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Projectile

About: Projectile is a research topic. Over the lifetime, 13047 publications have been published within this topic receiving 115563 citations.


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Journal ArticleDOI
TL;DR: In this paper, high-speed, high-definition imaging now offers a new spatial and temporal scale of observation that can be used to illuminate projectile dynamics, and a new relationship is derived, linking projectile velocity and size with the size of the resulting impact crater.
Abstract: Centimeter to meter-sized volcanic ballistic projectiles from explosive eruptions jeopardize people and properties kilometers from the volcano, but they also provide information about the past eruptions. Traditionally, projectile trajectory is modeled using simplified ballistic theory, accounting for gravity and drag forces only and assuming simply shaped projectiles free moving through air. Recently, collisions between projectiles and interactions with plumes are starting to be considered. Besides theory, experimental studies and field mapping have so far dominated volcanic projectile research, with only limited observations. High-speed, high-definition imaging now offers a new spatial and temporal scale of observation that we use to illuminate projectile dynamics. In-flight collisions commonly affect the size, shape, trajectory, and rotation of projectiles according to both projectile nature (ductile bomb versus brittle block) and the location and timing of collisions. These, in turn, are controlled by ejection pulses occurring at the vent. In-flight tearing and fragmentation characterize large bombs, which often break on landing, both factors concurring to decrease the average grain size of the resulting deposits. Complex rotation and spinning are ubiquitous features of projectiles, and the related Magnus effect may deviate projectile trajectory by tens of degrees. A new relationship is derived, linking projectile velocity and size with the size of the resulting impact crater. Finally, apparent drag coefficient values, obtained for selected projectiles, mostly range from 1 to 7, higher than expected, reflecting complex projectile dynamics. These new perspectives will impact projectile hazard mitigation and the interpretation of projectile deposits from past eruptions, both on Earth and on other planets.

31 citations

Patent
27 Apr 1973
TL;DR: In this article, a parachute-borne flare assemblage air-lifted by being fired from a rifled gun barrel is described, which includes a hollow projectile which houses the flare package proper.
Abstract: There is disclosed a parachute-borne flare assemblage air-lifted by being fired from a rifled gun barrel. This assemblage comprises a hollow projectile which houses the flare package proper. The package includes the flare composition, a main parachute for supporting the flare composition, a drag parachute for reducing the forward velocity and brake flaps for reducing the spin velocity imparted to the projectile when fired and thus also to the flare package and persisting after ejection of the flare package from the projectile. The flare package is ejected as a unit from the projectile by an ejection charge a predetermined time after firing of the projectile, or in other words, when the projectile has reached a selected point in its trajectory. Further ejection and ignition charges free at timed intervals the brake flaps for reducing the spin velocity and the drag chute for reducing the forward velocity of the ejected flare package. Also at timed intervals, components jacketing the package while in the projectile are released and thrown clear by the centrifugal force acting upon these components after ejection from the projectile. Finally, the main parachute unfolds and supports the flare composition which is ignited by an ignition charge, the ignition of which is initiated by the firing of the ejection charge ejecting the flare package as a unit from the projectile.

30 citations

Journal ArticleDOI
TL;DR: In this paper, the authors measured the energy of the lightest particle and the recoiling target nucleus at the same time to select the mass of the mass while the heavy particle is most sensitive to the depth from which both particles emerge.
Abstract: When the energies of a scattered projectile and the recoiling target nucleus are measured both at the same time, the energy of the lightest particle can be used to select the mass while the energy of the heaviest particle is most sensitive to the depth from which both particles emerge. This is shown for α particles of 30 MeV scattered at 82° on 12C, 13C, 16O and 27Al and the corresponding recoils. The depth resolution of about 50 nm is comparable to that obtained in the measurement of recoil energies from the elastic scattering of heavy ions. The selectivity is almost perfect even between the carbon isotopes. Given suitable improvements, the sensitivity may reach the ppm region.

30 citations

Journal ArticleDOI
TL;DR: In this article, a 3D transient non-linear adiabatic finite element simulation is performed using the commercial software Abaqus 6.9-EF1 for the penetration and perforation of a polycarbonate (PC) plate by an armor piercing 7.62mm projectile.

30 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used the measured time-of-flight spectra to determine the kinetic energy release for various fragmentation processes and distinguish between evaporation of neutral molecules from vibrationally excited ions on the one hand and super-asymmetric fission into two charged fragments on the other hand.
Abstract: Fragmentation of fullerenes by collisions with multiply charged ions has been studied experimentally for collision energies of For high projectile charges the potential energy of the projectiles is mainly responsible for the processes induced: the fragment spectra are dominated by multiply charged parent ions and small fragment ions such as and With decreasing projectile charge, fragmentation induced by the kinetic projectile energy becomes increasingly important, leading to a decreasing yield of surviving ions and an increasing number of fragments with n in the range 2-12 Widths and shapes of the fragment peaks in the measured time-of-flight spectra allow us to determine the kinetic energy release for various fragmentation processes and to distinguish between evaporation of neutral molecules from vibrationally excited ions on the one hand, and super-asymmetric fission into two charged fragments, on the other

30 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20242
2023650
20221,196
2021290
2020458
2019452