BATTLESHIPS AND BOMBS

Evening Star, Issue 22276, 29 February 1936, Page 11

BATTLESHIPS AND BOMBS

[E. X. H. Bentley, in the ‘ Spectator.’]

Battleships and bombs have boon a subject for argument ever since aeroplanes have been able to carry largo bombs. Any effective discussion on the subject is rendered difficult by tbo secrecy maintained by the Government authorities. But by careful searching amongst past records it is possible to unearth enough facts to give some indication of the possibilities of bombing attacks on a fleet. There arc, of course, two essential differences between a shell and a bomb. In the first place a shell has to be very heavy in order to stand the force of the explosion which fires it from the gun. A bomb can earrjf a much bigger explosive charge, in proportion to its weight. In the second, a bomb which falls 10ft or 15ft away from a ship will do as much damage as one which makes a direct hit; whereas a shell which just misses the ship does no damage at all. This means, in effect, a great enlargement of the bomber's target.

From time to time the champions of the battleship point to some new invention and say that the battleship now has nothing to fear from the aeroplane. One of these improvements is the bomb-proof deck, and another is the multiple pom-pom anti-aircraft gun. Many people still seem to think that a bomb-proof deck renders a battleship immune from bombs, although the belief has been proved to be wrong, both in theory and in practice. A. large bomb exploding close to the ship and below the level of the keel can break the ship’s back (because the explosion has the effect of lifting the ship at one point, instead of its weight of the ship being evenly supported over its whole length as it normally is). A bomb which explodes in the water alongside the ship will stave in the plates. In trials carried out by the U.S.A. a 5,000 ton cruiser (with 4in armour at the bows) was sunk by a single 6001 b bomb which hit the water near the hows, lifted the hull several feet, and made a large hole In the side.

The effect of anti-aircraft fire is perhaps the factor we know least about, for the reason that it is impossible to simulate war-time conditions in peace-time exercises. During the war one Hit in a thousand was considered a good average for the anti-aircraft guns at the front. Firing from a moving platform is obviously much more difficult; and even allowing for a very big increase in efficiency of anti-air-craft armament since then, the best that can be hoped for is to keep the aeroplane at a fairly respectful distance. -Another fact to remember is that the modern multi-barrelled guns use a great deal of ammunition, and a fleet subjected to continuous attack by a few hundred aeroplanes operating from a shore base might be in serious danger of running short pf ammunition. In one of the niglit raids on London by five German aeroplanes the A-A guns fired 15,000 rounds without bringing down one of the raiders. A well-known naval expert has stated that the new multiple pom-pom guns, although formidable 'against torpedo planes and low-flying bombers, are quite useless against aeroplanes bombing from high altitudes.

One of the few bombing trials of which the results were made public in this country took place in 1923, and it demonstrated that the accuracy obtainable was of a higher order than most people have belived. The target was a wireless-controlled ship which was steered on a zig-zag course at a speed of 14 knots, and the aeroplanes bombed from a height of B,oooft. The conditions wore not in favour of the bombers, because there was a high wind and also a good deal of cloud. (The weather and the zig-zagging of the ship would, of course, have made things more difficult for the anti-aircraft gunners on the ship.) Under these conditions live bombers scored 2 per cent, direct hits and 17 per cent, within the danger zone of loft from the hull—and bomb aiming has increased immensely in accuracy since 1923. Some high altitude bombing trials were made by the R.A.F. at the end of 1935 to test the accuracy of the latest instruments. Although no actual figures were given it was stated that the percentage of misses, even from a height of three miles (over 15,000 ft) was very small. Another deadly method of attack is by diving bombing, in which the aeroplane dives down from 10 or 15 thousand feet, aiming itself and its bomb straight at the battleship. The bomb is released at about 2,000 ft, just before the aeroplane flattens out of the dive; and at that range the chances of a direct bit, on a target of well over an acre in extent, are distinctly good. Diving almost vertically at about 350 miles an' hour, the bomber offers an extremely difficult target to the anti-aircraft gunners, for it takes less than half a minute from tho beginning of its dive to the tinie when it drops its bomb. This sort of attack would not be made by single aeroplanes, but in groups of about five at a time. Each pilot would attack from a different direction and would so time his dive that he reached the ship a few seconds after the one before him. Those tactics make it impossible for the anti-aircraft gunners to concentrate their fire on any single machine. Several years after the war the United States of America made extensive bombing trials, using surrendered German warships as targets; and the results gave naval authorities all over the world a good deal to think about. In addition to the sinking of the cruiser, already mentioned, a 23,000-ton battleship with heavy armour below the water line was sunk by two 2,0001 b bombs, neither of which made a direct hit on the ship. The report of the trials stated that “ it will he difficult, if not impossible, to build any type of naval craft of sufficient strength to withstand the destructive force that can be obtained with the largest bombs that aeroplanes may he able to carry from shore bases or sheltered harbours. ...” “Tho commission concludes that in coast defence operations, aeroplanes possess important tactical and strategical qualifications, and that in adequate numbers they may prove a decisive factor in such operations.” A fleet can of course defend itself to a certain extent by means of its own aeroplanes, but the number of these is limited. An aircraft-carrier has to steam against the prevailing wind whilst its aeroplanes are talcing off. And unless by a fluke this direction happened to bo the r.nnic as that taken by the rest of the fleet, it would not have time to fly off all its aeroplanes before getting too far from its consorts.

The question of battleships and bombs is of vital importance to the British Empire, and public opinion would be all in favour of some really conclusive tests carried out in a strictly impartial manner. The Royal Air Force would bo only too glad to show what they can do; and no doubt the Royal Navy would be equally willing to show the 11.A.!', that they can’t do it. The results of any such test.-, should be made public so that the taxpayer, as

well ns the Government, can judge whether the proportion of our defence estimates allotted to the senior and the junior services respectively is such as to give the maximum amount nt defence for the minimum expenditure.