October 10, 2022: The U.S. Air Force has finally determined that all the upgrades to the B-52H will require a new designation (B-52K and B-52K). The B-52G became the B-52H in 1961 when the then-new TF33 engines were installed.

The B-52H, the oldest and most useful American heavy bomber, is once more getting new engines, after using the TF33 since 1961. The new Rolls Royce engines will lower operating costs and extend the useful life of the B-52H into the 2060s, meaning these aircraft will have served for a century. The new engine is the Rolls Royce F130, the military version of the BR700. The BR700 weighs the same (two tons) as the current B-52 engine and over 3,700 have been built since 1995. Some BR700s replaced the TF33 on civilian aircraft but most sales were for new long-range twin-engine business jets. Many of these, like the Gulfstream 500/550, have been used in twin-engine versions of the American four-engine AWACs based on the B-707 air transport. Each F-130 is powerful enough to replace the two-engine TF33s on each of the four engine pylons.

An updated version of the current TF33 engines for the B-52H was proposed, but the air force determined that BR700 was a major upgrade of RF33-type engines, which were losing market share to these new designs. The current TF33 engine is the military version of the JT3D still used on civilian aircraft and is still in production with over 8.600 RF33/JT3Ds built since 1958. The only remaining customers (for replacement engines) for the TF33 are the B-52H and the E-3 AWACS, which is based on the Boeing 707. The B-52 uses eight while the E-3 uses four. Despite regular upgrades, the basic design of the TF33 is getting old and, along the with aircraft it was used on (DC-8 Boeing 707 and military versions like the KC-135), these older four engine jets are being replaced by twin engine jets, often using BR700s, a design that design that is inherently more efficient and cheaper to operate and maintain. The new engines cost about $4.3 million each and all 76 of the current B-52H aircraft will receive this replacement by 2038. In addition, the air force is purchasing 42 spare engines.

The air force has been seeking B-52H replacement engines for over two decades. Initial proposals called for replacing the eight engines on each B-52 with four larger turbofans as used on commercial aircraft for over fifty years. These larger and more recently introduced engines were designed to use less fuel, which became a major factor in the 1970s and ever since. The TF33s were tweaked to use less fuel and match other new user demands and this was enough to keep them in production. The TF33 is still less fuel-efficient than later designs like the F130 and the air force uses F130s in smaller transports because of that.

Another major factor in finally deciding to upgrade to an engine that has been around since the late 1990s was the growing use of computerized design of aircraft components and the ability to accurately test changes in aircraft using this software. Many modern civilian and military aircraft are designed entirely on computers and this has become reliable enough successfully to test proposed upgrades or design changes. This turned out to be a major factor in keeping the elderly B-52 going for so long. Designed in the 1950s, when it was all done on paper with slide rules or computers with less computing power than the average smartphone of today, more allowances had to be made for miscalculation. Aircraft designers in the 1950s tended to heavily “over-engineer” their designs, especially military aircraft. Just how over-engineered the B-52 was, came to light when the air force began using these computerized design tools to design upgrades or repairs for the B-52. A lot of money was saved on upgrades when the actual sturdiness of B-52 components was measured using these new tools. This led to more affordable and reliable upgrades for the B-52 over the last decade. This included some major changes, starting in 2013 with a major upgrade to digital communications. At the same time a redesign increased the number of guided bombs and missiles carried and allowed them to be carried internally as well as suspended from the wings. One of the shortcomings of underwing weapons pylons was that for larger missiles this created a lot more aerodynamic drag during flight. This increased fuel consumption, reduced flight endurance and caused wings to age more quickly. The B-52 was designed to carry a lot of weight. The aircraft itself weighs 83 tons but can carry up to 126 tons of fuel, bombs and cargo.

In 2014 B-52s began receiving upgrades of their communications to the digital CONECT (Combat Network Communications Technology) standard. That meant high-speed transfer of data. That made it possible to install glass cockpit tech. That meant several flat screen displays replacing a lot of mechanical switches and analog gauges. The flat screens can also display full color images, which can be updated via the CONECT tech. These technologies were expanded and upgraded in the B-52 over the next few years,

Many upgrades, like the internal rotary launcher, were made possible as B-52Hs were upgraded to use GPS guided (smart) bombs and that upgrade included major upgrades to the aircraft electronics. This meant new radars and a digital cockpit. The new electronics enabled the B-52H to use satellite communications and the Sniper targeting pod. Targeting pods enabled fighter or bomber pilots to get a close look at what was on the ground while still high enough (6,4000 meters/20,000 feet) to be immune to most ground fire. The new electronics also included improved warning of enemy SAMs (Surface to air Missiles) and jamming equipment to avoid getting hit.

Before the decision to replace the engines, B-52Hs were expected to remain in service until 2045. With the new engines, B-52s would maintain their status as the least expensive heavy bomber to operate. It held on to that record until 2011 when the upgraded B-1B pulled ahead for a few years while B-52 operating expenses increased. After that the B-52H was able to maintain its flight costs per hour while those of the B-1B began going up until both cost about $70,000 per flight hour. The B-1B is a 1980s design that did not age as efficiently as the B-52H it was designed to replace. Now B-1Bs are being retired and all will be gone from active service by 2036. The air force is building a new, less expensive to build and operate, B-21 stealth bomber to replace the existing B-2 stealth bomber which was so expensive that only 21 could be purchased. The B-2 cost nearly twice as much per flight hour as the B-52H. The B-21 is supposed to be less expensive per flight hour, at least compared to the B-2. The upgraded B-52K will still be the best bomber for the job in many cases.

