The most-produced version of the B-50 series was the B-50D. A total of 222 B-50Ds were built. The B-50D was primarily intended as a stopgap nuclear-capable medium bomber, pending the availability of the B-47.
The B-50D marked a major change in the B-50 series, which justified a new factory designation of Model 345-9-6. The most noticeable outward change introduced by the B-50D was a revised nose with a single large molded one-piece plastic cone and an optically-flat bomb-aimer's window in the lower portion which replaced the seven-piece B-29 unit that was used through the B-50B.
Starting with the 16th B-50D, receptacles were provided for the Boeing-developed boom-type inflight refuelling system. Two 700-gallon auxiliary fuel tanks could be carried on pylons underneath the outer wing panels. A new type of top forward turret was fitted. More efficient radar was fitted, and the number of crew members was reduced from 11 to 8, with the typical crew complement being pilot, copilot, engineer, radio/electronic countermeasures operator, left side gunner, right side gunner, top gunner, and tail gunner. Starting with the 16th B-50D, receptacles were provided for the Boeing-developed boom-type inflight refuelling system.
The first B-50D took off on its maiden flight in May of 1949. Deliveries to SAC began in late June of 1949. The first outfits to receive the B-50D were the 93rd and 509th Bombardment Wings. Initially, there were so many maintenance problems with the B-50Ds that SAC actually refused further deliveries until the defects could be fixed. Most of the B-50Ds that were delivered to SAC were grounded for extensive periods of time during 1949-50 because of problems with main fuel cells, inverters, turbosuperchargers, alternators, generators, and cracks in wing trailing edges. There were delays in the development of the boom-refuelling system, and neither the receiving end nor the feeding apparatus for the new equipment were actually fitted to most of the B-50Ds delivered, which led to several series of costly and time-consuming retrofits.
There were some problems in adapting the B-50D to carry atomic bombs. The B-50 was an adaptation of the B-29, which had been designed before the era of nuclear weapons. The bomb bay was really too small to house both the fairly large and heavy atomic bombs of the day plus the required accessory components such as arming controls, capsule insertion gear and other equipment needed for control, testing, and monitoring of the bombs. In those days, there was a high degree of secrecy surrounding the development of atomic bombs and there was little if any coordination between the USAF and the Atomic Energy Commission. This prevented necessary information from reaching Boeing engineers who were assigned the responsibility for fitting these new weapons inside the bomb bay of the B-50. This lack of communication led to a misunderstanding between the USAF and Boeing which resulted in the first few B-50Ds being delivered to SAC without having been adapted to carry both the Mark 3 and Mark 4 atomic bombs. A costly and time-consuming series of field fixes had to be carried out. In addition, the rapid development of new types of nuclear bombs meant that new types of associated components would have to be fitted into the narrow bomb bay of the B-50, and that the modifications would have to start all over again each time a new type of nuclear weapon was fielded.
The incessant modifications required by the development of new types of atomic bombs severely strained the capabilities of both the Boeing factory and of the Air Materiel Command teams that were deployed to SAC bases. Special care had to be taken so that SAC's overall deterrent capability would not be seriously compromised by the seemingly never-ending series of B-50D modifications. For example, it was agreed that only the first four aircraft of every B-50D wing would be modified to carry the most sophisticated atomic bombs of the period. The adaptation of 180 B-50Ds to accommodate the Mark 4 bomb's immediate successor had to be carefully scheduled, but there were some schedule overlaps and several serious delays. In March of 1953, the Mark 4 bombs were finally taken out of service, which meant that all of the remaining B-50Ds would immediately have to be modified as well. By late 1953, SAC began to replace some of its B-29 and B-50 bombers with new B-47s, but there were serious delays in the delivery of B-47s. In retrospect, the long series of modifications required by the rapid advances in atomic bomb technology so seriously delayed the B-50D that its advantages were more or less nullified.
The B-50D had been slated to receive the AN/APW-24, an improved bombing/navigation radar system. The APW-24 proved to be unsatisfactory because of lack of security, a high rate of malfunction, and a general inability to function properly in bad weather.
The last of 222 B-50Ds was delivered in December of 1950. Some of SAC's 5 wings of atomic-capable B-50Ds began to exchange their aircraft for B-47s in late 1953. The last B-50D (49-330) assigned to the 97th Bombardment Wing at Biggs AFB, Texas was phased out of the active nuclear force on October 20, 1955. The retired B-50Ds were then reconfigured for other roles such as aerial refueling tanker, weather reconnaissance, and training. These modified aircraft remained in USAF service for another ten years.
