MIL-HDBK-297

Abstract

This handbook has been prepared to provide a tutorial on the basic concepts of explosion phenomena and damage effects from nuclear and non-nuclear weapons. It is recommended reading for engineers desiring an introduction to these subjects as they relate to the vulnerability or survivability of ships and mission essential weapons systems, and to passive protection design. <br>Naval ships must be capable of carrying our their assigned missions and combat roles in man-made threat environments and survive the possible consequences which may result from engaging hostile forces. Viewed in totality, the combat survivability of a warship depends on two distinct but interrelated factors; namely, susceptibility and vulnerability. <br>The first factor, susceptibility, is defined as "the combined characteristics of all the factors that determine the probability of hit of a component, subsystem, or system by a given threat mechanism." Susceptibility may be characterized as the propensity of a ship's emissions (intentional and unintentional) to exploitation by threat surveillance sensors, weapon homing seekers, and warhead fuze mechanisms in performing their intended functions of detection attack (weapon launch) targeting, acquisition, and detonation against a ship. Intentional emissions, many of which are unique and readily classifiable, include electromagnetic radiations from on board communications, navigation, and command or control radars, and electro-acoustic-radiations from on board sonars. Unintentional emissions (signatures) include radiations and reflections which are inherent to a ship's configuration and design features, and include: acoustic (radiated noise), radar cross-section, infrared radiance, magnetic, pressure, seismic, and other signatures. <br>The second factor, vulnerability, is defined as "the characteristics of a system that cause it to suffer a finite level of degradation in performing its mission as a result of having been subjected to a certain level of threat mechanisms in a man-made hostile environment." Vulnerability may be characterized as the propensity of a ship's structure (hull, deckhouse, superstructure, hangars) and vital equipments or components to operational impairment as a result of the damage effects from weapon detonations. The level of damage, and degree of impairment, are a function of the following: type of warhead, size of explosive charge, location of the detonation, and a ship's inherent structural hardness to resist the weapon effects. The first two are directly related to the threat weapon, whereas the last one is directly related to the ship's design. The weapon hit location or detonation points resulting from "smart" weapons homing-in and exploding on a ship target are related to both the threat weapon; that is, its seeker and homing logic, and also the ship's signature profile and highlights which are design controllable. <br>It is seen that ship susceptibility comprises a sequence of signature-influenced engagement events (detection, targeting, attack, seeker lock-on, and warhead detonation), the outcome of which influences the vulnerability of a ship to damage from weapons effects. The interrelations between signature susceptibility and damage vulnerability are, however, complex since the degree of operational impairment to a ship and its mission-essential systems or equipments depends on where weapons hit and explode on the ship and its inherent hardness at such locations. <br>Survivability design of a Naval ship requires data in the form of design threat parameters, and other quantitative descriptors, which characterize the sensors, seekers or fuzes and the weapons, warheads, or explosives of antiship threat systems. These parameters constitute some of the key inputs to ship design criteria and formulas for determining the type, location, and distribution of passive survivability features. The logic diagram as shown on <a>figure 1</a> identifies the relationship between "threat" and "ship survivability design", traces the key steps of the process, and relates to the supporting publications in the NAVSEA documentation hierarchy at each node of the process. This handbook addresses only the weapons effects part of the threat environment severity levels (see <a>figure 1</a>). <b><u>Intended Use:</u></b> This handbook is intended for the use of ship design engineers desiring an introduction to survivability and vulnerability of ship and vital weapon systems and to passive protection design. <br>