GERMAN ARMY CONVOYS

Evening Star, Issue 23723, 2 November 1940, Page 8

GERMAN ARMY CONVOYS

WELL LIT SECRECY An August issue of ‘ The Motor ’ stated that wherever the Gentians attacked, it practically always started at dawn, preceded by overnight manoeuvring into position and considerable movement under the cover of darkness, bringing forward reserves, supplies, and equipment. Thousands of vehicles were used, but to facilitate such large-scale movements a special form of lighting was developed, one which would ■ not readily be seen from the air, yet would allow convoys to travel fast. The system comprises a hooded head lamp and a special rear lamp. The former gives an even spread of light up to a distance of 35 to 45yds, lighting anything up to a width of 28yds. The beam is controlled by a rheostat switch. Hear lighting takes the form of an interesting and ingenious distance indicating lamp built in conjunction with stop and tail lights. The head lamp lias to make possible a speed of about 20 m.p.h. in convoy without the light being detected by aircraft or ground observers, and the distance indicating lamp enables drivers to maintain correct intervals between vehicles.

Four panels arc cut in the face of the distance indicating lamp, through which little green lights shine. They are spaced fairly dose together in pairs with each pair separated by about ,*lin. If the driver is able to discern tlie four green lights on the vehicle ahead it is an indication that he is much too close. The individual grocn lights are visible up to a distance of

He has to drop back slightly, increasing the gap between the vehicles until each pair of lights merges together, so that all tho driver secs is two green panels. This is how they would be visible up to a distance of i‘lßyds, which is the spacing considered correct for convoy work by the Gorman authorities. At anything above that the panels merge again to appear as one light, indicating to the driver that he is too far away from the par ahead.

With this scheme it is possible to maintain a convoy speed considerably higher than that normally possible with a single poor red light and dim head-lamp illumination. Perhaps the most essential factor is that distances can be judged so well. The hooded head lamp is designed on an entirely new principle, having a very narrow strip-form reflector on the ellip-

toid principle, taking advantage of converging rays of light from 36-watt bulb illumination.

The hood actually comes down below the level of the bead-lamp aperture ; all upward rays are eliminated by virtue of the design of the reflector, and the hood tends further to cast the light downwards. The beam actually is 18in high at a distance of 25yds from the car. It strikes the road about 12yds ahead of the vehicle, giving a good spread, 4

The rheostat switch enables the beam to bo controlled in three different strengths, and owing to the even, weak light distribution on the ground, recognition by aircraft above a height of 1,500 ft with the dimmest beam, above 2,700 ft with the medium beam, and -I,Booft witli the brightest is made impossible. On very dark nights and witli long convoys, the beam strengths are reduced ; in any case it is probably only the leading vehicle that would use the brightest, the others relying upon the weakest beam in conjunction with the green distance indicators. Actually, with the distance-indicating equipment there is really no need to use head lamps.