Arrow-wing supersonic cruise aircraft structural design concepts evaluation. Volume 4: Sections 15 through 21

The analyses performed to provide structural mass estimates for the arrow wing supersonic cruise aircraft are presented. To realize the full potential for structural mass reduction, a spectrum of approaches for the wing and fuselage primary structure design were investigated. The objective was: (1) to assess the relative merits of various structural arrangements, concepts, and materials; (2) to select the structural approach best suited for the Mach 2.7 environment; and (3) to provide construction details and structural mass estimates based on in-depth structural design studies. Production costs, propulsion-airframe integration, and advanced technology assessment are included

Aeronautical Engineering. A continuing bibliography, supplement 115

This bibliography lists 273 reports, articles, and other documents introduced into the NASA scientific and technical information system in October 1979

Analysis and evaluation of mechanical performance of reinforced sandwich structures : X-CorTM and K-CorTM

X-CorTM and K-CorTM are foam based lightweight structural cores reinforced with ZFiber ® rods oriented in a truss pattern. They can generate sandwich structures which possess strength- and stiffness-to-weight ratios such to compete with aerospace grade honeycomb constructions. The enhanced tailoring ability to specific design needs, the flexibility in reinforcement type and arrangement, the variety between closed cell foamfilled or hollow core configurations for ultimate weight savings or structural multifunctionality, while utilising manufacturing procedures similar to traditional honeycomb sandwich structures (low cost out-of-autoclave manufacturing techniques included) make these novel materials an attractive alternative. The process of their implementation into current engineering practice requires a parallel comparison with existing competitor cores and a critical evaluation of their performance, identifying advantages and disadvantages. This study represents one of the first attempts to create a rigorous methodology for the analysis and evaluation of their mechanical behaviour and manufacturing sensitivities. The balance of out-of-plane properties (shear and compression), fundamental for a sandwich core material, has been investigated. The material energy absorption capacity for the aforementioned loading cases, as well as for in-plane crushing was evaluated. For this purpose, a new quasi-static test for progressive crushing of flat sandwich laminates was designed successfully. The experimental data gathered validate proposed analytical models which allowed further deductions on core parameters influence to be made. Those parameters were the pin insertion angle, pin lay-out, pin density and the role of the foam. A local-global FE modelling approach for Z-pinned sandwich cores is also provided and validated for X-CorTM structures. Structural differences between XCorTM and K-CorTM are at the base of a diverse mechanical response; their performance is sensitive to the manufacturing process, as it determines the quality of the pin-skin and pin-adhesive film interfaces. An ‘improved’ manufacturing technique designed for XCorTM resulted in a sandwich panel able to offer the same mechanical performance of a Nomex® honeycomb structure for a 25% of weight saving.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Damage tolerant wing-fuselage integration structural design applicable to future BWB transport aircraft

Wing joint design is one of the most critical areas in aircraft structures. Efficient and damage tolerant wing-fuselage integration structure, applicable to the next generation of transport aircraft, will facilitate the realisation of the benefits offered by new aircraft concepts. The Blended Wing Body (BWB) aircraft concept represents a potential revolution in subsonic transport efficiency for large airplanes. Studies have shown the BWB to be superior to conventional airframes in all key measures. Apart from the aerodynamic advantages, the BWB aircraft also provides a platform for wing-fuselage design changes. The main objective of this research is to design a damage tolerant wing-fuselage joint with a novel bird’s mouth termination for a BWB aircraft that has a similar payload range to the B767 aircraft. The damage tolerance analysis of the proposed BWB wing/fuselage integration structure includes assessments of fatigue crack growth life, residual strength and inspection capability. The proposed structure includes a bird’s mouth termination of the spars that facilitates smooth transfer of loading from the spar web into the root rib and the upper and lower skins and is novel in its application to the blended wing body configuration. A finite element analysis was required to determine local stresses for the prediction of fatigue crack growth life, residual strength and inspection capability and to identify weak spots in the proposed structure. The project aircraft wing comprises of three spars (front, centre and rear) and a false rear spar thus defining a four cell wing box. Wing root shear, bending moment and torque loads were derived and applied to a thin-walled three box idealisation of the proposed structure. The challenges experienced in replicating the loads obtained from the three box idealisation were addressed by modification of the boundary conditions. Checks for compression and shear buckling were also undertaken that confirmed that the applied loads were below the limits of the proposed structure. The finite element analysis showed very clearly that the stresses in the novel bird’s mouth spar termination were significantly lower than in the skin and that the skin remained the more critical damage tolerant component at the wing root when the structure was subjected to ultimate design stresses. The spar web at the bird’s mouth termination was shown to have a larger crack growth life compared to the skin. The thickness of the skin requires further investigation as a significant amount of local bending was experienced due to the applied pressure. The skin will sustain a two-bay crack at the design limit load thus proving the proposed wing fuselage integration structure to be damage tolerant. In conclusion, the main objective of the thesis has been achieved. An integrated wingfuselage joint with novel bird’s mouth spar termination and surrounding structure have been designed and substantiated (evaluated) by damage tolerance requirements.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Aeronautical Engineering: A continuing bibliography with indexes (supplement 206)

This bibliography lists 422 reports, articles and other documents introduced into the NASA scientific and technical information system in October 1986

Design and construction of a remote piloted flying wing

Currently, there is a need for a high-speed, high-lift civilian transport. Although unconventional, a flying wing could fly at speeds in excess of Mach 2 and still retain the capacity of a 747. The design of the flying wing is inherently unstable since it lacks a fuselage and a horizontal tail. The project goal was to design, construct, fly, and test a remote-piloted scale model flying wing. The project was completed as part of the NASA/USRA Advanced Aeronautics Design Program. These unique restrictions required us to implement several fundamental design changes from last year's Elang configuration including wing sweepback and wingtip endplates. Unique features such as a single ducted fan engine, composite structural materials, and an electrostatic stability system were incorporated. The result is the Banshee '94. Our efforts will aid future projects in design and construction techniques so that a viable flying wing can become an integral part of the aviation industry