical experiments throughout its service life. Its immense size, range and payload capacity lent itself to use in research and development programs. These included nuclear propulsion studies, and "parasite" programs in which the B-36 carried smaller interceptors or reconnaissance aircraft.[37]
In May 1946, the Air Force began the Nuclear Energy for the Propulsion of Aircraft (NEPA) project which was followed in May 1951 by the Aircraft Nuclear Propulsion (ANP) program. The ANP program required that Convair modify two B-36s under the MX-1589 project. One of the modified B-36s studied shielding requirements for an airborne reactor to determine whether a nuclear aircraft was feasible. The Nuclear Test Aircraft (NTA) was a B-36H-20-CF (Serial Number 51-5712) that had been damaged in a tornado at Carswell AFB on 1 September 1952. This plane, designated the NB-36H, was modified to carry a 1 MW, air-cooled nuclear reactor in the aft bomb bay, with a four ton lead shield between the reactor and the cockpit. The cockpit was encased in lead and rubber, with a 6-inch (15 cm)–thick acrylic glass windshield. The reactor was operational but did not power the plane; its sole purpose was to investigate the effect of radiation on aircraft systems. Between 1955 and 1957, the NB-36H completed 47 test flights and 215 hours of flight time, during 89 of which the reactor was critical. The NB-36H was scrapped at Fort Worth in 1958 when the nuclear aircraft program was abandoned.
Other experiments involved providing the B-36 with its own fighter defense in the form of parasite aircraft carried partially or wholly in a bomb bay. One parasite aircraft was the tiny McDonnell XF-85 Goblin, which docked using a trapeze system. The concept was tested successfully using a B-29 carrier, but docking proved difficult even for experienced test pilots. Moreover, the XF-85 was seen as no match for Soviet aircraft, and the project was cancelled.
More successful was the FICON project, involving a modified B-36 - called a GRB-36D "mothership" - and the RF-84K, a fighter modified for reconnaissance, in a bomb bay. The GRB-36D would ferry the RF-84K to the vicinity of the objective, whereupon the RF-84K would disconnect and begin its mission. Ten GRB-36Ds and 25 RF-84ks were built and saw active service until 1959.
Projects TIP TOW and Tom-Tom involved docking F-84s to the wingtips of B-29s and B-36s. The hope was that the increased aspect ratio of the combined aircraft would result in a greater range. Project TIP TOW was canceled when the combination of two EF-84Ds and a specially modified test EB-29A crashed, killing everyone on all three aircraft. This accident was attributed to one of the EF-84Ds flipping over onto the wing of the EB-29A. Project Tom-Tom, involving RF-84Fs and a GRB-36D from the FICON project (redesignated JRB-36F), continued for a few months after this crash, but was also canceled due to the violent turbulence induced by the wingtip vortices of the B-36.[38]
The operational life of the B-36 ended because:
★ Long range jet-powered bombers became feasible, with cruising speeds more than double that of the B-36.
★ The speed and operating ceiling of jet interceptors steadily rose.
★ Radar-guided surface-to air missiles capable of reaching 20,000 meters emerged.
★ The airframe, especially the wings, proved vulnerable to metal fatigue.
★ Wing flexing led to fuel leakage, a common problem.
The B-36 was gradually decommissioned as the B-52 entered service.
Only four (and a half) B-36 type aircraft survive today, from the 384 produced.[39]
★ YB-36/RB-36E serial number 42-13571. This was the first prototype to be converted to the bubble canopy used on production B-36s. It was on display in the 1950s at the former Air Force Museum on Wright-Patterson Air Force Base near Dayton, Ohio. When the Museum was moved to a different location on the base the cost of moving the bomber was more than simply flying a different B-36 to the new location and the aircraft was slated to be scrapped. Instead, Walter Soplata bought it and transported the pieces by truck to his farm in Newbury, Ohio, where it sits today in several large pieces.[40] The center fuselage currently stores a complete P-47N still contained in its original shipping crate.
★ RB-36H serial number 51-13730, is on display at the Castle Air Museum in Atwater, California.
★ B-36J serial number 52-2217, is on display at the Strategic Air and Space Museum (formerly located at Offutt Air Force Base) and now near Ashland, Nebraska.
★ B-36J serial number 52-2220, is on display at the National Museum of the United States Air Force (formerly The U.S. Air Force Museum) at Wright-Patterson Air Force Base near Dayton, Ohio. Its flight to the museum from Davis-Monthan Air Force Base in Arizona on 30 April 1959 was the last flight of a B-36. This B-36J replaced the former Air Force Museum's original YB-36 serial number 42-13571 (see above). This was also the first aircraft to be placed in the Museum's new display hangar, and was not moved again until relocated to the Museum's latest addition in 2003. It is displayed alongside the only surviving example of the massive 9 ft. XB-36 wheel and tire.
★ B-36J, serial number 52-2827, the final B-36 built, named "The City of Fort Worth," was scrapped on 12 February 1959 and is now undergoing restoration and reassembly at the Pima Air & Space Museum in Tucson, Arizona.
★ XC-99, serial number 43-52436, the sole example of the cargo version of the B-36, was stored for years at Kelly/Lackland AFB in Texas, and is now undergoing restoration and reassembly at the National Museum of the United States Air Force in Dayton, Ohio.
Main articles: Convair B-36 variants
In 1951, the USAF asked Convair to build a prototype all-jet variant of the B-36. Convair complied by adding swept wings and eight Pratt & Whitney XJ57-P-3 jet engines to a B-36F. The result was the B-36G, later renamed the Convair YB-60. The result was found inferior when compared to Boeing's YB-52, and the project was terminated.[41]
The B-36 was also the basis for the Convair XC-99, a double-decked military cargo aircraft, and the largest piston engined, land-based aircraft ever built, and the longest practical aircraft (185 ft, 56 m) of its era. Only one example was ever built, and it was extensively employed for nearly a decade, especially for cross-country cargo flights during the Korean War. In 2005, the XC-99 was dismantled with plans to move it from the former Kelly Air Force Base in San Antonio, Texas, where it has been retired since 1957, to the National Museum of the United States Air Force at Wright-Patterson Air Force Base near Dayton, Ohio. It is currently being transported in pieces aboard C-5 Galaxy transports as space and schedule permits.[42]
A commercial airliner derived from the XC-99, the Convair Model 37, never left the drawing board. It would have been the first "jumbo" airliner.[43]
In 1949, the B-36 was featured in the documentary film, ''Target: Peace'', which was centered around the operations of the 7th Bombardment Wing. Other scenes included B-36 production at the Fort Worth plant.
