Naval Air: A Small Wonder

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October 17, 2019: In Mid-2019 the U.S. Navy began testing the new VBAT VTOL (Vertical Take Off and Landing) UAV design on some of its ten Spearhead fast transport ships. These twin-hull 1,500 ton ships are built for speed (80 kilometers an hour) and stability and the ability to move up to 600 tons of cargo up to 1,000 kilometers and back on internal fuel. There is a hangar for a smaller (UH-60) helicopter and the flight deck can carry and operate one large (up to the 33-ton CH-53) cargo helicopter if the cargo must be landed in an area where there are no docks. The unique VBAT needs much less space to operate from. VBAT looks like a small fixed-wing UAV with a pusher propeller gasoline/oil (like a lawnmower) engine. The VBAT propeller is housed in a cowling combined with computerized flight controls similar to those that made the two-wheel self-balancing Segway scooters possible back in 2001. In other words, VBAT automatically takes off and lands at a location specified by the operator. After takeoff VBAT tips over and flies like any other fixed-wing aircraft. This way the 37.3 kg (82 pound) VBAT can carry a 3.6 kg (eight pound) payload and do it all for longer than current small quad-copter UAVs. VBAT usually carries a gimballed day/night vidcam that can transmit video up to 72 kilometers or store it when VBAT is flying missions up to 630 kilometers distant. Endurance (80 kilometers an hour with a one hour reserve) is eight hours. VBAT is small, only 2.4 m (8 feet) long with a wingspan of 2.74 M (9 feet) and is transported in broken down in weatherproof shipping containers. A two-man crew can assemble it, load flight parameters (for an automated mission) and have it ready for takeoff in 20 minutes. Different payload modules can be swapped out for ones that do mapping or terrain analysis. The onboard generator provides up to 500 watts for payload sensors. Max altitude is 4,700 meters (15,000 feet) and VBAT can handle winds of up to 48 kilometers an hour. It only needs a 3x3 meter (10 foot square) clear area for takeoff and landing. With performance like that the, army and navy were interested when VBAT was first shown in 2018. The manufacturer, MartinUAV, points out that VBAT is a scalable design and a 310 kg version, with a 45 kg payload, much longer range and endurance could quickly be built, tested and put into service. The two-man crew for VBAT can be trained in two weeks and each VBAT, depending on how many payload modules are provided, will cost a few hundred thousand dollars.

Meanwhile, there is potential competition. In early 2019 a Chinese destroyer in the South China Sea was seen using a new VTOL 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 use 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 and proceeds as a 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. There are several VTOL designs similar to the SD40 available. The VBAT takes the concept up a level.

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 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. VBAT is a lot cheaper than a helicopter-based UAV and may reduce the number of MQ-8s purchased.

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. China will probably have a VTOL UAV similar to VBAT before long. The tech used in VBAT is not exotic and Chinese manufacturers were quick to copy the Segway design over a decade ago.

 


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