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A dedicated bomber: the B-52D
After it became operational in 1955, the B-52 remained the main long-range heavy bomber of the US Air Force during the Cold War, and it continues to be an important part of the USAF bomber force today. Nearly 750 were built before production ended in the fall of 1962; 170 of these were B-52Ds.
As told by Scott Lowther in his book Boeing B-47 Stratojets & B-52 Stratofortress Origins and Evolution, the design of the B-52D was initiated in August 1953. With the advent of the B-52D model, Seattle began to share manufacturing responsibility with another facility, Boeing’s Wichita, Kansas factory. The first flight of a Wichita B-52D was on May 14, 1956, while the first Seattle B-52D flew on Sep. 28, 1956. Wichita delivered 69 B-52Ds while Seattle delivered 101.
The B-52D was to be a dedicated bomber. For this role it was capable of carrying the latest nuclear weapons such as the Mk 28, Mk 48, Mk 51 and Mk 57. It was also modified to be able to carry AGM-28 Hound Dog’ cruise missiles. The tail guns were four.50-caliber M3 machine guns coupled with the MD-9 fire control system.
The B-52 had begun life as a high-altitude bomber, its survival based on flying higher than enemy interceptors could reach. That seeming invulnerability was fading fast by the late 1950s, and the B-52D was the first B-52 model to incorporate low-level bombing. This would put for the al bomber down in the ‘clutter’ of terrain, difficult for air defence radar systems to spot until the aircraft was right on top of them.
But low-altitude high-speed flying presents difficulties, including being a very rough ride. While in later decades advanced technologies would be first tested and then incorporated that would reduce the turbulent ride at low altitude, in the late 1950s the new flight mode meant that the B-52D structure needed strengthening.
The ‘Hi-Stress’ programme, begun in the very late 1950s, took aircraft as they approached 2,000 hours and again at 2,500 hours and strengthened areas such as the aileron bay, fuselage bulkheads and numerous wing structures. Begun in 1972 and completed in 1977 was the ‘Pacer Plank’ programme which replaced many of the skin panels on the B-52D, not only getting rid of cracked or potentially cracked skins, but making the aircraft slightly more aerodynamic due to smother skin.
Starting in December 1965, the entire operational B-52D fleet went in for Big Belly modifications to make them more capacious bomb trucks. Main bomb bay capacity was increased to either 84 x 500lb bombs (Mk 82) or 42x 7501b bombs (M117), with a further 24 of either bomb being carried on external racks attached to pylons under the inner wing. These modifications did not change the B-52D’s ability to deliver nuclear weapons, but did raise the total payload capability to around 60,000lb. The bombs were loaded into the bomb bay in pre-loaded ‘clips’, greatly speeding the rearming process.
This capability was turned on North Vietnam (and targets in South Vietnam) starting in 1965, with Big Belly modified B-52D and B-52F bombers laying into the Jungle. Carpet bombing raids cleared large sections of forest and collapsed underground bunkers and tunnels, and filled the North Vietnamese Army and the Viet Cong with dread as the bombs came raining down largely without warning.
A hundred raids were performed in 1965. A number raised to 5,000 in 1966, 9,700 in 1967 and 20,560 in 1968. This expansion in missions was made possible due to the original base of operations in far-off Guam being replaced with a base in Thailand, merely an hour from the target.
Halt to air bombardment of North Vietnam
These missions continued into 1968 expanding to bomb North Vietnamese military targets in Laos and Cambodia. The Johnson administration cancelled the bombing of targets in North Vietnam just prior to the elections of 1968, but bombed the hell out of everyone else nearby; a policy that Nixon deescalated but did not end. There were about 19,500 sorties in 1969, 15,100 in 1970 and 12,550 in 1971.
By this point, everyone was largely sick of the war and just to be done with It. The Nixon administration wanted to pull US forces out of frontline fighting and turn the war over to the South Vietnamese; the North Vietnamese, utterly unsurprisingly, took advantage of that and launched fresh offensives.
The B-52D during Operation Linebacker II
So, the Nixon administration ended the Johnson administration’s bar on bombing North Vietnam directly, and began a series of bombing raids that hearkened back to the bomber raids of the Second World War. Ports, rail yards and industrial facilities of all kinds in North Vietnam came under heavy bombardment. An unfortunate first occurred for the B-52D on Nov. 22, 1972, when a North Vietnamese surface-to-air missile struck and damaged one, forcing it down. Fortunately, it was able to reach friendly territory and the crew escaped.
When the North Vietnamese delegation walked out of the Paris peace talks in mid-December 1972, Nixon ordered Operation Linebacker II, a massive concentrated strategic bombing campaign against North Vietnamese infrastructure that started on Dec. 18. Over an 11-day period some 741 sorties destroyed much of North Vietnam’s power generation and distribution infrastructure, a good fraction of its petroleum reserves and its desire to stay away from the peace talks. Soon after, they were back at the table in Paris and quickly reached an agreement to end hostilities.
B-52D bombers shot down during Operation Linebacker II
Unfortunately, surface to-air missiles brought down 15 of the bombers involved – the only B-52s lost to enemy action. The Soviet Union had provided a great many SA-2 ‘Guideline’ surface-to-air missiles and to defend against this threat the B-52Ds were equipped with an extensive suite of electronic countermeasures during the ‘Rivet Rambler’ programme of 1967 to 1969.
This included the addition of the AN/ALR-18 automated receiving set; the AN/ALR-20 panoramic receiving set; the AN/APR-25 radar homing and warning set; four of the AN/ALT-6B or AN/ALT-22 continuous wave jammers; two AN/ALT-16 barrage jammers; two AN/ALT-32H high- and one AN/ALT-32L low-band jammers; SIX AN/ALE-20 flare dispensers with 96 total flares, and eight AN/ALE-24 chaff dispensers with 1,125 bundles of radar disrupting chaff.
B-52D MiG kills during Operation Linebacker II
On the other hand, the December 1972 raids did also result in the only times when B-52s brought down enemy aircraft: B-52 tail gunners managing to shoot down two MiG-21 jet fighters. The last B-52 raids of the war occurred on Aug. 15, 1973; by the end, B-52D, F and G bombers had dropped some 2.63 million tons of ordnance on South East Asia.
Incredibly, the total destructive power contained within those tens of thousands of sorties, conducted over eight years, would have been equalled or surpassed by a single bomb of the type that the B-52 was actually meant to carry.
Perhaps ironically the B-52Ds with the Big Belly modifications used to bomb targets in Vietnam dispensed with the anti-flash white paintjob in favor of a gloss black underside. Here the risk of damage to the underside of the aircraft from a thermonuclear flash was minimal, but the risk of taking a missile or cannon fire from a North Vietnamese MiG was very real.
Landscapes hard to forget
The use of carpet bombing raids in Vietnam has been argued about for decades, both in terms of the moral justification for it and the actual tactical value it provided; but eyewitness testimony – including from Lowther’s own father – can attest to the fact that a number of B-52s, each laying down dozens of high explosive bombs on a stretch of jungle, resulted in landscapes that were hard to ignore or forget.
The last B-52D was retired in October, 1983.
Boeing B-47 Stratojets & B-52 Stratofortress Origins and Evolution is published by Mortons Books and is available to order here.
Photo credit: Senior Airman Carlin Leslie / U.S. Air Force