Ballast is a term applied to heavy matter, such as stone, sand, iron, or water placed in the bottom of a sailing ship or other vessel to sink it in the water to such a depth as to enable it to carry sufficient sail without oversetting. The term ballast is also applied to the sand placed in bags in the car of a hot-air balloon to steady it and to enable the aeronaut to lighten the balloon by throwing part of it out. Ballast is also the name for the material used to fill up the space between the rails on a railway in order to make it firm and solid. Research Ballast
Mahogany is a light hard wood from trees of the family Meliaceae, that was first introduced to Britain as ballast cargo from Cuba and Central America and became popular for making furniture during the 18th century. Mahogany is valuable as it shrinks very little when it dries, and suffers very little from warping or twisting. Research Mahogany
Slag is the chemical compound resulting during the smelting of metallic ores. It results because of the action of the flux on impurities in the ore. Slag generally consists of silicates, formed by the combination of silica with alumina, lime, magnesia, oxides of iron or other metals. By the formation of slag, the impurities in the ore are removed, and if the metallic contents of the slag are of no value the slag is regarded as smelters' refuse. Some slags, however, consisting mainly of metallic oxides produced during the refining processes, are resmelted and such slags are termed cinder or scoria. As slag has to be separated from the valuable metallic material, its fluidity, at the smelting temperature, is an important factor, and some substances such as an oxide of zinc are apt to make slags pasty.
Slags vary in chemical composition, but those which crystallise are regarded as definite chemical compounds. The colour of slags affords n indication of the composition, for example green denotes the presence of iron and copper oxide produces a red slag. Slags are used for various purposes, as ballast for railways, macadamising roads, making into bricks and others. Some slags may be burnt with lime, thus making an efficient hydraulic cement, and slag from the basic Bessemer process forms a fertiliser containing phosphorus. Research Slag
Aeronautics is the art of sailing in or navigating the air. The first form in which the idea of aeriallocomotion naturally suggested itself was that of providing men with wings by which they should be enabled to fly. By about 1905, however, it was generally admitted that it is impossible for man by his muscular strength alone to give motion to wings of sufficient extent to keep him suspended in the air. Hence later attempts at aerialnavigation structures of a different kind were generally tried, such as some sort of flying car, elevated and propelled by machinery which eventually gave rise to the modern aircraft, or a vehicle so buoyant as to float in the air, the balloon being the most common. Early pioneers in flight encountered one great difficulty in that of supporting in mid-air a sufficient weight of machinery to provide the necessary power for propelling and steering purposes.
The navigation of the air by means of the balloon dates only from nearly the close of the eighteenth century. In 1766 Henry Cavendish showed that hydrogen gas was at least seven times lighter than ordinary air, and it at once occurred to Dr. Black of Edinburgh that a thin bag filled with this gas would rise in the air, but his experiments were for some reason unsuccessful. Some years afterwards Tiberius Cavallo found that a bladder was too heavy and paper too porous, but in 1782 he succeeded in elevating soap-bubbles by inflating them with hydrogen gas. In this and the following year two Frenchmen, the brothers Stephen and Joseph Montgolfier, acting on the observation of the suspension of clouds in the atmosphere and the ascent of smoke, were able to cause several bags to ascend by rarefying the air within them by means of a fire below. These experiments roused much attention at Paris; and soon after a balloon was constructed under the superintendence of Professor Charles, which being inflated with hydrogen gas rose over 3000 feet in two minutes, disappeared in the clouds, and fell after three quarters of an hour about fifteen miles from Paris. These Montgolfier and Charles balloons already represented the two distinct principles in respect to the source of elevating power for balloons, the one being inflated with common air rarefied by heat, requiring a fire to keep up the rarefaction, the other being filled with gas lighter at a common temperature than air, and thus rendered permanently buoyant. Both forms were used for a considerable time, but the greater safety and convenience of the gaseous inflation finally prevailed. After the use of coal-gas had been introduced it superseded hydrogen gas, as being much less expensive, though having a far less elevating power.
The first person who made an ascent in a balloon was Pilatre de Rozier, who ascended 50 feet at Paris in 1783 in one of Montgolfier's. A short time afterwards M. Charles and M. Robert ascended in a balloon inflated with hydrogen gas, and travelled a distance of 27 miles from the Tuileries; M. Charles by himself also ascended to a height of about two miles. Since then a multitude of ascents and aerial voyages were made, with, strange to say, comparatively few disastrous results in the early years. Among the names of the earlier balloonists we may mention Lunardi, who first made an ascent in Great Britain in September 1784, unless we assign this honour to J. Tytler (' Balloon' Tytler), who seems to have made two short ascents from Edinburgh in the preceding month; Blanchard, who, along with the American Dr. Jeffries, first crossed the Channel from Dover to Calais, in January 1785; Garnerin, who first descended by a parachute from a balloon in October 1797; and Gay Lussac, who reached the height of 23,000 feet in September 1804.
