from victorysiren.com/x/index.htm

They're burning it, blowing it up, blasting it with sickening sound. A great experimental war is being waged on the enemy fog.

A remarkable action picture of a fog-dispersal system at the instant of ignition. The smoke soon disappears.

UNCLE SAM has declared war on fog. For the next five years, one million dollars a year will be spent by the Army, Navy and CAA in a great combined operation to lick this greatest of flying hazards.

The laboratory battlefield has been set up in an ideal spot - a former Naval air station at Arcata, Calif., along the Oregon border - a place on a steep hill near the ocean in the foggiest section of the United States.

Every major type of fog-dispersal technique known is now being set up, among them two revolutionary newcomers, a method of atomizing fuel by high pressure rather than heat, and a sonic method whereby fog is changed to rain by high-frequency sound-wave bombardment.

Fog dispersal is needed and it will continue to be needed. Present instrument landing techniques will bring a blind plane safely down to within 50 feet of the ground, but from then on the pilot wants to see what he's doing. Even when fully automatic landing become possible, the physical and psychological benefits of having the pilot able to see, will still make The sonic fog-dispersal method uses a set of 12 sirens spaced 100 feet apart along the approach. Below, closeup of a siren being operated by Comm. R.L. Champion, notable pioneer in fog dispersal.

a certain amount of fog clearance necessary. A ceiling of 200 feet could do the job.

The new high-pressure dispersal system is basically a pipe-line with nozzles set up a regular intervals of about 15 feet. The fuel flows through the pipe-line and is force up through the nozzles in the form of finely atomized spray which is ignited electrically by a unit known as a calrod. Gasoline, kerosene or diesel oil can be used. There is no smoke and no waste.

In the sonic method, sound waves produced by great sirens are made to sound the fog particles around, causing them to meet and merge, thus forming units large enough for precipitation as raindrops.

A major obstacle is the effect of the sirens on men who are close. In early tests personnel kept cotton covered with sponge rubber in their ears, and they reported no ear trouble - but most of them became nauseated from the terrific noise. The noise blasted birds from the sky!

One possible way around this obstacle may lie in the use of ultra-sonic transmitters which send waves out at such high frequencies that men and animals can't hear them. These will be tried out.

Navy officers believe the high-frequency sound system if successful will be more practical than thermal means. Installations would cost no more and operation would be more economical. A portable apparatus would greatly aid plane landings on carriers operating in fog.

Test will also be made of the effects of the sound on airmen, and even of possible damage to the aircraft in which they fly.

A third approach to the problem is the novel, promising, wind-curtain method. By it, a huge blower throws a curtain of hot air at right angles to the wind. This causes the wind to move in a vertical circle, dispersing the fog.

The present two best "bets" look like the high-pressure and sonic methods - but everything known will be both tried and improved, if possible. The war against fog is on, and Uncle Sam doesn't lose his wars.