The B-36 appeared in only one feature-length motion picture, ''Strategic Air Command'' (1955), starring Jimmy Stewart and June Allyson. In the film Jimmy Stewart's character is forced to crash land his B-36 in the Arctic. ''Strategic Air Command'' features many good aerial shots of B-36s and B-47s. The John Wayne 1957 film Jet Pilot also shows a F-94 Starfire intercepting a B-36 on a test mission.
In ''Top of the World'' (1955) a formation of early B-36s (without the four jet engines) is shown just before the end title [44].
Video of B-36 takeoff
1. Knaack, Marcelle Size. ''Post-World War II Bombers, 1945-1973''. Washington, DC: Office of Air Force History, 1988. ISBN 0-16-002260-6.
2. The name "Peacemaker," was forwarded to the USAF by Convair following a contest to name the bomber, and although not officially adopted, became the most common name used. It is often listed in sources as the "official" name.
Reference: Peacemaker Name Certificate
3. National Museum of the USAF website discussing what brought about the design of such a long ranged bomber.
4. Taylor 1969, p. 465.
5. Winchester 2006, p. 49.
6. Taylor 1969, p. 465.
7. Wagner 1968, p. 142. Quote: "A British engineer attacking 'piston-engined giantism,' wrote that British jets could reach B-36 height in less than eight minutes, were far faster at high altitudes and would find the B-36 'practically a sitting duck.'"
8. National Museum of the USAF webiste discussing what brought about the design of such a long ranged bomber.
9. Yenne 2004, p. 124-126.
10. National Museum of the USAF webiste discussing what brought about the design of such a long ranged bomber.
11. National Museum of the USAF webiste discussing what brought about the design of such a long ranged bomber.
12. National Museum of the USAF webiste discussing what brought about the design of such a long ranged bomber.
13. National Museum of the USAF webiste discussing what brought about the design of such a long ranged bomber.
14. Barlow, Jeffrey G. ''Revolt of the Admirals: The Fight for Naval Aviation, 1945–1950''. Washington, DC: Naval Historical Center, 1994. ISBN 0-16-042094-6.
15. Johnson 1978, p. 1.
16. Jacobsen and Wagner 1980, p. 4.
17. Johnson 1978, p. 1.
18. see http://www.air-and-space.com/peacemkr.htm for a table comparing the large aircraft designed in the 1940s
19. Jacobsen 1974, p. 54.
20. Yenne 2004, p. 136-137.
21. Yenne 2004, p. 137-138.
22. From the Maxwell Air Force Base website (original image).
23. [3] Quote attributed to Captain Banda when he toured an air cadet Michael R. Daciek, later Lt. Col. Daciek, on an inside tour of the XC-99 in 1953.
24. ''Convair XB-36 Peacemaker''. National Museum of the United States Air Force. [4] Access date: 4 September 2006.
25. ''Convair XB-36 Landing Gear''. National Museum of the United States Air Force. [5] Access date: 4 September 2006.
26. http://news.bbc.co.uk/2/hi/europe/6938856.stm
27. http://www.globalsecurity.org/wmd/systems/mk17.htm
28. Summary of Air Force accident report: http://www.air-and-space.com/b-36%20wrecks.htm#44-92035
29. See http://www.wpafb.af.mil/museum//research/bombers/bomber3.htm for more detail on the features and performance of each of 16 variants of the B-36
30. http://www.air-and-space.com/b-36%20wrecks.htm
31. Ricketts, Bruce. ''Broken Arrow, A Lost Nuclear Weapon in Canada''. Mysteries of Canada, 11 January 2006. Broken Arrow Access date: 17 August 2007
32. Doomsday
33. B-36 Wrecks
34. ''B-36 maintenance discussion''. Delphi Forums. [6]
35. http://www.pbs.org/wgbh/amex/bomb/filmmore/reference/interview/edmund10.html
36. http://forums.delphiforums.com/n/main.asp?webtag=B36forum
37. Miller and Cripliver 1978, p. 366, 369.
38. Lockett, Brian. ''Parasite Fighter Programs: Project Tom-Tom''.Goleta Air and Space Museum. [7] Access date: 3 February 2007.
39. Yenne 2004, p. 149.
40. http://www.aircraftresourcecenter.com/Fea1/101-200/Fea182_Walters-Farm_Williams/part1/Fea182.htm
41. [8] National Museum of the USAF factsheet about the YB-60
42. Air Force Linl XC-99 begins piece-by-piece trip to Air Force Museum by 1st Lt. Bruce R. Hill Jr.433rd Airlift Wing Public Affairs, 04/22/2004
43. National Museum of the USAF webiste discussing what brought about the design of such a long ranged bomber as well as it's variants.
44. Top of the World
----
★ Ford, Daniel. "B-36: Bomber at the Crossroads". ''Air and Space/Smithsonian''. April 1996. [9] Access date: 3 February 2007.
★ Jacobsen, Meyers K. ''Convair B-36: A Comprehensive History of America's "Big Stick"''. Atglen, Pennsylvania: Schiffer Military History, 1997. ISBN 0-7643-0974-9.
★ ___________. "Peacemaker." ''Airpower, Vol. 4, No. 6''. November 1974.
★ ___________. ''Convair B-36: A Photo Chronicle''. Atglen, Pennsylvania: Schiffer Military History, 1999. ISBN 0-7643-0974-9.
★ Jacobsen, Meyers K and Wagner, Ray. ''B-36 in Action (Aircraft in Action Number 42)''. Carrollton, TX: Squadron/Signal Publications Inc., 1980. ISBN 0-89747-101-6.
★ Jenkins, Dennis R. ''Convair B-36 Peacemaker''. St. Paul, Minnesota: Specialty Press Publishers and Wholsalers, 1999. ISBN 1-58007-019-1.
★ ___________. ''Magnesium Overcast''. St. Paul, Minnesota: Voyageur Press, 2001. ISBN 1-58007-042-6.
★ ___________. ''B-36 Photo Scrapbook''. St. Paul, Minnesota: Specialty Press Publishers and Wholesalers, 2003. ISBN 1-58007-075-2.
★ Johnsen, Frederick A. ''Thundering Peacemaker, the B-36 Story in Words and Pictures''. Tacoma, WA: Bomber Books, 1978.
