Murphy's Law: The Everlasting Evolving Bomber

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January 26, 2020: The U.S. Air Force has made official what had been a fifty year old reality; the B-52H bomber will no longer be considered capable of using nuclear bombs. Or, as it is officially described, “gravity bombs” which must be dropped from an aircraft that is right over the target. This reality was apparent back in 1969, with the cancellation of the B-70. This was a proposed replacement for the B-52 that was a lot more expensive but flew higher and faster to deliver nuclear gravity bombs. The B-70 was also much more expensive to operate and by 1969 it was obvious that ICBMs were the future, not manned aircraft. The long-range ballistic missiles were very difficult to intercept. Because they were based in underground silos or aboard nuclear subs, they made it much more difficult for an enemy to carry out a successful first strike or counterattack.

This did not make the B-52 obsolete because a few years later the air force found the B-52 was surprisingly effective carrying conventional bombs. Lots of them. B-52s could carry over a hundred non-nuclear 227 kg (500 pound) bombs that, when dropped in a pattern that creates a “carpet” of bombed-out terrain, had an impact superior to that of a nuclear weapon. Since there is no radiation created, friendly troops could immediately move in and occupy the torn-up terrain, often littered with the bodies of enemy troops and the wreckage of their equipment.

This effect was not a surprise to those air force officers who had seen the result of using a lot more B-17s (each carrying two dozen 500 pound bombs) carpet-bombing a German panzer division in a similar fashion. American troops rapidly moved in and encountered no opposition. Even Germans in bunkers were dead or dazed and not able to fight. The few who had survived the bombing completely had wisely fled the area to regroup elsewhere.

After World War II the air force never seriously considered adopting that successful July 1944 carpet-bombing tactic because the 1950s were all about nukes and the many ways to deliver them. Non-nuclear bombs dropped by a strategic bomber was an obsolete idea. But 21 years later in Vietnam, someone remembered and it was discovered that dozen or so B-52s could recreate the “panzer division killer” tactic and with the same impact on lots of irregular troops. From 1965 on the enemy was reluctant to concentrate a lot of forces for attack or defense lest they became a target of what came to be called “Arc Light” missions. Seven years later, when the last Arc Light of the Vietnam War was used, the B-52 was unofficially no longer a nuclear bomber but was kept in service in large part because of Arc Light. The nuclear mission was only possible because the B-52 could also carry cruise missiles. These one-ton weapons could be launched before encountering enemy air defenses and fly thousands of kilometers to deliver a conventional or nuclear warhead.

The ultimate tribute to the B-52 came in 2019 when the air force decided to retire its B-1B bombers, which were built in the 1980s, before the B-52Hs, which were built in the 1960s. It’s all about cost. One of the two older heavy bombers has to go because the new B-21 stealth bomber would enter service by the end of the decade. As part of that process, the B-1Bs will start to retire in 2025 and the last will be gone by 2035. The B-52s are to serve until the 2040s or even 2052, which will be a century after the first flight of the B-52.

The B-21 is supposed to be a more effective and cheaper version of the B-2 stealth bomber. The B-2 was so expensive that only 21 were built. The B-21 has to avoid the budget curse or be canceled or end up as updated and still way over budget B-2 replacement. The air force has established a tradition of over-promising and under-delivering that has created much less tolerance for projects that go way over budget and arrive very late as well.

B-21 is being built to quickly get to targets anywhere on the planet, avoid air defenses, and deliver conventional or nuclear weapons. The main job would be delivering conventional weapons, including standoff weapons against defended air space. Moreover, current stealth technology, which mainly renders radar much less effective, is vulnerable to growing improvements in heat detection systems which are already being primary sensors on some fighters (especially stealth ones that do not want to use a radar which tells everyone where it is). The B-21 won’t be cheap, at least not the way the B-52 was.