If the air force can achieve its goal of lower development and manufacturing costs, they will be able to buy at least a hundred B-21s. The first of these is expected to enter service by 2030 and for the next two or three decades it will serve along the B-52K, but not as a replacement for it. Nothing can replace the B-52 because it was a sturdy design that proved very adaptable to new technologies, especially the smart bombs and all the new electronics. Smart bombs have been around since the 1970s using laser guidance but the major revolution came with JDAM, which showed up three decades ago. GPS guidance was far more effective than expected and much cheaper than the 1970s laser guided bombs. The B-52H was the perfect “bomb truck” once it could handle JDAMs. One B-52H in the air could handle ground support for large areas, like all of Iraq or most of Afghanistan and provide the ground troops with reliable 24/7 close support. There were proposals to replace the B-52H with military or commercial transports converted into bomb trucks. These proposals were too expensive when the over-engineered B-52Hs kept flying. Like the DC-3/C-47 twin engine transport, which is closing in on a century of service, mainly as a commercial transport, the B-52H is a unique warplane that is doing the same thing but as a competitive warplane from the beginning.

Getting to B-52K means more than new electronics and engines. The B-52 is getting a modern APG-79 radar, the same one used by the F-18E carrier-based fighter aircraft. On the B-52 this AESA radar will be installed so that it looks down, not to the front. This will improve the ability of the aircraft to identify targets on the ground. Another upgrade for most, if not all B-52s is the On-Board Cargo System. Modifications are made in the bomb-bay so up to three special cargo containers in bomb-bay. Each container can hold up to 2.3 tons of supplies, tools or spare parts. This is useful when a few B-52s are removed to a new base that is not equipped to not handle B-52s. The maintainers can be brought as passengers (B-52s can accommodate five) or one of the business jets the air force has for such operations. This capability means a few B-52s can be sent anywhere and put to work.

The air force sees the B-52 as well worth all this investment in new equipment and capabilities. Another advantage of the B-52 is that even with the oldest (and no long made) spare parts, B-52 always had a ready supply at AMARC (Aerospace Maintenance and Recovery Center). This is where still flyable warplanes are retired, for use as spare parts and eventual scrapping or, if they are stored at a higher level of readiness (Type 1000 storage), for rapid restoration to flight status and a return to active duty.

This points out one of the major problems with modern warplanes; that some models have remained in service far longer than anyone expected. This happened partly because modern aircraft are built to last, and used engineering advances that worked out better than expected. Engineers tend to overbuild when they can or must. For example, commercial transports are very sturdy beasts, as they have to fly up to 12 hours a day for weeks at a time. Military aircraft fly less often, although their sturdiness is also meant to deal with the violent maneuvers of combat. But heavy bombers and transports can go on and on, as they don't fly as much as the civilian transports. The basic technology bombers and transports are based on hasn't changed much. The best example is the B-52 bomber, which entered service in the 1950s and the ones still flying were built over fifty years ago. Another example of older but still flyable aircraft are the hundred or so DC-3 civilian transports that began flying in the 1930s.

Most warplanes are in production for a decade or less. Once the manufacturing stops, it starts to become difficult to get spare parts. The tools and equipment used to make the aircraft components are usually scrapped. Making the parts from scratch is so expensive that it is often cheaper to scrap aircraft and buy a new design. But a new aircraft is often more than the budget can bear as well. The solution to this problem is cannibalization. That is, using some aircraft, either those wrecked in accidents or older models retired to the "boneyard", just for spare parts. This has been a practice in combat from the very beginning of military aviation. Especially during World War I, when far more aircraft were lost to bad landings and takeoffs than to enemy action. Such wrecks became a source of replacement parts for airframes and engines of aircraft still in service. The most efficient boneyard in the world is America’s AMARC. While some of the aircraft stored there are recalled to active service every year, all are liable for disassembly to provide parts for aircraft that are still flying. But other nations with smaller boneyards and more urgent needs can take the basic boneyard concept as far as they can get away with.

AMARC fills 500-2,000 spare parts orders each month. Not just for American aircraft, but for those of allies as well. Australia kept its 1960s era F-111's flying with spare parts from old U.S. F-111s stored at AMARC. The U.S. Air Force A-10, built in the 1970s, and not a popular air force candidate for a new model, is kept flying (because it's so damn useful) with parts from AMARC. Even when parts are still in production, a wartime surge, as was experienced during the Afghanistan campaign will outstrip the manufacturer's ability to produce them. In this case, AMARC delivered parts for the F-18 and continues to do so for other heavily used aircraft.

Even with the development of 3-D parts printing for metal parts there are still parts the 3-D printer cannot easily produce. In that case, AMARC is still relevant. AMARC was set up in 1985, consolidating boneyard operations already there and from other locations in the United States. In that first year, it delivered spare parts worth half a billion dollars. While the airframes, stripped of all their more valuable parts, are worth only about 25 cents a pound as scrap, some of the parts are worth their weight in gold. Engines, which often comprise a third (or more) of an aircraft's value, are the most valuable single items. And each engine consists of thousands of parts, some of which are worth quite a bit, even if the engine is no longer in use by any aircraft. Other nations cannibalize their retired or obsolete warplanes, but few have organized the operation as efficiently as the United States.