An Examination of Controlled Vortex Drag Using Stepped Afterbodies from M = 0.5 to 3.0

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Abstract:

A comparison of the zero lift drag coefficients of a stepped base projectile to flat base and truncated boattail base projectiles is presented. Three model configurations were investigated during the test program. These included an experimental 20mm round with a 7 12 deg., truncated boattail base, a round modified with a flat base, and a round modified with a stepped base. All of the projectiles were tested at sea level conditions in an indoor ballistic free-flight facility. This paper discusses the aerodynamic experiment and the data obtained. Results show that the zero lift drag coefficient of the stepped base projectile was less than that of the flat base round for the subsonic Mach number range and approximately the same for the transonic and supersonic ranges. However, the stepped base projectile produced zero lift drag greater than that of the boattail round at each Mach number. Keywords Base drag Separated flow projectile afterbody Ballistic testing.

Author(s):
Wikoff, Dennis ; Cottrell, Charles ; Packard, James
Author Organization(s):
AIR FORCE ARMAMENT LAB EGLIN AFB FL
Descriptive Note:
Final rept. Feb 1986-Sep 1988
Pagination:
0007

Security Markings

DOCUMENT & CONTEXTUAL SUMMARY

Distribution:
Approved For Public Release
Distribution Statement:
Approved For Public Release; Distribution Is Unlimited.

RECORD

Collection: TR
Identifying Numbers
Report Number(s):
AFATL-TR-88-123
Task Number(s):
86
Project Number(s):
ILIR
Monitor Series:
AFATL
 Subject Terms
Joint Capability Areas:
JCA_7.2.1_Mitigate Lethal Effects; JCA_7.2_Mitigate; JCA_7_Protection
Communities of Interest:
Weapons Technologies
Descriptor(s):
*BOATTAIL AFTERBODIES, *TRANSONIC CHARACTERISTICS, *AERODYNAMIC DRAG, PROJECTILES, FACILITIES, VORTICES, SUBSONIC CHARACTERISTICS, MACH NUMBER, RANGE(EXTREMES), FLOW SEPARATION, BALLISTICS, AERODYNAMICS, TRUNCATION, BASE FLOW, MODELS, FREE FLIGHT, TEST AND EVALUATION, CONTROL
Field(s)/Group(s):
Guided Missile Dynamics, Configurations and Control Surfaces, Fluid Mechanics
Keyword(s):
STEPPED AFTERBODIES, ZERO LIFT DRAG COEFFICIENTS, PE61101F, WUAFATLILIR8606
Report Date:
1988 Sep 01