★ Miller, Jay and Cripliver, Roger. "B-36: The Ponderous Peacemaker." ''Aviation Quarterly, Vol. 4, No. 4, 1978''.
★ Morris, Lt. Col. (ret.) and Allan, Ted. ''Flying the Aluminum and Magnesium Overcast''. The collected articles and photographs of Ted A. Morris, ©2000. [10] Access date: 4 September 2006.
★ Orman, Edward W. "One Thousand on Top: A Gunner's View of Flight from the Scanning Blister of a B-36." ''Airpower, Vol. 17, No. 2''. March 1987.
★ Pyeatt, Don. ''B-36: Saving the Last Peacemaker (Third Edition)''. Fort Worth, Texas: ProWeb Publishing, 2006. ISBN 0-9677593-2-3.
★ Taylor, John W.R. "Convair B-36." ''Combat Aircraft of the World from 1909 to the present''. New York: G.P. Putnam's Sons, 1969. ISBN 0-425-03633-2.
★ Wagner, Ray. ''American Combat Planes''. New York: Doubleday & Company, Inc., 1968. ISBN 0-385-04134-9.
★ Winchester, Jim. ''Military Aircraft of the Cold War (The Aviation Factfile)''. Rochester, Kent, UK: The Grange plc., 2006. ISBN 1-84013-929-7.
★ Yenne, Bill. "Convair B-36 Peacemaker." ''International Air Power Review, Vol. 13, Summer 2004''. London: AirTime Publishing Inc., 2004. ISBN 1-880588-84-6.
★ Cowtown.net: Portal to B-36 resources
★ Encyclopedia of American Aircraft
★ [http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=2584 XB-36 page}, and B-36A page on USAF National Museum web site
★ Aerospaceweb, with technical info and many pictures
★ "''Lt. Gen. James Edmundson interview transcript: Flying B-36 and B-47 planes.''". Race For the Superbomb. PBS Online.
★ B-36 operations Walker AFB Roswell New Mexico 1955-1957
The 'Convair B-36' was a strategic bomber built by Convair for the United States Air Force, the first operational bomber to truly have intercontinental range. Unofficially nicknamed the ' “Peacemaker,â€'[2] the B-36 was the first thermonuclear weapon delivery vehicle. It was the largest piston engined aircraft ever to be mass-produced. The B-36 was also the largest combat aircraft ever built, although there have been larger military transports. With a range of over 6,000 miles and a maximum payload over 72,000 lbs, it set the benchmark for subsequent US long range bombers still in service such as the B-52 Stratofortress and B-1 Lancer.
History
The genesis of the B-36 can be traced to early 1941, prior to the entry of the US into World War II. At that time it appeared that there was a very real chance that Britain could fall, making a strategic bombing effort by the US against Germany impossible.[3] A new class of bomber would be needed to fill this role, one that offered trans-Atlantic range so that it could bomb targets in Europe from bases inside the continental USA.[4] The United States Army Air Corps opened up a design competition for the ''very long-range bomber'' on 11 April 1941, asking for a 450 mph top speed, a 275 mph cruising speed, a service ceiling of 45,000 feet, and a maximum range of 12,000 miles at 25,000 feet.[5] These proved too demanding for any short-term design, so on August 19, 1941 they were reduced to a maximum range of 10,000 miles, an effective combat radius of 4,000 miles with a 10,000 pound bombload, a cruising speed between 240 and 300 mph, and a service ceiling of 40,000 feet.[4]
After the Cold War began in earnest with the 1948 Berlin airlift and the 1949 atmospheric test of the first Soviet atomic bomb, American military planners sought bombers capable of delivering the very large and heavy first-generation nuclear bombs. The B-36 was the only American aircraft with the range and payload to carry such bombs from airfields on American soil to targets in the USSR (storing nuclear weapons in foreign countries was, and remains, diplomatically sensitive).
The B-36 was arguably obsolete from the outset, being piston-powered in a world of jet interceptors.[7][8] But its jet rival, the B-47 Stratojet, which did not become fully operational until 1953, lacked the range to attack the Soviet homeland from North America and could not carry the huge first-generation hydrogen bomb (and neither could the other American piston bombers of the day, the B-29 Superfortress and its later revision the B-50).[9] Intercontinental ballistic missiles (ICBMs) did not become effective deterrents until the 1960s. Until the B-52 Stratofortress became operational in the late 1950s, the B-36, as the only truly intercontinental bomber, was the mainstay of the Strategic Air Command (SAC).[8]
Convair touted the B-36 as an "aluminum overcast", a "long rifle" to give SAC a global reach.[8] When General Curtis LeMay headed SAC (1949-57) and turned it into an effective nuclear delivery force, the B-36 formed the heart of his command. Its maximum payload was more than four times that of the B-29, even exceeding that of the B-52. The B-36 was slow and could not refuel in the air, but could fly missions to targets 3,400 miles (5,500 km) away and stay aloft as long as 40 hours.[8] Moreover, the B-36 was believed to have an ace up its sleeve: a high cruising altitude, made possible by its huge wing area, that put it out of reach of all piston fighters and early jet interceptors.[8]
Nevertheless, the B-36 was difficult to operate, prone in its early service years to catastrophic engine fires and other costly malfunctions. To its critics, these problems made it a "billion-dollar blunder". In particular, the United States Navy saw it as a costly bungle that diverted funding and interest from their pet project, aircraft carrier–based nuclear bombers. In 1947, the Navy attacked Congressional funding for the B-36, alleging that the aircraft failed to meet Pentagon requirements. The Navy believed that the dominance of the aircraft carrier in the Pacific during World War II proved that carrier-based air strikes would be decisive in future wars. To this end, the Navy designed ''United States'', a "supercarrier" capable of launching huge fleets of aircraft — or nuclear bombers. It then pushed to have funding transferred from the B-36 to the ''United States''. The Air Force successfully defended the B-36 project, and the ''United States'' was officially cancelled by Secretary of Defense Louis A. Johnson. Several high-level Navy officials questioned the government's decision, alleging a conflict of interest because Johnson had once served on Convair's Board of Directors. The uproar following the cancellation of ''United States'' was nicknamed the "Revolt of the Admirals".[14] The furor resulted in the immediately following ''Forrestal'' class of supercarriers, with very similar specifications.
