Table of US Strategic Bomber Forces
1945-49 | 1950-59 | 1960-69 | 1970-79 | 1980-89 | 1990-99 | 2000-12 | Notes

1. Includes the total number of bombers in the Strategic Air Command active inventory ("assigned resources," not bombers in inactive storage) as of the end of the year (December).

2. Primary Authorized Aircraft (PAA). Previously the term Unit Equipment (UE) was used. More recently the term Primary Mission Aircraft is used. All of the terms specify the number of aircraft assigned to operational units in combat ready condition. The difference between inventory and PAA are those planes used for training and those in maintenance.

3. Not all B-29 Boeing bombers were modified to carry nuclear weapons. On 31 December 1946 there were 23 nuclear modified B-29 bombers; on 1 March 1947 there were 35; on 1 December 1948 there were 38; in mid-January 1949 there were 66; and on 1 January 1950 there were 95. See David Alan Rosenberg, "U.S. Nuclear Stockpile, 1945 to 1950," Bulletin of the Atomic Scientists, May 1982, p. 30. The Strategic Air Command was established on 21 March 1946 as a combat command of the Army Air Forces. On 18 September 1947 the Department of the Air Force was created as a military service and SAC was reorganized and realigned.

4. Not all of the 385 Convair B-36 bombers that the Air Force accepted were modified to carry nuclear weapons. On 1 December 1948 there were four nuclear modified B-36 bombers; by mid-January 1949 there were 17; and by 1 January 1950 there were 34. Effective 1 October 1955, SAC's four heavy Strategic Reconnaissance Wings were redesignated heavy Bombardment Wings in recognition of the conversion of the RB-36 from a reconnaissance airplane to a bomber.

5. Not all of the 370 Boeing B-50 bombers that the Air Force bought were modified to carry nuclear weapons. On 1 December 1948 there were 18 nuclear modified B-50 bombers; by mid-January 1949 there were 38; and by 1 January 1950 there were 96. The B-50 was basically a B-29 that was to be a stopgap to be used until an aircraft more suitable for atomic weapon delivery became available. On 1 July 1950 there were a total of 264 nuclear modified B-29, B-36 and B-50 bombers. SAC's five wings of atomic-capable B-50s began to exchange their aircraft for new B-47s at the end of 1953. Those wings were the 509^th (Walker AFB, NM), 43^rd (Davis-Monthan AFB, AZ), 2d (Hunter AFB, GA), 93^rd Castle, AFB, CA), and 97^th ( Biggs, AFB, TX), all activated in July and August 1948.

6. The Air Force accepted a total of 2,041Boeing B-47s. The B and E versions had a maximum bomb load of 25,000 lb. Beginning with the 90^th B-47B the Air Force had a requirement that it carry two types of fission bombs. The first B-47 configured to carry thermonuclear weapons was delivered in January 1955. By the end of April 1956 over 1,100 B-47s could handle the new thermonuclear bombs. SAC's last two B-47s went to storage on 11 February 1966.

7. The first full wing of 36 General Dynamics B-58As achieved initial operational capability in May 1961. This was with the 43^rd Bomb Wing at Carswell AFB, TX. A second Bomb Wing, the 305^th at Bunker Hill AFB, IN had its full allocation a year later. In December 1965, Secretary of Defense Robert McNamara directed phaseout of the entire B-58 force by the end of June 1970. It was actually completed on 16 January 1970.

8. In June 1955 the Air Force took delivery of the first B-52. By October 1962 when the last B-52H was delivered to SAC Boeing had built a total of 744 bombers in models A-H, plus two prototypes. As of the end of 1996 all but 71 B-52Hs have been retired. The Air Force estimates that these planes will be structurally sound until about 2030, sixty eight years after entering service.

9. There were two wings of FB-111A aircraft, the 509^th Bomb Wing at Pease AFB, NH which was fully combat ready in October 1971 and the 380^th Strategic Aerospace Wing at Plattsburgh AFB, NY which was combat ready in 1972. A total of 76 FB-111As were accepted by the Air Force. On 10 July 1991 the SAC turned over its last FB-111A to the Tactical Air Command; 35 were redesignated F-111G, the rest were retired or sent to museums

10. One hundred B-1B bombers were purchased. Four have crashed, the most recent of which was on 30 November 1992 and one is considered a ground trainer, not part of Strategic Command's operational inventory. Under START II B-1Bs will no longer be counted as nuclear weapon carriers. Their transition to a conventional role is almost complete. By the end of 1997 the B-1 will be out of the SIOP altogether.

11. The first B-2 was delivered to the 509^th Bombardment Wing on 17 December 1993. The 21^st and last bomber will be delivered in 2000. The first 16 B-2s initially will only carry the B83 bomb. Eventually all of the planes will be able to carry both B61 and B83 bombs.

