Results 81 to 90 of about 133 (123)
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Wind Tunnel Tests of Whirl Flutter Aeroelastic Demonstrator
58th AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, 2017This article presents the design, development and wind tunnel testing of a whirl flutter demonstrator. First, the physical principle of the whirl flutter is explained. Next, the mechanical concept of the demonstrator is described, and preparatory experiments are outlined.
Jiri Cecrdle, Ondrej Vich, Petr Malinek
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Whirl-flutter investigation on an advanced turboprop configuration
29th Structures, Structural Dynamics and Materials Conference, 1988The whirl-flutter problem of an advanced turboprop configuration with two pusher propellers positioned at the aircraft fuselage cone is analyzed. Coupling between the two propellers and the flexible backup structure ― pylons and aft fuselage cone ― is ...
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Inflow Model Effects on Propeller Whirl Flutter
Proceedings of the Vertical Flight Society 80th Annual Forum and Technology DisplayThis paper investigates inflow model effects on propeller whirl flutter focusing on a propeller-nacelle test case from classical whirl flutter theory. The model is implemented into the Rotorcraft Comprehensive Analysis System framework considering two approaches to capture the inflow on the propeller disk: a uniform inflow model and the viscous vortex ...
Sai Vishal Gali +3 more
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Analysis of Proprotor Whirl Flutter: Review and Update
Journal of Aircraft, 2005Whirl flutter instabilities have been a matter of concern for propeller-driven aircraft, aircraft having tilting proprotors, and helicopters ever since two Lockheed Electras crashed more than 40 years ago. A significant body of literature exists, which details the analyses used to predict whirl flutter and the experiments that have validated the ...
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Modeling and Analysis of Proprotor Whirl Flutter
Proceedings of the Vertical Flight Society 77th Annual Forum and Technology Display, 2021Hao Kang +2 more
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New Design of Whirl Flutter Aeroelastic Demonstrator
his paper presents the new design of aeroelastic demonstrator for the experimental research into whirl flutter aeroelastic phenomenon. The demonstrator was adapted from the former aeroelastic model of a commuter aircraft for 40 passengers. It represents a half-wing with the span of 2.56 m with the nacelle and powered propeller (radius 0.35 m).Čečrdle, Jiří +5 more
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Whirl Flutter Test of Swept-Tip Tiltrotor Blades
Journal of the American Helicopter SocietyThe first whirl flutter test of the Maryland Tiltrotor Rig (MTR) was recently completed in the Naval Surface Warfare Center Carderock Division (NSWCCD) 8- by 10-ft large subsonic wind tunnel. The MTR is a Froude-scaled, 4.75 ftdiameter, threebladed, semispan, floor-mounted, optionally powered, flutter rig.
James Sutherland +2 more
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Predicting Whirl Flutter Bifurcations Using Machine Learning
Proceedings of the Vertical Flight Society 80th Annual Forum and Technology DisplayThis paper investigates the feasibility of using machine learning to predict whirl flutter bifurcation diagrams. The machine learning techniques selected for the study are XGBoost and the long short-term memory neural network. These techniques are selected for their suitability for sequential and nonlinear data.
Maia Gatlin, Cristina Riso
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Predicting Whirl Flutter Bifurcations Using Pre-Flutter Output Data
AIAA SCITECH 2023 Forum, 2023Sai Vishal Gali +2 more
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Insights on the whirl-flutter phenomena of advanced turboprops and propfans
30th Structures, Structural Dynamics and Materials Conference, 1989The new aircraft configurations that have two pusher propellers or propfans located at the rear fuselage are susceptible to a whirl-flutter-related instability characterized by a complex dynamic coupling involving not only the propeller-nacelle whirl modes but also the natural modes of the supporting backup structure. It is shown that the single-engine
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