Perhaps I should have added more information on the "coffin corner" remark. The B-47 had to fly as high and fast as possible to get the most cruse range possible. Refueling becomes tricky the closer one gets to the target so maximum range was a concern.
The B-47's difference between cruse and stall speed was just a few knots while the B-52 enjoyed a 70 knot difference since the B-52 had a redesigned wing, better engines and a higher maximum ceiling which allowed the B-52 to have a more comfortable cruse altitude.
Comparing a B-47 to a U-2 is interesting. Comparing combat (cruse) speed, combat (cruse) altitude and maximum takeoff weight of the two aircraft, not so much.
U-2 (459 kts) (72,000 ft) 40,000 lbs
B-47B 486 kts 43,000 ft 181,440 lbs
B-47E-IV 483 kts 38,550 ft 225,958 lbs
(If you want to check the above figures for the B-47, go to:
http://alternatewars.com/SAC/SAC.htm There you will find loads of aircraft specs.)
So, for the B-47B to B-47E-IV: greater weight, slightly reduced speed and altitude. To make up for the increased weight, the engine thrust was increased from 18,000 lbs to 19,000 lbs but the wing and airframe structure remains unchanged.
From an article in the Air Force Magazine titled "The B-47's Deadly Dominance" found on-line
"An increase in gross weight from 125,000 pounds in the B-47A to 206,700 in the B-47E was offset by
more powerful engines, water injection, and jet-assisted takeoff bottles. These combined to increase
the strain on wings and fuselage."
So perhaps one could say that the B-47, as initially designed, might have been a "decent" aircraft but as the specs changed, nothing was done to upgrade the wings and fuselage, that is, until the wings failed under the strain. At least 1000 B-47's were upgraded under "Project Milk Bottle" which finally fixed some of the wing design issues and there was the reduced speed and ceiling allowances but by then the damage had been done.
Yes, lessons were learned and progress was made but at a great loss of highly trained aircrews.
IMHO, the B-47 was not ready for "prime time." It was retired half way through it's originally specified service life. It had a lot of design issues that were never addressed but they were covered up.
Regards,
Jim
-----Original Message-----
From: Francesco Ledda <frledda@att.net>
To: Kenneth G. Gordon <kgordon2006@frontier.com>
Cc: milsurplus@mailman.qth.net; Jim Whartenby <old_radio@aol.com>
Sent: Fri, Oct 22, 2021 8:30 pm
Subject: Re: [Milsurplus] [Army-Radios] RS-6 Manual supplement ?