The Weakness of our Heavy Guns.
Admiral Robert E. Scott, late Admiralty superintendent of naval gun-carriages, has addressed to the Duke of Cambridge a letter, accompanied by voluminous documentary evidence, on the present condition of our heavy ordnance, and on its improvement and eimplirication. Most of the modern heavy guns which arc in use in this country are, it should be borne in mind, rifled cither on the " polygrove hook " or on the "polygrovo plain" system, and the twist in the rifling is an increasing one from the breech towards a point which, in the majority of cases, is to be found about halfway to the muzzle. At that point tho twist becomes uniform, and is so maintained to the end. Tho rifling begins immediately forward of the chamber; and the rotation of tho projectile is effected by means of bands of soft metal near its base. These bands are forced, by the explosion of the charge, to accommodate themselves to the grooves of the rifling. Tho work which is thus thrust upon the grooving at the breechend of the gun sooner or later causes the obliteration of the grooves in that part. Tho new heavy guns are consequently made with " liners " of steel, in which the grooves are cut. This " lining " is in two parts. That at the breech-end extends to a little in front of the trunnions, or of the position which the trunnions would occupy if there were any; and when the grooves are worn out it can be removed and replaced, though tho operation is todious and costly. An idea of the severity of the erosion may be gathered from tho fact that it is estimated that after having been fired no more than eighty times the new 111-ton guns will need relining. These points must be clearly comprehended before the gist of Admiral Scott's criticisms and suggestions can be understood. The criticisms are veiy much to the point. Admiral Scott fails to see that good shooting is favored by the projectile being held fast until the gas pressure rises sufficiently to force it through the smaller diameter of the neck of the shot-chamber, and bo to rifle it in an instant. He fails to see that good i shooting is favored by the check on the projectile, which is the consequence of the rapidly increasing twist of the grooviog. He fails to see the reasonableness of rotating a long projectile solely by the medium of the narrow rings of soft metal near its base. For what, in brief, is the history of the projectile from the moment of the explosion of the oharge behind it ? First, by means of a strong band, itis retardedfromdepartingwith a sudden rush ; then, after having squeezed through the band, it is allowed to gather way ; and then its way is again retarded by the increasing twist. It is obvious that the whole process puts a terrible strain upon the guu. It is impossible to wedge a large solid body into a smaller cylinder without straining both; and, therefore it is not to be wondered at that we very often hear of the
splitting of " liners." When tho projectile has got through the neck of the shot-chamber a now strain is put upon the gun, The projectile only fits tho rifling just where it ie provided with the rotating bands of soft metal; and along three-fourths of its length the projectile is, therefore, not supported in tho bore. Tho result is that tho bolt " wobbles" in the gun, and that the " wobbling " causes the delivery by the bolt of a succession of heavy blows upon tho interior of tho "liner." In the mcantimo tho increasing twist of tho rifling sets up a new retarding action, which develops yet another straining influence on the unfortunate gun. Small wondor, then, that, thus roughly treated, tho Colling wood's 44ton breech-loader burst, and the Active's 6-incli bveecli-loader Ulew ita muazXe off *, and still small wonder that the Imptkieuße's C-ineh guns are blowing their locks out of the breech-blocks, and that almost every day "liners" are discovered to be so eroded, dented, and otherwise damaged as to need renewal, the guns in the interval being absolutely useless. Admiral Scott's case against our modern heavy guns need not here be followed any further. Enough has already been said to show that it is a real and serious one.—Home paper.
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The Weakness of our Heavy Guns., Evening Star, Issue 7984, 13 August 1889
The Weakness of our Heavy Guns. Evening Star, Issue 7984, 13 August 1889
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