Improvements in Pitch Damping for the Aeroprediction Code with Particular Emphasis on Flare Configurations

New capability has been added to the NSWC aeroprediction code to allow aerodynamics to be predicted for Mach numbers up to 20 for configurations with flares. This new capability includes extending the static aerodynamic predictions for Mach numbers less than 1.2, improving the body alone pitch damping for Mach numbers above 2.0, and developing a new capability for pitch damping of flared configurations at Mach numbers up to 20.This new capability for flared configurations was validated for several different configurations in the Mach number range of 2 to 8.8. In general, pitch damping predictions of the improved capability was within 20 percent of either experimental data or computational fluid dynamics calculations. This accuracy level is believed to be quite adequate for dynamic derivatives in the preliminary design stage. These new additions to the aeroprediction code will be transitioned to users as part of the 2002 version of the code (AP02).

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“…Four cases for static aerodynamics of flares are considered in Ref. 11. Only two of those cases will be presented here.…”

Section: Static Aerodynamics Of Flared Configurationmentioning

confidence: 99%

Semiempirical prediction of pitch damping moments for configurations with flares

Moore¹,

Hymer

2001

39th Aerospace Sciences Meeting and Exhibit

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“…With referenceto Fig. 1, the center of pressure of the are using SBT can be shown to be 6 . N x c:p: / f D 2 3…”

Section: Static Aerodynamics Of Flared Projectilesmentioning

confidence: 99%

“…Four cases for static aerodynamics of ares are considered in Ref. 6. Only two of those cases will be presented here due to limited space.…”

Section: Static Aerodynamics Of Flared Con Gurationmentioning

confidence: 99%

Semiempirical Prediction of Pitch Damping Moments for Configurations with Flares

Moore¹,

Hymer

2001

Journal of Spacecraft and Rockets

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New capability has been added to the Naval Surface Warfare Center aeroprediction code to allow aerodynamics to be predicted for Mach numbers up to 20 for con gurations with ares. This new capability includes extending the static aerodynamic predictions for Mach numbers less than 1.2, improving the body alone pitch damping for Mach numbers above 2.0, and developing a new capability for pitch damping of ared con gurations at Mach numbers up to 20. This new capability for ared con gurations was validated for several different con gurations in the Mach number range of 2-8.8. Whereas ared con guration aerodynamics have been validated only up to Mach 8.8, static aerodynamics have been validated in previous references for other con gurations as high as Mach number 14. Most validations of the aeroprediction code have been performed between Mach numbers of 0.1 and 5, where most experimental data are available. In general, pitch damping predictions of the improved capability were within 20% of either experimental data or computational uid dynamics calculations. This accuracy level is believed to be quite adequate for dynamic derivatives in the preliminary design stage. These new additions to the aeroprediction code will be transitioned to users as part of the 2002 version of the code (AP02). Nomenclature= reference area (maximum cross-sectional area of body, if a body is present, or planform area of wing, if wing alone), ft 2 C A = axial force coef cient C AB ; C A f ; C AW = base, skin-friction, and wave components, respectively, of axial force coef cient C AF = forebody axial force coef cient .C AF D C A f C C AW / C D = drag coef cient C L = lift coef cient C M = pitching moment coef cient (based on reference area and body diameter, if body present, or mean aerodynamic chord, if wing alone) C Mq C C M P ® = pitch damping moment coef cient [C M .q/=.qd=2V 1 / C C M . P ®/=. P ®d=2V 1 /] C M® = pitching moment coef cient derivative, 1/rad C M .q/ = pitching moment coef cient due to a constant pitching rate of q C M . P ®/ = pitching moment coef cient due to a constant vertical acceleration of P ® C N = normal force coef cient C N® = normal force coef cient derivative, 1/rad d B = body diameter at base, ft d r = reference body diameter, ft ;`n;`a ;`f = body length, nose length, afterbody length, and are length, respectivelỳ 1 = distance from cone apex to are-cylinder juncture M 1 = freestream Mach number

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2002 Version of the Aeroprediction Code (AP02)

Moore¹,

Hymer

2004

Journal of Spacecraft and Rockets

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5.Dv,cpwo A%, -syAPI-08/03 ABSTRACT The AP05 code was evaluated when applied to configurations with boattails. Results of the evaluation indicated the AP05 predictions for normal force, center of pressure, pitch and roll damping moments needed improvement. As a result new and improved methods were developed and incorporated into the AP05 to be released as the AP09. Improvements include body alone lift characteristics for Mach numbers less than 2, low angle of attack improvements for roll and pitch damping for configurations with long boattails, incorporation of an improved boundary layer displacement model and refinement of several other existing methods. In addition, new methods were developed to predict nonlinear roll and pitch damping. Comparing the new and improved methods to existing experimental data indicated significant improvements in roll and pitch damping, normal force and center of pressure predictions compared to the AP05. However, validation of the AP09 code was not as complete as desired due to limited generic nonlinear roll and pitch damping data. Also, most of the available nonlinear dynamic derivative data has larger than desired accuracy boundaries due to model sting and wind tunnel wall interference issues. Weapons affected most by the new AP09 methodology are mortars, low drag bombs and projectiles in that order. However, the nonlinear dynamic derivative predictions affect all weapons. The AP09 is thus the most accurate and robust of the Aeroprediction Codes to date.

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Improvements in Pitch Damping for the Aeroprediction Code with Particular Emphasis on Flare Configurations

Cited by 3 publications

References 8 publications

Semiempirical prediction of pitch damping moments for configurations with flares

Semiempirical prediction of pitch damping moments for configurations with flares

Semiempirical Prediction of Pitch Damping Moments for Configurations with Flares

2002 Version of the Aeroprediction Code (AP02)

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