In 1836 a balloon carrying Messrs. Green, Holland, and Mason traversed the 500 miles between London and Weilburg in Nassau in eighteen hours. In 1859 Mr. J. Wise, the chief of American aeronauts, accompanied by several others, rose from New York, and landed, after a flight of 1150 miles, in twenty hours. In September 1862, the renowned aeronaut, Mr. Glaisher, accompanied by a Mr. Coxwell, made an ascent from Wolverhampton, and reached the estimated elevation of 37,000 feet, or 7 miles, a height far greater than any other then attained, if it can be depended on as exactly ascertained. But the aeronauts were for a time in great peril, Mr. Glaisher having become insensible, and Mr. Coxwell having his hands so severely frozen that he was unable to pull the valve for descent, and was compelled to use his teeth. Early aeronauts were clearly unaware of the thinning of the atmosphere and dramatic reduction in temperature with altitude. It is claimed that the first greatest really authentic height-35,000 feet-was attained by two German aeronauts at Berlin in 1901. The most daring early attempt at an aerial voyage was that of the Swede, Andree, who, with two companions in 1897 ascended from Spitzbergen in hopes of reaching the North Pole, their fate remaining unknown.
All the features of the ordinary balloon as now used are more or less due to Professor Charles, already mentioned. Early balloons were usually a large pear-shaped bag, made of pliable silk cloth, covered with a varnish of caoutchouc dissolved in oil of turpentine to render it air-tight. The ordinary size ranged from 20 to 30 feet in equatorialdiameter, with a proportionate height, but balloons of far greater dimensions were also constructed. A car, or basket, generally of wicker-work, supported by a network which extends over the balloon, contained the aeronaut; and a valve, usually placed near the top, and to which is attached a string reaching the car, gave him the power of allowing the gas to escape, whereby the balloon lowered at pleasure. A quantity of sand ballast in small bags was usually taken, and when the balloon tended to descend too far sand was thrown out and it rose again. The guide-rope, a long and heavy rope trailing over the ground, was sometimes used when the country was such that no serious damage would result from its trailing. The principle of this device was that as the balloon tended to rise it must lift more of the rope off the ground, while when the balloon sunk it was relieved of so much weight, and thus it tended to float at one level above the ground.
The problem of how to steer or propel a balloon in a desired horizontal direction was an early issue and numerous attempts at producing navigable balloons were made at the start of the 20th century. In a navigable balloon to be propelled through the air by some kind of motor, against the wind if necessary, the familiar balloon shape was departed from as quite unsuitable, and the 'air-ship' usually of an elongated form and more or less cylindrical or cigar-shaped adopted. A design still used a hundred years later.
Balloons of a fish or cigar shape, floated by gas, and propelled by a screw driven by a dynamo-electric machine, and steered by a large rudder, made several ascents in Paris in 1884 and 1885; and being generally able to return to the starting-point, at the time it was claimed for them that they had settled the question of balloon steerage, but it was several years before the matter was settled. The names of CountZeppelin and M. SantosDumont became well known in connection with such balloons. In 1897-1900 the former constructed a huge cylindrical air-ship of great length, with parabolic ends, divided into a number of separate chambers filled with hydrogen gas and these enclosed in an outer air balloon, the whole being braced and made rigid by an aluminium framework, and the means of propulsion being screws driven by Daimler petrol motors and fixed to the longitudinal axis of the air-ship. The success of this great structure, even after various improvements were introduced, appears to have been only partial, and want of sufficient funds brought operations to a stop for a while. M. SantosDumont constructed several navigable balloons, and one of them was so successful at Paris in 1901 as to gain a prize of 100,000 francs. On this occasion his airship made the journey from St. Cloud to the Eiffel Tower and back again, a distance of about 9.5 miles, in half an hour. M.M. Lebaudy of Paris also made some very successful trips with a dirigible balloon ; that is, one that can be steered or directed-to some extent at least.