The B-52 survives because it entered service in the 1950s at a time when budgets and delivery schedules met. Moreover, the B-52 is an example of how an aircraft that has been declared obsolete several times survived because new technology or tactics kept the B-52 competitive. The B-52 was originally designed as a high-flying long-range bomber that could deliver a lot of unguided bombs, including nuclear ones. Better Soviet (Russian) air defenses (radars and missiles) appeared to make the B-52 obsolete as a strategic nuclear bomber, but then cruise missiles were invented that allowed a B-52 to launch these before entering defended Russian air space. Even before that the B-52 demonstrated (in the 1960s over Vietnam) that it was very effective at delivering conventional bombs and airdropped naval mines, even over defended air space thanks to new electronic warfare defenses.

The B-1A was developed in the 1970s as a low flying, high-speed replacement of the B-52 as a nuclear weapon bomber. It was canceled because of cost overruns and the belief that Russian air defenses were adapting to handle a fast, low flying B-1. In the 1980s the cruise missile used as a “standoff” nuclear-armed missile made possible the revival of the B-1 as a slower, higher-flying B-1B. After all, those B-52s were getting older. Age did not damage the slow-moving B-52 as much as it did faster-moving aircraft like the B-1B. But the B-1B did manage to use its greater speed to replace the B-52 in situations where only one or two heavy bombers were covering a large area (in Afghanistan or Syria/Iraq). One B-1B carrying only smart bombs and missiles one could get to where it was needed faster than a B-52 even though the B-1B still cost more per hour to operate. The B-52 is, however, aging more economically and reliably than the B-1B. Thus the B-1Bs will retire first.

Another factor is that the B-52, lacking the movable wings of the B-1, is easier to adapt to new technology. Thus it was a lot easier to use a targeting pod on the B-52 (just hang it from a wing) compared to the B-1 (where the installation was more expensive and time consuming). The one tech that made the most difference for the B-52 was the smart bomb. The appearance in the 1990s of GPS and other inexpensive guided missiles and bombs revolutionized the role of bomber aircraft. Far fewer bombs were needed to destroy a specific target. That meant even the F-15E fighter-bomber, which could carry six tons of bombs and missiles, because more effective than a heavy bomber carrying five or six times as many unguided bombs.

To remain competitive the B-52 and B-1B had to rely on new technology to keep up. A recent example of this occurred in late 2017 when B-52Hs used their latest upgrade, the CRU (Conventional Rotary Launcher) in combat for the first time. CRU enables a B-52 to carry eight large (or 34 small) JDAM smart bombs internally. The CRU itself is an accessory and not all B-52Hs will carry them. But all B-52s are being modified so the CRU can quickly be removed or installed and work with the fire control system. The CRU allows more smart bombs and missiles to be carried that are reprogrammable by the crew while in the air. This is essential for most B-52 missions, which simply provide smart bomb support for a large area (most of Afghanistan, all of Iraq and so on). With the CRU dozens of smart bombs can be launched quickly and that was recently done in an attack on multiple heroin production sites in southern Afghanistan. Similar tactics can be used against North Korean artillery and missiles units.

The CRU is one of several new features associated with the 1760 IWBU (Internal Weapons Bay Upgrade). The B-52H has long had a CSRL (Common Strategic Rotary Launcher) for the internal weapons bay but that was only for nuclear weapons. Without a rotary launcher installed the internal bomb bay carries unguided bombs. Since the 1990s the B-52H has been carrying smart bombs externally, attached to hardpoints under the wings. Carrying anything on those hardpoints creates aerodynamic drag during flight which increases fuel consumption and requires more inflight refueling to obtain the same time in the air.

The first CRUs were delivered for installing and flight testing in mid-2016. Testing and delivery of more CRU continued until it was used in combat over Afghanistan in November. CRU and the IWBU continue to be upgraded so CRUs can handle JASSM cruise missiles and MALD (Miniature Air Launched Decoy), a small missile which not only acts as a decoy but also carries electronics for jamming and or deceiving enemy sensors.

Since 2013 there has been a major upgrade in B-52 electronics and fire-control systems. These changes included CONECT (Combat Network Communications Technology) and 1760 IWBU (Internal Weapons Bay Upgrade). The IWBU was necessary to use CRU but both upgrade programs are being applied throughout the air force to provide standardization of communications and use of smart bombs.

