The first full-scale production version of the B-36 was the B-36B. The B-36B differed from the B-36A in having six 3500 hp R-4360-41 Wasp Major engines with water injection. These engines had 500 more horsepower than the -25 engine, which enabled the B-36B to take off within a shorter runway distance and yielded slightly better performance at both high and cruising speeds. The B-36B had more and better electronic equipment, including the AN/APQ-24 bombing/navigation radar (replacing the APG-23A of the B-36A). The B-36B could carry up to 86,000 pounds of bombs (a 14,000 pound increase over the capacity of the B-36A). The gross weight was 328,000 pounds.
In addition, the B-36Bs were equipped from the start with six remotely-operated retractable turrets, each equipped with a pair of M24A-1 20-mm cannon, plus two more M24A-1 20-mm cannon each in nose and tail turrets. This was the most formidable armament yet fitted to any warplane. The six retractable turrets were mounted in pairs on the upper fuselage behind the cockpit and in dorsal and ventral positions on the rear fuselage. They were mounted on platforms which could be retracted or extended by means of motors via a pair of metal legs with joints which allowed the turrets and their platforms to be folded down or up. The turrets and their platforms were housed behind sliding doors when not in use. When ready for firing, the doors were opened and were slid to the side and the platforms were raised into position. Each 20-mm gun carried 600 rounds of ammunition, with the exception of the nose turret guns which had only 400 rounds each. Each gun had a cyclic rate of fire of between 750 and 850 rounds per minute. The turrets were aimed remotely by gunners operating computing optical gunsights. The nose turret was directed by a hemispheric optical sight mounted inside an installation situated in the nose that was offset below and to the right of the nose center. The six retractable gun turrets were directed by yoke or pedestal sights mounted at six side blisters (two blisters in the forward crew compartment, four blisters in the rear). The tail guns were directed by an AN/APG-3 radar, with the sighting station located in the rear of the aft crew compartment. Unlike in the B-29 and B-50, a separate sight was slaved to each turret, and control of the turrets could not be passed back and forth between gunner stations.
The optical sighting station that directed the retractable fuselage turrets were situated inside hemispherical blisters. Each upper and lower visual sighting station included a reflector sight, sun filters, and free gyroscopes to transmit target lead data to the fire control computer. Each sighting station had a ring-and-bead sight as an emergency backup in case the computing system failed. Yoke-type sights were situated in the upper blisters, pedestal-type sights in the lower blisters.
The nose sighting station was a horizontally-mounted, double-prism periscopic sight that gave the gunner a complete hemisphere of vision when sighting through the eyepiece. However, the nose turret itself was limited to only 60 degrees in azimuth and slightly less in elevation/depression. The sight had at its forward end a spherical glass dome head which projected through the nose of the B-36. Rotation of the gunner's hand grips positioned scanning prisms located in a prism head.
The radar-aimed tail turret could be aimed at up to 40 degrees off centerline, either in azimuth or to the left or right. The APG-3 radar in the tail provided target range, azimuth, and elevation and angular speed relative to the bomber to the sighting station at the rear of the aft crew compartment. It was more accurate than the visual sights and could be used at night or in bad weather. The radar in the tail automatically swept back and forth until it located a target. The gunner then manually locked onto the target by taking the antenna out of its sweep mode. From that point on, the fire control system automatically tracked the target, ignoring any other targets that might be present.
Each of the sighting stations was provided with a separate electromechanical computer which made the calculations needed for a firing solution. The gunner sighted directly on the target, and the computer sent instructions to the turrets to aim it in the correct direction. The computer took account of the target's range and velocity with respect to the bomber and the rate of change of the target's azimuth and elevation. Each gunner manually inputted the bomber's current altitude and airspeed.
The crew of the B-36B was normally fifteen, a pilot, copilot, radar operator/bombardier, navigator, flight engineer, two radiomen, three forward gunners, and five rear gunners.
The first B-36B took off on its maiden flight on July 8, 1948. The performance was much better than expected. An average cruising speed of 303 mph could be maintained. At its combat weight of 227,000 pounds, the B-36B had a top speed of 381 mph and a service ceiling of 42,500 feet.
The B-36B was equipped with the Sperry-built K-1 bombing system. The earliest version of the K-1 was little more than a refined AN/APQ-24. The heart of the system was an AN/APS-23 radar and a Farrand Y-1 optical bombsight, both coupled with an A-1 electromechanical bombing computer. The system could use either its radar or an optical bombsight for bomb aiming and dropping. The search radar was the AN/APS-23, built by Western Electric. A vertical retractable periscope bombsight, the Farrand Y-1, was an integral part of the K-1 system. It made it unnecessary to use an optically-flat glass bomb-sighting window. The Sperry SRC-1 bombing/navigation computer (sometimes known as A-1 or AN/APA-59) operated by determining the relative position of a recognizable landmark and tracked the landmark either optically or by radar. It compensated automatically for crosswinds. The operator centered the crosshairs on the aiming point and allowed them to drift away under the influence of crosswinds. At a particular point, the operator then moved the crosshairs back to the aiming point and the computer determined the wind values. The computer then used this value to compensate for both evasive maneuvers and crosshair corrections. The entire system continuously computed and displayed ground speed, ground track bearing, wind velocity and direction and the aircraft's latitude and longitude positions. The APQ-24 allowed the B-36 to take evasive action during its bomb run, which was not possible for US bombers of World War 2, which had to fly straight and level over their targets.
