New Method to Predict Nonlinear Roll Damping Moments

Moore, Frank G.; Moore, Linda Y.

doi:10.2514/1.34974

Cited by 5 publications

(7 citation statements)

References 11 publications

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“…The roll dynamics of rockets are well known to be over damped [ 10 , 11 , 13 ] and thus they can be modelled as a first-order differential equation [ 10 ]. The solution to a step response of a first-order system can be approximated as a bi-linear model, as shown in Fig.…”

Section: Methodsmentioning

confidence: 99%

“…The idea is to use a minimal mathematical modelling approach [ 6 – 9 ] to describe the overall effect of complex dynamics on the inertia, damping and non-linear spring dynamics of the pitch, yaw, and roll axes of the rocket. For example, it is known that aerodynamic drag changes in each axis as a function of speed [ 10 – 12 ], and there are also changes in mass and inertia in each axis dueto centre of mass and pressure changes over time [ 10 , 13 ].…”

Section: Introductionmentioning

confidence: 99%

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Minimal modelling approach to describe turbulent rocket roll dynamics in a vertical wind tunnel

Hann

Snowdon

Rao

et al. 2011

Proceedings of the Institution of Mechanical Engineers, Part G:

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The roll dynamics of a 5-kg, 1.3 -m high sounding rocket are analysed in a vertical wind tunnel. Significant turbulence in the tunnel makes the system identification of the effective inertia, damping, and asymmetry with respect to roll challenging. A novel method is developed, which decouples the disturbance from the rocket frame's intrinsic roll dynamics and allows accurate prediction of roll rate and angle. The parameter identification method is integral-based, and treats wind disturbances as equivalent to a movement in the actuator fins. The method is robust, requires minimal computation, and gave realistic disturbance distributions reflecting the randomness of the turbulent wind flow. Two models, one with constant damping and one with fin angle-dependant damping were considered. The mean absolute roll rate of the rocket frame observed in experiments was 16.4°/s and both models predicted the roll rate with a mean absolute error less than 0.10°/s with a standard deviation less than 0.08°/s. The roll angle (measured by an encoder), was tracked by the model with a mean absolute error less than 0.20° and a standard deviation less than 0.15°. These results prove the concept of this minimal modelling approach which will be extended to varying wind speed, and pitch, and yaw dynamics in the future.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Minimal modelling approach to describe turbulent rocket roll dynamics in a vertical wind tunnel

Hann

Snowdon

Rao

et al. 2011

Proceedings of the Institution of Mechanical Engineers, Part G:

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“…(6), accurate enough at low angles of attack, is replaced in Eq. (8) by the experimental or calculated wingalone normal-force coefficient C Nw at the angle of attack .…”

Section: Description Of the Methodsmentioning

confidence: 99%

Prediction of Nonlinear Rolling and Magnus Coefficients of Cruciform-Finned Missiles

Morote

Liaño

2010

Journal of Aircraft

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A new method based on strip and slender-body theories has been developed to predict the aerodynamic roll and wing-induced Magnus coefficients of cruciform-tailed missiles at high angles of attack. The method is applicable over the Mach number range, up to large angles of attack at arbitrary bank angles, providing analytical expressions of the nonlinear rolling moments: roll damping, roll driving, induced roll moments, and additional coupling terms. The analytical expressions fit the form of the Maple-Synge expansion and the degree of nonlinearity shown by experimental results.= wing area (two panels) V = speed of missile V n = component of speed normal to missile axis T = fin cant deflection ' = bank angle Subscripts sbt = slender-body theory wb = wing in presence of body

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“…However, the true aim of this work is the nonlinear roll derivatives of cruciform configurations, for which only the wing-normal-force components in the presence of the body are relevant. In addition, the theoretical methods to predict the roll derivatives are very limited (see the exhaustive survey made by Moore and Moore [6] concerning the rolldamping coefficient). Also, Magnus force will be addressed in Sec.…”

Section: Wing-normal Force In the Presence Of The Bodymentioning

confidence: 99%

“…The present method predicts a similar behavior at any Mach number, as long as C N2 is positive and C N4 negative (AR 2). Figure 10b presents the comparison between the roll-damping coefficient estimates and the experimental values given in [6] for the basic finner at two supersonic Mach numbers. The AP05 code [13] was used to set the value of C N0 .…”

Section: Nonlinear Rolling Momentsmentioning

confidence: 99%

Prediction of Nonlinear Rolling and Magnus Coefficients of Cruciform Finned Missiles

Morote

Liaño

2009

AIAA Atmospheric Flight Mechanics Conference

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New Method to Predict Nonlinear Roll Damping Moments

Cited by 5 publications

References 11 publications

Minimal modelling approach to describe turbulent rocket roll dynamics in a vertical wind tunnel

Minimal modelling approach to describe turbulent rocket roll dynamics in a vertical wind tunnel

Prediction of Nonlinear Rolling and Magnus Coefficients of Cruciform-Finned Missiles

Prediction of Nonlinear Rolling and Magnus Coefficients of Cruciform Finned Missiles

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