A new era in naval replenishment operations got under way on 27 November, 1964, when the USS Sacramento (AOE-l) steamed out of Long Beach with a detachment of officers and enlisted men from Helicopter Combat Support Squadron One and two new UH-46A helicopters. These aircraft were the first in the Navy to be developed specifically to conduct vertical replenishment operations at sea.
The UH-46A Sea Knight is a turbine-powered, tandem-rotor helicopter, designed and built by the Boeing Company’s Vertol Division. It is powered by two T58-GE-8B free- turbine engines, each rated at 1,250 shaft horsepower. This allows the aircraft to carry up to 25 combat-ready troops or up to 6,000 pounds of cargo, the latter internally or externally. The helicopter’s rear-loading ramp and roller tracks permit the rapid loading and unloading of internal loads, and facilitating jettison cargo in an emergency. The cargo hook, from which external loads are suspended, has a 10,000-pound capacity. The aircraft is fully instrumented and capable of all-weather operations. On most VERTREP operations it is manned by a crew of four: pilot, co-pilot, and two crewmen.
The UH-46A can deliver its cargo to ships within a 100-mile radius and return without refueling at speeds up to 140 knots. The arm of replenishment ships thus has been effectively extended many miles by this aircraft.
Many of the advantages of VERTREP are self-evident. The receiving ships are not hindered in their maneuvers and operations to any great extent. (At least one VERTREP has been carried out while the receiving destroyer maintained constant visual contact with a Soviet submarine!) Less time is involved in maneuvering ships alongside each other, and rigging transfer lines, and the dangers inherent in these operations are eliminated. Fewer personnel are required to man replenishment stations, and the rate of cargo transfer equals and often exceeds that done by alongside methods.
Since the replenishment ship can conduct both VERTREP and alongside replenishment operations simultaneously, more ships can now be supplied in the same period of time. Personnel transfers are faster and more comfortable by helicopter than highline, particularly in heavy seas. There is also far less damage and breakage by VERTREP than by alongside methods, and ships can now be supplied while many miles from the supplier.
The UH-46AS are now found aboard the Navy’s newest replenishment ships: the Sacramento, Mars (AFS-l), and Sylvania (AFS-2). These ships were designed to handle these large helicopters and have adequate hangar, flight deck, and maintenance facilities to support helicopter detachments. Additional ships of both types are now under construction.* A great many more replenishment ships are being modified or built to support helicopters on a limited basis for short periods. These ships will have helicopter platforms and refueling facilities. This will greatly enlarge the helicopter’s field of operations and help make its services available on a larger scale.
Some present-day limiting factors in the UH-46 VERTREP operations are:
• Available fuel will allow just over two hours in flight before refueling. This often interrupts the VERTREP operations as the second helicopter cannot pick up cargo while the first is on deck being refueled. When possible, refueling is accomplished aboard a nearby carrier rather than aboard the replenishment ship.
• With the present helicopter configuration, the cargo hook must be removed from its normal position before anything—personnel, mail, or cargo—can be lowered by cable out of the rescue hatch. Removing the hook is not difficult, but it is time consuming and, in spite of safety precautions, the danger always exists that the hook could be dropped through the open hatch and lost, thereby eliminating the VERTREP capability of that aircraft.
• Due to reduced clear deck space and inaccessability to the storage areas, replenishment of the smaller ships is often delayed. Two helicopters working together can quickly saturate the landing area of a destroyer, even using a Drone Anti-Submarine Helicopter (DASH) platform. Breaking down the helicopter loads and stowing them in the smaller ships creates delays and causes the aircraft to circle or hover waiting for space to be cleared before landing the next load.
• Lift capabilities of the helicopters are adversely affected by increased heat or humidity and adverse or no-wind conditions. This is particularly noticeable in the South China Sea. This is often a difficult point for nonaviation officers to understand and commitments are sometimes made without regard to environmental conditions which may make accomplishment of a given replenishment task impossible or marginal.
• The cargo hook is located some 20 feet behind the pilot and no visual contact is possible as a deck load is approached for pickup. All directions must be relayed to the pilot by a helicopter crewman. Rear-view mirrors on the helicopters have provided only a partial solution for this problem.
The UH-46A has proven itself to be an extremely versatile machine and has been utilized to carry everything from movies to light bulbs, from other helicopters to A-4 Skyhawk airframes, and from bombs to butter. The principal VERTREP cargo thus far has been ammunition and missiles of all types from the AOEs, and dry stores, frozen food, aviation equipment, and other material from the AFSs. The missiles and ammunition are carried in special slings or regular cargo nets and the rest on pallets covered with neoprene wraparounds, in wire “cargotainers,” or in cargo nets. There has been some difficulty with cargo which is light and not tightly packed. Portions have blown out as the aircraft moved through the air at speeds up to 100 knots. Since all transfer material must be reused by the supply ships, these baskets, slings, nets, and other equipment, must all be returned to the ship after being emptied of cargo.
A normal helicopter load consists of two to four pallets, the number depending on their individual weight, each with a cargo sling connected to a collector ring which is, in turn, attached to a long wire or dacron pennant which is attached to the cargo hook of the aircraft. This pennant must be attached from the deck while the helicopter hovers over the load. Upon delivery, the load is placed in position on the deck by lowering the helicopter slowly from a high hover and the load is released manually by the crewman who is inside the helicopter watching the load through the open hatch.
All deck personnel stand well clear of the load when it is released as the pennant is also released and is a potential safety hazard when falling to the deck.
Current plans call for approximately 20 UH-46AS to be used in VERTREP operations. These are to be divided between Helicopter Combat Support Squadron One on the West Coast and Helicopter Support Squadron Four on the East Coast. Unless more ships are built with the necessary hangar space and maintenance facilities, this number should be sufficient to meet present operational commitments, train new flight crews and maintenance personnel, and carry out periodic re-work and modifications. However, any increase in the number of commitments the squadrons must meet should be accompanied by an increase in aircraft.
For a complete picture of the vertical replenishment program, it should be mentioned that the U. S. Marine Corps is the major operator of the H-46 helicopter, using the CH-46 as a troop transport aircraft. These aircraft are currently being used in the Vietnamese War and, while principally a troop carrier, are also used to carry cargo, vehicles, and any other material. This, too, is a form of vertical replenishment which is now a proven and accepted method of moving materials from one place to another. There appears to be no reason for rivalry or competition between the Navy and Marine Corps as far as the VERTREP program is concerned. A general rule would probably indicate that the Navy handles transfers between ships while the Marines handle support of their troops ashore. This does not preclude the mutual co-operation in the event a job could be carried out more easily, faster, or more effectively by either group regardless of the operational area.
We find ourselves at the very beginning of a long road of fleet support activities using helicopters. The UH-46A may not be the ultimate aircraft for this job, but it has played an extremely important part in initiating the program and proving its feasibility. Significant changes will be incorporated as the program develops: night VERTREP operations have already begun, hooks that can be lowered and raised from within the helicopter are being developed, rotating cockpits for greater pilot visibility or controls by the cargo hatch to facilitate hook ups are under consideration, and longer range and greater lifting power are problems now being solved. Ideas and methods now undreamed of will one day make the practice of ships coming alongside for anything other than petroleum products a thing of the past. With the advent of large numbers of nuclear-powered ships, replenishments will be carried out with two ships which never see each other.
* See Robert W. Baker, “USS Sacramento (AOE-1)," U. S. Naval Institute Proceedings, September 1964, pp. 164-166; and Bernard A. Lienhard, “Combat Store Ships,” U. S. Naval Institute Proceedings, March 1965, pp. 148-151.