When you have a mountain to climb, it makes sense to get an early start. With that in mind, South Korea is moving rapidly into the demonstrator phase for a stealthy combat drone that it does not expect to field until late in the next decade.

Probably deciding that they would have trouble leaping into such an advanced field of combat aircraft development, the defense ministry's designers have chosen a configuration much like those of proposed Western aircraft. Yet it is worth bearing in mind that Western countries such as the U.S., Britain and France are, like South Korea, still studying such aircraft, with varying degrees of seriousness. So the Northeast Asian country, with an aerospace sector that has never built a manned combat aircraft, is already seeking to enter into the first rank in the unmanned field. And it is doing this while separately pursuing a program for a stealthy manned fighter called KF-X.

Or, more accurately, the project is being pursued by the defense ministry—more specifically by its ambitious Agency for Defense Development, for decades the home of much of the country's most advanced talent in aerospace technology. Both the KF-X and the combat drone program are at a stage at which design engineers are laying the groundwork, knowing that the military could use their proposed product and hoping that parliament will pay for full-scale development.

Korean Air Aerospace has won a contract to build a combat drone demonstrator and should begin flight testing in 2013. The air force, meanwhile, plans on the follow-on production aircraft serving as its premier combat aircraft by the end of the next decade. Under that scheme, the KF-X would be the second-tier fighter.

Scant specifications that the company issued at the Seoul International Aerospace & Defense Exhibition described the demonstrator, with a span of 4.5 meters and length of 3.5 meters (14.8 X 11.5 ft.). The accompanying large-scale model of the aircraft, the KUS-X, showed a highly swept wing blending into the body, which features an inlet above and behind the nose, and shielded by it. It is likely that the full-scale production aircraft, if built, will follow much the same design.

The manufacturer, a division of the airline Korean Air, has been working on the project since 2009, say company executives. The Agency for Defense Development largely designed the aircraft but kept out of sight at the exhibition.

Although Korean Air officials, citing security rules, declined to give details of the design, important features were readily evident from the model. These included two weapon bays inboard of the main gear, inside the body, not the wing, and well aft. The inlet duct evidently curves down to an engine mounted low in the deep body section. The space above the duct would be available for avionics—and probably fuel, since weapon bays take much of the wing-root volume.

Doors on the bays and access panels were serrated, as they usually are in stealthy designs. Wing sweep was greater than 45 deg. and the aspect ratio of the tapered wing somewhat greater than BAE Systems chose for its otherwise similar Taranis technology demonstrator.

The model of the South Korean demonstrator showed no sign of sensors, but protrusions for them would not be expected on a stealthy aircraft. The intended engine was not revealed and may not have been chosen.

Whether South Korea has the experience to smoothly turn the KUS-X into a production aircraft is uncertain. The country's background in combat aircraft development is limited to making light-attack versions of high-performance jet and propeller trainers, but its range of surveillance drones is growing rapidly.

Korean Air has become the national specialist in pilotless aircraft, while rival Korea Aerospace Industries (KAI), with a much larger force of development engineers, handles manned fighters and helicopters. In Japan, Fuji Heavy Industries is the national unmanned-aircraft specialist, while in China it is the Shenyang and Guizhou plants of aeronautics group Avic.

Korean Air has been developing this specialty by working up from battlefield surveillance and reconnaissance drones, a range of which it exhibited at the show.

Absent, however, was its largest production aircraft, a propeller-driven, medium-altitude and long-endurance surveillance drone called MUAV. Already launched as a production program, it is intended to be adaptable as a high-altitude jet aircraft. But the jet derivative now seems unlikely to go ahead, since South Korea is moving toward buying Northrop Grumman RQ-4 Global Hawks for that mission.

A bigger production program is in prospect for a Predator-like Korean Air drone called the KUS-15, which the South Korean army would operate as a surveillance and reconnaissance system at corps level. With a slender wingspan of 16 meters, the KUS-15 is of the size of the 1-metric-ton (2,200-lb.) General Atomics MQ-1B Predator and follows much the same configuration, with two major variations: It has no large radome for a satellite communications antenna, and its V tail rises from the fuselage instead of descending from it to protect the rear airscrew from striking the ground. That seems to indicate great confidence in attitude control on takeoff and landing—or a redesign before the type goes into production. It is unclear when a production contract will appear, although industry officials have said that the army does want such an aircraft. Importantly, there is reason to think that a specific need and prospective production order, at least, lie behind all of the military drone designs that Korean Air displayed at the show; they were not just design exercises.

A model of the KUS-15 displayed by Korean Air revealed an electro-optical sensor under the nose and a radome, presumably for a synthetic-aperture radar, under the belly. There were no weapons, but it would be surprising if South Korea, with its serious defense problem, did not consider eventually arming the aircraft, if only to give North Korea more to think about.

Korean Air says the KUS-15 is capable of automatic takeoff and landing and of automatic flight. A key issue for drones flying over the mountainous peninsula is to avoid hitting terrain.

A smaller battlefield drone is also under development, the KUS-11, intended to be operated at division level. Korean Air says it is designed to land in rough terrain and can be adapted for either a skid or wheeled undercarriage. Its sensor is an electro-optical and infrared camera. The ceiling is given as 4,500 meters and maximum speed 210 kph (130 mph).

These aircraft follow earlier battlefield surveillance and reconnaissance drones developed by Korean Air.

The company and rival KAI have separately developed small unmanned tiltrotors in cooperation with the civil Korea Aerospace Research Institute. The institute and KAI are testing a 40% scale model of their aircraft, although they have built the full-size version. Despite the civilian origins of the project, they are trying to interest the defense ministry in it. It is unclear whether it would be a competitor to a Korean Air military product.

In yet another pilotless aircraft project, the institute and KAI are developing a unmanned ground-observation version of a general aviation aircraft.