Design and development
In 1941, the fall of Britain to a German invasion seemed imminent. This would have left the United States Army Air Corps (AAC) with no bases in Europe from which to bomb Germany. American bombers would have had to reach Europe from bases in North America, necessitating a combat range of at least 5700 miles, the length of a Gander, Newfoundland–Berlin round trip. The AAC therefore sought a bomber of truly intercontinental range.[15][16]
On 11 April 1941, the AAC announced a design competition for an aircraft with a 275 mph (445 km/h) cruising speed, a service ceiling of 45,000 ft (14,000 m), capable of delivering 10,000 lb (4,500 kg) of bombs to targets 10,000 miles (16,000 km) away. These requirements far exceeded the technology of the day. The B-36 concept began with a proposal by Consolidated Vultee Aircraft Corporation (later CONVAIR) to meet this requirement; the same design request led to the Northrop YB-35. Though the need to bomb Germany from North American bases never arose, the project was not canceled because the B-36 was seen as playing a possible eventual role in the Pacific war.[15]
The B-36 took shape as an aircraft of immense proportions,[18] two-thirds longer than the previous superbomber, the B-29 Superfortress. The wingspan and tail height of the B-36 exceeded those of the Antonov An-22, the largest ever mass-produced propeller-driven aircraft. Only with the advent of the Boeing 747 and the C-5 Galaxy, both designed two decades later, did aircraft capable of lifting a heavier payload than the B-36 become routine.
The wings of the B-36 were large even when compared with present-day aircraft, exceeding, for example, those of the C-5 Galaxy, and enabled the B-36 to carry enough fuel to fly very long missions without refueling. The wing area permitted cruising altitudes above the operating ceiling of 1940s-era fighters, jet as well as piston. All versions of the B-36 could cruise at over 40,000 feet (12,000 m). B-36 mission logs commonly recorded mock attacks against US cities while flying at 49,000. In 1954, the gun turrets and other nonessential equipment were removed, resulting in a "featherweight" configuration that is believed to have had a top speed of 423 mph (700km/hour) [19], and to have been capable of cruising at 50,000 feet (15,000m), perhaps even higher. [20]
The large wing area and the option of starting the jet engines gave the B-36 a wide margin between Stall speed (VS)] and maximum speed (VNE) at these altitudes. This made the B-36 more maneuverable at high altitude than the USAF jet interceptors of the day, which either could not fly above 40,000 feet, or if they did, were likely to stall out when trying to maneuver or fire their guns (see Jacobson and Meyer, "The Big Stick"). However, the US Navy argued that their F2H Banshee fighter could intercept the B-36, thanks to its ability to operate at more than 50,000 feet.[1] The Air Force declined the Navy's invitation to a fly-off between the Banshee and the B-36. Later, the Secretary of Defense, Louis A. Johnson [2], who considered the US Navy obsolete and favored the US Air Force, forbade putting the Navy's claim to the test.
The propulsion system alone made the B-36 a very unusual aircraft. All B-36s featured six Pratt & Whitney R-4360 Wasp Major radial piston engines, each with 28 cylinders displacing 4,360 in³ (71.4 L). Even though the prototype R-4360 engines delivered a total of 18,000 hp (13.4 MW), early B-36s were slow and required long takeoff runs. The situation improved with later versions of the R-4360, delivering 3,800 hp (2.8 MW) apiece for a total 22,800 hp.[21] Each engine drove an immense three-bladed propeller, 19 ft (5.8 m) in diameter, mounted in the pusher configuration. Although rarely employed, this configuration prevents propeller turbulence from interfering with airflow over the wing.
Beginning with the B-36D, Convair suspended a pair of General Electric J47-19 jet engines from each wing; these engines were also retrofitted to all extant B-36Bs. The jet pods greatly improved takeoff performance and dash speed over the target. In normal cruising flight, the jet engines were shut down to conserve fuel.
Thus the B-36 came to have ten engines, more than any other mass-produced aircraft. If all engines functioned normally at full power during the pre-takeoff warm up, the lead flight engineer would say to the captain "six [engines] turning and four [engines] burning". Erratic reliability led to the wisecrack "two turning, two burning, two joking and two smoking," with two engines not accounted for.[23]
The B-36 required a standard crew of 15. As in the B-29, 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, one rode through the tunnel on a wheeled trolley, by pulling oneself on a rope. The rear compartment led to the rear gun turret, and featured six bunks and a galley.
The XB-36 featured single-wheel landing gear whose tires were the largest ever manufactured up to that time, 9 ft, 2 in (2.7 m) tall, 3 ft (1 m) thick, and weighing 1,320 lb (600 kg), with enough rubber for 60 automobile tires.[24] These tires placed so much weight per unit area on runways that the XB-36 was restricted to the Fort Worth airfield next to where it was manufactured, and to a mere two USAF bases. At the suggestion of General 'Hap' Arnold the single-wheel landing gear was soon replaced by a more conventional four-wheel bogie.An image of the four-wheel landing gear may be found here. At one point a tanklike tracked landing gear[25] was also tried on the XB-36, but proved heavy and noisy and was quickly abandoned.
Weaponry
The four bomb bays could carry up to 86,000 pounds of bombs, more than ten times the load carried by the WWII workhorse, the B-17 Flying Fortress - roughly equal to the B17s all-up weight. The B-36 was not designed with nuclear weaponry in mind, because the mere existence of such weapons was top secret during most of the period when the B-36 was engineered (1941-46), and their mode of delivery had yet to be determined. Nevertheless, the B-36 stepped into a nuclear delivery role immediately upon becoming operational. In all respects but speed, the B-36 could match what was arguably its Soviet counterpart, the Tu-95 (still in service).[26] Until the B-52 came on line, the B-36 was the only means of delivering the first generation Mark-17 hydrogen bomb,[27] 25 feet (7.5 m) long, 5 ft (1.5 m) in diameter, and weighing 42,000 lb (19,000 kg), the heaviest and bulkiest American nuclear weapon ever. Carrying this massive weapon required merging two adjacent bomb bays.
The defensive armament consisted of six remote-controlled retractable gun turrets, and fixed tail and nose turrets. Each turret was fitted with two 20 mm cannon, for a total of 16 cannons, the greatest defensive firepower ever carried by a bomber. Recoil from gunnery practice could cause the on-board electronics to malfunction, solid state then being unknown. This contributed to the crash of B-36B 44-92035 on 22 November 1950.[28]
The Convair B-36 was the only plane designed to carry the T12 Cloud Maker, a gravity bomb weighing 43,600 lb and designed to produce an Earth quake bomb effect. The T12 still remains the heaviest conventional bomb to have been employed by the United States.
