Dynamics of Ultralight Aircraft: Motion in Vertical Gusts PDF Download
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Author: Robert T. Jones
Publisher:
ISBN:
Category :
Languages : en
Pages : 18
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Book Description
Author: Robert T. Jones
Publisher:
ISBN:
Category :
Languages : en
Pages : 18
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Book Description
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 1074
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Book Description
Author: Robert L. Swaim
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 40
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Book Description
The effects of spanwise distribution of longitudinal and vertical components of gust velocity and longitudinal distribution of the lateral component on the lateral-directional response of a hovering VTOL aircraft are analyzed. Results show that spanwise effects of the longitudinal and vertical components are negligible, and the longitudinal distribution of the lateral component is significant in computing the power spectral densities of gust-induced side force, yawing moment, rolling moment, and the aircraft sideslip, yaw, and roll root-mean-square response angles. If the gust-induced angles of attack and sideslip angles are in the nonlinear range of lift curve slope, the above conclusions, which are based on linear aerodynamic theory, may not hold and an analysis based on momentum transfer of gust energy to the aircraft is recommended. Flow field interaction effects due to engine intake and exhaust also were not considered. (Author).
Author: Frederick O. Smetana
Publisher:
ISBN:
Category : Gust loads
Languages : en
Pages : 62
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Author: Pau Castells Marin
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
The prediction of the aircraft response to gust and turbulence is of major importance for different purposes. Gust load analysis is an essential part of aircraft design and certification. The effect of gust and turbulence on aircraft flight dynamics is also of interest. Models able to capture relevant effects at these conditions in early design phases are essential in order to anticipate and assess the aircraft response and flight control laws in realistic atmospheric disturbances before flight test. This work proposes a modelling strategy to capture relevant physics when simulating the aircraft response to gust and turbulence for flight dynamics investigations. The model provides accuracy at a low computational cost as well as consistency with gust loads analysis enabling multidisciplinary design. The approach is based on the integration of a nonlinear quasi-steady flexible flight dynamics model with an unsteady aeroelastic model linearized around a nonlinear steady state. The gust-induced forces have a significant impact on aircraft flight dynamics. Low computing times are required to cover several flight conditions and aircraft parameters. A computationally efficient multipoint aerodynamic model, which captures both unsteady aerodynamic and gust propagation effects, is generated from linearized Computational Fluid Dynamics (CFD) simulations in the frequency domain. The model is identified through a rational function approximation allowing for time domain simulations. A reduced number of additional aerodynamic states is sufficient to capture the main effects at low frequencies for flight dynamics analysis. The impact of dynamic flexibility on the response is also evaluated. Only the most energetic flexible modes are retained to reduce the number of states and ensure a low computation time. The approach is applied to simulate the vertical and lateral response of a passenger aircraft to theoretical disturbance profiles as well as realistic atmospheric turbulence at different flight conditions. Aerodynamic nonlinear effects, such as local stalls due to shock motion, in transonic conditions may appear. The linearized model is able to capture the global aircraft response at these conditions with low amplitude shock motions. Results are compared and validated with a CFD simulation based approach, coupled with a structural dynamics and flight mechanics solver. Measures from flight test are also used to assess the modelling approach. The effect of uncertainties on the response is analysed, in terms of the turbulence variation along the wingspan. Simulation results show that relevant aerodynamic effects due to gust and turbulence are captured in the frequency range of interest for flight dynamics investigations.
Author:
Publisher:
ISBN:
Category : Research
Languages : en
Pages : 892
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Book Description
Sections 1-2. Keyword Index.--Section 3. Personal author index.--Section 4. Corporate author index.-- Section 5. Contract/grant number index, NTIS order/report number index 1-E.--Section 6. NTIS order/report number index F-Z.
Author: Abbott Allen Putnam
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 13
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Book Description
A set of equations based on the first mode of wing bending is presented for determining the dynamic response of an airplane wing structure as induced by gusts. The representation of the airplane is such that the aerodynamic damping of the vibratory motion of the wing is separate from that of the vertical motion of the airplane as a whole. An easily evaluated solution of the equations for a unit-jump forcing function is also presented which may be built up to determine the response of any forcing function. A chart is included by which, for a conventional airplane, a typical forcing function for any gradient gust may be chosen quickly.
Author: Frederick O. Smetana
Publisher:
ISBN:
Category : Gust loads
Languages : en
Pages : 60
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Book Description
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 654
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Author: John Marshall Eggleston
Publisher:
ISBN:
Category : Atmospheric turbulence
Languages : en
Pages : 68
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Book Description
Summary: The report is separated into two parts. In the first part the theoretical basis for calculating the lateral motions of an airplane flying through continuous random atmospheric turbulence is presented. The lateral motions are derived in terms of (1) the transfer functions relating the motion in the various degrees of freedom to the yawing moment, rolling moment, and side force, (2) the statistical forces and moments at the center of gravity due to gust velocities acting on the lifting surfaces of the airplane, and (3) the power spectra of the three orthogonal components of gust velocity acting on the airplane along the flight path. The method takes into account the random variations of gust velocity across the span and along the fuselage. Solutions are given in the form of equations relating the power spectra of the angular motions of the airplane to the power spectra of the gust velocities.
