Pressure Distribution on Sabots in Hypervelocity Flight

Guillot, Martin; Dick, Jason N.; Reinecke, W. G.

doi:10.2514/2.3229

Cited by 3 publications

(4 citation statements)

References 1 publication

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“…During this phase, the flow structure near the leading edge of the sabot changes from a single normal shock into a system of multiple bow shocks, each emanating from an individual sabot petal. This results in a bimodal pressure distribution within the scoop and has also been observed in surface pressure distributions measured in wind tunnel experiments [9]. This phase of the interaction occurs relatively rapidly, and the speed of the normal shock convection can be estimated from the rate at which the stagnant mass of air within the scoops is depleted.…”

Section: Phase Ii: Normal Shock Convectionmentioning

confidence: 79%

“…However, since the area between the petals continues to decrease, the supersonic flow will choke again, resulting in a second normal shock called the throttling shock. This phenomenon has also been observed in the surface pressure distributions measured in wind tunnel experiments [9]. The location of the throttling shock depends on the area ratio and the Mach number of the supersonic flow between the petals.…”

Section: B Phase I: Choked Flowmentioning

confidence: 83%

“…Earlier modeling efforts [5]- [7] that focussed on the sabot discard problem met with mixed success. The so-called AVCO code, which was developed as a result of these studies, relied on empirical data for the details of its model and has therefore had limited applicability, as was also found by recent studies conducted at the IAT [8], [9]. In fact, due to the lack of widely applicable sabot discard models, the trajectory analysis codes tend to use experimental measurements to account for the effect of sabot discard rather than predictions by any particular model.…”

Section: Introductionmentioning

confidence: 94%

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Effect of electromagnetic launch on armature/sabot discard

Erengil

Zielinski²

2001

IEEE Trans. Magn.

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This paper presents the validation of a sabot discard model, developed at the Institute for Advanced Technology (IAT), for predicting armature/sabot separation, and quantifies the effect of electromagnetic launch on sabot discard as well as on the sub-projectile. The experimental data used to validate the model were obtained at the Army Research Laboratory (ARL) Transonic Experimental Facility at Aberdeen Proving Ground, MD. Five shots were conducted at a nominal velocity of 1350 m/s and armature/sabot petal trajectories were reduced from x-ray images taken at six downrange stations. The residual electromagnetic force on the launch package after muzzle exit was also determined from experimental data. The sabot discard model uses analytical expressions to estimate surface pressure distributions, which are then integrated, in a time-marching algorithm, for linear and angular accelerations, and subsequently for sabot petal trajectories. The most significant attribute of this model is that it does not rely on any empirical data for modeling and is therefore expected to be widely applicable. The results from this study have shown that the comparison between predicted and measured armature/sabot petal trajectories is excellent. Furthermore, the model has demonstrated quantitatively the delayed armature/sabot discard caused by the residual electromagnetic force and the additional deceleration of the sub-projectile due to the delayed mechanical disengagement.

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Section: Phase Ii: Normal Shock Convectionmentioning

confidence: 79%

Section: B Phase I: Choked Flowmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 94%

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Effect of electromagnetic launch on armature/sabot discard

Erengil

Zielinski²

2001

IEEE Trans. Magn.

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“…[6][7][8] However, if the separation is done only with the difference in aerodynamic drag in free flight between the projectile and the sabot, a long travel distance, say, a few meters or more, is necessary in order to obtain the required separation distance; the assistance of a mechanical sabot "stripper" is necessary. In many cases of such aeromechanical separation, the sabot is composed of several pieces, each of which will experience an aerodynamic lift force.…”

Section: Introductionmentioning

confidence: 99%

Impactless, in-tube sabot separation technique useful for modest-sized supersonic ballistic ranges

Sasoh

Oshiba

2006

Review of Scientific Instruments

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A simple and high performance sabot separation technique which is useful even in about 10-m-long supersonic ballistic ranges has been developed. The normal in-flight sabot separation distance is vastly reduced by adding an addition tube with no diaphragm that may cause damage to the projectile. The launch tube of the ballistic range is subdivided to the acceleration, ventilation, and sabot separation sections. In the ventilation section, both the precursor shock wave driven by the sabot when coasting through the acceleration section and the driver gas is vented out to the dump chamber. In the sabot separation section, only the sabot experiences a great dragging pressure imbalance whereas the drag to the projectile is kept negligible. Initially, the whole system except for the driver gas chamber is connected without any diaphragm; the range operation is not accompanied by any high-speed impact among the sabot, diaphragm, and other related solid parts. The experimental environment can be kept clean. The influence of the muzzle blast is eliminated within a reasonably short distance from the muzzle because it delays owing to the ventilation section. Calibration experiments and the demonstration of flow visualization and boom measurement of supersonic flight were conducted using a 25 mm bore, Mach-2 ballistic range.

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The Texas A&M University Hypervelocity Impact Laboratory: A modern aeroballistic range facility

Rogers

Bass

Mead

et al. 2022

Review of Scientific Instruments

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Novel engineering materials and structures are increasingly designed for use in severe environments involving extreme transient variations in temperature and loading rates, chemically reactive flows, and other conditions. The Texas A&M University Hypervelocity Impact Laboratory (HVIL) enables unique ultrahigh-rate materials characterization, testing, and modeling capabilities by tightly integrating expertise in high-rate materials behavior, computational and polymer chemistry, and multi-physics multiscale numerical algorithm development, validation, and implementation. The HVIL provides a high-throughput test bed for development and tailoring of novel materials and structures to mitigate hypervelocity impacts (HVIs). A conventional, 12.7 mm, smooth bore, two-stage light gas gun (2SLGG) is being used as the aeroballistic range launcher to accelerate single and simultaneously launched projectiles to velocities in the range 1.5–7.0 km/s. The aeroballistic range is combined with conventional and innovative experimental, diagnostic, and modeling capabilities to create a unique HVI and hypersonic test bed. Ultrahigh-speed imaging (10M fps), ultrahigh-speed schlieren imaging, multi-angle imaging, digital particle tracking, flash x-ray radiography, nondestructive/destructive inspection, optical and scanning electron microscopy, and other techniques are being used to characterize HVIs and study interactions between hypersonic projectiles and suspended aerosolized particles. Additionally, an overview of 65 2SLGG facilities operational worldwide since 1990 is provided, which is the most comprehensive survey published to date. The HVIL aims to ( i) couple recent theoretical developments in shock physics with advances in numerical methods to perform HVI risk assessments of materials and structures, ( ii) characterize environmental effects (water, ice, dust, etc.) on hypersonic vehicles, and ( iii) address key high-rate materials and hypersonics research problems.

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Pressure Distribution on Sabots in Hypervelocity Flight

Cited by 3 publications

References 1 publication

Effect of electromagnetic launch on armature/sabot discard

Effect of electromagnetic launch on armature/sabot discard

Impactless, in-tube sabot separation technique useful for modest-sized supersonic ballistic ranges

The Texas A&M University Hypervelocity Impact Laboratory: A modern aeroballistic range facility

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