Boeing NB-47E Stratojet
The USAAF began research into a jet bomber as early as 1943, issuing a specification for an all-jet bomber that could fly at 550 mph at 45,000 feet with a range of 3500 miles. Boeing, Consolidated, North American and Martin all submitted proposals, all with conventional straight wings and wing-mounted jets. Boeing’s proposal had six engines in the forward fuselage to lower drag, which the USAAF rejected as a fire hazard. Work stalled on the project until after the war ended in Europe and American engineers discovered German research into swept wings. This solved a myriad of problems, and Boeing was able to move the engines into pods beneath the wing, with four of the engines in two pylon-mounted pods and the other two slung under the wingtips. The USAAF accepted this design as the XB-47.
The first XB-47 Stratojet was flown in December 1947, and was so revolutionary that test pilots were apprehensive about flying it. The wing was very thin to reduce drag, and would flex as much as five feet up and down; because of the thinness of the wing, the landing gear was mounted in tandem in the aircraft, in a position that the XB-47 would be at the right angle for takeoff while sitting still. It was also fast, exceeding the original specification by 50 mph. In early test flights, the XB-47 regularly outran chase aircraft.
If anything, the Stratojet was too fast: it had such a high landing speed that Boeing had to attach a dragchute, and more or less invent anti-lock brakes to slow it down. In contrast, it was sluggish if attempting a fully-loaded takeoff, and eventually (in the B-47E), water injection was added along with provision for Jet-Assisted Take Off (JATO) rocket bottles to get it into the air more efficiently. Once in the air, however, the B-47 flew magnificently, and its speed was such that it only had twin 20mm cannon in the tail for defense.
Though it did not have the bombload of the earlier B-36 Peacemaker and its successor, the B-52 Stratofortress, the B-47 bridged the gap between the two. To compensate for lesser range (mitigated by aerial refueling), B-47s were based in a ring around the Soviet Union, from freezing Thule AB in Greenland to sweltering Sidi Slimane in Morocco. As Soviet defenses became more potent, the B-47 force was switched from high-level bombing to low-level penetration, using the Stratojet’s speed to dash to the target, snap upwards into a climb, and literally toss a nuclear bomb onto its target; besides giving defenses less time to react, it also bought time for the B-47 to escape the nuclear shockwave. It also shortened the lifespan of the Stratojet force, leading to an extensive refit program in 1958 to repair the damage done to wing spars and airframes.
By the early 1960s, the stress of low-level flight and newer designs, as well as improvements in missile design, had rendered the B-47 largely obsolete. The last bomber B-47Es were retired by 1965, followed by the RB-47H and EB-47L by 1969. Only a handful of test aircraft remained until the type’s final grounding in 1977. Of 2032 B-47s built, only 32 survive today in museums.
B-47E 53-2104 was delivered to the USAF's 310th Bomb Wing at Smoky Hill AFB, Kansas in 1954, and remained there until it was modified to a NB-47E experimental testbed in either 1960 or 1965, possibly operating from Edwards AFB, California, and in 1969 was loaned to the US Navy. A pylon was installed outboard of the left wing main engine pod, and various engines were mounted on the pylon for testing; 53-2104 carried a TF34 turbofan that was being tested for the S-3 Viking program. When it was finally retired in 1977, 53-2104 was the last operational B-47 in the world. It was stored for a time at MASDC before being donated to the Pueblo Weisbrod Museum in the 1980s.
Today, 53-2104 shows a little wear and tear from being out in the open, but is still in good shape. (There has even been talk of restoring it to flight status, given when it was finally grounded, though this would be extremely expensive to do.) Interestingly enough, it still technically belongs to the US Navy. According to one of the docents, the museum found some spare tires for the aircraft from USAF stocks, and planned to install them on 53-2104, but learned they had to have Navy permission before doing so!
As a NB-47E, it lacks tail guns, and the engine test pylon can be made out between the left wing's engines, though it's hard to see against the trees. This picture was taken in June 2020.
