The University of Western Ontario, London 72, Canada
Faculty of Social Science
Department of Psychology
October 26, 1973
Dear Mr. Dayan:
I suppose that the following idea has already been considered by weapons developers and rejected. I am writing to you, nevertheless, on the slim chance that no one has ever considered it, in which case it could be of use to you. On the expectation that a single letter would not be brought to your attention, or to the attention of other people competent to evaluate it, I have taken the liberty of sending copies to several high-ranking Israeli officials.
The problem is to protect an airplane form an antiaircraft missile; one solution is for the airplane to release a decoy to attract the missile — a decoy which is compact, light, inexpensive, and yet which is attractive to the missile.
I have in mind the air bags being introduced in American automobiles to prevent accident injury. The bags are relatively inexpensive, compact, and light. They are triggered and inflate to full size in less than 1/20 sec.
Suppose that at the first sign of an approaching missile, a larger version of this bag was released from the target airplane, and suppose that the bag inflated to something like a 30-meter diameter in ½ sec. Suppose also that the bag was filled with a light gas so that instead of falling, it sat right on the path of the escaping airplane. A missile approaching from the rear, then, would be confronted with a choice of the bag or the more distant airplane (at A). Even better, the airplane might lie in the bag's shadow (at B), presenting the missile with only the bag as target.
October 26, 1973
The bag could, of course, be given a radar-reflective coat to make it "louder" to radar-guided missiles, or could be filled with hot gas to make it "louder" to heat-seeking missiles. The loudness of the bag — its size, its radar reflectivity, its heat, and its proximity compared to the escaping airplane — might make it the missile's preferred target.
An improved version of this defense would be to have the airplane eject several bags. At the first sign of an approaching missile, for example, bags could be ejected at the rate of 2/sec. The effect would be to provide a larger number of decoys and to increase the probability that the airplane would be hidden in the shadow of the last bag ejected:
Multiple bags would also afford greater protection from side attack:
October 26, 1973
If, as soon as an approaching missile was detected, the plane began ejecting bags and began turning away from the missile at the same time, the missile would have more and more bags to distract it and the plane would lie increasingly in the shadow of its last bag. But even with a single bag, a missile programmed to seek the most reflective, or hottest target might prefer the bag to the airplane (even when the airplane did not lie in a protective shadow and when it continued to present a viable, but less salient, target).
Mechanically, the development of this defence poses few problems. Rapidly inflatable bags are already under production. All that remains is: (a) to make the bags bigger, (b) if necessary, to make them more radar-reflective or hotter, and (c) when more than one bag is to be ejected, to build a device which will release the bags at a fast rate. It would seem that the air bag defence could be built and tested in very short time and at very small cost.
Numerous difficulties might be encountered, but all of these, hopefully, could be resolved. If there was danger of a missile passing right through a bag unharmed and undetonated, for example, the bag could be reinforced with wires so that the missile would either detonate or be enveloped and its guidance thereby disrupted. If the missile only sought targets following the approximate trajectory of the original fix, the decoys could be made smaller and denser so as to drop behind the airplane more gradually rather than coming to a sudden halt. If the missile sought not the loudest target but the one most resembling its original fix, then the radar or heat characteristics of the bag could be made to resemble the airplane's, rather than being maximized.
What the air bags offer is an inexpensive and near-instant "forest" of large objects behind which an airplane can retreat. In more ambitious use, hundreds (perhaps thousands) of such bags could be sown prior to a bombing run, permitting the attacking bombers to emerge from the retreat into a protective screen.
Similar uses can be imagined in land and marine engagements. When a target has 2 or 3 sec warning of an approaching missile, a bag package could be shot from a hand-held gun in the direction of the approaching missile — a bag package that inflated as little as 20 meters in front of a tank, for example, and which detonated the approaching missile at that point (or which enveloped the missile and dragged it downward) would minimize damage considerably in comparison with a direct hit.
Lubomir S. Prytulak, Ph.D.
Yigal Allon, Haim Bar-Lev,
David Elazar, Shmuel Gonen,
Six registration receipts which appear not here but below the "image" version of the Dayan letter (click "To Image" at the top of this page), show that it was mailed on 26-Oct-1973 from London Ontario and was addressed to six people:
Moshe Dayan, Defense Minister Shmuel Gonen, Major General, Commander of the Southern Front Haim Bar-Lev, Minister of Commerce Aharon Yariv, General Yigal Allon, Deputy Prime Minister David Elazar, Lieutenant General, Chief of Staff