XB-47D

[fishjay]

Was production of the B-47D (turboprop) ever considered? From what I have read the speed of the D model was very close to the jet powered model. How did the aircraft's range compare with other versions of the B-47?

Does anyone have a decent 3-view of this aircraft?

Thanks,

Fishjay (Lester)

 

[saturncanuck]

I took the opportunity to look at my Putnam's Boeing, and it says the following...

"Two B-47B's (51-2046 and 2103) were converted to XB-47D to serve as test beds for the Wright YT-48-W-1 turboprop engines."

From this I think we can assume that the aircraft in question were merely used as test beds for the engines, in much the same way that the B-47B (51-2059) was converted by Canadair as the CL-52 as a test bed for the Orenda PS-13 Iroquois engine.

Therefore, no production was planned, and if the aircraft were never converted back they should have been NB-47D.

 

[robunos]

see 'Boeing's B-47 Stratojet', Alwyn.T.Lloyd, specialty press, pp. 186-190

cheers,
Robin.

 

[saturncanuck]

What does it say?

see 'Boeing's B-47 Stratojet', Alwyn.T.Lloyd, specialty press, pp. 186-190

cheers,
Robin.

 

[robunos]

What does it say?

In a nutshell, some guy named Gene Root from thr RAND corporation had a theory that 'a smallcross-sectioned aircraft powered by turboprops could penetrate Soviet airspace and he envisioned large fleets of turboprop bombers.'
Part of this reasoning was that turboprops had a lower fuel consumption than the then current jet engines. Therefore the USAF became interested and ordered Boeing to convert Two B-47s into turboprop testbeds as XB-47Ds.
The Wright YT49-W-1 engines were plagued with problems, as were the Curtiss CT846S-A turboelectric propellors, indeed, the engine failed it's 50 hour qualification test, the result being that the first flight did not occur until august 1955, instead of early 1953. Further engine/propellor problems restricted flght testing to only 50 hours over a period of 18 months, however the aircraft reached 597mph at 13,500 ft, at that time a record for a propellor driven aircraft.
An amusing anecdote, at the conclusion of the program, the AF asked Boeing to ferry the two aircraft to Tinker AFB, where they would be converted back to bombers. Boeing replied that such a flight would need one or two stops to replace the engines and/or propellors. The AF forgot about the plan and the aircraft were instead scrapped at Seattle.

cheers,
Robin.

 

[saturncanuck]

Thanks for clearing that up and, a funny story.

Reminds me of one I heard a few years ago when interviewing a chap about our Canadair waterbombers back in 1983. He was the flight engineer.

The early CL215's were notorious for leaking in the water doors. One day, they came out in the morning at their base at The Soo and all they found were two, tight ropes! They called their base and told them they were US that morning. When asked why, he replied, "The pilot and I are having an argument over why. He says the plane won't fly cause its on its side, and I say it won't fly cause its under 30 feet of water."

LOL

 

[Aeroengineer1]

I actually came across the first mention of the XB-47D here on this site in a previous thread in which it was not the topic of the thread, but mentioned in the thread. I do not have too much info on the beast, but I thought that it would be fun to modify a scale model of a standard B-47 to the XB-47D. I will share what I have found on it, though it is not much more that what I have been able to find after a few nights of searching on the web. Are there any more detailed pictures that are had out there. More specifically of the engine installation. From what I have read, there were a handful of prop installations tried. The only numbers that I have found have been a general mention of a 15' diameter 4 blade prop with a 24" chord. I have found some general information on the Curtis Wright YT49W-1 and YT47W-1 turboprop engines. I did find it interesting that the YT47 was slated to have almost double the SHP while actually burning less fuel. Comparing the YT47 vs the YT49 the SHP was 11400hp vs 8500hp with 6380lb/hr vs 6815lb/hr respectively at takeoff condition. I do believe that it was the YT49 that made it into the aircraft for testing. It seems that the major element that would have effected fuel consumption in such a was was the increased pressure ratio of the YT47 over the YT49 (12:1 vs 6:1). I have some pdf documents, but they are too big to upload. The are found though on the following website http://www.alternatewars.com/SAC/SAC.htm. If you have not been to this website I would highly recommend that you do. The individual that scanned this documentation does post here, though I do not remember his screen name. There is great information on many aircraft, engines, and designations on this site.

I am very much interested in the variations from the standard bomber to the XB-47D. The areas that I do know are the revised engines and outrigger gear, the fairing over the tail turret, a flap modification, and there is a large antenna on the top of the tail that does not appear to be present in other models. Thanks for your help.

Adam

 

[Sundog]

I'm not sure if I have more pictures, but I would guess the large fairing on the top of the vertical tail isn;t for an antenna, but, rather a camera fairing for recording during flight testing.

 

[robunos]

'Boeing's B-47 Stratojet', Alwyn T. Lloyd, Specialty Press, pp.186-89.

cheers,
Robin.

 

[Aeroengineer1]

I will have to try and find that book, though is can you give any clue to the contents of those pages? Is it mostly documentation, or is it pictures? I am interested in both but accurate diagrams and pictures are most helpful in this case. As for the fairing on top of the vertical, I too think that it could be a camera, I have one more picture which I forgot to post last night which shows the top of the wing painted presumably black. It is also tuffed. There is a little window to the side of that fairing, and this appears as if it would give a good angle to see the tufts of the wing. I also noticed that the outrigger gear do not appear to be modifications of the originals, but new sturdier units.

Adam