In 1903-4 a large air-ship was constructed by Dr. F. A. Barton at Alexandra Park, London. This structure had a bamboo framework suspended below it, connected with which was the propelling machinery, two engines each of 4.7 ihp, driving a series of fans, there being a large square sail serving as a rudder. In 1905 an improved form of this air-ship was experimented with, the name Barton-Rawson air-ship, 'designed for the War Office', later being given to it. In this form it consisted of a silkballoon 180 feet long and 40 in diameter, with a bamboo car 127 ft. long and 18 ft. high, carrying a 50-horsepower motor at either end driving four propellers 7 ft. in diameter and revolving at a high speed, the total weight being about 14,000 lbs. Ascents made in July 1905 were not very successful, the air-ship driving with the wind and being unable to take a course of its own. The British War Office expressed its readiness to give an order for an air-ship on certain conditions, one being that it must be able to turn in a circle of 100 yards radius.
Besides balloons, which are lighter than a corresponding volume of air, and air-ships depending on the same principle, various apparatus were constructed for aerialnavigation that are heavier than the air at the start of the 20th century at a time when the feasibility of attaining success with such was supported by the flight of birds, many of which are decidedly heavy compared with their expanse of wing. Some of these apparatus were intended more for gliding or soaring through the air than for actual flight, having somewhat the nature of a huge bird with outstretched wings, beneath which a man attached himself, and on springing from a height gradually descends to the bottom - an idea revisited some years later for the hang-glider.
The kite, or structures on the same principle, were much experimented with, and it was found considerable weights can be raised and carried in this way. The kite rises in the air if drawn along by its string, and if instead of drawing it along a propeller is fitted to drive it through the air it ought to ascend in the same manner. Hence the invention of the aeroplane, which shows a large flat surface contrived to float nearly horizontally in the air, but with the front edge very slightly raised, so that in being propelled rapidly along it receives the pressure of the air on the under side, the air thus tending to counteract the force of gravity. Sir H. S. Maxim in 1894 constructed a huge machine with main and several subsidiary aeroplanes, propelled by two large screws driven by steam-engines of 300 hp, and able to rise with a great weight. As a model, at least, Prof. Langley's aerodrome had some success, flying through the air a distance of three-quarters of a mile. It had two rigid pairs of wings about 12 ft. in width, with large screw-propellers between them driven by a small steam-engine. Aviation is the term applied to attempts at flight otherwise than by balloons.
Manned balloons were successfully used for taking meteorological and military observation from the end of the 19th century. The latter class of balloons were usually 'captive' balloons - balloons that are kept by a rope from going farther than is desired, and that can be drawn back at will. Their use was only really suited for fairly calm weather and in certain circumstances. The balloon may have had a telephone connection with the earth below. There was a balloon service in the British army, the duties falling upon the Royal Engineers. Since about 1900 small captive and other balloons have sent up for purely scientific purposes, unaccompanied by any person, but provided with self-recording thermometers, barometers, etc., by which valuable facts have been ascertained. Some of these early balloons reached heights of 60,000 or 70,000 feet. During the siege of Paris in 1870-71 over sixty persons (including Gambetta) and innumerable letters left the city in balloons. Research Aeronautics
SBT is an abbreviation for Screening Breath Tester
SBT is an abbreviation for Screening Breath Test
SBT is an abbreviation for Segregated Ballast
SBT is an abbreviation for Surface-Barrier Transistor Research SBT
WB is an abbreviation for Water Ballast
WB is an abbreviation for Waybill
WB is an abbreviation for West Bound
WB is an abbreviation for Wideband
WB is an abbreviation for Weather Bureau
WB is an abbreviation for World Bank Research WB
The Sindhurakshak is a Russian built, Indian Kilo Class (Type 636) submarine designed for anti-submarine and anti-ship warfare in the protection of naval bases, coastal installations and sea lanes, and also for general reconnaissance and patrol missions. The submarine consists of six watertight compartments separated by transverse bulkheads in a pressurised double-hull. This design and the submarine's good reserve buoyancy lead to increased survivability if the submarine is holed, even with one compartment and two adjacent ballast tanks flooded. The foreplanes are positioned on the upper hull in front of the fin or sail. The command and control systems and fire control systems are located in the main control room which is sealed off from the other compartments. The design is a development of the 877EKM Kilo class, with the length of the hull being extended by two frame spacings (2 x 600 mm).