Production
The XB-36 on its first flight.
| Variant | Built |
|---|---|
| XB-36 | 1 |
| YB-36 | 1 |
| B-36A | 21 |
| B-36B | 62 |
| B-36D | 26 |
| RB-36D | 24 |
| B-36F | 36 |
| RB-36F | 24 |
| B-36H | 83 |
| RB-36H | 73 |
| B-36J | 33 |
| 'Total' | '384' |
The first prototype XB-36 flew on 8 August 1946. The speed and range of the prototype failed to meet the standards set out by the Army Air Corps in 1941. As is often the case with aircraft pushing the size envelope, the XB-36 experienced a number of problems. (For instance, the B-29 Superfortress was plagued by engine problems, and available engines were too weak to afford the Boeing XB-15 a useful top speed.) Many problems with the XB-36 stemmed from its "placeholder" engines, weaker engines used until the intended powerplant became available.
A second aircraft, the YB-36, flew on 4 December 1947. It featured a redesigned high-visibility "bubble" canopy, which was later adopted for production. Altogether, the YB-36 was much closer to the production aircraft. Additionally, the engines used on the YB-36 were a good deal more powerful and more efficient. The YB-36 was actually beaten to the air by the first production model: a single B-36A was built with enough equipment to fly to Wright Field, where its airframe was subjected to a battery of physical tests.
The first of 21 B-36As were delivered in 1948. They were admitted interim airframes, intended for crew training and later conversion. No defensive armament was fitted as none was ready. Once later models were available, all B-36As were converted to RB-36E reconnaissance models. The first B-36 variant meant for normal operation was the B-36B, delivered beginning in November 1948. This aircraft met all the 1941 requirements, but had serious problems with engine reliability, and with the availability of armaments and spare parts. Later models featured more powerful variants of the R-4360 engine, improved radar, and redesigned crew compartments.[29]
The four jet engines raised fuel consumption, thus reducing range. Meanwhile, new air-to-air missiles made hand-aimed guns mounted in heavy turrets obsolete; they were also unreliable. In February of 1954, the USAF awarded Convair a contract to reduce the weight of the entire B-36 fleet by implementing a new "Featherweight" design in three configurations:
★ I removed the 6 movable gun turrets and other defensive hardware.
★ II removed the rear compartment crew comfort features, and all hardware accommodating the XF-85 parasite fighter.
★ III incorporated both I and II.
The six turrets eliminated by I reduced the crew from 15 to nine. III enabled a longer range and an operating ceiling of at least 47,000 feet (14,000 m), features especially valuable for reconnaissance missions. The B-36J-III configuration (the last 14 made) featured a single radar-aimed tail turret, extra fuel tanks in the outer wings, and landing gear allowing the maximum gross weight to rise to 410,000 pounds (190,000 kg). Production of the B-36 ceased in 1954.
Reconnaissance capability
More than a third of all B-36 models were reconnaissance models, designated RB-36. Before the development of the Lockheed U-2, the RB-36 was the mainstay of American photo reconnaissance over hostile territory. It was the only American aircraft having range enough to fly into Asia from bases in the USA, and size enough to carry the bulky high-resolution cameras of the day. The RB-36 performed a number of rarely acknowledged reconnaissance missions and is suspected of having carried out numerous penetrations of Chinese (and possibly Soviet) airspace.
The RB-36 was well-suited for such reconnaissance missions. Its high cruising altitude made it difficult to intercept, and its fuel capacity enabled missions up to 50 hours long. The RB-36 featured a pressurized camera compartment staffed by a crew of seven, in place of a forward bomb bay. The aft bomb bay contained tanks for extra fuel. The RB-36 cameras could produce very high resolution photographs: pictures of a golf course taken from 40,000 ft (12,000 m) show recognizable golf balls. RB-36s were distinguished by the bright aluminum of the camera compartment (contrasting with the dull magnesium of the rest of the fuselage) and by a series of radar domes under the aft fuselage, varying in number and placement.
Operational history
RB-36D.
The B-36, including its RGB-36, RB-36, and XC-99 variants, was in service as part of the USAF Strategic Air Command from 1948 through 1958.
Unlike the B-52, which has seen action in the Vietnam War and the two Gulf Wars, no B-36 ever dropped a bomb or fired a shot at an enemy. The closest the B-36 came to seeing action was during the 1956 Hungarian Revolution and the Suez Crisis, when nuclear-armed B-36s were dispatched to Turkey and Morocco.
Though the B-36 had a better than average overall safety record, ten crashed between 1949 and 1954 (three 36Bs, three 36Ds, and four 36Hs). Goleta Air and Space Museum maintains a web site with photographs and lengthy excerpts from the official crash reports.[30]
A B-36 was also involved in two "Broken Arrow" incidents. On 13 February 1950, a B-36, serial number 44-92075, crashed in an unpopulated region of British Columbia reputedly after ditching its bomb over the ocean (recovery teams also searched the crash site for its remains and accompanying "bird-cage"), resulting in the first loss of an American nuclear weapon.[31] On 22 May 1957, a B-36 accidentally dropped a Mark-17 hydrogen bomb on a deserted area while landing at Kirtland AFB in Albuquerque NM. Only the conventional trigger detonated, the bomb being unarmed. These incidents were classified for decades. See list of military nuclear accidents.[32][33]
Maintenance
Personnel and equipment required to get and keep a B-36 airplane in the air.
The B-36 needed a great deal of maintenance between flights; although in an emergency an aircraft could be "turned" in a few hours for a ferry flight, it took much longer to get the airplane ready for an operational mission.[34] In January 1951, a B-36 amassed 200 hours of flight time (8.3 standard 24-hour missions), an apparent record.
The B-36 was too large to fit in most hangars. Moreover, even an aircraft with the range of the B-36 needed to be stationed as close to the enemy as possible, and this meant the northern USA, Alaska, and the Arctic. As a result, most "normal" maintenance, such as changing the 56 spark plugs (always at risk of fouling by the leaded fuel of the day) on each of its six engines, or replacing the dozens of bomb bay light bulbs shattered after a gunnery mission, was performed out of doors, in 100-degree summers and 60-below winters. Special shelters were built so that the maintenance crews could enjoy a modicum of protection while working on the engines. Often, ground crews risked slipping and falling from ice-covered wings, or being blown off by a propeller running in reverse pitch. Some procedures even required a mechanic to sit astride a running engine, a 19-foot diameter propeller at his feet, his hand near the 34-inch diameter cooling fan.
