B-47 Wings

[KJ_Lesnick]

I'm curious why the B-47 had such a high incidence to them?  It was well beyond what would be needed in flight and most of the time you'd be riding nose down somewhat...

[rickshaw]

Like the Whitley.  Perhaps it ensured an optimised cruise angle and good vision, placing the tailplane out of the turbulent air behind the mainplane.

[pyro-manic]

BUFF is the same, isn't it? Takes off at a very odd nose-down angle.

[Dizzyfugu]

I'd assume that the angle was deemed necessary in order to get the thing off of the ground. With the tandem landing gear, take-off and landing have to be done with the fuselage in a relatively level position - and I'd guess that a variable incidence wing (as used/tested on the concetually similar XB-51 prototypes) would have been too heavy or complicated for such a huge and heavy aircraft?

[Mossie]

I was going to suggest the same, the B-47 had a long, long take off run, despite being fitted with JATO rockets.

[PR19_Kit]

With a bicycle undercarriage it was impossible to rotate like a 'normal' trike geared aircraft, so the take-off speed was bound to be higher unless something else was done, thus the high wing incidence.

Even with the ultra-long runways that the SAC specified at that time the Stratojets till used most of them before becoming airborne. When I watched them at Brize Norton it always seemed as if they were going off the end but I never actually saw that happen, although there were a few close calls.

[Rheged]

MANY years ago, I watched film of a B 47 (or it might have been a B 52)  taking off just before  one of Avro's finest  leapt into the air like an oversized, delta-wing fighter. The difference was startling!! I think it was a news item concerning Red Flag.  The suggestion was made that since UK did not operate  with nuclear bombers already in flight, we had to  design them to get off quick if there was an alert.

[kitnut617]

A few years ago, B-52's used to appear at the Lethbridge Airshow, they would come up from Fairchild AFB but stop-over for a couple of nights at Calgary YYC because the Lethbridge airfield couldn't handle them.  They would use Calgary' main 12,675 foot runway and the time or two I watched them take-off from there, they only took about 1/3 to 1/2 the length of runway to get in the air and then fly down the rest before pulling up to gain height.  YYC's new 14,000 foot runway should be a doodle for them if they ever re-appear at the Airshow which isn't likely now that the B-52's aren't at Fairchild anymore.

[pyro-manic]

I wouldn't think they'd be taking off at anything like full combat weight if they were due to appear at an airshow, though. That would significantly reduce the take-off run.

[kitnut617]

Not much fuel either I'd say, Fairchild is only about 450 miles from Calgary.  Even so, it did surprise me just how quick it did get into the air --- and they just sort of float up in a level plane

[NARSES2]

A few years ago, B-52's used to appear at the Lethbridge Airshow, they would come up from Fairchild AFB but stop-over for a couple of nights at Calgary YYC because the Lethbridge airfield couldn't handle them.  They would use Calgary' main 12,675 foot runway and the time or two I watched them take-off from there, they only took about 1/3 to 1/2 the length of runway to get in the air and then fly down the rest before pulling up to gain height.  YYC's new 14,000 foot runway should be a doodle for them if they ever re-appear at the Airshow which isn't likely now that the B-52's aren't at Fairchild anymore.

I have memories of seeing a B-52 take off and must admit it seemed to have been undecided if it wanted to go any higher after the initial leap from the ground. Seemed to fly along at a low steady altitude for an age before climbing ?

[Runway ? ...]

Sometimes you use the entire runway,
http://www.youtube.com/watch?v=PLxEHIbHUlY
you paid for it.

[aston]

I have a partial memory of reading of some American aircraft designers (from Boeing?) visiting a UK makers factory (Boulton Paul?) in the early 50s and noting wing-underslung engines on a developmental aircraft and being told of it being noticed that on take-off the wing flexed with the thrust to give an advantageous angle of attack which then settled down in flight ..... or something. Maybe it was research to that effect? The British aircraft was cancelled -  ,......

Does this make sense??

---------------------

Aha ..... it was about the Miles M52.

[Dizzyfugu]

Yes, at least on flexible wings like the B-47's. Due to the underslung nacelles, the thrust would certainlay have caused a for- and upward twist/torsion of the wings, but I doubt that it was significant. But it makes IMHO sense, even though I'd fear that this phenomenon will certainly  have caused some wear and tear issue.