Earlier upgrades enabled B-52 crew to program (enter GPS coordinates for a target) smart bombs carried. Initially, this was done so smart bombs carried under the wings could be programmed by the crew and later that was expanded to include those carried internally. This upgrade simply means wiring the bomb bay so that smart bombs can be plugged into the upgraded aircraft fire control system. This was important because that made it possible to carry other programmable weapons like the MALD and the JASSM (long-range smart bombs used for taking out enemy air defenses). By 2017 about half the B-52s had their bomb bay wiring upgraded.

Back in 2006, the B-52 was modified so it could carry over a hundred of the 130 kg (285 pound) Small Diameter Bombs (SDB, also known as the GBU-39/B). The bomb rack inside the B-52 was modified to carry 32 SDBs instead of 15 larger bombs. The B-52 could already carry more SDBs under its wings using special racks that held 4 SBDs where one larger bomb would normally be. Initially, all these SDBs had to be programmed (with target location) on the ground. This was all for mass precision strikes from one bomber, something that has not been required yet. The large bomb capacity of the B-52 was a 1960s innovation which enabled one B-52 to carry 108 500 pound unguided bombs for carpet bombing missions.

Until the programming upgrades, the SBDs carried internally had to receive their target coordinates on the ground, not in the air. The ability to enter or change GPS coordinates in smart bombs is necessary now because heavy bombers typically stay in the air over the combat zone for 8 hours or more at a time, delivering smart bombs as needed by troops on the ground. The B-52 also has its own targeting pod now that enables the crew to spot targets, program one of its smart bombs, and take them out without needing GPS coordinates from someone on the ground.

Despite being the oldest American combat aircraft in service, the B-52s have been regularly upgraded with new electronics and minor tweaks for new bombs. For example in mid-2017 the B-52H was certified as able to use PDU-5 leaflet bomb. This is a variant of the cluster bomb long carried by B-52s. But instead of dispersing 247 bomblets from a larger canister the PDU-5 disperses 60,000 leaflets over several square kilometers. The PDU-5 has been used regularly since 2001 to warn people (usually in target areas) that a bombing or artillery attack is coming. Normally PDU-5s are delivered by jet fighters but helicopters have been used and the test drops from the B-52H is to ensure that there are no problems with the bomb colliding with the aircraft once dropped. The B-52H PDU-5 test wasn’t an upgrade as much as a standard safety check. As with the CRU, the B-52H isn’t able to use a newly installed feature until after several tests followed by use, if possible, in a combat zone.

Another reason for the longevity of the B-52 has been its reliability and relatively low maintenance cost. The B-52H has a better reliability record than much more recent aircraft and much smaller aircraft. For example, the U.S. Air Force mission capable or “readiness rate” (percentage of available aircraft able to do their job) varies by type and technology. Age has less to do with it than you might think. As of 2015, the B-52H rate was 72 percent compared to 47 percent for the B-1B heavy bomber and 71 percent for the F-15E fighter bomber.

With all these upgrades since the 1990s there was little mention of nuclear weapons, expect an occasional mention that the B-52 fire control system was still capable of handling nuclear gravity bombs. Which are basically dumb bombs with some capability to have the altitude of detonation adjusted but not much else. The B61 300 kg and B83 1.1 ton nuclear bombs look just like another dumb bomb filled with high explosives. The B-52 bomb racks must be able to accept and release these two bombs and that is a simple bit of engineering. As a practical matter, the air force appears to have abandoned the B-52 as a nuclear gravity bomb delivery system over a decade ago.

At the same time, the greater bomb carrying capability makes the B-52 even more effective, as it is cheaper to have one "bomb truck" over the combat zone rather than several fighter-bombers. With a max takeoff weight of 240-250 tons the BUFF (Big Ugly Fat Fellow) is basically a large aircraft designed to carry bombs cheaply and efficiently. The readiness rate of these bombers remains high because it was not designed to operate at supersonic speed or carry out stressful maneuvers. Although the remaining B-52s are all at least 50 years old, most of the internal gear has been replaced with modern electronics and furnishings. It’s all flat screens and modern gear. Look closer and you see a lot of 50 year old metal.

 


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