The wing roots were thick enough, 7 ft (2.1 m), to enable a flight engineer to access the engines and landing gear by crawling through the wings. This was possible only at altitudes not requiring pressurization.
The Wasp Major engines also had a prodigious appetite for lubricating oil, each engine requiring a 100 gallon (380 L) tank. A former ground crewman has written: "[I don't recall] an oil change interval as I think the oil consumption factor handled that." It was not unusual for a mission to end because one or more engines ran out of oil. Though the B-36 could continue flying with as many as three inoperative engines, the extra stress on the remaining engines put them at risk of failing.
Engine fires
Like all large aircraft powered by piston engines, the B-36 was prone to engine fires, a problem exacerbated by the pusher configuration. When a crash occurred for any reason, the magnesium-rich airframe burned readily.
When thinking about these engine fires, keep in mind that:
★ The ambient temperatures typical of the B-36's cruising altitude and of the high latitude bases where it was often stationed, were usually far below freezing.
★ Radial aircraft engines like the R-4360 are air-cooled. Hence the large volume of air flowing past the cylinders during flight underwent substantial warming.
The design of the R-4360 engine tacitly assumed that it would be mounted in the conventional tractor configuration - propeller/air intake/28 cylinders/carburetor - with air flowing from left to right. In this configuration, the carburetor is bathed in air warmed by engine cooling and so is unlikely to ice up. However, the B-36 employed the R-4360 engine in the pusher configuration - air intake/carburetor/28 cylinders/propeller. Because the carburetor is now in front of the engine, it cannot benefit from engine heat. Hence when intake air was cold and humid, ice gradually obstructed the carburetor air intake, which in turn gradually increased the richness of the air/fuel mixture until the unburned fuel in the exhaust caught fire. Engine fires of this nature led to the first loss of an American nuclear weapon, described above. The later addition of electric heating to the carburetor intakes eliminated the problem.
Crew experience
Training missions were typically in two parts; first, a 40 hour flight - followed by some time on the ground for refueling and a bit of maintenance - then a 24 hour second flight. When thinking about missions of such great duration, two facts should be kept in mind:
★ Given a sufficiently light load, the B-36 could fly at least 10,000 miles (16,000 km) nonstop
★ The highest cruising speed of any version, the B-36J-III, was only 230 mph (380 km/h). Turning the jet engines on could raise the cruising speed to over 400 mph (650 km/h), but the resulting higher fuel consumption reduced the range.
Hence, a 40 hour mission, with the jets used only for takeoff and climbing, flew about 9200 miles (15000 km). Many missions were flown "around the flag pole", meaning they began and ended at the same base.
The B-36 was not a particularly enjoyable aircraft to fly. Its overall performance, in terms of speed and manuverablity, was never considered sprightly. Lieutenant General James Edmundson likened it to "...sitting on your front porch and flying your house around."[35] And despite its immense exterior size, the pressurized crew compartments were relatively cramped, especially when occupied for 24 hours by a crew of fifteen in full flight kit. Although the rear compartment included six bunks, and the radio compartment behind the flight deck included a couple of bunks, crewmen usually chose to sleep in their seats.
War missions would have been essentially one-way; taking off from forward bases in Alaska or Greenland, overflying the USSR, and landing in Europe or the Middle East. Ironically, recollections of crew veterans reveal that while crews were confident of their ability to complete a mission if called upon to do so, they were less confident of surviving the weapon delivery itself.[36] Their concerns were a function of the relatively low speed of the aircraft coupled with the extreme destructive power of the bombs they were carrying, resulting in the plane still being in harms way once the bombs were released and detonated on target. These concerns were borne out by the 1954 Operation Castle tests, in which B-36s flew near detonations in the 15 megaton range, at distances believed typical of wartime delivery, and experiencing serious heat and blast damage.
Experiments
NB-36H nuclear reactor testbed
The B-36 was employed in a variety of aeronautical experiments throughout its service life. Its immense size, range and payload capacity lent itself to use in research and development programs. These included nuclear propulsion studies, and "parasite" programs in which the B-36 carried smaller interceptors or reconnaissance aircraft.[37]
In May 1946, the Air Force began the Nuclear Energy for the Propulsion of Aircraft (NEPA) project which was followed in May 1951 by the Aircraft Nuclear Propulsion (ANP) program. The ANP program required that Convair modify two B-36s under the MX-1589 project. One of the modified B-36s studied shielding requirements for an airborne reactor to determine whether a nuclear aircraft was feasible. The Nuclear Test Aircraft (NTA) was a B-36H-20-CF (Serial Number 51-5712) that had been damaged in a tornado at Carswell AFB on 1 September 1952. This plane, designated the NB-36H, was modified to carry a 1 MW, air-cooled nuclear reactor in the aft bomb bay, with a four ton lead shield between the reactor and the cockpit. The cockpit was encased in lead and rubber, with a 6-inch (15 cm)–thick acrylic glass windshield. The reactor was operational but did not power the plane; its sole purpose was to investigate the effect of radiation on aircraft systems. Between 1955 and 1957, the NB-36H completed 47 test flights and 215 hours of flight time, during 89 of which the reactor was critical. The NB-36H was scrapped at Fort Worth in 1958 when the nuclear aircraft program was abandoned.
Other experiments involved providing the B-36 with its own fighter defense in the form of parasite aircraft carried partially or wholly in a bomb bay. One parasite aircraft was the tiny McDonnell XF-85 Goblin, which docked using a trapeze system. The concept was tested successfully using a B-29 carrier, but docking proved difficult even for experienced test pilots. Moreover, the XF-85 was seen as no match for Soviet aircraft, and the project was cancelled.
GRB-36 carrying YRF-84F. USAF Museum Photo Archives carrying an F-84 Thunderjet
More successful was the FICON project, involving a modified B-36 - called a GRB-36D "mothership" - and the RF-84K, a fighter modified for reconnaissance, in a bomb bay. The GRB-36D would ferry the RF-84K to the vicinity of the objective, whereupon the RF-84K would disconnect and begin its mission. Ten GRB-36Ds and 25 RF-84ks were built and saw active service until 1959.
