Boeing B-47 Stratojet

[Steve Pace]

The only picture I've ever seen of XB-47 number two (46-066) - Life magazine.

 

[Kosmos929]

My memory fails me. What was the date?

 

[aim9xray]

Oddly enough, this aircraft has survived the years and is on display today at the Chanute Air Museum, Rantoul, Illinois... see http://www.aeromuseum.org/aircraft_xb47.html

 

[Bailey]

Another photo here: http://www.airliners.net/photo/USA---Air/Boeing-XB-47-Stratojet/1455740/M/

Cheers Bailey

 

[archipeppe]

Someone has a good cutaway of B-47?

 

[Steve Pace]

Someone has a good cutaway of B-47?

Who might that be?

 

[Triton]

Boeing advertisement from 1948 showing evolution of the B-47's wing found on eBay.

URL: http://cgi.ebay.com/1948-VINTAGE-EVOLUTION-WING-BOEING-AIRCRAFT-PRINT-/160483159413?pt=LH_DefaultDomain_0&hash=item255d8aad75

Added from “Found on Ebay” thread

 

[hesham]

Hi,


the Boeing Models, 424,432 and 450-1;


http://coollib.net/b/150691/read

 

[hesham]

We can transfer this topic to Postwar Aircraft Projects section;


From Le FANA 432,here is some Boeing B-47 projects.

 

[hesham]

As I said before,we can transfer this topic to Postwar section,


from Le FANA 431,here is the Boeing Model-413 (which looks like Model-424)
and Model 450-1-1 & Model 450-2-2.

 

[GTX]

That first one looks like a B-29 with jet pods.

 

[hesham]

That first one looks like a B-29 with jet pods.

My dear GTX,yes,it is,please read the comment.

 

[famvburg]

I have seen a 3 view in an old APR issue and it is very similar to a B-29 with B-45-type nacelles.

 

[Cy-27]

The Evolution that led to the B-47

I came across this intriguing wind tunnel model (below) from 1944 of a Boeing Model 432 that I had not come across before, which led to dome digging. All I know about the Boeing Model 432 is that the project arose from a 1943 US Army Air Force (USAAF) requirement for a jet bomber / reconnaissance aircraft that ultimately led to the XB-47.

North American, Convair and Boeing all responded with proposals. The first Boeing proposal, the Model 424, was a modification of a conventional propeller-driven bomber design, a scaled-down version of the Boeing B-29 Superfortress fitted with four TG-180 turbojets.

The US National Advisory Committee for Aeronautics (NACA) performed wind tunnel tests on a model of the design. The NACA wind tunnel tests showed that the model suffered from excessive drag. Boeing engineers then tried a revised design, the Model 432, which had the four engines buried in the forward fuselage. Changing the engine layout didn't really reduce drag all that much. The main benefit of the change was found to be structural advantages. The Boeing engineers turned to the swept-wing of 35 degrees.

Boeing then modified the Model 432 design with swept wings and tail, resulting in the Model 448, which was presented to the USAAF in September 1947.

The Model 448 had the four TG-180s in the forward fuselage as had the Model 432, plus two TG-180s buried in the rear fuselage. Boeing submitted the Model 448 to the USAAF in October 1945, only to have it rejected. The Air Force strongly disliked fitting the engines in the fuselage on safety ground in the event of in-flight fires and the engines were moved back out on the wings.

That led straight back to the drag problem, but the engineering team came up with a clean, elegant solution, with the engines in streamlined pods attached to the wings. This innovation led to the next iteration, the Model 450, which featured two TG-180s in a single pod mounted on a pylon about a third of the way outboard on each wing, plus another engine slung from the wingtip.

The USAAF was very pleased with the refined Model 450 design, and in April 1946 the service ordered two prototypes, to be designated XB-47. Assembly began in June 1946 and the Stratojet flew on into fifties history.

Searching in an Artwork folder I also found some drawings of the designs mentioned above, that led eventually to the Boeing B-47 Stratojet.

