With the youngest B-52 turning 56 this year, Boeing looks at updating the big bomber.
By John Likakis
First flown in 1952, the B-52 entered service with the U.S. Air Force in 1955. Production of the big eight-engine bomber continued for only 7 years after that, with the last B-52 coming off Boeing’s assembly line in October 1962.
In what has to be one of aviation’s most astounding design successes, Boeing’s big bomber continues in service more than half a century later. And the U.S. Air Force is planning, or rather counting, on keeping the airplane in service for at least another 30 years. As of this writing, the seventy-six big Boeings still flying with the Air Force constitute nearly half of the U.S. bomber force.
But no airplane can sustain the wear and tear of 6 decades of continuous service without running into problems. Metal fatigue, corrosion, and even simple chafing between parts, as the airplane heats and cools, all can add up to loss of performance and, if not corrected, even loss of the aircraft.
Then there’s the simple fact that avionics and electronics have come a long way since 1962. Yes, the airplane’s systems have been updated periodically. But after a certain point, it becomes uneconomical to update systems piecemeal.
Boeing and the U.S. Air Force are both keenly aware of all of these things. For years, Boeing has been keeping a close eye on the B-52, monitoring its maintenance and performance. More recently, the company has been working with the Air Force to develop a comprehensive B-52 overhaul and modernization program.
If all aspects of the program are completed, Boeing’s biggest bomber should continue in active service well beyond the year 2050. That means that the B-52 may well become one of only two designs still in service a century after being introduced. (The other would be Lockheed Martin’s C-130 Hercules.) In fact, it may even become the only design ever to have examples of 100-year-old airframes still flying operational military missions.
The important questions are: What kind of age-related issues is Boeing dealing with? And how are those problems being mitigated?
According to Boeing, the current B-52 fleet has many decades left in its predicted service life in terms of flight hours. While an average commercial airliner might average 3,000 flight hours per year, the B-52’s average is on the order of 250 hours. So despite the calendar age of the airframes, they have not accumulated worrisome numbers of hours in the air.
Boeing also notes that the U.S. Air Force conducts heavy maintenance on each B-52 on a regular cycle, with an approximate 4-year interval between visits to Programmed Depot Maintenance. Boeing partners with the Air Force in monitoring and inspecting the B-52 fleet for stress-corrosion cracking, which is the most likely cause of significant airframe distress on aircraft of this vintage. Numerous preventative maintenance actions are being employed and continue to be further developed to ensure this age-related threat does not impact the fleet’s mission readiness.
An example of such preventative measures is a set of procedures that will be prototyped on a B-52 at Boeing’s San Antonio facility. The process is extensive, but will restore some of the aircraft’s coatings that serve to impede corrosion. It also will give maintainers a chance to inspect some areas of the airframe that do not normally get much attention. According to Boeing, the process does involve disassembly to provide access to key airframe components to enable restoration of the corrosion prevention barrier. Generally, the restoration will involve stripping, re-priming, and re-painting those components.
The B-52 has always been a systems-intensive aircraft. Back when the B-52 was new, vacuum tubes powered much of the equipment. Modern electronics now pack a whole lot of amazing computing power into tiny boxes. (The average smartphone puts more computing power in your back pocket than was featured in the entire electronics suite of the original B-52.)
Boeing is involved in numerous upgrades in the B-52. It developed the B-52 Combat Network Communications Technology (CONECT) system, which provides communications and situational awareness upgrades, and is currently being installed in the B-52 fleet. With its high-speed network and general-purpose computing resources, CONECT implements a solid architectural foundation for additional upgrades. A follow-on to CONECT is the integration of Link 16 capability, which was initiated in 2017. Other communications upgrades that also exploit the CONECT foundation are anticipated in the near term.
Also initiated this year was the B-52 Radar Modernization Program. It will replace the existing radar with modern radar, with the intent to leverage an already developed radar system. In addition, Boeing is upgrading legacy computational systems that support such functions as the Global Positioning System interface and targeting pod control.
According to Boeing, engine overhaul costs have skyrocketed as the engines have aged. In 1996, an overhaul cost about $236,000. The same overhaul costs upwards of $2 million today, mostly due to the need to replace more critical components, such as turbine wheels and high-pressure fans, on engines that have been out of production for decades. The way Boeing sees it, upgrading the B-52 to brand-new engines will eliminate overhaul costs, because such new engines presumably will not accumulate enough hours over the next 35 years to require an overhaul.
