Effect of Unsymmetrical Nose-bluntness on the Stability Derivatives of a 10 Degree Cone at Mach-14 PDF Download
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Author: Otto Walchner
Publisher:
ISBN:
Category :
Languages : en
Pages : 27
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Book Description
In the analysis of the free flight motion of bodies of revolution, the tricyclic theory assumes that a small configurational asymmetry does not violate the rotational symmetry of the stability derivatives in pitch and yaw but does produce a non-zero trim angle. Tests at Mach 14 show that a small unsymmetric nose bluntness destroys the rotational symmetry of the stability derivatives of a slender cone at hypersonic Mach numbers and therefore severely violates the assumptions of the tricyclic theory. Restoring and damping derivatives in pitch and yaw are reported for a 10 deg cone with symmetric and unsymmetrically blunted noses. The effect of non-equal stability derivatives on the motion are shown for a simplified case. (Author).
Author: Otto Walchner
Publisher:
ISBN:
Category :
Languages : en
Pages : 27
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Book Description
In the analysis of the free flight motion of bodies of revolution, the tricyclic theory assumes that a small configurational asymmetry does not violate the rotational symmetry of the stability derivatives in pitch and yaw but does produce a non-zero trim angle. Tests at Mach 14 show that a small unsymmetric nose bluntness destroys the rotational symmetry of the stability derivatives of a slender cone at hypersonic Mach numbers and therefore severely violates the assumptions of the tricyclic theory. Restoring and damping derivatives in pitch and yaw are reported for a 10 deg cone with symmetric and unsymmetrically blunted noses. The effect of non-equal stability derivatives on the motion are shown for a simplified case. (Author).
Author: Otto Walchner
Publisher:
ISBN:
Category : Aerodynamic load
Languages : en
Pages : 0
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Book Description
In the analysis of the free flight motion of bodies of revolution, the tricyclic theory assumes that a small configurational asymmetry does not violate the rotational symmetry of the stability derivatives in pitch and yaw but does produce a non-zero trim angle. Tests at Mach 14 show that a small unsymmetric nose bluntness destroys the rotational symmetry of the stability derivatives of a slender cone at hypersonic Mach numbers and therefore severely violates the assumptions of the tricyclic theory. Restoring and damping derivatives in pitch and yaw are reported for a 10 deg cone with symmetric and unsymmetrically blunted noses. The effect of non-equal stability derivatives on the motion are shown for a simplified case. (Author).
Author: Otto Walchner
Publisher:
ISBN:
Category :
Languages : en
Pages : 46
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Book Description
The pressure distribution over a 10 deg cone was measured in ARL's 20-inch hypersonic wind tunnel at Mach-14 and for various angles of attack and sideslip. The effect of different unsymmetrically blunted noses, with small bluntness ratios, on the pressure distribution is investigated. Test results relate any small unsymmetrical nose bluntness to the rotational symmetry of the flow over a body of revolution at high Mach numbers. The reported test complement, AD-711 921. (Author).
Author: James T. Clay
Publisher:
ISBN:
Category : Noses (Aircraft)
Languages : en
Pages : 46
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Book Description
A theoretical and experimental study to evaluate the influence of spherical nose bluntness, of cone angle, c. g. location and Mach number on the stability characteristics in pitch of blunt slender cones was conducted. A 10- degree half-angle cone with nose bluntness ratios from .025 to .30 was investigated. The observed effect of the nose bluntness on the stability derivatives was quite similar to earlier results with a 5.6 degree half-angle cone. Again, a severe breakdown of the damping derivatives was found for large bluntness ratios. An estimate of the pitch-induced angles of attack for large bluntness ratios was based on the physics of the blast wave type flow. It was found that these induced angles differ from those applicable for pointed cones or for small bluntness ratios where the flow has mainly conical character. The tangent cone method in connection with these different types of pitch-induced angles of attack qualitatively predicts the observed breakdown of the damping derivatives.