 

[The Artist]

Oddly enough, this aircraft has survived the years and is on display today at the Chanute Air Museum, Rantoul, Illinois... see http://www.aeromuseum.org/aircraft_xb47.html

The Chanute Air Museum has announced that it will close down on 12/31/2015.

http://www.illinoishomepage.net/story/d/story/chanute-air-museum-closing-for-good/34873/j76_FGQ4SEGr9uO-fnW4-w

 

[Moose]

Oddly enough, this aircraft has survived the years and is on display today at the Chanute Air Museum, Rantoul, Illinois... see http://www.aeromuseum.org/aircraft_xb47.html

The Chanute Air Museum has announced that it will close down on 12/31/2015.

http://www.illinoishomepage.net/story/d/story/chanute-air-museum-closing-for-good/34873/j76_FGQ4SEGr9uO-fnW4-w

"The move will be expensive" where are they moving the collection?

 

[The Artist]

I'm not with that museum so I don't know what their plans really are. I have heard, through local conversations, that one or two if the aircraft are likely to go to the James S. McDonnell Air Park at the St Louis Science Center, and a few of the aircraft might (might) go to the Prairie Aviation Museum in Bloomington, Illinois.

In my opinion, based on how they looked the last time I saw them, some of the aircraft like the C-97 might have to be scrapped. Those are aircraft that have been kept outdoors all these years. The B-58 is indoors, so it might be worth moving to some other museum. One of the biggest losses will be that training missile silo deeply imbedded in the floor of the one hangar bay. It is not likely to be moved anywhere.

Again. I'm not with that museum, so I don't know for sure what is going to happen to the collection.

 

[Pioneer]

We can transfer this topic to Postwar Aircraft Projects section;


From Le FANA 432,here is some Boeing B-47 projects.

Thank you hesham.
That Gunship has me fascinated indeed
Obviously a project in relation to the Vietnam War
Had to find out what it said in French ..... alas Google Translate :
"Project gunship four TAT-161 ventral turrets in 1966 or 1967. The small drawing diagrams the fuselage section with the ammunition boxes cylindrical above turrets."

Regards
Pioneer

 

[hesham]

Hi,

Slideshow | NASM.1993.0055_ref724

 

[Hank58]

The Evolution that led to the B-47

I came across this intriguing wind tunnel model (below) from 1944 of a Boeing Model 432 that I had not come across before, which led to dome digging. All I know about the Boeing Model 432 is that the project arose from a 1943 US Army Air Force (USAAF) requirement for a jet bomber / reconnaissance aircraft that ultimately led to the XB-47.

North American, Convair and Boeing all responded with proposals. The first Boeing proposal, the Model 424, was a modification of a conventional propeller-driven bomber design, a scaled-down version of the Boeing B-29 Superfortress fitted with four TG-180 turbojets.

The US National Advisory Committee for Aeronautics (NACA) performed wind tunnel tests on a model of the design. The NACA wind tunnel tests showed that the model suffered from excessive drag. Boeing engineers then tried a revised design, the Model 432, which had the four engines buried in the forward fuselage. Changing the engine layout didn't really reduce drag all that much. The main benefit of the change was found to be structural advantages. The Boeing engineers turned to the swept-wing of 35 degrees.

Boeing then modified the Model 432 design with swept wings and tail, resulting in the Model 448, which was presented to the USAAF in September 1947.

The Model 448 had the four TG-180s in the forward fuselage as had the Model 432, plus two TG-180s buried in the rear fuselage. Boeing submitted the Model 448 to the USAAF in October 1945, only to have it rejected. The Air Force strongly disliked fitting the engines in the fuselage on safety ground in the event of in-flight fires and the engines were moved back out on the wings.

That led straight back to the drag problem, but the engineering team came up with a clean, elegant solution, with the engines in streamlined pods attached to the wings. This innovation led to the next iteration, the Model 450, which featured two TG-180s in a single pod mounted on a pylon about a third of the way outboard on each wing, plus another engine slung from the wingtip.

