Winged-boat Aircraft Carrier for Commercial Transportation
While aircraft carriers were initially developed for military service, there may be commercial application for fast wing-in-ground effect vessels designed to carry an onboard payload was well as an aircraft.
There are military transport aircraft that due to their weight, are required to take off from runways carrying minimal fuel compliment. However, once the large aircraft is airborne at its cruising altitude, a military tanker aircraft flying ahead of it extends a fuel line to transfer a massive volume of fuel to the airborne heavy transport plane. There may be scope to apply such a precedent to heavy lift wing-in-ground effect transport vessels. Modern computer control could theoretically guide a flying aircraft to touch down on a pad built on the deck of a fast-moving winged boat.
The laden winged boat would depart from a seaplane runway and accelerate to lift-off, perhaps to an elevation of 150 meters (500 feet) until it is away from shore where it can drop down to a cruising elevation a few meters above water, at its cruising speed. At that point in time, a computer guided aircraft that departed from a coastal airport would touch down on its deck. The high cruising speed of the winged boat would allow it to carry the additional weight, with minimal reduction in flight elevation.
Scale of Vessel
A winged boat that lifts off from and touches down on coastal seaplane runways can be built to much greater size and weight of commercial freight aircraft, one drawback being the restrictions on landing weight at majority of large commercial airports that have restricted length of runway. There may be scope to design multiple wings such as the tandem layout into large multi-hull winged boats, to increase payload carrying capacity. The use of hydrofoils would assist during lift-off from extended length seaplane runways, perhaps up to five times the length of a paved commercial airport runway.
While the comparatively short airport runway would require rapid acceleration and a steep climbing angle from a freight aircraft, an extended length of seaplane runway would allow for a slower rate of acceleration and much gentler climbing angle to comparatively tiny flight elevation. Such factors allow for the winged boat to be built to greater scale and greater weight than a freight aircraft. It may become possible for a winged boat to carry three to five times the number of shipping containers as a freight aircraft developed for such a purpose.
While present day winged boats use the same fuel as aircraft, it may become possible to adapt a future small-scale (radiation-free) nuclear power technology for mega-size winged-boat propulsion. Such vessels could carry high-priority shipping containers between offshore coastal terminals where the containers may be transferred to or from local river barges, trucks or freight trains. A future thorium-based technology would be a possible option and perhaps offer lower transportation costs than vessels powered by hydrocarbon fuel. Using such a fuel would enhance the economics of carrying an aircraft on its deck.
Advances in materials chemistry has developed a version of silicon carbide that offers extreme thermal conductivity and capable of 1,400 degrees Celcius operation. It can serve as the heat exchanger material in externally heated, high-temperature, compact size closed-cycle turbine engines that operate at extreme gas pressures. Materials such as zirconia oxide offer extreme insulating properties at extreme temperatures. While hydrogen engine propulsion may also be possible, the winged vessel would repeatedly have to be refueled while in flight mode, on extended-distance trans-oceanic voyages. However, in the early stages of service, hydrocarbon fueled engines would provide the propulsion.
One future aircraft concept involves the combination of a detachable fuselage or ‘pod’ being carried by a backbone carrier aircraft that included control area, wings with fuel tanks and engines along with tailfin and rear winglets. Upon arrival at a terminal, the ‘pod’ is lowered to the ground and detached while the powered flight section proceeds to the maintenance area for inspection and refueling. The refueled powered-flight section proceeds to a terminal to attach to a ‘pod’ that is ready for departure. The ‘pod’ may carry parcel freight or it may be carry passengers.
On certain routes, there may be scope to combine the pod concept with heavy-haul winged ship service. The autonomously or semi-autonomously controlled flight section would carry a laden ‘pod’ to a winged ship that has departed from its terminal and is riding on the dynamic air cushion, then tough down on the deck of the fast moving winged ship to transfer the pod. Special locking mechanisms would secure the ‘pod’ to the winged ship as the flight section uncouples the pod. Following the transfer, the powered-flight section becomes airborne and returns to a nearby airport.
Hydrocarbon fuel accounts for the single largest cost item involved in commercial aircraft operation. Energy consumption increases to the relative cube of the speed meaning that doubling the speed requires 8-times the energy. For equal weight and speed as a propeller driven commercial airplane flying at 10,000 feet in 70 percent the air density, a winged ship traveling in ground effect mode would consume about third the amount of fuel. Traveling at half the speed as a commercial jet liner flying at 35,000 feet in 25 percent the air density, it would consume 1/3rd x 1/8th x (.7/.25) = 1/8th to 1/6th the energy.
There is economic benefit to winged ships carrying an aircraft pod in westbound trans-Atlantic passenger transportation. When it is midnight in Western Europe, it is 6:00PM in New York. A midnight westbound departure from Europe would require 12 hours to travel to New York, arriving at 6:00AM. During the overnight westbound voyage, passengers would be able to sleep and perhaps avoid the effects of jet lag upon arrival. Westbound high-priority containers would also leave Europe during the late evening and arrive at Eastern U.S. at the start of the following day.
Advanced developments in autonomous vehicle control technology would allow an airplane carrying a pod to touch down on the deck of a fast moving winged boat perhaps moving faster than the airplane’s landing and take-off speeds. Mechanical guidance technology would assure that the pod is secured at the proper location on deck and also assist the carrier airplane to lift off. On approach to the destination, a carrier plane guided by autonomous control and mechanical guidance would touch down on the deck and ready to secure the pod that it will carry to a nearby airport.
Heavy-haul winged boats could carry payloads that would be beyond the capability of freight aircraft and the airport terminals to which they fly. Such aircraft are restricted in areas of landing weight. Winged boats of much greater weight, greater physical size and greater payload carrying capacity would be able to touch down on and lift off from designated seaplane water runways. In service, they would carry a few dozen high-priority shipping containers of goods regarded as being critical. Winged boats would carry such freight while consuming a fraction of the energy of container carrying commercial airplanes.
Designated Water Channel Runways
In the interest of protecting aquatic wildlife, there may be need to build special water channel runways where winged boats may touch down upon arrival and lift off upon departure. These runways could exist in an estuary or a bay, where physical barriers on both sides supported by buoys of several miles in length would keep out aquatic lifeforms to protect them from wing boat hydrofoils. While touch down speeds of 120 kilometers per hour may be possible, lift-off speeds of 120 to 150 kilometers per hour may also be possible with trans-oceanic cruising speeds of 250 to 500 kilometers per hour.
Winged boats capable of carrying many times the payload of freight aircraft are becoming technically possible, including the ability when operating in ground effect mode, to accept a laden aircraft touching down on to its deck. The economic case of the technology would depend on the future market size that will seek high priority delivery of shipping containers.
The opinions expressed herein are the author's and not necessarily those of The Maritime Executive.