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JournalISSN: 0021-8669

Journal of Aircraft 

About: Journal of Aircraft is an academic journal. The journal publishes majorly in the area(s): Aerodynamics & Angle of attack. It has an ISSN identifier of 0021-8669. Over the lifetime, 9967 publication(s) have been published receiving 182903 citation(s).
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Journal ArticleDOI
Raymond M. Hicks1, Preston A. Henne2Institutions (2)
Abstract: A study was conducted to assess the feasibility of performing computerized wing design by numerical optimization. The design program combined a full potential, inviscid aerodynamics code with a conjugate gradient optimization algorithm. Three design problems were selected to demonstrate the design technique. The first involved modifying the upper surface of the inboard 50% of a swept wing to reduce the shock drag subject to a constraint on wing volume. The second involved modifying the entire upper surface of the same swept wing (except the tip section) to increase the lift-drag ratio subject to constraints on wing volume and lift coefficient. The final problem involved modifying the inboard 50% of a low-speed wing to achieve good stall progression. Results from the three cases indicate that the technique is sufficiently accurate to permit substantial improvement in the design objectives.

893 citations

Journal ArticleDOI
Abstract: A surface spline is a mathematical tool for interpolating a function of two variables. It is based upon the small deflection equation of an infinite plate. The surface spline depends upon the solution of a system of linear equations, and thus, will ordinarily require the use of a digital computer. The closed form solution involves no functions more complicated than logarithms, and is easily coded. Several modifications which can be incorporated are discussed.

723 citations

Journal ArticleDOI
Avi Seifert1, A. Darabi1, Israel WygnanskiInstitutions (1)
Abstract: It was recently demonstrated that oscillatory blowing can delay separation from a symmetrical airfoil much more effectively than the steady blowing used traditionally for this purpose. Experiments carried out on different airfoils revealed that this flow depends on many parameters such as, the location of the blowing slot, the steady and oscillatory momentum coefficients of the jet, the frequency of imposed oscillations, and the shape and incidence of the particular airfoil. In airfoils equipped with slotted flaps, the flow is also dependent on the geometry of the slot and on the Reynolds number in addition to the flap deflection that is considered as a part of the airfoil shape. The incremental improvements in single element airfoil characteristics are generally insensitive to a change in Reynolds number, provided the latter is sufficiently large. The imposed oscillations do not generate large oscillatory lift nor do they cause a periodic meander of the c.p. C* C D = dp Ct =

641 citations

Journal ArticleDOI
Lawrence W. Carr1Institutions (1)
Abstract: Nomenclature c = chord CD =drag coefficient, D/qA CL =lift coefficient, L/qa CP = pressure coefficient, P-PW /q CM = pitching-moment coefficient, M/qA D =drag, Ib k = reduced frequency, wc/2U L =lift, Ib M =Mach number; pitching moment, ft-lb P = pressure, lb/in q = dynamic pressure, 1 /2p U R, Re, Re, Rn = Reynolds number t time U,V = freestream velocity, ft/s x = distance a = angle of attack, deg f =nondimensional chord length, x/c $tr transition location co = rotational frequency, rad/s p = density, lb/ft A = sweep angle, deg

631 citations

Journal ArticleDOI
Abstract: The Boeing Blended-Wing-Body (BWB) airplane concept represents a potential breakthrough in subsonic transport efficiency. Work began on this concept via a study to demonstrate feasibility and begin development of this new class of airplane. In this initial study, 800-passenger BWB and conventional configuration airplanes were sized and compared for a 7000-n mile design range. Both airplanes were based on engine and structural (composite) technology for a 2010 entry into service

557 citations

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