51,884 research outputs found
Optimal design of a flying-wing aircraft inner wing structure configuration
No full textFlying-wing aircraft are considered to have great advantages and potentials in
aerodynamic performance and weight saving. However, they also have many
challenges in design. One of the biggest challenges is the structural design of
the inner wing (fuselage). Unlike the conventional fuselage of a tube
configuration, the flying-wing aircraft inner wing cross section is limited to a
noncircular shape, which is not structurally efficient to resist the internal
pressure load. In order to solve this problem, a number of configurations have
been proposed by other designers such as Multi Bubble Fuselage (MBF),
Vaulted Ribbed Shell (VLRS), Flat Ribbed Shell (FRS), Vaulted Shell
Honeycomb Core (VLHC), Flat Sandwich Shell Honeycomb Core (FLHC), Y
Braced Box Fuselage and the modified fuselage designed with Y brace
replaced by vaulted shell configurations. However all these configurations still
inevitably have structural weight penalty compared with optimal tube fuselage
layout. This current study intends to focus on finding an optimal configuration
with minimum structural weight penalty for a flying-wing concept in a preliminary
design stage.
A new possible inner wing configuration, in terms of aerodynamic shape and
structural layout, was proposed by the author, and it might be referred as
‘Wave-Section Configuration’. The methodologies of how to obtain a structurally
efficient curvature of the shape, as well as how to conduct the initial sizing were
incorporated.
A theoretical analysis of load transmission indicated that the Wave-Section
Configuration is feasible, and this was further proved as being practical by FE
analysis. Moreover, initial FE analysis and comparison of the Wave-Section
Configuration with two other typical configurations, Multi Bubble Fuselage and
Conventional Wing, suggested that the Wave-Section Configuration is an
optimal design in terms of weight saving. However, due to limitations of the
author’s research area, influences on aerodynamic performances have not yet
been taken into account
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The David W. Fentress Family Letters, 1856-1969
No full textTranscript of a letter by an unidentified author to David Fentress regarding sharing federal newspapers and the banning of federal newspapers in some areas. The author passes on the news of the war including the destruction of the Federal merchantmen by the Confederate fleet. He passes along world news: Russia preparing to go to War with Europe and how that could negatively affect the Confederacy. There is also speculation on the future of the war
The David W. Fentress Family Letters, 1856-1969
No full textTranscript of a letter by an unidentified author to David Fentress regarding sharing federal newspapers and the banning of federal newspapers in some areas. The author passes on the news of the war including the destruction of the Federal merchantmen by the Confederate fleet. He passes along world news: Russia preparing to go to War with Europe and how that could negatively affect the Confederacy. There is also speculation on the future of the war
Gliding swifts attain laminar flow over rough wings
No full textSwifts are among the most aerodynamically refined gliding birds. However, the overlapping vanes and protruding shafts of their primary feathers make swift wings remarkably rough for their size. Wing roughness height is 1–2% of chord length on the upper surface—10,000 times rougher than sailplane wings. Sailplanes depend on extreme wing smoothness to increase the area of laminar flow on the wing surface and minimize drag for extended glides. To understand why the swift does not rely on smooth wings, we used a stethoscope to map laminar flow over preserved wings in a low-turbulence wind tunnel. By combining laminar area, lift, and drag measurements, we show that average area of laminar flow on swift wings is 69% (n = 3; std 13%) of their total area during glides that maximize flight distance and duration—similar to high-performance sailplanes. Our aerodynamic analysis indicates that swifts attain laminar flow over their rough wings because their wing size is comparable to the distance the air travels (after a roughness-induced perturbation) before it transitions from laminar to turbulent. To interpret the function of swift wing roughness, we simulated its effect on smooth model wings using physical models. This manipulation shows that laminar flow is reduced and drag increased at high speeds. At the speeds at which swifts cruise, however, swift-like roughness prolongs laminar flow and reduces drag. This feature gives small birds with rudimentary wings an edge during the evolution of glide performance