The USAAF was very pleased with the refined Model 450 design, and in April 1946 the service ordered two prototypes, to be designated XB-47. Assembly began in June 1946 and the Stratojet flew on into fifties history.

Searching in an Artwork folder I also found some drawings of the designs mentioned above, that led eventually to the Boeing B-47 Stratojet.

Yikes! That Model 432 is ugly. Goes right into the "fugly" category. I cannot believe it had any structural advantages over layouts with wing-mounted engines. Medium to high aspect ratio wings are wing-bending-moment critical (hence few spars, with the loads primarily carried in the wing skins, and the skins get thick). Moving the engines out on the wing puts their mass outboard and greatly reduce wing-bending moments (and correspondingly wing skin thickness and weight). That's the "span loading" concept.

 

[apparition13]

Yikes! That Model 432 is ugly. Goes right into the "fugly" category. I cannot believe it had any structural advantages over layouts with wing-mounted engines. Medium to high aspect ratio wings are wing-bending-moment critical (hence few spars, with the loads primarily carried in the wing skins, and the skins get thick). Moving the engines out on the wing puts their mass outboard and greatly reduce wing-bending moments (and correspondingly wing skin thickness and weight). That's the "span loading" concept.

Looks a bit like an amphibian, as does the 448. I think Convair had an amphibian or sea plane with a similar design.

 

[taildragger]

The Evolution that led to the B-47

I came across this intriguing wind tunnel model (below) from 1944 of a Boeing Model 432 that I had not come across before, which led to dome digging. All I know about the Boeing Model 432 is that the project arose from a 1943 US Army Air Force (USAAF) requirement for a jet bomber / reconnaissance aircraft that ultimately led to the XB-47.

North American, Convair and Boeing all responded with proposals. The first Boeing proposal, the Model 424, was a modification of a conventional propeller-driven bomber design, a scaled-down version of the Boeing B-29 Superfortress fitted with four TG-180 turbojets.

The US National Advisory Committee for Aeronautics (NACA) performed wind tunnel tests on a model of the design. The NACA wind tunnel tests showed that the model suffered from excessive drag. Boeing engineers then tried a revised design, the Model 432, which had the four engines buried in the forward fuselage. Changing the engine layout didn't really reduce drag all that much. The main benefit of the change was found to be structural advantages. The Boeing engineers turned to the swept-wing of 35 degrees.

Boeing then modified the Model 432 design with swept wings and tail, resulting in the Model 448, which was presented to the USAAF in September 1947.

The Model 448 had the four TG-180s in the forward fuselage as had the Model 432, plus two TG-180s buried in the rear fuselage. Boeing submitted the Model 448 to the USAAF in October 1945, only to have it rejected. The Air Force strongly disliked fitting the engines in the fuselage on safety ground in the event of in-flight fires and the engines were moved back out on the wings.

That led straight back to the drag problem, but the engineering team came up with a clean, elegant solution, with the engines in streamlined pods attached to the wings. This innovation led to the next iteration, the Model 450, which featured two TG-180s in a single pod mounted on a pylon about a third of the way outboard on each wing, plus another engine slung from the wingtip.

The USAAF was very pleased with the refined Model 450 design, and in April 1946 the service ordered two prototypes, to be designated XB-47. Assembly began in June 1946 and the Stratojet flew on into fifties history.

Searching in an Artwork folder I also found some drawings of the designs mentioned above, that led eventually to the Boeing B-47 Stratojet.

Yikes! That Model 432 is ugly. Goes right into the "fugly" category. I cannot believe it had any structural advantages over layouts with wing-mounted engines. Medium to high aspect ratio wings are wing-bending-moment critical (hence few spars, with the loads primarily carried in the wing skins, and the skins get thick). Moving the engines out on the wing puts their mass outboard and greatly reduce wing-bending moments (and correspondingly wing skin thickness and weight). That's the "span loading" concept.

