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Old 18th July 2011, 14:10
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Re: The Boeing B-47 and the shaky start of the jet bomber

Quote:
Originally Posted by Pilot View Post
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.
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