Portrait of author David Foster at the National Library of Australia, Canberra, 8 June 2011 /
No full textTitle from acquisitions documentation.; Part of the collection: Portraits of author David Foster at the National Library of Australia, Canberra, 8 June 2011.; Acquired in digital format; access copy available online.; Mode of access: Online.; Photographed by a staff member of the National Library of Australia
Author David Foster with academic Jeff Doyle at the National Library of Australia, Canberra, 8 June 2011 /
No full textTitle from acquisitions documentation.; Part of the collection: Portraits of author David Foster at the National Library of Australia, Canberra, 8 June 2011.; Acquired in digital format; access copy available online.; Mode of access: Online.; Photographed by a staff member of the National Library of Australia
Author David Foster and academic Jeff Doyle at the National Library of Australia, Canberra, 8 June 2011 /
No full textTitle from acquisitions documentation.; Part of the collection: Portraits of author David Foster at the National Library of Australia, Canberra, 8 June 2011.; Acquired in digital format; access copy available online.; Mode of access: Online.; Photographed by a staff member of the National Library of Australia
David Braithwaite at White Waltham Steam Fair
No full textDavid Braithwaite, fairground enthusiast and author photographed at White Waltham Steam Fair, August 1964
David Zimmer Christmas letter
No full textThis Christmas letter written November 30, 1999, by David Zimmer is titled "Season's Greetings from the last of the Red-Hot-Santas!" It features an illustration of Santa Claus with a guitar, and a summary of Zimmer's year.
David Zimmer (1929-2005) was born in Harrisburg, Ohio. He enlisted in the U.S. Army and served for two years during the Korean War at the Brooke Army Medical Center in San Antonio, where he performed in drag for wounded soldiers. After the war, he returned to Ohio. Zimmer performed as Dolly Divine, a name inspired by the song "Hello Dolly." In 1964, he established the Berwick Ball with Orn Huntington, another important early gay activist in Central Ohio. The Ball began as a formal Halloween costume ball that provided a safe space to gather and enjoy drag shows for the gay community each year; over the years, it grew into an annual Halloween tradition and an important fundraiser for the AIDS movement and other charities. During the 1970s, Zimmer was also known for hosting lavish parties at his Harrisburg home. In 1989, he moved to the German Village area of Columbus where he remained active in the community. During the 1990s, Zimmer continued to perform in and out of drag and commissioned costume designer Dick Frank to make elaborate outfits. Zimmer worked for Huntington National Bank for 39 years and was a member of the Harrisburg United Methodist Church, Veterans of Foreign Wars and the German Village Society
David Zimmer Christmas letter
No full textThis Christmas letter was written December 7, 2004, by David Zimmer. It features a small illustration of Santa Claus, a summary of Zimmer's year, and a clipping from the Village Crier recognizing his 75th birthday celebration.
David Zimmer (1929-2005) was born in Harrisburg, Ohio. He enlisted in the U.S. Army and served for two years during the Korean War at the Brooke Army Medical Center in San Antonio, where he performed in drag for wounded soldiers. After the war, he returned to Ohio. Zimmer performed as Dolly Divine, a name inspired by the song "Hello Dolly." In 1964, he established the Berwick Ball with Orn Huntington, another important early gay activist in Central Ohio. The Ball began as a formal Halloween costume ball that provided a safe space to gather and enjoy drag shows for the gay community each year; over the years, it grew into an annual Halloween tradition and an important fundraiser for the AIDS movement and other charities. During the 1970s, Zimmer was also known for hosting lavish parties at his Harrisburg home. In 1989, he moved to the German Village area of Columbus where he remained active in the community. During the 1990s, Zimmer continued to perform in and out of drag and commissioned costume designer Dick Frank to make elaborate outfits. Zimmer worked for Huntington National Bank for 39 years and was a member of the Harrisburg United Methodist Church, Veterans of Foreign Wars and the German Village Society
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