I've read that a major reason for the underestimation of the B-47's performance was an overestimation of the drag produced by externally mounted jet engines due to experience with piston engine nacelles and a misunderstanding of how much of their drag was due to intake and exhaust of cooling air. This probably contributed to the British enthusiasm for buried engines also.

 

[Grey Havoc]

View: https://www.youtube.com/watch?v=rzt2BRdEe6g

 

[Vahe Demirjian]

That first one looks like a B-29 with jet pods.

My dear GTX,yes,it is,please read the comment.

The Boeing Model 413 could have been a better choice for the USAAF/USAF's first purpose-built reconnaissance plane than the XF-11 or XF-12 because it was powered by jet engines and would have flown faster than the XF-11 or XF-12 (in other words, the USAAF picking the Model 413 instead of the XF-11 or XF-12 would have made the first year of Howard Hughes' life after WW2 easier).

 

[TMD]

B-47's at March AFB Museum and Pima Air Museum.

 

[Mark Nankivil]

Oddly enough, this aircraft has survived the years and is on display today at the Chanute Air Museum, Rantoul, Illinois... see http://www.aeromuseum.org/aircraft_xb47.html

46-066 was dismantled and moved to Edwards, one of those to survive the closure of Chanute. Thanks to the Flight Test Historical Foundation.

Enjoy the Day! Mark

 

[TMD]

B-47 cockpit that was used to film the movie Strategic Air Command. This was a real B-47 cockpit that came off of a discarded aircraft.

 

[donfenix]

This is such a great thread with amazing pictures, I thought I should post the 3-views from the evolution of the B-47's initial concept (Model 424) all the way to the final design (Model 450-3-3). Almost 2/3 of aviation value created today can be traced back to George Schairer's adoption of the swept back wings and the podded engines on the B-47. It was truly revolutionary for its time. To Boeing's credit, they sent Schairer to Germany in May 1945 with von Karman, then dared to listen to him when he suddenly decided to adopt swept wings upon inspecting German labs and data in Brunswick, they then took a big risk/gamble, and reaped massive rewards for the next 7 to 8 decades. Boeing used to be so daring and innovative. So many aircraft are evolved and optimized versions of the B-47 and its children (the B-52 and the 367-80). We owe so much to Schairer's bold move.

 

[southwestforests]

While this B-47 thread is getting some love, have this seen about 3 hours ago,

https://us-air-force-historical-society.tumblr.com%2Fpost%2F802420917140602880

View: https://www.tumblr.com/us-air-force-historical-society/802420917140602880?source=share

Some detail about the flight,

17 June 1986 | This Day in Aviation

During the 43 minute trip, the aircraft had several systems fail, including airspeed sensors, intercom, and partial aileron control. On approach to Castle Air Force Base, a 16 foot (4.9 meters) approach parachute was deployed. This created enough aerodynamic drag to slow the airplane while the early turbojet engines were kept operating at high power settings. These engines took a long time to accelerate from idle, making a go-around a very tricky maneuver. Releasing the chute allowed the airplane to climb out as the engines were already operating at high r.p.m.

 

[TomcatViP]

Thanks for your late posts both of you

And don´t forget to watch Strategic Air Command with some nice shots (cockpit view included) of the B-47.

 

[NUSNA_Moebius]

Seems like a lot of potential was left on the table with the B-47, with such a high focus on the B-52, B-58 and others. Was there any interest from foreign buyers for improved variants?

Reengined with a quartet of more powerful, more efficient engines (TF-33s for commonality?) and perhaps a wet wing and external hard points inboard like the B-52 would’ve given it great flexibility……

Granted there were alot of other designs available for those non-bomber tasks. And for poops and laughs a full turboprop implementation would’ve been fascinating.

 

[Archibald]

Seems like a lot of potential was left on the table with the B-47, with such a high focus on the B-52, B-58 and others. Was there any interest from foreign buyers for improved variants?

Reengined with a quartet of more powerful, more efficient engines (TF-33s for commonality?) and perhaps a wet wing and external hard points inboard like the B-52 would’ve given it great flexibility……

Granted there were alot of other designs available for those non-bomber tasks. And for poops and laughs a full turboprop implementation would’ve been fascinating.

