The Elements of Air Defense

Trained observers, recently back from London, tell us that, with the exception of some reconstruction necessary for public safety, the city looks the same as when the debris of the Big Blitz was cleared away. Once in a while, a stray minion of the Luftwaffe manages to sneak up the Thames estuary and drop a few bombs, but the effect is negligible. Coastal communities occasionally take a drubbing in propaganda retaliatory bombings, but these usually cost more aircraft than the raids are worth according to the traditionally accepted 10 per cent maximum loss scale.

Two main factors are responsible for the comparative safety of London in recent months. One is the fact that the original Blitz was designed to crack England's will to resist, rather than to destroy any specific military target. This has obviously failed. If anything made the average Briton yearn to warm his spirits over the glow from Berlin's flames, it was the Big Blitz. The second, and more dependable factor, is the state of perfection to which the air defense system has integrated fighter planes, anti-aircraft, observers, balloon barrages, and the omnipotent Radar.

The defense of Britain is entrusted to the Fighter Command of the RAF. Its headquarters acts as a hub for a radially designed organization, which divides all England into a number of districts, under the executive control of a subsidiary unit of the command, called a group. Through these groups, the headquarters of Fighter Command passes orders to the component subdivisions of the organization, charged with the actual repelling of the enemy.

The best method of studying the defense system is to observe the most complicated one, the southern group, charged with the safety of London. Because the Group's command covers a wide area, it is further split into sectors, and a sector headquarters is interposed between the wings or actual airplane, balloon, artillery and observation groups.

To effect additional flexibility, all wings are in direct telephonic control with sector, group and fighter-command headquarters. To make for greater efficiency under fire, all group units are circumferentially connected.

The key to all anti-aircraft defense is Radar, the method of radio-location which applies the electronic principle that, a projected high-frequency beam, striking an object in space, will bounce off at the same angle at which it was projected, but in the opposite direction, the same as a bouncing ball. Having determined these two angles, and the known hypotenuse, calculating the position, speed and altitude of the approaching aircraft is a simple geometric problem. Fixed Radar installations have their range efficiency seriously curtailed, like television, by the curvature of the earth.

Once the Radar units detect the presence of approaching enemy aircraft, they report the direction and size of the attacking fleet to Command and Group headquarters. At once, commands go out from Command to group, from group to sector control, thence to wings and squadrons of the RAF, from which ships are dispatched to intercept the enemy.

At the same time, all the ground installations are put on the alert. Barrage balloons, radio- locators, observation posts and similar auxiliaries operate directly under the command of the sector control.

Anti-aircraft artillery, searchlights and predictors are under the command of the regular Army (ground forces). Liaison officers link these units to Command and group control to secure efficient cooperation.

The great test of the effectiveness this defense system will come, in all probability, before Germany really thinks invasion is about to happen. By concentrated air attack on London, they hope to put the air strength on the defensive, or at least off offensive balance, robing strength needed for the air umbrella which must cover any attempted landing operation on Hitler's Festung Europa.

If the net protecting England functions well, keeping enemy aircraft out of the bomber takeoff zones, the beginning of Hitler's end is close at hand.

This article was originally published in the August, 1943, issue of Air News magazine, vol 7, no 2, pp 20-21.
The original article includes diagrams of a barrage balloon ground station and a fighter base.
Air News drawings by Robert Lindgren; credits to King Features Syndicate.