PROTECTION FROM AIR RAIDS

New Zealand Herald, Volume LXXIV, Issue 22777, 10 July 1937, Page 13 (Supplement)

PROTECTION FROM AIR RAIDS

STATEMENTS have been made that our defence against invading aircraft is deficient because ground troops are controlled by the Army and air fighters by the Royal Air Force, states the military correspondent of The Observer, London. Further, the guns are administered by the .Royal Artillery, the searchlights by the Royal Engineers, the Observer Corps is civilian, and protective measures against gas and fire are looked after by the Home Office. , Critics of our methods point to the German anti-aircraft defence, which is completely in the hands of one department, and neglect to give any credit for the very complete system of correlation which has been worked out for!the defence of London and other important centres. ' 40,000 Feet Range Whether the defence is in the hands of one or two, or even three or four, separate services does not matter provided that in action they are under one command. Unity of command is provided for in our defence scheme. Germ'an ideas differ to some extent from our own, but whether these ideas are better than ours only actual test can determine. The German military authorities have allowed something to be known of the defences of Berlin,

uuu uinu auuuu tective measures for other parts oi Germany. We, with the necessity for getting re; cruits for a voluntary service, have advertised our own methods fairly completely. The Germans believe in the use oi two different types of gun for fighting aircraft from the ground. They have e very quick-firing weapon of about bore for tackling low-flying aircraft, anc an effioient high-altitude weapon of approximately 3}in. bore, which is said tc

he Defences of London and Berlin

AN ANSWER TO CRITICS IN BRITAIN

be capable of driving a shell to a height of 40,000 'feet. They have also been experimenting with a rocket typo of projectile, but of this very little is known. The present British gun has an altitude range of only about 18,000 ft., but the new guns will have a range of at least 30,000 ft. Rocket Projectile There is also in preparation a rapidfire gun firing a shell of about 21b., but no official information is available as to whether it is to be used in the organised defence of London and other cities. It will certainlj' be used in the field against low-flying aircraft. The German searchlights have always been good, and there is little to chooso between theirs and ours. They are believed to be experimenting with an extremely efficient typo of mercury arc, but they have no monopoly of theso lamps, for British, as well as American and Dutch, companies are already producing them, at any rate in the laboratory. The Searchlights The advantage of this type of lamp is that it requires no carbons and no adjustment of the light. Once the light is switched on it remains constant and does not flutter. In theory the German predictor is a better instrument than ours. The predictor is v a complicated calculating instrument, which solves the problem of the direction in which the gun is to be pointed and the height at which the shell is to burst. It allows for the speed'of the aircraft, the direction of its travel, whether it is climbing or descending, and the amount of its drift. The name predictor indicates that its work is so to aim the gun that the bursting shell and the aircraft will meet on their respective courses. It is, in fact, an electrical and mechanical means of doing what the game shot does in-

•tinctively when he swings 011 to, and in front of, a flying bird. The British predictor is worked by six men. The German instrument, which also allows for swooping or curved flight, requires ten men to work it. It is also a considerably bigger piece of apparatus. Germany's Predictor British authority is of opinion that the additional complications necossary to allow for curved flight are not worth while, in that every .man added to the predictor crew multiplies the chances of mistakes. A good deal has been heard lately of the balloon apron, or "barrage," for anti-aircraft defence. We have been told that both the German and French balloon aprons are sot much higher in t|}e air than ours. Since our defence spokesmen have wisely declined to give any actual figures in connection with our balloon aprons, copying the reticence in this matter of other countries, no comparison can bo made. Mobile "Aprons" The Germans are said to have some mobile aprons, but their efficiency is> doubted, as a kite balloon cannot bo towed very fast when it is inflated, and if it is taken from place to placo deflated the filling of the gas bag will occupy a considerable time. Multiple tube filling cuts down the time considerably, but hydrogen tubes are weighty things to cart about. Critics who compare the air defences of one country with those of another usually fail to take into consideration the fact that arrangements which are quite suitable for one typo of terrain might bo quite unsuitable for another. , The British defence scheme has been worked out for our own country. Our military authorities are satisfied that it will be efficient when we have the men and the material to make it complete.