Aerial Delivery of Supplies
MAJOR RAYMOND C. ALTERMATT, Q.M.C.
The Quartermaster Review
The origin of the parachute dates back many years. The first record of its use was described by a passenger of a burning balloon, who made a successful escape by parachute in July 1908. However, the parachute was considered only as an exhibition item for many years and was only seen at county fairs and carnivals. In the fall of 1916 an Austrian pilot on the Russian front made a parachute jump from a burning plane, the first practical application of the parachute to military requirements.
The possibility of transporting troops and supplies by air and landing at points behind enemy lines was conceived by General “Billy” Mitchell in the First World War. General Mitchell planned such an operation for our 1919 campaign. British Handley Page airplanes were to be used in the operation, but the fighting was ended before the plan could be tried out.
Today many successful airborne operations have been accomplished. Such operations are destined to become more and more important as our equipment and methods are improved. Air Quartermaster and other supply personnel are potentially involved in the airborne movements of the future to a great extent. An understanding of the problems involved in resupply by air should be a subject for study by such personnel. There are many ramifications to the problem of supply by air so, in the interests of brevity, only supply by parachute will be discussed in this article.
From an operational standpoint, resupply by air can be divided into two categories: First, an emergency expedient to supply units which are isolated or which have been cut off from their normal supply channels by terrain, distance, or enemy activity. In such cases, supplies are usually required at regular intervals in relatively small quantities. Second, supply of an airborne operation consisting of a large organization requiring hundreds of tons of supplies daily over a period of only a few days, that is, until supply by ground or water is accomplished.
The extent to which supply by air can be employed depends, primarily, upon the following eight factors:
Degree of air supremacy; availability and capacity of aircraft; weight, size, and shape of supplies to be transported; selection of dropping ground; intercommunication, ground-air; accuracy of dropping; weather visibility and wind; and collection of supplies on ground.
There are two methods by which supplies can be delivered by air. The first, which is the most obvious and logical, is delivery by airplane. Supplies are loaded into cargo airplanes in the rear areas and flown to airfields in forward areas, where the planes land and distribute their cargo to the units. This method, of course, requires a high degree of air supremacy and adequate landing fields in forward areas.
We are more concerned with the second method, whereby supplies are transported by airplanes and delivered by means of parachutes and aerial containers or free-fall containers. Free-fall containers are still the subject of intensive study and research and little can be told of their effective and efficient use at the present time.
Equipment used in dropping supplies consists of two major items – the parachute and the supply containers. Aerial delivery and cargo parachutes were gradually evolved from personnel parachutes to perform the specific job for which they have been designed. At the present time, five sizes and weights of parachutes are in current use. The aerial delivery parachute, known as type G-1, is a 24′ canopy for use with loads up to 300 pounds. It was developed several years ago and was standardized in December of 1942.
The parachutes, cargo, dropping, are known as types G-2, G-3, G-4, and G-5. Their canopies measure 24′, 28′, 36′, and 48′, respectively, and are capable of carrying loads up to 3,000 pounds. Parachute assemblies consist of the canopy and pack. Early models of the canopies were of cotton fabric, later changed to rayon. Some of the larger canopies are now being made of nylon because of its lightness and strength. For identification purposes, canopies are made in various colors-red, green, blue, yellow, or natural. By establishing a color code, the type of supplies being delivered is easily determined by the color of the canopy. For instance, blue canopies might designate water, red canopies, ammunition, green canopies, rations, etc.
Cargo parachutes, being larger and constructed of heavier material than the aerial-delivery parachutes, are dropped from higher altitudes, for, as the size or weight of the canopy increases, the greater is the opening time required. The Army Air Force Board considers 200 feet to be the best altitude for dropping supplies and equipment from aircraft by parachute, with variations depending upon the type of load. Dropping at such low altitudes eliminates drift and assures greater accuracy in landing supplies in the desired drop zone. It also eliminates oscillation of the load to a great extent.
Loads of less than 125 pounds should be dropped from approximately the 200-foot level in order to permit the suspension lines to untwist. It has been found that, with light loads, the suspension lines have a tendency to twist as they come in contact with the propeller blast, thereby prohibiting full inflation of the parachute before impact. Loads greater than 125 pounds exert enough pressure to untwist suspension lines at a faster rate and may, in many cases, be dropped from a minimum of 100 feet.
For dropping heavy loads and to aid in the reduction of load oscillation. triple and quadruple clusters of cargo parachutes have been designed. Gross loads up to 4,200 pounds have been successfully dropped by the four-cluster arrangement. A somewhat similar method for dropping supplies is known as the “controlled ground pattern.” While the cluster usually consists of three or four cargo parachutes attached to one heavy load, the controlled ground pattern consists of three or four separate loads and parachutes tied together with web belting so as to bring the load within one drop area and to prevent it from being scattered over a large area of the drop zone.
