This article is within the scope of the Aviation WikiProject. If you would like to participate, please visit the project page, where you can join the project and see lists of open tasks and task forces. To use this banner, please see the full instructions.AviationWikipedia:WikiProject AviationTemplate:WikiProject Aviationaviation articles
This article is within the scope of WikiProject Physics, a collaborative effort to improve the coverage of Physics on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.PhysicsWikipedia:WikiProject PhysicsTemplate:WikiProject Physicsphysics articles
There are two sorts of annular wing: the plane of the ring faces the direction of travel, or the edge of the ring faces the direction of travel, with the aircraft suspended beneath, in helicopter fashion.
Conclusion: Although highly nonplanar lifting systems offer the possibility of dramatic reductions in vortex drag for wings with specified lift and span', they are not a panacea. Rather, nonplanar wings likely will provide small improvements in total drag when their effect on wing weight is considered, but may still be worthwhile as increments in performance become progressively more difficult to achieve. These configurations do provide more substantial performance benefits in some cases. This is especially true when the concept is fully exploited by resizing or even redesigning the aircraft. In addition to reductions in vortex drag, some of configurations mentioned here have desirable effects on structures, stability and control characteristics, vortex wake hazards, and other practical aspects of the design. Some particularly interesting concepts that warrant further study include the split tip design, which demonstrates that by manipulating the wake shape as well as the wing shape, some of the advantages of nonplanar wings may be enhanced. The C-wing configuration remains an intriguing design concept with many beneficial characteristics when applied to large aircraft or tailless designs. The implications of this approach remain to be more fully explored.
Applicability of these statements to closed wings must be ascertained.
Abstract: A theoretical method for predicting minimum induced-drag conditions in a nonplanar lifting systems is presented in this paper. The procedure is based on lifting line theory and the small perturbation acceleration potential. Under the hypotheses of linearity and rigid wake aligned with the freestream, optimality conditions are formulated using the Euler–Lagrange integral equation with constraints on fixed total lifting force and wing span. Particular attention is paid to analysis and numerical treatment of the Hadamard finite-part integrals involved in the solution process. The minimum induced-drag problem is then formulated and solved numerically and analytically. In the case of annular wings, closed-form expressions for the optimal circulation distribution, the normalwash, the induced-drag coefficient, and the efficiency are presented. Optimal annular wings and C-wings are extensively analyzed, and comparisons with available results in the literature are presented. It is confirmed that a C-wing presents almost the same induced drag (under optimal conditions) as the corresponding closed-wing system. However, the optimal distributions of circulation are significantly different. All optimal wing systems are also compared to an optimal cantilevered wing and a biplane.
Great find! I've been searching for more info on this plane since I saw the airliners.net pic years back. AniRaptor2001 19:35, 26 May 2009 (UTC)
The Belarus example is definitely not presented correctly. It's an interesting design, but the description as posted here doesn't make any aerodynamic sense. Power is meaningless in this context and, as is the point of this page, attached vortices exist on every standard wing design and they increase induced drag. This closed design may reduce the vortices, thereby reducing induced drag, but this claim says the opposite. I'm removing the performance claim, if anyone can find a better translation of the aerodynamics claims or find a more reputable source I would be happy to be proven wrong. 24.140.19.68 (talk) 16:05, 1 October 2012 (UTC)[reply]
Since at least 2009 the article has stated that "the annular wing dates to Terry in 1964 / the boxplane was first proposed by Miranda in 1972". Who is Terry? Who is Miranda? -Ashley Pomeroy (talk) 00:04, 7 May 2011 (UTC)[reply]
.jpg){kind=small}
