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An analysis by Captain John C Lyons of leaflet dissemination devices released from aircraft as developed through the Second World War. Descriptions of the various methods employed to drop leaflets from planes are given including the advantages and disadvantages of each method. Not all methods employed or experimented with are detailed in the article but nevertheless it gives a good overall picture of the means used to drop leaflets. The article is undated but appears to have been written in the closing months of the war in Europe, around April or May 1945.
AIR DISSEMINATION DEVICES
by Captain John C Lyons, AUS
The purpose of this article is to review all of the different air dissemination devices which have been evolved at various times in the different theaters and to explain the operational problems which each was designed to solve. In each case the given device was designed to cope with the needs of a particular kind of operation. No one of them is the final answer to all problems of leaflet distribution everywhere.
1. The Ordinary Package
The oldest – and simplest – form of packing for distribution from aircraft is the ordinary leaflet package, wrapped in tough paper and fastened at either end with gummed paper tape. If one end is torn before the package is thrown from the plane, the item will disintegrate when it strikes the slipstream. For distribution from bombing aircraft, it was found, in the Mediterranean Theater that 4000 of the standard size leaflets (5” x 8”) made a package of the size and weight most easily handled by the air crews. For distribution from fighters and fighter-bombers a much smaller package is indicated; in the MTO packages of 500 leaflets were used in this type operation.
There are, however, several very serious objections to package distribution:
a) accuracy of distribution. When packages are thrown from aircraft operating at considerable altitude, they disintegrate a short distance below the plane and the free-flying leaflets are carried by wind drift scores of miles from the point above which the packages were torn open. Elaborate calculations were made to allow for this drift, but it was never generally felt that really accurate distribution from high-altitude planes is possible by this method.
b) manual effort. Package distribution demands considerable physical effort on the part of the air crews – and at a time when they should be most occupied with their normal duties in the plane – and is resented by them for this reason. This is especially true when the leaflets are disseminated in connection with a regular bombing mission or when the crews are working under oxygen.
c) premature breakage. Packages often break in handling inside the aircraft, littering the interior of the plane and making leaflets additionally unpopular with the airmen. Or, packages burst as they are thrown out of the plane, the leaflets are caught in an updraft, and blown back into the interior. Or, leaflets caught in an updraft sometimes foul communication wires or cause other annoying damage to apparatus on the outside of the aircraft.
d) too stout packages. When the packages are made too stout – in order to meet the objections of breakage and premature disintegration – other problems arise. Solid packages have sometimes been caught in a strong wind current and slammed back against the plane, causing dents in or other damage to the wings or framework of the aircraft. There are many cases on record where packages fell to the ground undisintegrated, thereby defeating the whole purpose of airborne scatter.
In summary, the ordinary package is the simplest – but the least satisfactory – method of dropping leaflets from aircraft. The objections are less numerous when the operation is carried out at a low altitude, but there are objections even so.
2. Quick Release Gunny Pack
This was worked out by the British in the Southeast Asia Command where larger concentrations of population and more open country (as compared with North Burma) placed less premium on “pinpoint” accuracy. It is designed to avoid breakage in handling, make sure that the leaflets are well clear of the plane before they become free-flying (and thus do not blow back into the plane or foul appliances on the outside), and minimize the physical effort required of the air crews. It does not meet the objection of wind drift when the operation is carried out at high altitude.
The pack is made of cheap burlap, – in two parts which are held together by a securing cord (this cord runs around the pack through loops and fastens in front in a slipknot). To this slipknot is attached one end of a static line, whose other end is tied to a fixed part of the aircraft. When the pack is pushed through the escape hatch it falls to the end of the static line, the slipknot releases the securing cord, and the two halves fall apart – releasing the leaflets. The empty pack is retrieved by pulling in the static line. Each pack contains about 10,000 leaflets, packed in bricks of 500 each.
It is to be noted that at one time a similar device was used by the RAF in North Africa. This was a canvas (or burlap) sack similar to a small mailbag. The nose was closed by a slipknot to which was tied one end of a static line, whose other end was attached to the aircraft. The jerk of the static line opened the nose of the bag and the leaflet bricks fell out. The bags were then retrieved by hauling in the static lines.
3. The Head Bomb
This device was worked out in Italy to achieve all the advantages mentioned under (2), – plus the very important one of relieving the air crews of all manual effort during flight. It is shackled in the bombrack just like a bomb, and is dropped by the bomb-release mechanism in singletons, sticks, or the entire bombload – according to target requirements. Each item contains about 40,000 standard (5” x 8”) leaflets. Eight bombs can be fitted into the bombrack of a B-25 or B-26.
Materials required are some rough lumber slats, nails, and stout twine. The slats form a sort of “coffin” inside which leaflet packages are fitted. The “coffin” is held together by twine which passes around and around the item through loops formed by bent nails. The twine ends in a slipknot to which a square of plywood is attached by a length of cord. When the device is released the plywood square is caught by the air current and acts as a sort of parachute, pulls loose the slipknot, unwinds the twine, and the device falls apart. The disintegration takes place at about 150 feet below the plane. The materials are, naturally, not retrieved.