Serials of B-50D Superfortress:
47-163/170 Boeing B-50D-65-BO Superfortress
c/n 15847/15854
163,164,167,170 converted to TB-50D aircrew
trainer.
170 later converted to KB-50D, prototype for
later KB-50J and KB-50K programs.
48-046/052 Boeing B-50D-70-BO Superfortress
c/n 15855/15861
All converted to TB-50D aircrew trainers
046 converted to KB-50D, prototype for
subsequent KB-50J and KB-50K programs.
0049 to KB-50J
48-053/062 Boeing B-50D-75-BO Superfortress
c/n 15862/15871
0059 to KB-50J
48-063/072 Boeing B-50D-80-BO Superfortress
c/n 15872/15881
0066 to KB-50J
48-073/082 Boeing B-50D-85-BO Superfortress
c/n 15882/15891
73 modified as WB-50D weather recon aircraft.
075 converted to DB-50D Rascal launcher
48-083/092 Boeing B-50D-90-BO Superfortress
c/n 15892/15901
0086 to KB-50J
48-0093/0102 Boeing B-50D-95-BO Superfortress
c/n 15902/15911
48-0103/0112 Boeing B-50D-100-BO Superfortress
c/n 15912/15921
105,108 modified as WB-50D weather recon
aircraft.
48-0113/0127 Boeing B-50D-105-BO Superfortress
c/n 15994/16008
0123 to KB-50J
113,116,121,124 modified as WB-50D weather
recon aircraft.
49-0260/0292 Boeing B-50D-110-BO Superfortress
c/n 16036/16068
260,261,264,266,281,284/288,291 converted to
WB-50D weather recon aircraft.
49-0293/0325 Boeing B-50D-115-BO Superfortress
c/n 16069/16101
296,298,300,302,304,310,311,313,324 converted
to WB-50D weather recon aircraft.
WB-50D #49-310 temporarily designated JB-50D
while used for experimental work.
0321 to KB-50J
49-0310 is on display at WPAFB Museum.
49-0326/0358 Boeing B-50D-120-BO Superfortress
c/n 16102/16134
0332,0333,0337,0341,0345,0351 converted to
WB-50D weather recon aircraft.
0344,0350,0356 to KB-50J
49-0359/0391 Boeing B-50D-125-BO Superfortress
c/n 16135/16167
371 and 375 converted to WB-50D weather recon
aircraft.
0373,0378,0389,0391 to KB-50J
49-0389 on display at WPAFB museum, marked as
KB-50J 48-0014
Specification of Boeing B-50D Superfortress:
Engines: Four Pratt & Whitney R-4360-35 Wasp Major 28-cylinder, four-row air cooled radials with General Electric CH-7-B1 turbosuperchargers. Performance: Maximum speed 395 mph at 30,800 feet. Cruising speed 244 mph. Combat ceiling 36,650 feet. Initial climb rate 2225 feet per minute. Combat radius 2396 miles with 10,000 pounds of bombs. Maximum range 5762 miles. Takeoff ground run 6420 feet at sea level. Takeoff over 50-feet obstacle 8025 feet at sea level. Dimensions: Wingspan 141 feet 3 inches, length 99 feet 0 inches, height 32 feet 8 inches, wing area 1720 square feet. Weights: 80,609 pounds empty, 121,850 pounds combat, 173,000 pounds maximum takeoff. Armament: Four 0.50-inch machine guns in forward dorsal turret, two 0.50-inch machine guns in rear dorsal turret, two 0.50-inch machine guns in forward ventral turret, two 0.50-inch machine guns in rear ventral turret, two 0.50-inch machine guns and one 20-mm cannon in tail turret. Maximum internal bombload 20,000 pounds.
Sources:
-
American Combat Planes, Third Enlarged Edition, Ray Wagner, Doubleday,
1982.
-
Post World War II Bombers, Marcelle Size Knaack, Office of Air Force
History, 1988.
-
Boeing Aircraft Since 1916, Peter M. Bowers, Naval Institute Press,
1989.
- United States Military Aircraft Since 1909, Gordon Swanborough and Peter M. Bowers, Smithsonian, 1989.
