Missile Aerodynamics - Past, Present, Future

Nielsen, Jack N.

doi:10.2514/3.57725

Cited by 16 publications

(6 citation statements)

References 18 publications

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“…As was stated in Ref. 9, linear theory predicts the aircraft flowfield more accurately than the corresponding store loads. The somewhat smaller discrepancy between the Theory-Theory predictipn and test data, compared to the PANAIR prediction, in the region of the large nacelle-inlet shock might be attributed to this observation.…”

Section: Theoretical Flowfield Predictionsmentioning

confidence: 92%

Recent improvements in prediction techniques for supersonic weapon separation

Cenko

Waskiewicz

1983

Journal of Aircraft

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The influence function method (IFM) has demonstrated a unique capability for accurately predicting store aerodynamic characteristics in an aircraft flowfield. To apply this method, one must know the force and moment influence functions of the respective stores involved. These are obtained from a separate "calibration" wind tunnel test where the forces and moments on the subject store are measured as the store is traversed through an oblique shock generated by a wedge or inclined plate. It was recently determined that these calibration forces and moments could be accurately predicted by the PANAIR pilot code, thus opening up the possibility for determining the required influence functions theoretically. This suggests that, in many instances, further economies in weapon separation testing are possible by using theoretically determined weapon calibrations. In addition, a procedure has been developed which combines PANAIR predictions of the parent aircraft flowfield with PANAIR store "calibrations." This process enables the calculation of supersonic store behavior without the need of any a priori experimental data, at a considerable cost savings compared to using the PANAIR pilot code to calculate the store forces and moments at every point in the traverse.

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Section: Theoretical Flowfield Predictionsmentioning

confidence: 92%

Recent improvements in prediction techniques for supersonic weapon separation

Cenko

Waskiewicz

1983

Journal of Aircraft

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“…Unfortunately, little is known about the influence of timedependent motions (e.g., pitching oscillations) on the time evolution of the leeward vortex structure or the flowfield in general. In his broad survey of missile aerodynamics, Nielsen 3 does not even discuss time-dependent motions. This is unlike the relatively large body of past and ongoing theoretical and experimental research dealing with unsteady flows around two-and three-dimensional airfoils.…”

Section: Introductionmentioning

confidence: 98%

“…3 While much remains to be investigated, a reasonable overall understanding of the steady flow around an axisymmetric body is evolving. Unfortunately, little is known about the influence of timedependent motions (e.g., pitching oscillations) on the time evolution of the leeward vortex structure or the flowfield in general.…”

Section: Introductionmentioning

confidence: 99%

“…§ Again, the body's shadow caused by the projection of the laser sheet from top to bottom is seen in the photographs as darkened regions. For both runs, the body underwent the pitching motion a(t)deg= 15 ± 15 deg the Reynolds number was R D = 4x\Q3 . At the lower reduced frequency, K=0.2, the forebody vortices from one cycle convect to this position (x/L = 0.15), at the beginning of the following cycle (a = 0 deg).…”

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confidence: 99%

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Unsteady flow around an ogive cylinder

Gad‐el‐Hak

1986

Journal of Aircraft

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The time-dependent flow around ah ogive cylinder undergoing large-amplitude, harmonic pitching motion was investigated using flow visualization techniques. The slender body of revolution was towed in an 18 m water channel at Reynolds numbers up to 1.2xl0 5 . Fluorescent dyes were either introduced uniformly from the body's porous surface or placed as horizontal sheets in the slightly stratified tank prior to a run. The dyes were excited with a sheet of laser light projected in the desired plane to mark the flow in the separation region around the body, the flow in the wake, and the potential flow away from the body. The separation process and the geometry of the leeward vortices were studied under different reduced frequencies and Reynolds numbers. The unsteady separation phenomenon is found to be significantly different from the separation on a body in steady flight. Two distinct separation regions, the forebody and aftbody vortex pairs, evolve in the unsteady case. NomenclatureD = maximum body diameter / = pitching frequency H = height of separation region K -reduced frequency, irfD/UL =body length R D = Reynolds number, U^D/v t = time, s £/«, = towing speed x,y,z = Cartesian coordinates fixed with the body oi(t) = time-dependent angle between the body centerline and the towing direction di(t) =rate of change of angle of attack

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“…References 15-18 represent only a few of the recent ones. Wardlaw, 1 Nielsen, 19 and Esch 20 give many more references in their studies in which the available predictive methods and experimental techniques are also reviewed. However, these studies are generally devoted to the simple-type missile bodies such as tangent ogive body, sharp cone cylinder, etc.…”

Section: Introductionmentioning

confidence: 99%

Aerodynamics of complex bodies of revolution

Atli

1988

AIAA Journal

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The aerodynamics of five complex bodies of revolution are investigated experimentally and theoretically at a low Mach number (M f ^ 0.1) and over the range of angle of attack from 0 to 35 deg. The geometrical forms of the bodies are generally complex with the discontinuities in the slope of the body surface. The surface-flow visualization is performed by using the oil method. The balance measurements were made and the results compared with the potential theory and the method based on the crossflow analogy. It was observed that the discontinuities in the slope of the body surface make the flow separation and consequently the flowfield very complicated. It was also found that the method of crossflow analogy is applicable not only to simple-type bodies of revolution but also the complex ones. Nomenclatureof corresponding cylinder to body of revolution ( = S p /l) /(X) = normal force distribution / = total body length l r = reference length M^ = freestream Mach number M Coo = crossflow Mach number ( = M^ sina) q^ = freestream dynamic pressure (q^ = ^p R = local body radius Re d = Reynolds number based on the maximum body diameter d (Re d -V^d/v) R e cd s = crossflow Reynolds number based on d s ( = F^ sina ds/v) Re t -Reynolds number based on / S = local cross-sectional area ( = nR 2 ) S b = body base area S p = body planform area ( = Jo 2R d*) S r = reference area S, = body flat-nose area V^ = freestream velocity W = body volume ( = &nR 2 d*) x= body axis (axial distance from body nose) x c = axial distance from body nose to centroid of body planform area x cp = axial distance from body nose to center of pressure x m = pitching moment center (axial distance from body nose to pitching moment center) a = angle of attack p = density of air D = kinematic viscosity of air r\ -correction factor for influence of fineness ratio

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Missile Aerodynamics - Past, Present, Future

Cited by 16 publications

References 18 publications

Recent improvements in prediction techniques for supersonic weapon separation

Recent improvements in prediction techniques for supersonic weapon separation

Unsteady flow around an ogive cylinder

Aerodynamics of complex bodies of revolution

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