Here's my 2cts, for what it is worth... B-47 was ruinous and dangerous to fly. It paid a heavy price to being the first mass produced, swept wing, large bomber.
The number of mishaps was huge.

Boeing B-47 Stratojet - Wikipedia

en.wikipedia.org

https://aviation-safety.net/asndb/type/b47

Boeing B-47 Stratojet - Wikipedia

en.wikipedia.org

A case could be make that B-47 flaws made the B-52 success.

 

[TomcatViP]

10% of accident does not constitute a record loss rate for a 1950s jet. But true, takeoff & landings were challenging. Navigation was in every instance a factor of life & death and the fact that it had been kept in service during the Vietnam war increases the overall loss ratio.

But remember that the 47 routinely flew loop and roll maneuver as part of the Nuclear store delivery. Good luck surviving that in a today modern A320 or 737....

(especially when today pilots (some) get frightened by a... stick pusher, fielded for the first time in the B-47)

 

[PMN1]

We can transfer this topic to Postwar Aircraft Projects section;


From Le FANA 432,here is some Boeing B-47 projects.

Is the drawing above the gunship version a version with engines buried in the wings?

 

[NMaude]

10% of accident does not constitute a record loss rate for a 1950s jet.

The B-58 Hustler had a far worse crash rate, IIRC by the time it was retired ~30% of the B-58s built had been lost in crashes.

 

[Archibald]

Project FAST FLY was the retirement of B-47s plus KC-97 tankers, circa 1966. Also the B-52B.

By December 1956 the Strategic Air Command had 27 combat-ready B-47 wings, with 1204 combat-ready B-47 crews and 1306 B-47 aircraft assigned.

PROJECT FAST FLY COMPLETED
In the first half of 1966 the accelerated phase out of all B-47, KC-97, and B-52B aircraft, was completed. On 11 February, SAC's last two B-47 bombers (there were still RB-47s assigned to the 55th Strategic Reconnaissance Wing) were transferred to the storage facility. By June 30, 1003 B-47s were in storage at Davis Monthan AFB, Arizona.

 

[NMaude]

I don't know why the USAF retired almost all of their B-47s then because despite their age they still had a lot of useful life left in them.

 

[Archibald]

I don't know why the USAF retired almost all of their B-47s then because despite their age they still had a lot of useful life left in them.

McNamara wanted to shrink the Strategic Air Command and got ride of many obsolete / unuseful nuclear strike systems.
-Long range subsonic cruise missiles
-B-47
-B-58
-B-52B
-Titan I (kerolox ICBM)
-Atlas F (kerolox ICBM)
He also capped Minuteman deployement to 1000 missiles.
McNamara wanted a missile force made of Minuteman and Titan II (54 of them) as for bombers : B-52s and FB-111A. He rejected AMSA a few times.

 

[NMaude]

Personally I think that McNarama was a fool, a micro-managing control-freak who was ill-suited to being the US's SecDef, he may've been a great CEO of Ford and a banker but he was the wrong man to be the US SecDef (He has a lot to answer for). The B-47 may've been obsolete as a medium strategic nuclear bomber it however still had a lot of life left as reconnaissance and ECM aircraft.​

 

[TomcatViP]

Don´t underestimate the fact that cutting the B-47 freed a lot of pilot and WSO for a combat tour in Vietnam. On aspect of efficiently reshape the SAC and USAF, the B-47 would certainly have been expensive to fly with the JATO takeoff. Anyone would not have missed the point as it was the most numerous bomber airframe flown at the time. The range also put it also in direct competition with the latest TAC nuclear capable fighters, that albeit taking off from forward airfield in NATO and allied countries closer to the Soviet Union, did the job better while being cheaper, as in multi-role squadrons.
(please, note that I did not crosscheck any of the assertions made in that post)

B-47 Jet-Assisted Take Off (JATO)

heroicrelics.org