Boeing supports the U.S. Air Force in its efforts to modernize the B-52 propulsion system. In fact, a re-engine program is viewed as a crucial element to keeping the fleet viable and mission-ready through 2050 and beyond. New engines will significantly improve operational capabilities and save taxpayer dollars through reduced maintenance costs and increased fuel efficiency. They also will deliver significant environmental benefits in terms of carbon footprint and noise reduction. The proposed re-engine program would replace the engine core, as well as the struts, nacelles, fairings, engine accessories, and engine instruments — that is what makes it a complete solution.
According to B-52 Program Director James Kroening of Boeing, the company “has studied both four- and eight-engine configurations and determined a commercial, eight-engine solution provides the greatest efficiency and the lowest technical risk to the program. Beyond that, no determination has been made with regard to the specific replacement engine.”
Despite both Boeing and the U.S. Air Force saying they have not even begun selection of a replacement engine, there is no shortage of speculation about some possible replacements for the venerable Pratt & Whitney TF33 turbofans that currently power the bomber. Two of the most-discussed engines are a variant of the Rolls Royce BR725 engine and a version of Pratt & Whitney’s PW800. At a glance, both of these powerplants seem like reasonable candidates, as they meet the dimensions and thrust requirements.
The B-52 already has the ability to drop more than 100 conventional bombs at a time: during Vietnam, B-52s flying Arc Light strikes routinely dropped as many as 108 of the then-current 500- and 750-pound bombs per airplane. The B-52 was modified to carry (and drop) all sorts of things before that war, and the airframe has been continually modified, updated, tweaked, and groomed to handle just about anything the U.S. Air Force cares to drop, lob, or fire at an adversary.
The latest addition to the munitions inventory is the small-diameter bomb (SDB). The SDB is still fairly new to the arsenal, and many frontline aircraft are still in the process of undergoing testing to make sure the bombs separate cleanly and safely from the aircraft.
We asked Boeing if the B-52 would be outfitted to deliver SDBs. According to a Boeing spokesperson, “the USAF has not yet initiated integration of the Small Diameter Bomb on the B-52. However, its potential future integration will not present conflict with other payloads, as the B-52 has always been and continues to be capable of carrying a wide array of weapons, and can do so in combinations as circumstances require.”
Not Ready to Retire
For more than 60 years, Boeing’s big bomber has been a mainstay of America’s force mixture. It has proven to be rugged, reliable, and astonishingly adaptable to weapons and roles the original designers could never have imagined.
When Boeing’s engineers first started sketching the outlines of the B-52, their counterparts at other companies were just beginning work on what became the Century Series of fighters — the F-100 Super Sabre, F-101 Voodoo, F-102 Delta Dagger, F-104 Starfighter, F-105 Thunderchief, and the F-106 Delta Dart. None of those airplanes are still in service. But the B-52 continues flying, fighting, and serving the country. And it looks like it will be the world’s first Centenarian Bomber.
Image #1 – A B-52 Stratofortress deployed to Andersen Air Force Base, Guam, stands ready for its next mission. Bombers deployed from the 2nd Bomb Wing at Barksdale AFB, LA., provide a continuous bomber presence in the Asia-Pacific region. (Courtesy of U.S. Air Force. Photo by Senior Master Sgt. Don Perrien.)
Image #2 – A B-52 from the 2nd Bomb Wing banks right during a Combat Hammer mission at Hill Air Force Base, Utah. Combat Hammer is an air-to-ground Weapons System Evaluation Program maintained by the 86th Fighter Weapons Squadron. (Photo courtesy of the U.S. Air Force)
Image #3 – Aerial refueling gives the B-52 the ability to fly nearly anywhere on the globe, or maintain in-the-air combat readiness as many of the big bombers did during the Cold War
Image #4 – Members of the 2nd Maintenance Squadron wait to tow a B-52 at Barksdale Air Force Base, LA. A0049 was part of Operation Allied Force in 1999, meant to ensure an ending to all military action, violence and repression in Kosovo and a withdrawal of Serbian military, police and paramilitary forces. (Photo courtesy of the U.S. Air Force.)
Image #5 – Back in the 1960s, when Lockheed needed to flight-test the D-21 drone, it used the B-52 to carry the prototype aloft. (Photo courtesy of the U.S. Air Force)
Image #6 – One of the keys to keeping the B-52 flying to midcentury will be replacing its engines. This B-52 trails lots of smoke created by the excess fuel that must be fed to the old TF33 engines in order to cool the turbine sections. Newer engines would eliminate this, while increasing overall efficiency by as much as 40 percent. (Photo courtesy of the U.S. Air Force)