Projects TIP TOW and Tom-Tom involved docking F-84s to the wingtips of B-29s and B-36s. The hope was that the increased aspect ratio of the combined aircraft would result in a greater range. Project TIP TOW was canceled when the combination of two EF-84Ds and a specially modified test EB-29A crashed, killing everyone on all three aircraft. This accident was attributed to one of the EF-84Ds flipping over onto the wing of the EB-29A. Project Tom-Tom, involving RF-84Fs and a GRB-36D from the FICON project (redesignated JRB-36F), continued for a few months after this crash, but was also canceled due to the violent turbulence induced by the wingtip vortices of the B-36.[38]
Obsolescence
The operational life of the B-36 ended because:
★ Long range jet-powered bombers became feasible, with cruising speeds more than double that of the B-36.
★ The speed and operating ceiling of jet interceptors steadily rose.
★ Radar-guided surface-to air missiles capable of reaching 20,000 meters emerged.
★ The airframe, especially the wings, proved vulnerable to metal fatigue.
★ Wing flexing led to fuel leakage, a common problem.
The B-36 was gradually decommissioned as the B-52 entered service.
Survivors
B-36J serial number 52-2220 on display in the Cold War Gallery at the National Museum of the United States Air Force
Only four (and a half) B-36 type aircraft survive today, from the 384 produced.[39]
★ YB-36/RB-36E serial number 42-13571. This was the first prototype to be converted to the bubble canopy used on production B-36s. It was on display in the 1950s at the former Air Force Museum on Wright-Patterson Air Force Base near Dayton, Ohio. When the Museum was moved to a different location on the base the cost of moving the bomber was more than simply flying a different B-36 to the new location and the aircraft was slated to be scrapped. Instead, Walter Soplata bought it and transported the pieces by truck to his farm in Newbury, Ohio, where it sits today in several large pieces.[40] The center fuselage currently stores a complete P-47N still contained in its original shipping crate.
★ RB-36H serial number 51-13730, is on display at the Castle Air Museum in Atwater, California.
★ B-36J serial number 52-2217, is on display at the Strategic Air and Space Museum (formerly located at Offutt Air Force Base) and now near Ashland, Nebraska.
★ B-36J serial number 52-2220, is on display at the National Museum of the United States Air Force (formerly The U.S. Air Force Museum) at Wright-Patterson Air Force Base near Dayton, Ohio. Its flight to the museum from Davis-Monthan Air Force Base in Arizona on 30 April 1959 was the last flight of a B-36. This B-36J replaced the former Air Force Museum's original YB-36 serial number 42-13571 (see above). This was also the first aircraft to be placed in the Museum's new display hangar, and was not moved again until relocated to the Museum's latest addition in 2003. It is displayed alongside the only surviving example of the massive 9 ft. XB-36 wheel and tire.
★ B-36J, serial number 52-2827, the final B-36 built, named "The City of Fort Worth," was scrapped on 12 February 1959 and is now undergoing restoration and reassembly at the Pima Air & Space Museum in Tucson, Arizona.
★ XC-99, serial number 43-52436, the sole example of the cargo version of the B-36, was stored for years at Kelly/Lackland AFB in Texas, and is now undergoing restoration and reassembly at the National Museum of the United States Air Force in Dayton, Ohio.
Related models
Main articles: Convair B-36 variants
In 1951, the USAF asked Convair to build a prototype all-jet variant of the B-36. Convair complied by adding swept wings and eight Pratt & Whitney XJ57-P-3 jet engines to a B-36F. The result was the B-36G, later renamed the Convair YB-60. The result was found inferior when compared to Boeing's YB-52, and the project was terminated.[41]
The B-36 was also the basis for the Convair XC-99, a double-decked military cargo aircraft, and the largest piston engined, land-based aircraft ever built, and the longest practical aircraft (185 ft, 56 m) of its era. Only one example was ever built, and it was extensively employed for nearly a decade, especially for cross-country cargo flights during the Korean War. In 2005, the XC-99 was dismantled with plans to move it from the former Kelly Air Force Base in San Antonio, Texas, where it has been retired since 1957, to the National Museum of the United States Air Force at Wright-Patterson Air Force Base near Dayton, Ohio. It is currently being transported in pieces aboard C-5 Galaxy transports as space and schedule permits.[42]
A commercial airliner derived from the XC-99, the Convair Model 37, never left the drawing board. It would have been the first "jumbo" airliner.[43]
B-36 in the Media
In 1949, the B-36 was featured in the documentary film, ''Target: Peace'', which was centered around the operations of the 7th Bombardment Wing. Other scenes included B-36 production at the Fort Worth plant.
The B-36 appeared in only one feature-length motion picture, ''Strategic Air Command'' (1955), starring Jimmy Stewart and June Allyson. In the film Jimmy Stewart's character is forced to crash land his B-36 in the Arctic. ''Strategic Air Command'' features many good aerial shots of B-36s and B-47s. The John Wayne 1957 film Jet Pilot also shows a F-94 Starfire intercepting a B-36 on a test mission.
In ''Top of the World'' (1955) a formation of early B-36s (without the four jet engines) is shown just before the end title [44].
Specifications (B-36J-III)
Media
Video of B-36 takeoff
References
1. Knaack, Marcelle Size. ''Post-World War II Bombers, 1945-1973''. Washington, DC: Office of Air Force History, 1988. ISBN 0-16-002260-6.
2. The name "Peacemaker," was forwarded to the USAF by Convair following a contest to name the bomber, and although not officially adopted, became the most common name used. It is often listed in sources as the "official" name.
Reference: Peacemaker Name Certificate
3. National Museum of the USAF website discussing what brought about the design of such a long ranged bomber.
4. Taylor 1969, p. 465.
5. Winchester 2006, p. 49.
6. Taylor 1969, p. 465.
7. Wagner 1968, p. 142. Quote: "A British engineer attacking 'piston-engined giantism,' wrote that British jets could reach B-36 height in less than eight minutes, were far faster at high altitudes and would find the B-36 'practically a sitting duck.'"
8. National Museum of the USAF webiste discussing what brought about the design of such a long ranged bomber.
9. Yenne 2004, p. 124-126.
10. National Museum of the USAF webiste discussing what brought about the design of such a long ranged bomber.
11. National Museum of the USAF webiste discussing what brought about the design of such a long ranged bomber.
12. National Museum of the USAF webiste discussing what brought about the design of such a long ranged bomber.
13. National Museum of the USAF webiste discussing what brought about the design of such a long ranged bomber.
14. Barlow, Jeffrey G. ''Revolt of the Admirals: The Fight for Naval Aviation, 1945–1950''. Washington, DC: Naval Historical Center, 1994. ISBN 0-16-042094-6.