Containers for use in the aerial delivery of supplies are constantly being revised and developed to meet changing conditions and requirements. New developments and requirements arising in the training of Airborne units or under actual combat conditions in the field are forwarded to the Army Air Forces Division, Materiel and Services, Materiel Command, who arrange and contract for pilot models. Actual tests are then conducted by the Proving Ground Command and, if the model is considered successful and fulfills the military requirements, it is approved by the Army Air Forces Board. Final approval and standardization rests with Headquarters, Army Air Forces.
Eight containers for use in the aerial delivery of supplies have been developed and standardized. These are known as types A-3, A-4, A-5, A-6, A-7, A-8, A-9, and A-10. Recently, however, Type A-3 has been merged with Types A-4 and A-6 (liquid dropping containers) and Type A-9 has been merged with Type A-7 (slings). These are Army Air Force Supplies, Class 20, and are standard equipment.
Type A-4 is an adjustable reinforced canvas container, 12″x 24″x 30″. One end is opened for loading and is closed with laced flaps. It can be used for the delivery of supplies such as rations, medical supplies, and clothing. (Clothing, however, is one item which is often dropped in bundles, free fall, as there is no danger of damage.) Two corrugated fiber boxes 12″x 12″x 30″ are available to be used with this container for additional protection of fragile articles. The type A-4 container was the first to be developed and was standardized in November 1940. It was primarily intended for dropping supplies to Infantry, Cavalry, and Armored Car units.
The Type A-5 container is a sheet of heavy canvas 15′ long and 56″ wide with a pad of felt. It was developed primarily for the purpose of dropping rifles to parachute troops. Rifles are placed on the felt pad and rolled up in the canvas to form a roll approximately 18″ in diameter. The ends are protected with removable end caps.
Type A-6 container is a canvas cover fitted over a 12″x 12″x 30″ corrugated fiber carton. A shock-absorbing pad is attached to the bottom. The unit is used for dropping rations or three plastic water containers of five-gallon capacity, which fit into the fiber carton. The water containers may, of course, be used for dropping other liquids such as milk or medicine.
Container Type A-7 is an adjustable webbing sling designed to carry a standard ammunition box. It can be adapted to carry other equipment or supplies such as three standard five-gallon Quartermaster water cans.
The Type A-8 container is a rigid, octagonal-shaped box 50″ long and 18″ in diameter. It is constructed of fiber board and may be collapsed for stowing. Shock pads, for both the inside and outside of the container, have been designed to absorb landing shocks. This container was an on-the-job development designed to fill the need for a rigid container for dropping rifles to parachute troops and to supplement the A-5 container, which must be dropped from a greater height.
Type A-10 container is nothing more than a cargo net measuring approximately 9’x 9′, with a 3½” diamond mesh. It is used for dropping miscellaneous supplies, either Class I, III, IY, or V. This net was developed early in 1942 for Infantry paratroops for use in the resupply of general classes of supplies common to the various services.
The containers described above are those frequently encountered in dropping Quartermaster supplies and are used with the parachute, Type G-1. Many other special containers have been devised or are being developed. Ordnance materiel is being dropped in containers known as the “paracrate” and the “parachest.” The British have several types of aerial containers and the Australian Army has recently developed a container known as the “storpedo.”
To aid the pilot of cargo planes, dropping zones should be clearly marked. The dropping zone should preferably be near a prominent landmark, which can be readily spotted from the air. Prearranged ground panels or other signals and markers should be established for both day and night operations in the event of emergencies. Another method would be the use of a two-way receiver-transmitter radio, operated on an Army frequency band, between the aircraft and the ground troops. Weather conditions often play a large part in determining the manner and direction in which the plane flies over the drop zone, and the pilot must be the one to decide upon the direction of his approach. However, ground signals should be displayed to indicate the general direction for planes to fly over the target to prevent two or more planes from approaching the dropping zone simultaneously from different directions.
Dropping zone sites are usually chosen by the ground troops and approved by the air liaison officer. They vary in size depending on the terrain, some averaging only 150 yards long by 50 yards wide. One observer of air resupply operations in overseas theatres advocates the use of two dropping areas. In other words, free-drop and parachute packages should be dropped in different areas to avoid damage to containers already dropped. Ground troops should observe a danger area of at least 100 yards on each side of the dropping zone as a safety precaution against descending containers.
Two methods are in use for ejecting parachute containers from the cargo airplanes. One method utilizes a para-rack, in which the containers and parachutes are placed in a rack under the plane and released mechanically. The other method is the manual ejection of the containers from the door of the plane. In either case, the signal for dropping the supplies is given by the pilot by means of a system of colored lights when the plane is over the drop zone.
Personnel should be trained to clear the drop zone quickly of supplies by definite assignment of the necessary tasks. One section of the ground crew should gather up the parachutes. If wet or damp, they should be suspended from the apex and dried before stacking. Another section of the ground crew should pick up the rations and medical supplies; another section the ammunition, and so on. Free-drop bundles should be removed last.
As the stature and importance of the airplane as a transportation medium for large divisions of the Army is developed, so will the need for sufficient supply of those troops by cargo airplanes become increasingly important. Air Quartermaster personnel should acquaint themselves with the problems incident to the resupply of units by air in preparation for the time when supplies transported by cargo planes will be measured in tons instead of pounds.