Boeing NB-47E Stratojet
The USAAF began research into a jet bomber as early as 1943, issuing a specification for an all-jet bomber that could fly at 550 mph at 45,000 feet with a range of 3500 miles. Boeing, Consolidated, North American and Martin all submitted proposals, all with conventional straight wings and wing-mounted jets. Boeing’s proposal had six engines in the forward fuselage to lower drag, which the USAAF rejected as a fire hazard. Work stalled on the project until after the war ended in Europe and American engineers discovered German research into swept wings. This solved a myriad of problems, and Boeing was able to move the engines into pods beneath the wing, with four of the engines in two pylon-mounted pods and the other two slung under the wingtips. The USAAF accepted this design as the XB-47.
The first XB-47 Stratojet was flown in December 1947, and was so revolutionary that test pilots were apprehensive about flying it. The wing was very thin to reduce drag, and would flex as much as five feet up and down; because of the thinness of the wing, the landing gear was mounted in tandem in the aircraft, in a position that the XB-47 would be at the right angle for takeoff while sitting still. It was also fast, exceeding the original specification by 50 mph. In early test flights, the XB-47 regularly outran chase aircraft.
If anything, the Stratojet was too fast: it had such a high landing speed that Boeing had to attach a dragchute, and more or less invent anti-lock brakes to slow it down. In contrast, it was sluggish if attempting a fully-loaded takeoff, and eventually (in the B-47E), water injection was added along with provision for Jet-Assisted Take Off (JATO) rocket bottles to get it into the air more efficiently. Once in the air, however, the B-47 flew magnificently, and its speed was such that it only had twin 20mm cannon in the tail for defense.
Though it did not have the bombload of the earlier B-36 Peacemaker and its successor, the B-52 Stratofortress, the B-47 bridged the gap between the two. To compensate for lesser range (mitigated by aerial refueling), B-47s were based in a ring around the Soviet Union, from freezing Thule AB in Greenland to sweltering Sidi Slimane in Morocco. As Soviet defenses became more potent, the B-47 force was switched from high-level bombing to low-level penetration, using the Stratojet’s speed to dash to the target, snap upwards into a climb, and literally toss a nuclear bomb onto its target; besides giving defenses less time to react, it also bought time for the B-47 to escape the nuclear shockwave. It also shortened the lifespan of the Stratojet force, leading to an extensive refit program in 1958 to repair the damage done to wing spars and airframes.
By the early 1960s, the stress of low-level flight and newer designs, as well as improvements in missile design, had rendered the B-47 largely obsolete. The last bomber B-47Es were retired by 1965, followed by the RB-47H and EB-47L by 1969. Only a handful of test aircraft remained until the type’s final grounding in 1977. Of 2032 B-47s built, only 32 survive today in museums.
B-47E 53-2104 was delivered to the USAF's 310th Bomb Wing at Smoky Hill AFB, Kansas in 1954, and remained there until it was modified to a NB-47E experimental testbed in either 1960 or 1965, possibly operating from Edwards AFB, California, and in 1969 was loaned to the US Navy. A pylon was installed outboard of the left wing main engine pod, and various engines were mounted on the pylon for testing; 53-2104 carried a TF34 turbofan that was being tested for the S-3 Viking program. When it was finally retired in 1977, 53-2104 was the last operational B-47 in the world. It was stored for a time at MASDC before being donated to the Pueblo Weisbrod Museum in the 1980s.
Today, 53-2104 shows a little wear and tear from being out in the open, but is still in good shape. (There has even been talk of restoring it to flight status, given when it was finally grounded, though this would be extremely expensive to do.) Interestingly enough, it still technically belongs to the US Navy. According to one of the docents, the museum found some spare tires for the aircraft from USAF stocks, and planned to install them on 53-2104, but learned they had to have Navy permission before doing so!
As a NB-47E, it lacks tail guns, and the engine test pylon can be made out between the left wing's engines, though it's hard to see against the trees. This picture was taken in June 2020.