[Milsurplus] B-47 facts and figures, was RS-6 Manual supplement ?

[Jim Whartenby]

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 lbsB-47B        486 kts          43,000 ft         181,440 lbsB-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 bymore powerful engines, water injection, and jet-assisted takeoff bottles. These combined to increasethe 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
Too much agreement kills a chat.  E. Cleaver

-----Original Message-----
From: Francesco Ledda <frledda at att.net>
To: Kenneth G. Gordon <kgordon2006 at frontier.com>
Cc: milsurplus at mailman.qth.net; Jim Whartenby <old_radio at aol.com>
Sent: Fri, Oct 22, 2021 8:30 pm
Subject: Re: [Milsurplus] [Army-Radios] RS-6 Manual supplement ?

That is right!

Sent from my iPad

> On Oct 22, 2021, at 20:05, Kenneth G. Gordon <kgordon2006 at frontier.com> wrote:
> 
> On 22 Oct 2021 at 21:33, Jim Whartenby via Milsurplus wrote:
> 
>> Do you know of any other aircraft where a few knots of airspeed was
>> the only difference between flying and stalling? 
> 
> U-2: 5 knots.
> 
> Ken W7EKB
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