The Head bomb does not solve the problem of getting a time-burst at a predetermined altitude above ground level; it is, therefore, not the ideal device for high-level operations. It does solve the problem of getting the leaflets out of the plane without damage to the aircraft or annoyance to the airmen. It would be very useful in low-level operations where the need for a time-fused device does not exist, – and where as many as 40,000 leaflets over a single target are desired. Even where smaller quantities are normally desired, Head bombs of smaller dimensions might be the answer to local problems in low-level operations.
4. The Leaflet-Dropping Belly Tank
Conditions peculiar to North Burma led to the development of this device for use on fighter aircraft. Scattered population called for hitting accurately with small quantities of leaflets tiny villages or open clearings in the jungle. This was to be done by fighter aircraft operating “at tree-top level”. Also, a single aircraft would normally want to leaflet a dozen or more targets on a single mission. It became apparent very quickly that the pilot could not carry out his normal functions, locate targets, toss out leaflet packages, etc. at the same time – and that some device was required to enable him to do his job efficiently.
The leaflet-dropping belly tank is a modification of the standard 75-gallon fuel tank from which the tail has been cut and which is attached to the belly of the plane by the usual methods. An electric motor in the nose of the tank is connected with a toggle-switch on the pilot’s instrument panel. The motor controls a plunger which operates on a shaft that runs the length of the tank. When the tank is packed with leaflets this plunger is retracted to the nose of the tank. The leaflet bricks are held in the tank by spring-controlled flaps at the rear of the device. As the motor operates, the plunger presses slowly against the leaflet contents, forcing them through the flaps at the rear. When the motor stops, pressure on the plunger stops likewise, and the springs close the flaps at the rear and prevent additional leaflets from falling out. A half-second’s contact of the toggle-switch will force out one brick of 500 standard-size leaflets. When fully loaded, the tank contains 16 such bricks. It is thus possible for a pilot, during a single mission, to hit 16 targets with 500 leaflets each.
Ideal for the purpose for which it was developed, this device is practical only when two conditions apply: a) very low-level operations, and b) large numbers of tiny targets on each of which it is desired to place only a very small number of leaflets.
5. Time-Fused Package
In an effort to create a device which can be dropped from high-level aircraft and which is equipped with a fuse that will explode, disintegrate the item, and scatter the leaflets at a short distance above target level – this package was evolved and used by the RAF in the Middle East. In the reports thereon there is no indication of the quantity of leaflets each package contains; from the dimensions, one can assume that the contents would be 4000-5000 standard size leaflets.
The top, bottom, and side-walls are made of heavy cardboard or light sheet metal. The time-fuse fits in an aperture in the top. The fuse is held in place by a threaded lug on the inside of the top. Inside there is a plate into which a number of holes have been bored. The cords which hold the top, bottom, and side-walls together terminate in the baseplate. When the fuse explodes, the plate is shattered, releasing the cords and allowing the device to fall apart, scattering the leaflets at the point of burst.
It is to be noted that a similar device was at one time used in England. It was later abandoned as unsatisfactory in favor of the Monroe bomb.
The objections to this device seem to be:
a) complicated construction. The only part which is a piece of standard equipment is the fuse. The other parts have to be manufactured. The creators appear to have had considerable difficulty in getting the different fuses with which they experimented to function-uniformly.
b) lack of consistent bursting point. Because of its shape, the item could not be expected to fall with a uniform rate of speed, as would a streamlined and finned piece of apparatus. Therefore, an ordinary time-fuse would not burst any two items at the same height above the ground. This objection was supposed to be met by the use of a barometric fuse, but barometric fuses are notoriously capricious. The numerous tests and retests reported by the creators of the device reflect the trouble they were having in this respect.
c) manual labor. The device has to be thrown out of the aircraft by hand; it does not answer the problem of how to relieve the aircrews of the physical effort which takes them away from their normal duties in the air.
6. The Monroe Bomb
During the fall and winter of 1943-44, this device was developed in England. With exception of the fuse and primer-cord, it is made from salvage material available in any air unit. Tests have shown that it can be dropped from any operational height and made to function at lower altitudes; it is dropped from the bombrack like any bomb. It was designed especially for use with the B-17’s and 10 of these items will fit in a B-17 bombrack.
It contains approximately 80,000 standard size leaflets; each bomb weighs 300 lbs.
