The B-52 was first designed as a turboprop driven version of the B-36 in 1948, but it never got off the drawing board. It was not until 1951 that the B-52A was cleared for limited production, in fact only three were built. It went through numerous design and equipment modifications with the B-52H being the final model. A total of 744 B-52's of all types have been built.

The crew of the B-52H was originally six. The pilot and co-pilot sat side-by-side on the upper flight deck, with the pilot on the left. Behind them on the upper flight deck were the electronic warfare officer and the gunner, seated side-by-side and facing to the rear. All four of these crew members sat in upward-firing ejector seats. These seats do not have zero-zero capability, but are good at 165 km/hr and zero altitude. The radar navigator who was responsible for weapons delivery and for guiding the aircraft past terrain while flying at low altitude, plus the navigator who was responsible for getting the aircraft from point A to point B, both sat side-by side on the lower fuselage deck, facing forward. Both of these crewmen sat on downward-firing ejector seats. These downward-firing seats are cleared for operation at speeds as low as 220 km/hr at a minimum altitude of 250 feet.

The most noticeable difference between the B-52H and earlier versions was the replacement of the water-injected J57 turbojet engines by Pratt & Whitney TF33-P-3 turbofans. The TF33 engines of the B-52H offered 30 percent more thrust than the J57s of the G-model, even when the J57s were using waster injection. A maximum thrust of 17,100 pounds could be delivered, producing much better airfield performance and an extra margin of safety during heavyweight takeoffs. The use of the new engines markedly altered the appearance of the nacelles. It was quite easy to tell the difference between previous types and a B-52H. The TF33 engine had a larger forward compression stage than the J57, which required a larger-diameter intake and a by-pass air outlet.

The TF33 was much cleaner and quieter when operating at full power and was much quieter, which results in a less-noisy cabin and a corresponding reduction in crew fatigue. The TF33 was also much more economical, offering a notable improvement in range. Combat radius of the B-52H was 4176 nautical miles with a 10,000 pound bomb load.

The defensive tail armament was changed. The quartet of 0.50-inch machine guns carried by earlier versions was replaced by a single Gatling-like General Electric M61 20-mm six-barrelled rotary cannon. The maximum firing rate was 4000 rounds per minute.

The B-52H was provided with equipment intended to make low-altitude operations safer and easier on the crews. The new systems provided relief from the tremendous strain posed on pilots and navigators in flying at low altitudes at high speeds for long periods of time. An advanced capability radar was fitted which could give three- dimensional information using a video display on the pilot's and navigator's instrument panel. The height of the terrain was shown continuously at selected distances of three, six or ten miles ahead of the aircraft. The pilot could select either a PLAN mode which gave a map-like display or a PROFILE mode which showed the terrain height at various ranges ahead of the aircraft. In order to assist the pilot in flying at low level, control wheel steering was built into the autopilot. This reduced the amount of control forces and the frequency of control movements required to fly the aircraft. In October of 1991, the gunner's station was removed as an economy measure, reducing the crew complement to only five. The gunner's ejector seat was, however, retained and can now be occupied by an instructor or flight examiner who often goes along on training missions.

The B-52H has eight Pratt & Whitney TF33-P-3 turbofans, each rated at 17,000 pounds thrust for takeoff. It has a maximum speed 632 mph at 23,800 feet, 603 mph at 35,000 feet, slowing to 560 mph at 46,650 feet. Its operational cruising speed is 525 mph and a stalling speed 169 mph. The B-52H's service ceiling 47,700 feet with a combat radius of 4825 miles with 10,000 pound bombload. The take-off ground run for takeoff over a 50-foot obstacle is 9580 feet. With a length 156 feet 0 inches, the B-52H has a wingspan of 185 feet 0 inches, a height of 40 feet 8 inches with a wing area 4000 square feet. It weighs 172,740 pounds empty, 306,358 pounds combat and 488,000 pounds is its maximum takeoff weight. In a conventional conflict, the B-52 can perform strategic attack, air interdiction, offensive counter-air and maritime operations. During Desert Storm, B-52s delivered 40 percent of all the weapons dropped by coalition forces. It is highly effective when used for ocean surveillance and can assist the U.S. Navy in anti-ship and mine-laying operations. Two B-52s, in two hours, can monitor 140,000 square miles (364,000 square kilometers) of ocean surface.

Today, the B-52H is the only version of the Stratofortress still in service, with all previous versions having either been consigned to storage or scrapped. It is likely that the B-52H will still be in service well into the 21st century.

Michael Russell

Your Independent guide to Aviation