Author:
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ISBN:
Category : Aeronautics
Languages : en
Pages : 738
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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.
Author:
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ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Experiments were performed in ARL's 20-inch hypersonic wind tunnel on a 10 degree half-angle circular cone model whose pointed tip was removed by one or more planar slanted cuts. The projected frontal nose area was 1/2 percent of the base area. The configurational asymmetry of this moderate bluntness destroys the rotational symmetry of the shock wave over the entire model. In turn, the rotational symmetry of the surface pressure distribution is also lost. Depending on the nose configuration, asymmetric sideloads were observed at axial flow conditions which may or may not cause the vehicle to trim in free flight. Nose asymmetry combined with mass asymmetry, therefore, may produce a rolling moment even at zero trim. The stability derivatives are not identical in pitch and yaw, as would be expected for a body of revolution, and vary differently as functions of the angle of attack and angle of sideslip. (Modified author abstract).
Author: Otto Walchner
Publisher:
ISBN:
Category :
Languages : en
Pages : 32
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Book Description
Experiments were performed in ARL's 20-inch hypersonic wind tunnel on a 10 degree half-angle circular cone model whose pointed tip was removed by one or more planar slanted cuts. The projected frontal nose area was 1/2 percent of the base area. The configurational asymmetry of this moderate bluntness destroys the rotational symmetry of the shock wave over the entire model. In turn, the rotational symmetry of the surface pressure distribution is also lost. Depending on the nose configuration, asymmetric sideloads were observed at axial flow conditions which may or may not cause the vehicle to trim in free flight. Nose asymmetry combined with mass asymmetry, therefore, may produce a rolling moment even at zero trim. The stability derivatives are not identical in pitch and yaw, as would be expected for a body of revolution, and vary differently as functions of the angle of attack and angle of sideslip. (Modified author abstract).
Author: Brian Quinn
Publisher:
ISBN:
Category :
Languages : en
Pages : 33
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Book Description
The flow around a blunted slender cone performing pitching oscillations is theoretically analyzed by means of Chernyi's blast-wave piston analogy. Stationary and transient shock shapes and pressure distributions are presented in power series form. Within the region of applicability, the stationary pressure agrees well with Chernyi's numerical integration. Normal force and pitching moment coefficient derivatives are presented and the results are plotted for a 10 degree cone. The theoretical static and dynamic stability derivatives agree satisfactorily with recent experiments in a Mach 14 wind tunnel. It is concluded that the experimentally observed reduction in static and dynamic stability due to increased nose bluntness may be attributed to blast wave effects. (Author).
Author: A. E. Hodapp (Jr.)
Publisher:
ISBN:
Category : Aerodynamics, Hypersonic
Languages : en
Pages : 32
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Book Description
Author: Kevin E. Yelmgren
Publisher:
ISBN:
Category : Aerodynamics, Hypersonic
Languages : en
Pages : 52
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Book Description
A 10 degree half angle circular cone with 1.6% nose bluntness was mounted to the sting-strut support system of ARL's 20-inch Mach 14 wind tunnel by means of a two-degree of freedom flexure. The small amplitude ((approximately equal to symbol)3 deg.) free oscillation technique allowed the investigation of planar motion in pitch, or planar motion in yaw, or nonplanar motion in pitch and yaw combined. In the case of planar motion, the logarithmic amplitude decayed linearly with time. In the case of nonplanar motion, however, the amplitude decay of both the pitch and yaw components was modulated. Such a beating would be expected if the pitch and yaw motions were coupled. The wind-off runs in vacuum did not show this type of beating; only the wind-on runs did. It is, therefore, conjectured that the nonplanar tests indicate the presence of an aerodynamic acceleration coupling term, pitching moment due to yaw acceleration and vice versa, which has a measurable effect on the motion. The observed beat period equals nearly one hundred pitch or yaw oscillation periods.
