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Lockheed U-2 with strut-braced wing

hesham

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Hi,

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19810011539_1981011539.pdf
 

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Clioman

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By chance, came across something this week that made me go look for previous postings on the U-2 -- and found this thread. Speaking of trussed wings, there is mention of a similar Northrop proposal considered by the CIA as a possible U-2 replacement because of concerns regarding its detectibility by Soviet radar. The reference is in the CIA's history of the U-2 and Oxcart:

"In the late summer of 1956, [Richard Bissell and his Air Force assistant] visited a number of airframe contractors in a search for new ideas. Among the more unusual was Northrop Aviation's proposal for a gigantic aircraft with a very-high-lift wing. Because it would not be made of metal, the wing would require a type of bridge truss on its upper side to give it rigidity. The proposed aircraft would achieve altitudes of 80,000 to 90,000 feet but only at subsonic speeds, just enough to keep it airborne. The slow-flying Northrop design did not solve the problem of radar detection, and in 1957 the emphasis switched to supersonic designs..."

Anybody know anything more about this proposal?
 

Clioman

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That certainly seems to fit the description -- what caught my eye was the comment that the wing is "not made of metal," so as to reduce the radar signature. How many wooden (or plastic)-winged airplanes had a span of 195 feet?
 

hole in the ground

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I think more than the apsn, possibly the aspect ratio and chord thickness would be more of an issue. And althought the above image looks to be quite a high aspect ratio (higher than gliders?) it is braced, so maybe the structure can be supported.
 

Orionblamblam

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Clioman said:
That certainly seems to fit the description -- what caught my eye was the comment that the wing is "not made of metal," so as to reduce the radar signature. How many wooden (or plastic)-winged airplanes had a span of 195 feet?

"Not made of metal" could be vague. It might have a metal spar, but fiberglass ribs and skin, for example. It's not *entirely* made of metal...
 

Stargazer2006

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A Lockheed U-2 with underwing struts

A study was conducted to determine whether subsonic manned research aircraft utilizing strut-braced wings of high-aspect-ratio had performance improvements when compared to a baseline concept. The effect of increased wing aspect ratio on structural weight, system weight, and maximum range and altitude was determined for configurations with and without strut bracing.

The significant results of the study indicated that an optimum cantilever configuration with a wing aspect ratio of 26 has a 19 percent improvement in cruise range when compared to a baseline concept with a wing aspect ratio ofapproximately 10. An optimum strut-braced configuration with a wing aspect ratio of 28 has a 31 percent improvement in cruise range when compared to the same baseline concept. The increased improvement in range capability is due to the reduction in wing weight resulting from the use of long, braced struts and the aerodynamic advantages in making these lifting struts. All configurations assume the same mission payload and fuel.

From:
A STUDY OF HIGH-ALTITUDE MANNED RESEARCH AIRCRAFT, EMPLOYING STRUT-BRACED WINGS OF HIGH-ASPECT-RATIO
Paul M. Smith, John DeYoung, William A. Lovell, Jack E. Price, and G. Fred Washburn
KENTRON INTERNATIONAL, INC., an LTV company
CONTRACT NAS1-16000, February 1981
 

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Stargazer2006

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Re: A Lockheed U-2 with underwing struts

hesham said:

... which proves my point as to the limitations of the search engine. I typed "Lockheed" "U-2" and "strut" and nothing came up. I have noticed before that the presence of a hyphen or quotes next to a word in the title often makes it invisible in the searches. That's why you should always write a little text, not just give a picture and a link, because the search on the page contents works, it's only the titles that pose a problem.
 

Jemiba

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Maybe a good advice : Don't use hyphens in the search engine and no plural forms.
Worked well and I found both topics ... before I merged them ! ;)
 

Stargazer2006

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Jemiba said:
Maybe a good advice : Don't use hyphens in the search engine and no plural forms.
Worked well and I found both topics ... before I merged them ! ;)

Thanks Jens! ;D

But as one who has used quite a few search engines in the past, I still think this particular one is illogical at times... Hence, for instance, my use of the European quote signs « and » (Alt+0171 and Alt+0187) in the titles because they are separated from the words they contain by a space, and do not therefore compromise their being found by the engine.
 
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