12. There is no easy or accurate method for estimating the actual number of weapons the bomber forces carry. How each bomber is loaded is determined by its Single Integrated Operational Plan (SIOP) mission. The SIOP is the central nuclear war plan of the U.S. It is developed by the Joint Strategic Target Planning Staff at the Strategic Air Command in Omaha, Nebraska. It is incredibly complex once matching over 10,000 nuclear warheads with their targets taking into account factors of reliability, timing, target hardness, collateral damage, etc. The U.S. bomber's role in the overall plan must be integrated with ballistic missile salvos from SSBNs and land based forces in the U.S. and Europe. When bombers were on alert at each SAC base those in the northern parts of the U.S. had the least distance to fly over the north pole and would have been the first to reach the Soviet Union. Therefore it is likely that those bombers had a full complement of SRAMs intended for defense suppression and making corridors through which following bombers would fly. The counting assumptions for bomber loadings of nuclear weapons are as follows:

a) 1946-1948: Actual number of bombs in the stockpile as of June 30; Rosenberg.

b) 1949-1950: Rosenberg reports 240 mechanical assemblies as of June 30, 1949 and "at least 292" nuclear components and 688 mechanical assemblies as of 30 June 1950. We assume that there were 200 bombs by the end of 1949 and 400 by the end of 1950.

c) 1951-1952: Prior to the deployment of the B-47 bomber, the assumption is that there is a sufficient number of bombs for each PAA aircraft.

d) 1953-1955: B-29, B-36 and B-50 bombers continue to carry one bomb per aircraft. The assumption for the B-47 bomber from 1953 to 1965 is that there were an average of 1.5 bombs per aircraft; based on Department of Defense, OSD, "Memorandum for the President, Recommended FY 1965-FY 1969 Strategic Retaliatory Forces," 6 December 1963, p. 1-2 (partially declassified).

e) 1956-1959: B-36 and B-47 bombers carry one and 1.5 bombs, respectively (see above). B-52 average loading is two bombs per bomber.

f) 1960: With the introduction of the versatile B28 bomb in quantity the B-52 bomber force loading goes up to 3.3 bombs per plane; see Department of Defense, OSD, "Memorandum for the President, Recommended FY 1965-FY 1969 Strategic Retaliatory Forces," 6 December 1963, p.1-2 (partially declassified).

g) 1961-1962: The B-58 bomber carries one bomb until 1964. B-47 and B-52 bomber force loadings continue as above.

h) 1963: The average bomb force loading per B-52 bomber increases to four.

i) 1964-1969: The B-58 is modified to carry four bombs. B-52 bomber force loadings

gradually increase from 4.5 to 8 bombs per plane. The average bomb loadings are assumed to be: 4.5 in 1964, 5 in 1965, 5.5 in 1966, 6 in 1967, 7 in 1968, and 8 in 1969.

j) 1970-1971: The average bomb loadings for the B-52 and FB-111A bombers are eight and six respectively.

k) 1972-1986: Twenty FB-111A bombers carry six SRAMs each and no bombs. The remaining FB-111A bombers carry six bombs each. The remaining SRAMs are carried on B-52 bombers. B-52 bombers loaded with SRAMs carry 12 SRAMs and four bombs. The remaining B-52 bombers carry an average of eight bombs. B-1B bombers beginning in 1986 carry eight bombs.

Bomb	Weight (lb)	Yield (kt)	Entry-Exit
Mark 4	10,800	1-31	03/49-05/53
Mark 6	8,500	8-160	07/51-01/61
Mark 5	3,100	11-47	05/52-01/63
Mark 7	1,650	8-60	08/52-06/67
These were followed by large thermonuclear bombs: (Yield in Megatons)
B15	7,000	1.70-3.75	04/55-04/65
B17/24	42,000	10-15	10/54-10/57
B21	17,000	4-5	12/55-11/57
B36	17,500	9-10	04/56-01/62
B39	6,650	3.75	02/57-11/66
B41	10,000	10	09/60-07/76
B53	8,850	9	08/62 -to date
Finally there were lighter-weight, smaller-diameter, lower-yield bombs:
B28	2,000	up to 1.45 Mt	08/58-04/92
B43	2,100	up to 1.0 Mt	04/61-04/91
B61	700	100-500 kt	01/68- to date
B83	2,400	1.2 Mt	09/83- to date

14. Eighty percent of the total inventory of nuclear armed Hound Dog (AGM-28B) air-to-surface missiles are force loadings.

15. Counting assumptions for nuclear-armed Short Range Attack Missiles (SRAM) (AGM-69A). The total number of operational SRAMs is 1140 from 1975-1986; HAC, FY 1982 DOD, Part 2, p. 101. The SRAM inventory peaked in 1975 at 1471. During the 1972-74 period, SRAM operational missiles were assumed to be the same ratio of operational/total inventory as in 1975. The SRAM was retired for safety reasons at the end of 1991.

16. Counting assumptions for nuclear armed Air-Launched Cruise Missiles (ALCM) (AGM-86B). The number of ALCMs is assumed to be 12 per modified and deployed B-52G/H bomber. A few hundred ALCMs were converted to conventional versions and some were used in the Gulf War. With the retirement of B-52Gs and a portion of the B-52Hs several hundred ALCMs are being placed in a "hedge" and/or reserve status.

17. Advanced Cruise Missiles supplement and replace ALCMs.

last revised 11.25.02