MYSTERY CANNON

Waipa Post, Volume 32, Issue 1928, 30 October 1926, Page 6

MYSTERY CANNON

THEIR CONSTRUCTION. The secrets of the longrange German cannon that bombarded Paris from a distance of 60 miifles, closely guarded even after the Armistice, have now been permitted to leak out, •following tile recent death of the inventor, Dr Fritz Rausenberger, of the Krupp firm. It has been generally guessed that 'the guns were the longest pieces of artlilllery that had ever been constructed, and the new information confirms these conjectures, for their length was 36 meters, or about 128 ft (statefs Science Service). Each gun was assembled out of three prin'cipail parts. Into an ordinary 15in. naval gun an. linneir tube of 8.2 m calibre, 9S.4ft long, was fitted, and over the part that projected beyond the naval gun an additional strengthening ihoop was shrunk on. The total weight of the piece was 154 tons. The weight of the B.2in shell was 2201 b; it wall thlickness was about 23in at the base, anil a little over liin at the top. Its head was given an extraordinarily long (taper, loin to 20in to aid in overcoming the resistance of the air. To obtain its unprecedented range, the gun had 1 to be fired alt an extreme elevation. Theoretically, 45 degrees would have Ibsen the proper angle, but this would have been correct only in a vacuum, and to get ithe shell far up into the thlin air, where resistance was 'low, the gun was set at 50 (degrees. The angle of elevation remained fixied and 1 I to correct for difieren’ccts in wind, a'ir pressure, etc., the powder charge was varied, being calculated anew for eaclh sepajrate shot. The charge for the longest range at which any jfcf -the guns were ever fired, 800 mliles, was 6601 b. At. ithe range of 74 miles he shell reached heights of over 25 miles, making more than two thirds of its

flights at elevations of over six miles or half a mlffle higher than Moun/t 'Everest. The flight of time was three minutes. Due to 'Ohe great length of ithe gun and the very heavy powder charge, the comparatively light shell left the gun’s muzzle at the velocity of over a mile per sdcond, wiith the enormous muzsile enengy of 45,000 foot tons — enough to (lift the whole mass of the world’s largest battleship a foot in the air. Because the shells tended to drop on ;their target, the ctity of Paris, sidewise, Instead of endwise as a projectile naturally does, it was necessary to provide them with two fuses to ensure their explosion on impact. The fuse system worked successfully, 'for none of the shells that struck Paris' failed to explode. Another (difficulty arose due' to the long high flight of the- shell; the rotation of the earth tended to deflect its path, sometimes nearly as muejh as .half a mile. The terrifically high pressure, temperature, and friction of the discharge of the piece tended to make the barrel (bulge slliightly, and because of its great length the gun tended to “whip,” raising the danger of a premature explosion of the shell in (the tube. This did happen once, ruining one of the four guns. The other three according to the Armistice, were dismantled and destroyed. The designer of 'the battery, Dr. Friltz Rausenberger, of Baden-Baden was a well known authority on Ballistics and had for several years been associated with 'the Krupp* firm. In addition to the long-range gun he designed the great 42-centimeter “Big Bertha” that destroyed the Belgian forts early 'in the war. This was a relatively short-barrsrtled howitzer, of no great range, hut <of terrific smashing power, due to the enormous weight of its shells, and the heavy charge of high explosive (they carried.