The B-52F (Model 464-260) differed from the E primarily in being equipped with more powerful J57-P-43W, -P-43WA, or P-43WB turbojets, which each offered a normal rating of 11,200 lb.s.t dry and 13,750 lb.s.t. with water injection. Incorporation of these new engines required some internal changes, and a slight modification had to be made to the wing structure in order to incorporate two additional water tanks in the wing.
The only noticeable external difference introduced on the F was the addition of a set of "hard-drive" alternators to supply electrical power to the aircraft. These units were attached to the left-hand side of each podded pair of engines. These replaced the often troublesome air-driven turbines and alternators that were located inside the fuselage on earlier B-52 versions. The air-driven turbines had on one occasion disintegrated, sending red-hot fragments into the fuselage fuel cells, causing a catastrophic fire and loss of the aircraft. The fitting of the new alternator required some redesign of the engine cowling cover, which produced a noticeable bulge on the lower left-hand side. There were small ram intakes cut into the lower lip of each engine air intake. These were intended to provide cooling air for engine oil and constant speed drive units.
There were two B-52F contracts. AF33(600)-32863 signed July 2, 1956 covered Seattle-built B-52Fs (as well as a small number of B-52Es). Serials were 57-0030/0073. AF33(600)-38264 signed on the same date covered 44 B-52Es and 45 B-52Fs, all of which were to built at Wichita. Serials of the B-52Fs were 57-0139/0183.
The first Seattle-built B-52F (57-0030) flew for the first time on May 6, 1958, with the first Wichita-built following eight days later. Seattle built 44, whereas Wichita built 45. This was to turn out to be the last B-52 version to be built at Seattle, all subsequent Stratofortresses being built solely at Wichita.
B-52F deliveries lagged a few months behind schedule because of fiscal restrictions imposed by the Defense Department in late 1957 that limited the amount of authorized overtime at Boeing. Consequently, B-52Fs did not start reaching SAC until June 1958, the 93rd Bomb Wing being the first recipient.
All 89 B-52Fs were accepted by the USAF between June 1958 and February 1959. After the delivery of the last B-52F from Seattle, the Seattle plant transferred all B-52 engineering responsibility to Wichita.
The first B-52Fs (as well as some preceding B-52s) had problems with fuel leaks. Marman clamps, the flexible fuel couplets that interconnected fuel lines between tanks, broke down on several occasions, creating a fire hazard. A September 1957 project known as *Blue Band* put new clamps on all B-52s, but these did not work very well and soon caused problems on their own. The aluminum clamps developed early signs of stress corrosion, indicating a high probability of failure in the near future, and another program knows as Hard Shell was instituted in which the aluminum clamps were replaced with stainless steel strap clamps. Hard Shell was completed in January of 1958, but the results were still not entirely satisfactory because of deficient latch pins. A new project known as Quickclip started in mid 1958 involved the installation of a safety strap around the modified clamps to prevent the fuel from leaking out. Additional B-52Fs entering the inventory after the fall of 1958 were also fitted with Quickclip safety straps.
Subsequent modifications gave the B-52F enhanced conventional warfare capability. In June of 1964, the Air Staff approved the modification of 28 B-52Fs under a project known as South Bay. They could carry 24 750-pound bombs externally. The bombs were carried on external pylons installed underneath each wing inboard of the inner engine pods. These pylons had originally been designed to carry the Hound Dog cruise missile. This essentially doubled the aircraft's conventional bombload, raising total bombload to 38.250 pounds. The expanding Vietnam war led Secretary of Defense Robert MacNamara to request that 46 other B-52Fs be similarly modified under a program known as Sun Bath.
57-030/037 Boeing B-52F-100-BO Stratofortress c/n 17424/17431 57-038/052 Boeing B-52F-105-BO Stratofortress c/n 17432/17446 57-053/073 Boeing B-52F-110-BO Stratofortress c/n 17447/17467 57-074/094 Boeing B-52F Stratofortress - all cancelled 57-139/154 Boeing B-52F-65-BW Stratofortress c/n 464128/464143 57-155/183 Boeing B-52F-70-BW Stratofortress c/n 464144/464172
Engines: Eight Pratt & Whitney J57-P-43WA turbojets, each rated at 11,200 lb.s.t dry and 13,750 lb.s.t. with water injection. Performance: Maximum speed 638 mph at 21,000 feet, 570 mph at 46,500 feet. Cruising speed 523 mph. Stalling speed 169 mph. Initial climb rate 5600 feet per minute. Service ceiling at combat weight 46,700 feet. Combat radius 3650 miles with 10,000 pound bombload. Ferry range 7976 miles. Takeoff ground run 7000 feet. Takeoff run over 50-foot obstacle 9100 feet. Dimensions: Length 156 feet 6.9 inches, wingspan 185 feet 0 inches, height 48 feet 3.6 inches, wing area 4000 square feet. Weights: 173,599 pounds empty, 291,570 pounds combat, 450,000 pounds maximum takeoff. Armament: Four 0.50-inch M3 machine guns with 600 rpg in tail turret. Maximum offensive payload 43,000 pounds.