SPARS

Immediately preceding the Glossary at the back of this text IS a tutorial showing you how to use Spar-tanBuild and SpartanView and describing some addi tional features... 

Many models can be built with the tools that have already been described Some mod els however require special techniques (or are more easily built) using some of the Spar tanBmld tools described m the following table... 

Iceland spar, see Calcium carbonate lodyrite, see Silver iodide... 

Fig. 5.5 Adsorption isotherms of butane at 0°C on Iceland Spar ground for 1000 h. Curve (i), the solid was outgassed at 25°C. Curve (ii), the solid was outgassed at 1S0°C. O, adsorption p Q, desorption.

Heavy oil conversion Heavy oils Heavy spar Heavy water... 

Ice cream imitation Iceland spar Ice milk Ice removal... 

The prices for acid-grade fluorspar dry basis from Mexico and the RepubHc of South Africa for 1993 were Mexican spar, fob Tampico,... 

Ma.gnesium Oxide. Magnesium oxide behaves in a similar manner to other metal oxides. However, most spars contain practically no magnesium oxide, so it does not affect yield loss or plant operation. 

Based on previous spHts ia milling operations, about a 60% yield or 146 x 10 t of acid-grade spar could be expected. At the production rates of the early 1990s, this would be a 24-yr supply. Additional suppHes are expected to be brought iato production, however, and no decline ia available reserves is expected through the year 2000. 

Most of the acid-grade spar used for HF production ia the United States is imported. More than two-thkds of the fluorspar consumed ia the United States goes iato production of HF nearly 30% is consumed as a flux ia steelmaking and the remainder is consumed ia glass manufacture, enamels, welding rod coatings, and other end uses or products (see Fluorine compounds, inorganic-calcium). 

Iceland spar s the purest limestone, virtually pure calcite of about 99.9% CaCO. It is also known as optical calcite its occurrence is rate. 

Barium [7440-39-3] Ba, is a member of Group 2 (IIA) of the periodic table where it Hes between strontium and radium. Along with calcium and strontium, barium is classed as an alkaline earth metal, and is the densest of the three. Barium metal does not occur free in nature however, its compounds occur in small but widely distributed amounts in the earth s cmst, especially in igneous rocks, sandstone, and shale. The principal barium minerals are barytes [13462-86-7] (barium sulfate) and witherite [14941-39-0] (barium carbonate) which is also known as heavy spar. The latter mineral can be readily decomposed via calcination to form barium oxide [1304-28-5] BaO, which is the ore used commercially for the preparation of barium metal. 

The first report concerning barium compounds occurred in the early part of the seventeenth century when it was noted that the ignition of heavy spar gave a peculiar green light. A century later, Scheele reported that a precipitate formed when sulfuric acid was added to a solution of barium salts. The presence of natural barium carbonate, witherite [14941-39-0] BaCO, was noted in Scodand by Withering. 

Barite [13462-86-7], natural barium sulfate, BaSO, commonly known as barytes, and sometimes as heavy spar, tiU, or cawk, occurs in many geological environments in sedimentary, igneous, and metamorphic rocks. Commercial deposits are of three types vein and cavity filling deposits residual deposits and bedded deposits. Most commercial sources are replacement deposits in limestone, dolomitic sandstone, and shales, or residual deposits caused by differential weathering that result in lumps of barite enclosed in clay. Barite is widely distributed and has minable deposits in many countries. 

Series major additive Cu Al -r 4 Cu -r Mg, Si, Mn Strong age-hardening alloy aircraft skins, spars, forgings, rivets. 

Aluminium-lithium alloys Al -r 3 Li Low density and good strength aircraft skins and spars. 

The surfaces to be protected should be the total surface, including inserts, spars and pipes. The upper 1.5 m of the side walls and the covers should be provided with a coating of recognized quality [10] to protect against corrosion. 

Glue was also used to join the numerous small plywood and wood details necessary to fabricate the structural frameworks typical of early aircraft. Fig. 1 shows a monoplane wing circa 1930 fabricated primarily from wood that was joined via more than one thousand glued joints [2]. Note the many small stringers and gussets bonded together to form the ribs and spars of the wing. 

Early trailing edge design was eomprised of a C-shaped spar bonded to upper and lower facesheets with honeyeomb eore between (Fig. 36). The spar was either a simple extrusion if eonstant dimension, or built-up from two L-shaped legs if it needed to taper from one end to the other. Faeesheets were simple eonstant-thiekness sheet material. 

An alternate method involved pre-machining the core detail to contour while it was stabilized in a frozen block of water or other medium. This entailed the expense and time to freeze the block and keep it frozen during machining as well as the risk of contaminating the core bond surfaces. In addition it was difficult to maintain the dimensional tolerances necessary to match the spar dimensions to the core adequately. Both spar and core details had machining tolerances and significant hand sanding of the core was often required to match the details. 

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