The Boeing B-47 and the shaky start of the jet bomber

[General Savage]

THE GREAT LEAP FORWARD INTO THE JET AGE

The Boeing B-47 Stratojet was the first swept-winged jet bomber built in quantity for any air force, and was the mainstay of the medium-bombing strength of the Strategic Air Command throughout the 1950s. A total of 2041 Stratojets were built, making the B-47 program the largest American bomber project since the end of the Second World War.
The aircraft was primarily designed to drop nuclear bombs on the Soviet Union.

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The first XB-47 (46-065) [photos above] rolled out of the factory at Seattle, Washington, on September 12, 1947. It was powered by six 2750 General Electric J35-GE-7/9 turbojets. It was the first large American jet aircraft to feature a swept wing.
The first flight of the XB-47 took place on December 17, 1947, with Bob Robbins and Scott Osler at the controls.

A LONG GESTATION PERIOD

The size of the crew (three men) was unusually small for an aircraft of the size and complexity of the B-47, with the three-member crew having to confront more than three hundred gauges, dials, switches, and levers. The B-47 went through a long gestation period during which many problems had to be fixed, and it took a long time before the Stratojet could be considered as being combat-ready. The early service of the B-47 was marked by frequent crashes and accidents, and the plane got a reputation as a crew-killer. Although there was nothing intrinsically wrong with the Stratojet, the B-47 was relatively difficult to land and terribly unforgiving of crew mistakes or inattention. Fifty-five percent of B-47 accidents were traced to human error, either by aircrews or maintenance personnel. It took a long time before more effective crew training was able to reduce the accident rate to a more acceptable level. By 1954, training had become sufficiently effective that the B-47 now had the lowest accident rate of any jet aircraft. Nevertheless, the B-47 never outlived its early reputation as a crew-killer. As veteran Stratojet pilot Brig. General Earl C. Peck observed in 1975, the B-47 was often admired, respected, cursed or even feared, but almost never loved.

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All who fly the skies today in the safety and comfort of jet airliners owe much to the B-47s development.

[Pilot]

So everything wrong with training?

[Bill Walker]

So everything wrong with training?

I don't think it was that simple. Along with the usual problems for pilots not used to jets (high fuel consumption and high landing speeds) the B-47 had terrible high speed handling qualities. A lot of accidents were the result of unintentional overspeeds at high altitudes, and sloppy recovery methods from this.

At least part of this can be traced to poor testing and the resulting poor flight manual data. The B-47 introduced the term "coffin corner" to the aviation world. This was one corner of the flight envelope where low speed limits and high speed limits came together. If you were at the right weight and high enough altitude, you could have one airspeed where too quick a rearward movement of the stick produced pre-stall buffet, and too rapid forward movement of the stick produced mach buffeting. The only way out of this was to slowly pull back power, maintain airspeed and angle of attack, and patiently wait for the aircraft to descend. Easier said than done if you have an inflight emergency, or if you are in a combat situation.

Another early issue was the terribly slow throttle response of the engines at low power settings. In a go around you might need 15 or 20 seconds from when you moved the throttles forward to when anything significant happened. The eventual solution was to use a small drag chute during approach, which kept the engines running at higher power. Punching off this chute gave an immediate apparent power boost. Until this was worked out, go-arounds caused many accidents.

Today we simply would not accept these qualities in an aircraft. In the late 1940s it was considered acceptable because of the great speed advantage the B-47 had - when it wasn't trying to kill you.

[Pilot]

Thank you Bill, you are very informed about this type!

Cheers :)