Characteristics of unmanned cargo aircraft
Unmanned Cargo Aircraft (UCA) can be used for both civil and military purposes. Civil UCA are, in their simplest form, almost identical to manned aircraft, but with the crew taken out and special guidance and control equipment put in. But UCA can be much more, as is shown by the following examples:
- Duty length of a crew is not an issue, so UCA can have a cruising speed that is optimized to consume as little fuel as possible. The optimal speed will mostly be around 450 km/h, so a trip from eastern China to Paris will take one day. This is much faster than other forms of transport except manned aircraft, and fast enough for most cargo.
- The low cruising speed allows a light and efficient construction, the use of efficient propeller propulsion, and it makes the use of short, unpaved, runways possible. Also, the reduced fuel consumption yields greater range than comparable manned aircraft.
- Because there is no need for a pressurized crew cabin, a UCA can be made lighter and simpler than manned aircraft while still being able to fly efficiently at altitudes up to at least 6 km. Because the cross-section of the fuselage does not need to be circular, as is the case with a pressurized cabin, it can be shaped efficiently, for example to fit the shape of square cargo containers.
- The cargo area can be relatively small because no humans need to be accommodated. This gives the opportunity to use shapes like a Blended Wing Body (BWB) or flying wing, which is 15-20% more aerodynamically efficient than a conventional aircraft shape.
- One controller on the ground can control 10 to 30 UCA. This means huge savings in crew salary costs (a single long-range aircraft may require eight to twelve crews). There are no stopover crew costs. It is possible to assign dedicated controllers to handle all UCA take-offs and landings at specific airports, like pilots do for ships entering harbours. The knowledge of local circumstances of these controllers can increase safety and efficiency.
- The risk of fire is an acknowledged safety hazard in cargo aircraft. UCA open the potential for innovative fire suppression techniques, like filling the cargo area and every empty void in the aircraft with inert gas (nitrogen) generated by onboard equipment.
- Many of the characteristics mentioned above are especially beneficial for small UCA. This makes it possible to open markets that cannot support present-generation cargo aircraft, as is elaborated on in the next section.
All in all, UCA with a cargo capacity of 2 to 20 tonnes, a range from 1000- 10,000 km and a cruising speed of about 450 km/h seem to offer the best near-term potential. The payload and range figures are quite global, offering the possibility to develop a family of UCA. The American Federal Aviation Administration predicts that in forty years’ time, some 40% of air cargo will be transported by unmanned aircraft.
UCA cannot compete with large manned cargo aircraft like the Boeing 747F, in which 50% of total air cargo is transported (CargoMap, 2013). Much cargo is transported in the bellies of widebody passenger aircraft. Since airlines choose their routes on the basis of passenger demand, the extra cost of transporting cargo are unbeatable by any aircraft including UCA. But UCA come to their own in markets that support only small volumes of cargo. Examples of these ‘thin’ routes are those flown by package transporters like FedEx and DHL. It may be some time before UCA are allowed to fly on these routes because this would involve flying in the same airspace as manned aircraft, which is not yet allowed. Much more interesting in the short term are routes between regions that have economic potential but no proper transport infrastructure, and their markets in, for example, Western Europe and the U.S. These regions can be found in China, Africa and South America, but also in Australia and Eastern Europe. The increasing volume of trade between China and India can also generate a market for UCA. The Internet has made it possible for almost everyone, anywhere, to buy and sell goods and perform the necessary financial transactions, but shipping goods to customers from anywhere to everywhere is not possible, or practical, in many parts of the world.
Examples of what can be done with UCA are:
- Moving finished products from isolated areas, unlocking their economic potential. The required infrastructure, like a runway, control equipment and loading facilities are much cheaper and easier to realize and maintain than infrastructure for ground transport.
- Supplying areas with limited transport infrastructure with specific, high-value, raw materials, production equipment and spare parts, needed for the economic utilization of local resources.
- Moving goods on ‘thin’ routes that do not support larger, manned, aircraft. This is especially interesting on long routes, where the efficiency advantage of UCA is greatest.
- Moving goods on routes that would need a stopover at a ‘hub’ airport if served by manned aircraft. Their low operating cost enable UCA to make direct flights with low volumes of cargo. Even with the relatively low cruising speed of UCA delivery speed may be comparable with that of manned aircraft while the hassle, cost and risk of theft or loss involved in processing cargo at hubs are avoided.
- Moving goods on ‘irregular’ routes. Because there is no crew that wants to return home after a working day, a UCA can fly all over the world while only returning to its home base for heavy maintenance. A business model like that of car renting companies is possible: an operator rents a UCA out to a shipper who leaves it at its destination where it is rented out to the next client.
- Transporting emergency supplies like medicines to disaster areas.