garnetpalmetto
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A Few Questions About Variable-incidence Wings

Mon Jul 27, 2009 2:22 am

Last weekend I took my fiancee to Charleston, SC and, among other things we visited the USS Yorktown (CV-10) at the Patriot's Point Naval & Maritime Museum. My fiancee being a fledgling aviation geek I was showing her the various planes they have on the Yorktown's flight deck and while showing her an F-8 Crusader, a few questions came to mind: firstly, did variable-incidence wings have any combat applications ? I know they helped reduce landing/take-off distances but did they have any other uses? How were they controlled - was it an automatic feature or did a pilot have to manually set the angle of incidence? Also, why did they never quite catch on? I know they were also a feature on the XB-51, but beyond that I can't think of a combat aircraft they appeared on. Was the weight penalty from the variable-incidence mechanism just not worth the returns?
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HaveBlue
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RE: A Few Questions About Variable-incidence Wings

Mon Jul 27, 2009 2:56 pm



Quoting Garnetpalmetto (Thread starter):
I know they helped reduce landing/take-off distances but did they have any other uses? How were they controlled - was it an automatic feature or did a pilot have to manually set the angle of incidence?

It wasn't to reduce landing distance so much as landing speeds. Or more specifically the F-8 needed a certain AoA maintained on approach to the carrier which would have reduced pilot visibility and, with the F-8's particuliar landing gear configuration, produced a real danger of tail scraping. Being able to raise the wing gave the pilot better visibilty while keeping the fuselage more level to the flight deck on approach and landing.

It was controlled by the pilot and ony had 2 settings... flush with the fuselage and 7 degrees of incidence.
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boeingfixer
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RE: A Few Questions About Variable-incidence Wings

Mon Jul 27, 2009 3:08 pm

The variable incidence feature on both the F-8 and XB-51 was essentially for a single purpose. It allowed the aircraft a slower approach/takeoff speed without having a prohibitively high fuselage deck angle. In essence it allowed the wing to fly at a higher angle of attack without the associated complexities, weight and design of longer landing gear.

The F-8 wing incidence is controlled via an Incidence control in the cockpit and a hydraulic actuator at the forward end of the wing. The trailing edge flaps are also mechanically linked with the wing incidence as well as the aileron power control and are drooped to 20 degrees with the wing raised and are faired with the wing lowered.

As for the XB-51, I have no clue as to how they designed the system to work.

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John
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kc135topboom
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RE: A Few Questions About Variable-incidence Wings

Mon Jul 27, 2009 4:21 pm

 
boeingfixer
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RE: A Few Questions About Variable-incidence Wings

Mon Jul 27, 2009 7:17 pm



Quoting KC135TopBoom (Reply 3):
The XB-51;

http://en.wikipedia.org/wiki/XB-51

Saw it. Only thing is that it doesn't explain the design of the Variable Incidence on the XB-51, if it was automatic or how it generally functioned as the OP questioned.
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kc135topboom
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RE: A Few Questions About Variable-incidence Wings

Mon Jul 27, 2009 11:46 pm



Quoting BoeingFixer (Reply 4):
Only thing is that it doesn't explain the design of the Variable Incidence on the XB-51, if it was automatic or how it generally functioned as the OP questioned.

The variable incidence of the wing on the XB-51 was manually set by the pilot. As to if it would have gotten an automatic system, if it went into production, I don't know.
 
ebj1248650
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RE: A Few Questions About Variable-incidence Wings

Tue Jul 28, 2009 12:09 am



Quoting KC135TopBoom (Reply 5):
The variable incidence of the wing on the XB-51 was manually set by the pilot. As to if it would have gotten an automatic system, if it went into production, I don't know.

We're talking about an airplane from the early to middle 50's. Was the technology in place to make variable incidence automatic?
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