Two unidentified unmanned aerial vehicles (UAV), thought to have been sent by North Korea, were found crashed, one in the city of Paju (close to the demilitarized zone that separates North and South Korea) on March 24 and the other on Baengnyeong Island (a S. Korean island in the Yellow Sea across from the North) on March 31.
On April, another UAV turned up in Samcheok (a town 130 kilometers away from the Border between the two Koreas), which is believed to have crashed somewhere in October of last year. Given that the UAVs that crashed in Paju and Baengnyeong Island, shared almost the same specifications, North Korea may have been mass-producing spy drones. And theses spy drones must have been manufactured for military purposes because they were equipped with parachutes.
These crashed spy drones seem to have been manufactured specifically for military surveillance. Though some point out that the resolution of the photos found on the spy drones’ cameras is very low, no better than Google Earth, the UAVs were impeccable as secret spy drones since they were capable of taking pictures at low altitudes at specific locations at specific times. They were designed to fly close to the ground to take close-up pictures in case of an emergency, so scoffing at their low-resolution photos is absurd. Since no pilots are needed, UAVs of this kind can be employed as disposable spy drones in order to obtain much more vivid images than satellite photos.
South Korea’s Defense Ministry said no cables connecting the built-in cameras and transmitters were found. In other words, none of the photos taken by the spy drones could have made it back to North Korea. For those who use drones for aerial surveillance purposes, retrieving the cameras is the most important part of their reconnaissance missions.
The 13kg drone that crashed-landed in Paju was equipped with two GY352 dual axis gyros (manufactured by Japanese Futaba), a Canon 550D DSLR camera and an OS 160 FX engine, produced by Japanese model engine manufacturer O.S. Engines. The OS 160 FX engine has a capacity of 26cc and can produce 3.7 horsepower at 9,000 rpm.
The OS 160 FX engine is called a nitro engine since it runs on methanol laced with nitromethane and lubricating oil. It is sometimes called a glow engine since it uses glow plugs instead of spark plugs. Nitro fuel is several times more expensive than gasoline, but many of those who enjoy flying model aircraft for hobby or recreational reasons opt for nitro fuel since it promises higher output.
UAVs, powered by this engine, can fly for 10-12 minutes with 450-550 cc of nitro fuel. The S. Korean Defense Ministry said the fuel tank capacity was 4.97 liters. Approximately speaking, a drone of this kind can fly for a maximum of 120 minutes at a speed of 100-120km per hour with its 4.97 liter fuel tank fully filled. If so, it can fly up to 240 km. In other words, the maximum flight range of 240 km is only possible in theory.
However, these estimates raise a question. Samcheok, where one of the three crashed spy drones was found is 130 kilometers away from the Border. Besides, military authorities said that the spy drone appeared to have been sent from 15-20 km north of the Border. This is somewhat questionable because simply flying back to the North without making any landing in the South requires a drone of the same kind to make a round-trip flight of at least 300 km.
Under such circustances, can we argue that the crashed drone found in Samcheok came from the North If it is true that drones of this kind can fly up to 240 km at a speed of 120 km per hour, the spy drone found in Samcheok would never have made it back to the North. Flying back to the North after completing a reconnaissance mission in the South would be possible for a drone that can fly at a speed of over 150 km per hour with over 6 liters of fuel.
The S. Korean Defense Ministry announced that the spy drone found crashed on Baengnyeong Island was powered by a Roto 35FS engine, made in Czechoslovakia, and a 3.4 litre gasoline tank. This engine consumes about 1.2 litres of gasoline per hour. The S. Korean Defense Ministry announced that the flight range of the Baengnyeong Island spy drone was 180 -300 km.
Given the types of fuel, capacity and engine, it would be far-fetched to assume that the spy drone discovered in Samcheok was sent from North Korea and was programmed to fly back to the North.
The key to solving this mystery lies with the photos taken by the spy drone found in Paju and flight waypoints recorded in GPS units in it. The Defense Ministry said the camera was connected to the computer main board. Then, it is estimated that the built-in computer had been programmed to push the shutter button at specific locations at specific time intervals. Thus, there is nothing weird about the fact that none of the pictures taken by the drone contained images of North Korea.
There are several possible scenarios for the Samcheok spy drone. First, the spy drone was launched from some location in the South and its photo files were supposed to be retrieved in the South and later sent to the North. Second, the spy drone was launched from somewhere in the South and was supposed to fly to the North. Third, the spy drone was launched from somewhere in the North and was supposed to be retrieved by someone in the South. Fourth, the spy drone was launched from somewhere in the North and was supposed to fly back to the North. The last scenario seems unfeasible considering varied circumstances.
Eventually, we now have to count on the flight route data stored for photographing and avigation. South Korea’s Defense Ministry said it had yet to analyze the data. Our questions over the flight path of the spy drone would be answered when the outcome of the Defense Ministry’s analysis comes out. At the moment, we had better wait and see. Still, there is another option. We can build a UAV, which weighs exactly the same as the crashed spy drone and is powered by the same kind of engine, and we can fly the UAV to see how long it can fly.