18 of the B-36Bs could carry the remotely-controlled Bell VB-13 "Tarzon" bomb (2 bombs per aircraft). This was a free-falling weapon based on the British "Tallboy" bomb of World War 2. It was 25 feet long, 54 inches in diameter, and weighed 12,000 pounds. It was cigar shaped, with two lift shrouds, one annular shroud around the center of gravity and the other an octagonal shroud at the end. The Tarzon had a rudder and elevator controlled by radio and four ailerons gyro-stabilized by pneumatic controls, which could be used to guide the bomb both in range and azimuth during its fall. It was equipped with a flare in its tail, and an observation post was installed in the belly of the bomber where a controller could guide the bomb to its target by using a joystick. Guidance was entirely visual, and the bomb could not be dropped through overcast.
The B-36Bs were first assigned to the 7th Bombardment Group at Carswell AFB (which already had B-36As, the first planes arriving in November of 1948. By the end of 1948, there were 35 B-36s in service with SAC at Carswell AFB.
On December 5, 1948, a long range mission of 4275 miles was flown at high altitude. Except for climb and descent, an average cruising speed of 303 mph was maintained during the the entire 14 hour flight at 40,000 feet. This was surpassed during a similar mission on December 12, when the average speed rose to 319 mph.
On December 7-8, 1948, a 7th BG B-36B flew a 35 1/2 hour round-trip simulated bombing mission from Carswell to Hawaii. On the way, the aircraft's 10,000 pound bombload was dumped in the ocean a short distance from Hawaii. The total distance flown exceeded 8000 miles.
A second unit, the 11th Bombardment Group (Heavy) became operational at Carswell with the B-36B.
On January 20, 1949, five B-36Bs from Carswell AFB participated in a flyover of Washington, DC to celebrate the inauguration of Harry Truman as President of the United States.
On January 29, 1949, a B-36B piloted by Major Stephen Dillon established a record bomb lift by taking a pair of dummy 42,000 lb. Grand Slam bombs aloft at Muroc AFB. The first bomb was released at an altitude of 35,000 feet, the second from 40,000 feet.
Eleven B-36s participated in an aerial demonstration and static display at Andrews AFB, Maryland, where President Truman personally inspected the aircraft on February 15.
In March of 1949, a B-36B was used to establish a distance record of 9600 miles flown in 43 hours 37 minutes, carrying a 10,000-pound bombload for 5000 miles. The plane flew a course across the USA from Fort Worth to Minneapolis and Great Falls, Montana and then turned and flew to Key West, Florida where President Truman was vacationing. On the return trip, the bombload was released into the Gulf of Mexico, and the plane flew back to Great Falls and Spokane, Washington, before returning to Fort Worth.
The last B-36B was accepted in September of 1950.
From the outset, the B-36B aircraft had undergone a steady increase in weight which had a detrimental effect on performance. The remotely-controlled turrets and the 20-mm cannon were quite complex and were prone to frequent failures. The defensive armament system was designed and built by General Electric. At first, defects with both the gun and the turret postponed the system's installation in the B-36, resulting in the B-36As initially being delivered without any armament fitted. Once the guns were installed, a lack of 20-mm ammunition delayed the start of testing until mid-1949. As late as February of 1950, the commander of the 8th Air Force was complaining that there was little point in driving a B-36 around carrying a lot of guns that didn't work.
Many of the B-36B's initial problems resembled those of any other new and complex aircraft. Parts shortages were acute, and it was often necessary to cannibalize some B-36Bs to keep others flying. Ground support equipment such as empennage stands, dollies, and jacks were continually in short supply. The B-36B aircraft were in a constant state of flux, either being reconfigured or awaiting modification. In reality, full operational capability was not achieved until 1952.
Of the 73 B-36Bs built, 64 were converted to B-36D configuration with the addition of four General Electric J47-GE-19 turbojets paired in pods underneath the outer wings. They were redelivered with jets by February 1952 and were redesignated B-36D or RB-36D
Serials of B-36B:
44-92026/92037 Consolidated B-36B-1-CF Peacemaker
44-92038/92049 Consolidated B-36B-5-CF Peacemaker
44-92050/92064 Consolidated B-36B-10-CF Peacemaker
44-92065/92079 Consolidated B-36B-15-CF Peacemaker
44-92080/92087 Consolidated B-36B-20-CF Peacemaker
44-92088/92094 Consolidated B-36B Peacemaker
44-92095/92098 Consolidated B-36B Peacemaker
Specification of Convair B-36B:
Engines: Six 3500 Pratt & Whitney R-4360-41 Wasp Major air cooled radial engines. Performance: Maximum speed 381 mph at 34,500 feet. Cruising speed 202 mph. Initial climb rate 1510 feet per minute. Service ceiling 42,500 feet. Combat ceiling 38,800 feet. Combat radius 3740 miles. Total mission time 42.43 hours. 8175 miles range. Weights: 140,640 pounds empty, 227,700 pounds combat, 311,000 pounds maximum takeoff. Dimensions: Wingspan 230 feet 0 inches, length 162 feet 1 inches, Height 46 feet 8 inches, wing area 4772 square feet. Armament: Two 20-mm M24A1 cannon each in six retractable, remotely-controlled fuselage turrets, tail turret and nose mounting, with 92000 rounds of ammunition. Normal bomb load up to 72,000 pounds. Maximum bomb load 86,000 pounds
Sources:
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United States Military Aircraft Since 1909, Gordon Sqanborough and Peter
M. Bowers, Smithsonian, 1989.
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Post-World War II Bombers, Marcelle Size Knaack, Office of Air Force
History, 1988.
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General Dynamics Aircraft and their Predecessors, John Wegg,
Naval Institute Press, 1990.
-
American Combat Planes, Third Enlarged Edition, Ray Wagner, Doubleday,
1982.
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Truman, David McCullough, Simon and Schuster, 1992.
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Bell Aircraft Since 1935, A. J. Pelletier, Naval Institute Press,
1992.
- Convair B-36: A Comprehensive History of America's "Big Stick", Meyers K. Jacobsen, Schiffer Military History, 1997.
