In early 2019 a Chinese destroyer in the South China Sea was seen using a new VTOL (Vertical Take Off and Landing) UAV off its helicopter deck. The VTOL UAV was easily identified as the Chinese made SD40, a UAV offered for sale to commercial users for operating over land or sea. The SD40 is small, only 40 kg (88 pounds) and apparently intended for naval use on smaller ships (corvettes and patrol boats) because Chinese destroyers used larger manned and unmanned helicopters due to their larger payloads, longer flight time and better stability in high winds (as are frequently encountered at sea). But the SD40 is of a hybrid quadcopter/fixed wing propeller driven UAVs. The SD40 is a triple fuselage battery powered quadcopter (for takeoff and landing) that switches to a gasoline-powered rear propeller (in the larger main fuselage) driven fixed wing aircraft once aloft. The two smaller outer fuselages each contain two of the quadcopter rotors and batteries for takeoff, landing or hovering. The 3.7 meter (11.8 feet) fixed wing provides plenty of lift and stability for level flight and a max speed of 180 kilometers an hour. Cruising speed is 100-140 kilometers an hour. Max payload is 6 kg (13 pounds) which will handle a wide range of day/night vidcams or even a lightweight radar (SAR or lidar). SD40 has an endurance of up to six hours (depending on how much hovering is done). Max altitude is 5,000 meters (16,000 feet) although normal operating altitudes are 1,000-3,000 meters.
These VTOL designs are becoming more popular because they can operate off smaller ships and patrol boats and have better endurance and stability (in high winds) than heavier helicopter UAVs. The U.S. Navy gained practical experience in this when they used (and still use) the 1.4 ton MQ-8B Fire Scout helicopter UAV. The MQ-8B lacked the stability in bad weather and other conditions that larger helicopters can handle. The Navy bought 29 MQ-8Bs after 2009 and accumulated over 12,000 flight hours with it. The basic design was good, but it was too small.
In 2013 the navy experimented transferring the control hardware and software of the MQ-8B to a larger helicopter (a navalized Bell 407) to become the 2.7 ton MQ-8C. This provided the greater stability, endurance and triple the payload of the 8B version. The navy now has 24 MQ-8Cs in service and will eventually acquire about a hundred for use of the 3,200 ton LCS type ships and other smaller vessels.
China has more options when it comes to different types of UAVs because it has the largest number of UAV developers/manufacturers in the world and dominates the quadcopter market. The Chinese Navy has been seen testing a large variety of these commercial designs, including some similar to the MQ-8B. China also has a larger number of small warships and patrol boats than the United States and many of these can accommodate a smaller VTOL UAV.