15. Johnson 1978, p. 1.
16. Jacobsen and Wagner 1980, p. 4.
17. Johnson 1978, p. 1.
18. see http://www.air-and-space.com/peacemkr.htm for a table comparing the large aircraft designed in the 1940s
19. Jacobsen 1974, p. 54.
20. Yenne 2004, p. 136-137.
21. Yenne 2004, p. 137-138.
22. From the Maxwell Air Force Base website (original image).
23. [3] Quote attributed to Captain Banda when he toured an air cadet Michael R. Daciek, later Lt. Col. Daciek, on an inside tour of the XC-99 in 1953.
24. ''Convair XB-36 Peacemaker''. National Museum of the United States Air Force. [4] Access date: 4 September 2006.
25. ''Convair XB-36 Landing Gear''. National Museum of the United States Air Force. [5] Access date: 4 September 2006.
26. http://news.bbc.co.uk/2/hi/europe/6938856.stm
27. http://www.globalsecurity.org/wmd/systems/mk17.htm
28. Summary of Air Force accident report: http://www.air-and-space.com/b-36%20wrecks.htm#44-92035
29. See http://www.wpafb.af.mil/museum//research/bombers/bomber3.htm for more detail on the features and performance of each of 16 variants of the B-36
30. http://www.air-and-space.com/b-36%20wrecks.htm
31. Ricketts, Bruce. ''Broken Arrow, A Lost Nuclear Weapon in Canada''. Mysteries of Canada, 11 January 2006. Broken Arrow Access date: 17 August 2007
32. Doomsday
33. B-36 Wrecks
34. ''B-36 maintenance discussion''. Delphi Forums. [6]
35. http://www.pbs.org/wgbh/amex/bomb/filmmore/reference/interview/edmund10.html
36. http://forums.delphiforums.com/n/main.asp?webtag=B36forum
37. Miller and Cripliver 1978, p. 366, 369.
38. Lockett, Brian. ''Parasite Fighter Programs: Project Tom-Tom''.Goleta Air and Space Museum. [7] Access date: 3 February 2007.
39. Yenne 2004, p. 149.
40. http://www.aircraftresourcecenter.com/Fea1/101-200/Fea182_Walters-Farm_Williams/part1/Fea182.htm
41. [8] National Museum of the USAF factsheet about the YB-60
42. Air Force Linl XC-99 begins piece-by-piece trip to Air Force Museum by 1st Lt. Bruce R. Hill Jr.433rd Airlift Wing Public Affairs, 04/22/2004
43. National Museum of the USAF webiste discussing what brought about the design of such a long ranged bomber as well as it's variants.
44. Top of the World
----
★ Ford, Daniel. "B-36: Bomber at the Crossroads". ''Air and Space/Smithsonian''. April 1996. [9] Access date: 3 February 2007.
★ Jacobsen, Meyers K. ''Convair B-36: A Comprehensive History of America's "Big Stick"''. Atglen, Pennsylvania: Schiffer Military History, 1997. ISBN 0-7643-0974-9.
★ ___________. "Peacemaker." ''Airpower, Vol. 4, No. 6''. November 1974.
★ ___________. ''Convair B-36: A Photo Chronicle''. Atglen, Pennsylvania: Schiffer Military History, 1999. ISBN 0-7643-0974-9.
★ Jacobsen, Meyers K and Wagner, Ray. ''B-36 in Action (Aircraft in Action Number 42)''. Carrollton, TX: Squadron/Signal Publications Inc., 1980. ISBN 0-89747-101-6.
★ Jenkins, Dennis R. ''Convair B-36 Peacemaker''. St. Paul, Minnesota: Specialty Press Publishers and Wholsalers, 1999. ISBN 1-58007-019-1.
★ ___________. ''Magnesium Overcast''. St. Paul, Minnesota: Voyageur Press, 2001. ISBN 1-58007-042-6.
★ ___________. ''B-36 Photo Scrapbook''. St. Paul, Minnesota: Specialty Press Publishers and Wholesalers, 2003. ISBN 1-58007-075-2.
★ Johnsen, Frederick A. ''Thundering Peacemaker, the B-36 Story in Words and Pictures''. Tacoma, WA: Bomber Books, 1978.
★ Miller, Jay and Cripliver, Roger. "B-36: The Ponderous Peacemaker." ''Aviation Quarterly, Vol. 4, No. 4, 1978''.
★ Morris, Lt. Col. (ret.) and Allan, Ted. ''Flying the Aluminum and Magnesium Overcast''. The collected articles and photographs of Ted A. Morris, ©2000. [10] Access date: 4 September 2006.
★ Orman, Edward W. "One Thousand on Top: A Gunner's View of Flight from the Scanning Blister of a B-36." ''Airpower, Vol. 17, No. 2''. March 1987.
★ Pyeatt, Don. ''B-36: Saving the Last Peacemaker (Third Edition)''. Fort Worth, Texas: ProWeb Publishing, 2006. ISBN 0-9677593-2-3.
★ Taylor, John W.R. "Convair B-36." ''Combat Aircraft of the World from 1909 to the present''. New York: G.P. Putnam's Sons, 1969. ISBN 0-425-03633-2.
★ Wagner, Ray. ''American Combat Planes''. New York: Doubleday & Company, Inc., 1968. ISBN 0-385-04134-9.
★ Winchester, Jim. ''Military Aircraft of the Cold War (The Aviation Factfile)''. Rochester, Kent, UK: The Grange plc., 2006. ISBN 1-84013-929-7.
★ Yenne, Bill. "Convair B-36 Peacemaker." ''International Air Power Review, Vol. 13, Summer 2004''. London: AirTime Publishing Inc., 2004. ISBN 1-880588-84-6.
External links
★ Cowtown.net: Portal to B-36 resources
★ Encyclopedia of American Aircraft
★ [http://www.nationalmuseum.af.mil/factsheets/factsheet.asp?id=2584 XB-36 page}, and B-36A page on USAF National Museum web site
★ Aerospaceweb, with technical info and many pictures
★ "''Lt. Gen. James Edmundson interview transcript: Flying B-36 and B-47 planes.''". Race For the Superbomb. PBS Online.
★ B-36 operations Walker AFB Roswell New Mexico 1955-1957
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