While the Monroe bomb was by far the best solution of the problem of dropping leaflets from high levels that has been worked out to date, there are certain objections:
a) irregular rate of fall. Since the item is cylindrical (not streamlined and finned), it will tumble in flight and consequently no two will fall at the same rate of speed. It cannot be expected that the fuses will burst any two at the same height above the ground. To overcome this, experiments were tried with barometric type fuses. It appears that these did not prove to be satisfactory. Attempts were made to equip the device with fins, but Ordnance experts are not convinced that it will ever be possible so to modify this device as to obtain optimum results in this respect.
b) weight and shape. The weight of the loaded bomb (300 lbs) makes it somewhat hard to handle, although this in itself does not constitute a major objection. However, its weight and shape limit its use to bombers; it is not suitable for suspension under the wings of fighters and fighter-bombers. It is consequently less advantageous than a devise which can be used interchangeably in bombers and/or on fighters and fighter-bombers, — since the latter would involve a single manufacturing operation.
c) quantity of leaflets. There are many targets which do not require as many as 80,000 leaflets at one drop, and this is the minimum which can be dropped when the Monroe bomb, is being used.
7. The M-26 Leaflet Bomb
To meet some of the objections inherent in the Monroe bomb, the writer worked with the 15th Air Force Ordnance Section during the spring and summer of 1944 on the development of this (at that time) latest device. It is an adaptation of a standard piece of Air Force equipment, – the parachute-flare bomb. The fuse used is the same one used in the flare-bomb. A minimum of constructional adaptation is required. The item looks like a bomb, is dropped like a bomb (according to tables prepared at the Aberdeen Proving Grounds), and acts like a bomb. These considerations are very important in causing it to be accepted by Air Force personnel with less reluctance than any device used previously.
Tests have shown that the device can be dropped from any operational height and caused to release the leaflets at from 1000-1500 feet altitude. The first large-scale use of it was made in connection with D-day in southern France. Since that time it has been in regular use in the Mediterranean theater. Further tests were made in England and it is being used there in fighter and fighter-bomber operations, Additional tests and suggestions for further refinements have since been made in the States. Most recently it has been tested in Burma with a view to its use in operations there.
Each bomb contains approximately 14,000 standard size leaflets. The bombs are dropped by bomb-release, – either singly, in sticks, or the entire load – as called for by target requirements. On all-leaflet missions 17 can be carried in the bombracks of a B-25 or B-26. When used in conjunction with regular bombing missions, it has been found that any bomber can take two of these items without sacrifice of regular HE complement – in the event that the HE bombs being used are 500-lb or larger.
The advantages of the M-26 leaflet bomb are:
a) Since it is an item with which Air Force personnel are familiar, very little special instruction need be given a unit using it for the first time.
b) The smaller number of leaflets (14,000) makes it more suited to diversified targets than the larger Monroe bomb. If a larger concentration of leaflets is desired, more bombs are dropped.
c) Being streamlined and finned, it has a uniform rate of fall and will function regularly at the desired height – to the extent that the clockwork fuse can be depended on to function accurately.
d) The device can be used either in the racks of bombers or under the wings of fighters or fighter-bombers.
e) Being light (overall weight 50-60 lbs), it is easily handled by a single person. This feature makes it popular with Air Force personnel who have to do the work.
8. M-15 and M-16 Leaflet Bombs
These are adaptations of the larger and smaller Cluster Adapter Bombs designed originally for dispersing the so-called “butterfly” bombs. These have not yet been used operationally, but Air Force Ordnance Section has run numerous tests and is satisfied that the results are as good as those obtained with the M-26. Dropping tables and fuse-setting tables have been prepared by USAAF Ordnance and distributed to Air Force units in all theaters.
According to figures submitted by Air Force Ordnance in connection with tests, the M-15 weighs 54 lbs when loaded and contains approximately 7250 leaflets. The larger M-16 weighs 181 lbs when loaded and contains approximately 30,000 leaflets.
These two items possess all the advantages listed for the M-26, including that of being usable under the wings of fighters and fighter-bombers as well as in the racks of bombers. (In earlier reports from Air Force Ordnance it was stated that this last was not true. The mechanical objections thereto have since been corrected.)
Further, Air Force Ordnance in Washington states that manufacture of the M-26 has been discontinued. Hence, future stocks of M-26 leaflet bombs will be limited to the supply of M-26 parachute flare bombs existing in the theater and to that percentage of same which Air Force authorities in the theater are willing to release for use as leaflet bombs. Also, each M-26 leaflet bomb will necessitate the dismantling of an M-26 parachute-flare bomb.
On the other hand, empty M-15 and M-16 casings (with fuses) are being shipped regularly to theaters. These shipments can he increased as needed on request from Air Force authorities in the theaters involved.
In the light of the foregoing, it is recommended that, in all theaters where extensive future leaflet bomb operations are contemplated, plans and calculations be based on the probable use of the M-15 and M-16 rather than on the use of the M-26.
Note. Before any decision is made to undertake operations with any of the devices described in this article, it is recommended that Air Force Ordnance in the theater be queried as to
a) whether there exist in the theater stocks of the proposed device in quantities sufficient to meet the estimated need (or whether materials and facilities for manufacture are possible) and
b) in the event that the device in question is an adaptation of a standard piece of Air Force equipment, whether the percentage of these stocks Air Force Ordnance is willing to release for use as leaflet bombs will meet the requirements.
[Source: TNA WO 204/6417, transcribed by www.psywar.org]