The power of the diesel generators has been increased and the main propulsion shaft speed has been reduced to provide a substantial reduction in the acousticsignature of the submarine. The low noise level of the submarine has been achieved with the selection of quiet machinery, vibration and noise isolation and a special anti-acoustic rubber coating applied on the outer hull surface. The Sindhurakshak has a displacement of 2,350 tons. Maximum diving depth is 300 m. Speed is 11 knots when surfaced and 20 knots when submerged. Sea endurance is 45 days. Range is 7,500 miles when snorkelling at 7 knots and 400 miles when submerged at 3 knots. The submarine is equipped with six 533 mm forward torpedo tubes situated in the nose of the submarine and carries eighteen torpedoes with six in the torpedo tubes and twelve stored on the racks. Alternatively the torpedo tubes can deploy mines. The submarine can carry 24 mines with two in each of the six tubes and twelve on the racks. Two torpedo tubes are designed for firing remote-controlled torpedoes with a very high accuracy. All torpedo tubes and their service systems provide effective firing from periscope to operational depths. The computer-controlled torpedo system is provided with a quick-loading device. It takes only 15 seconds to prepare stand-by torpedo tubes for firing: The first salvo is fired within two minutes and the second within five minutes. Research Sindhurakshak
The Wasp Class is the US Navy's large-deck multipurpose amphibious assault ship. The mission of these ships is to enable the Navy and Marine Corps team to accomplish smooth transition from the sea to the land battle, primarily as the centrepiece of a Navy Amphibious Ready Group (ARG). A multi-mission amphibious-ready group is fully capable of amphibious assault, advance force, and special purpose operations, as well as non-combatant evacuation and other humanitarian missions. LHDs embark, transport, deploy, command and fully support all elements of a Marine Expeditionary Unit (MEU) of 2,000 Marines, inserting forces ashore via helicopters, landing craft and amphibious vehicles. The Wasp Class is the first specifically designed to employ air-cushion landing craft (LCACS), and to carry a squadron of Harrier II (AV-8B) STOVL (Short Take Off Vertical Landing) jets for operational support. LHDs are fully-equipped with command and control systems for flagship command duty. The Wasp Class carries a mix of assault helicopters, plus six to eight Harriers for close air support.
The ship's air traffic control system supports simultaneous Harrier and helicopter operations on the ship's 819 ft by 112 ft flight deck. The ship has two deck edge aircraft elevators, each 50 feet wide and 45 feet long, with a lifting capacity of 75,000 pounds. The elevators fold for transit through the Panama Canal, and are the largest folding elevators in the Navy. The ship can also fully maintain all embarked aircraft. The ships are armed with two semi-active radar-guided NATOSea Sparrow Missile Systems (NSSMS) for anti-air warfare protection, two Rolling Airframe Missile (RAM) Systems and two Phalanx Close-in Weapon-System (CIWS) mounts to counter threats from low flying aircraft and close-in small craft. Six Super Rapid Blooming Offboard ChaffDecoy System (SRBOC) launchers augment LHD 6's anti-ship missile defences. Four 50 calibre machine-guns and three 25mm machine-guns are also fitted.
The ship's assault support system synchronises the simultaneous horizontal and vertical flow of troops, cargo and vehicles throughout the ship, for efficient
and fast insertion of forces ashore via helicopters, landing craft and amphibious vehicles. Six 12000-pound capacity cargo elevators transport material and supplies from cargo holds to staging areas for loading. Cargo to be loaded aboard waiting landing craft within the well deck is moved via a monorail system. This system consists of 2900 feet of track in a six-track layout directly over the ship's vehicle storage area and well deck. Five 32-foot cargo monorail trains each with a capacity of 6000 pounds carry material at speeds up to 600 feet per minute (6.8 miles per hour) from the staging area to the landing craft in the well deck.
The ship's vehicle storage area typically accommodates five M-1 tanks, 25 Light Amphibious Vehicles (L.A.V.), eight Howitzer M-198 guns, 68 military trucks (HMMVVVs), 10 logistics vehicles (Dragon Wagons), 12 five-ton trucks, two water trailers, a fuel service truck, four rough terrain forklifts and two generator trailers. These vehicles can be loaded aboard landing craft, and the majority can be rigged for transportation to the beach by helicopter. Off the beach, landing craft are launched and recovered through the very large stern gate which opens the 13,600 square-foot well deck to the sea. This well deck is 267 feet long and 50 feet wide, and is designed specifically for the fly-in/fly-out capabilities of the air cushioned landing craft (LCAC). To launch and recover conventional landing craft, the ship can ballast over 15,000 tons of seawater to allow these craft to float into and out of the well deck. Research Wasp Class
Abbreviations
Research Ballast
