On the night of 4–5 February 1958, two Boeing B-47 Stratojet bombers from MacDill Air Force Base, Florida, were flying a simulated bombing mission. The second bomber, B-47B-50-BW serial number 51-2349, was under the commander of Major Howard Richardson, USAF, with co-pilot 1st Lieutenant Bob Lagerstrom and radar navigator Captain Leland Woolard. Their call sign was “Ivory Two.”
Carried in the bomb bay of Ivory Two was a 7,600-pound (3,448 kilogram) Mark 15 Mod. 0 two-stage radiation-implosion thermonuclear bomb, serial number 47782. The bomb had an explosive yield of 1.69–3.8 megatons.
After completing their simulated bombing mission, the B-47s were returning to their base in Florida.
On the same night pilots of South Carolina Air National Guard were on alert at Charleston Air Force Base with their North American Aviation F-86L Sabre interceptors. The fighters were fully armed with twenty-four 2.75-inch (70 mm) rockets. At 00:09 a.m., the pilots were alerted for a training interception of the southbound B-47s. Within five minutes three F-86Ls were airborne and climbing, with air defense radar sites directing them. In of of the F-86Ls, 52-10108, an upgraded F-86D Sabre, was 1st Lieutenant Clarence A. Stewart, call sign “Pug Gold Two.”
The flight of interceptors came in behind the bombers at about 35,000 feet (10,668 meters). Tracking their targets with radar, they closed on the lead B-47, Ivory One, from behind. Ivory Two was about 1 mile (1.6 kilometers) in trail of Ivory One, but the airborne radars of the Sabres did not detect it, nor did the ground-based radar controllers.
At 00:33:30, 5 February, Lieutenant Stewart’s fighter collided with the left wing of Major Richardson’s bomber. The Sabre lost both wings. Lieutenant Stewart fired his ejection seat. His descent from the stratosphere took twenty-two minutes and his hands were frostbitten from the cold. He spent five weeks in an Air Force hospital. Pug Gold Two crashed in a farm field about 10 miles (16 kilometers) east of Sylvania, Georgia.
The B-47 was heavily damaged. The outboard engine had been dislodged from its mount on the wing and hung at about a 45° angle. The wing’s main spar was broken, the aileron was damaged, and the airplane and its crew were in immediate jeopardy. If the number six engine fell free, the loss of it’s weight would upset the airplane’s delicate balance and cause it to go out of control. The damaged wing might itself fail, and the damage to the flight controls made it difficult to fly.
Major Richardson didn’t think they could make it back to MacDill, and the nearest suitable airfield, Hunter Air Force Base, Savannah, Georgia, advised that the main runway was under repair. A crash on landing was a likely outcome.
With this in mind, Richardson flew Ivory Two out over Wassaw Sound, and at an altitude of 7,200 feet (2,195 meters) the hydrogen bomb was jettisoned. It landed in about 40 feet (12 meters) of water near Tybee Island. No explosion occurred.
The B-47 safely landed at Hunter AFB, but was so badly damaged that it never flew again. Major Richardson was awarded the Distinguished Flying Cross for his handling of the incident.
The missing Mark 15 has never been found and is considered to be “irretrievably lost.” It is known as “The Tybee Bomb.”
Designed by Boeing, the Stratojet was a high-subsonic-speed strategic bomber and reconnaissance aircraft, in service from 1951 until 1977. The B-47 could fly higher and faster than jet fighters of the time, and it was also highly maneuverable. The B-47 was flown by a two pilots in a tandem cockpit. A navigator/bombardier was at a station in the nose.
The Boeing B-47B Stratojet was the first full-production model. The B-47B is 106 feet, 10 inches (32.563 meters) long with a wingspan of 116 feet , 0 inches(35.357 meters), and an overall height of 27 feet, 11 inches (8.509 meters). The wings are shoulder-mounted with the leading edges swept at 35°. The B-47B has an empty weight of 78,102 pounds (35,426 kilograms), and a gross weight of 184,908 pounds (83,873 kilograms). The maximum takeoff weight was 200,000 pounds (90,718 kilograms).
From 1953 to 1957, the B-47B fleet underwent an extensive modification program which brought them up to the B-47E configuration.
The B-47B was originally powered by six General Electric J47-GE-11 turbojet engines in four nacelles mounted on pylons below the wings. All B-47Bs after serial number 51-2046 were equipped with J47-GE-23 engines. The airplanes built with the -11 engines were retroffitted with the -23s. Under the modification and upgrade program, the -23s were replaced by the J47-GE-25. This engine has a 12-stage axial-flow compressor, eight combustion chambers, and single-stage turbine. The J47-GE-25 is rated at 5,970 pounds of static thrust at Sea Level, at 7,950 r.p.m. and 1,250 °F. (677 °C.) turbine outlet temperature (TOT). (7,200 pounds of thrust with water injection). It has a maximum diameter of 3 feet, 1 inch (0.940 meters) and length of 12 feet, 0 inches (3.658 meters) and weighs 2,653 pounds (1,203 kilograms).
The B-47B Stratojet had a cruise speed of 498 miles per hour (801 kilometers per hour), and maximum speed of 608 miles per hour (978 kilometers per hour) at 16,300 feet (4,968 meters) and 565 miles per hour (909 kilometers per hour) at 35,000 feet (10,668 meters). The service ceiling was 33,900 feet (10,333 meters) and combat ceiling 40,800 feet (12,436 meters).
The combat radius of the B-47B was 1,965 miles (3,162 kilometers with a 10,000 pound (4,536 kilograms) bomb load. Two jettisonable underwing fuel tanks could carry 1,780 gallons (6,738 liters) each. The maximum ferry range was 4,444 miles (7,152 kilometers).
For defense the B-47B was armed with two Browning AN-M3 .50-caliber machine guns in a remotely-operated tail turret. The co-pilot acted as the gunner using an optical sight. The machine guns were replaced by two M24A1 20 mm autocannons and radar control.
The maximum bomb load of the B-47B was 18,000 pounds (8,165 kilograms). The B-47 could carry two 7,600 pound (3,447 kilogram) Mark 15 two-stage radiation implosion thermonuclear bombs, each with an explosive yield of 3.8 megatons, or a single 10,670 pound (4,808 kilogram) B-41 three-stage, 25 megaton bomb.
Beginning in 1953, the B-47B fleet underwent an extensive modification program which brought them up to the B-47E configuration.
A total of 2,032 B-47s were built by a consortium of aircraft manufacturers: Boeing Airplane Company, Wichita, Kansas; Douglas Aircraft Company, Tulsa, Oklahoma; Lockheed Aircraft Company, Marietta, Georgia. 399 of these were B-47Bs.
The Stratojet is one of the most influential aircraft designs of all time and its legacy can be seen in almost every jet airliner built since the 1950s: the swept wing with engines suspended below and ahead on pylons. The B-47 served the United States Air Force from 1951 to 1977. From the first flight of the Boeing XB-47 Stratojet prototype, 17 December 1947, to the final flight of B-47E 52-166, was 38 years, 6 months, 1 day.
© 2018, Bryan R. Swopesby