Scientific and Technical Aerospace Reports


Book Description

Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.







NASA Technical Note


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Whirl Flutter of Turboprop Aircraft Structures


Book Description

Whirl Flutter of Turboprop Aircraft Structures, Second Edition explores the whirl flutter phenomenon, including theoretical, practical, analytical and experimental aspects of the matter. Sections provide a general overview regarding aeroelasticity, discussions on the physical principle and the occurrence of whirl flutter in aerospace practice, and experimental research conducted, especially from the 60s. Other chapters delve into analytical methods such as basic and advanced linear models, non-linear and CFD based methods, certification issues including regulation requirements, a description of possible certification approaches, and several examples of aircraft certification from aerospace. Finally, a database of relevant books, reports and papers is provided. This updated and expanded second edition covers new chapters including both analytical and experimental aspects of the subject matter. - Provides complex information on turboprop aircraft whirl flutter phenomenon - Presents both theoretical and practical (certification related) issues - Includes experimental research as well as analytical models (basic and advanced) of matter - Includes both early-performed works and recent developments - Contains a listing of relevant books and reports










NASA Technical Report


Book Description




Review of Propeller-rotor Whirl Flutter


Book Description

A summary is made of the state of the art of propeller-whirl flutter -- a precession-type instability that can occur on a flexibly mounted aircraft engine-propeller combination. This report reviews the literature relating to this problem from the time it first became of concern on conventional turboprop and V/STOL aircraft. Included in the survey are a description of the basic mechanism of whirl flutter, a summary of generalized trend studies on idealized systems, the status of methods for predicting propeller aerodynamic coefficients, the effects of flapping hinged blades and twisted flexible blades on whirl flutter, and some approaches for including propeller whirl modes as a part of the flutter evaluation for complete aircraft. Also, brief consideration is given to the response of flexibly mounted propeller-nacelle systems to random atmospheric turbulence. Whirl flutter of conventional propeller-nacelle systems is now a reasonably well understood phenomenon and amenable to analysis. For propeller-rotor systems with flapping blades, however, comparisons between experiment and theory suggest the need for further refinements in the mathematical model.