Droner - Ubemannede lastefly utvikles raskt - AW&ST

Unmanned Cargo Aircraft Head Toward Flight Tests Graham Warwick Just a few years ago, large unmanned cargo aircraft looked to be decades in the future. But the growth in e-commerce and demand for rapid delivery has encouraged startups to launch development of autonomous freighters, targeting entry into service as early as 2020.   California-based Elroy Air andNatilus are close to flying subscale prototypes of their unmanned cargo aircraft while Sabrewing Aircraft, another startup based in the state, hopes to fly its 65%-scalevehicle this fall. And they are not alone. The Chinese Academy of Sciences in October flew a 3,300-lb.-payload unmanned cargo aircraft, the AT200, based on the Pacific Aerospace P-750XL utility turboprop built in New Zealand. In December, Chinese package carrier SF Express conducted emergency logistics tests with a version ofTengoen Technologies’ TB001 medium-altitude UAV, and the young Chinese manufacturer has revealed plans for an eight-turbofan cargo UAV capable of carrying 20 tons more than 4,100 nm. Even Boeing has joined the fray, flying a prototype electric vertical-takeoff-and-landing (eVTOL) cargo UAV. Natilus plans a Boeing 747-size transpacific unmanned freighter Elroy Air wants to replace trucks on inefficient routes Sabrewing targeting a small regional unmanned freighter The startups are attracting investment. Richmond, California-based Natilus closed a second round of seed funding in November with investments from aerospace accelerator Starburst Ventures and others. In December, San Francisco-based Elroy secured $4.6 million in seed funding led by aerial mobility investor Levitate Capital. And Camarillo-based Sabrewing in January announced it was nearing completion of its first financing round, raising “just under $1 million” in angel funding led by The Drone Fund.

China flew an unmanned cargo aircraft based on the P-750 utility turboprop in 2017. Credit: China Acadamy of Sciences/ChinaNewsService

The amounts are small as are the teams. But the growing interest is significant given that all the recent activity around unmanned logistics has been focused on small package-delivery drones and that, less than five years ago, large cargo UAVs were viewed as distant prospects. Natilus was established in 2014 with the goal of creating “a mode of transportation between air and sea freight for transpacific, transatlantic and Europe-to-Asia routes,” says Aleksey Matyushev, CEO and co-founder. Air freight is fast but expensive. Sea freight is cheaper, but slow. Natilus is pursuing a third option: a large unmanned cargo aircraft that can carry the same amount of freight as a Boeing 747 the same distance, at half the cost. Using turboprop engines to lower fuel costs it would be slower, at Mach 0.4, but still faster than a ship. As a first step, the startup has built a 2,200-lb., 30-ft.-span subscale prototype, a seaplane now being prepared for flight from San Pablo Bay north of San Francisco. Natilus’ original idea was for its unmanned freighter to operate from water, over water to make certification easier. “When we started, the regulatory environment was not there, but in the last year and a half there have been huge steps at the FAA,” says Matyushev. General Atomics is certifying its Predator UAV and  Natilus will follow, he says.

Natilus is preparing for flight tests of its subscale, seaplane first prototype. Credit: Natilus

For now, there are advantages to the prototype being a seaplane. “The FAA’s test sites are too expensive. Flying from water lets us create our own test space,” says Matyushev. The prototype is powered by a single Rotax 912 piston engine. For its larger aircraft, the startup plans to use available turboprop or turbofan engines. While Elroy and Sabrewing will use a hybrid-electric powertrain, Natilus will not use electric propulsion. “We don’t believe in it for freighters,” he says. Natilus’ next aircraft will be a blended wing-body (BWB) landplane. The growth in e-commerce means freighters typically run out of volume before reaching their weight limit, he says, and “a BWB provides 30% more volume.” The company’s end goal is a 747-/777-size transpacific unmanned freighter with 100-120-ton cargo capacity. It is also looking at a 767-size aircraft with 40-ton payload. But the first product is to be a 20,000-lb. gross-weight small regional freighter with a 3.5-4.5-ton cargo capacity, powered by a Pratt & Whitney Canada PT6A. This can be certified under the FAA’s revamped Part 23 rules, he says.

Elroy Air has built a full-scale nonflying model of its electric VTOL cargo aircraft. Credit: Elroy Air

The company is developing its own autopilot. Initial prototype flights will be remotely controlled, with autonomous functionality to be added incrementally. The eventual goal is for a single ground pilot to manage up to five air vehicles. The large unmanned freighter will fly lower and slower than commercial air traffic, but will still share airspace and have to be equipped to see and avoid. Matyushev sees large unmanned aircraft operating into major cargo hubs such as Anchorage, Alaska, where freighters make up most of the traffic, and he believes that, initially, air traffic control could be handled procedurally. He points out that rules have been developed enabling the Global Hawk UAV to make long-range flights. Natilus plans to fly the small regional freighter in 2020 and have it certified within 3.5 years. The seed funding will pay for the prototype, and a Series A financing round is planned in a few months. “We are good on capital,” he says.

Sabrewing’s transpacific Draco-2 is planned to lead to a Caravan-size cargo UAV. Credit: Sabrewing Aircraft

Elroy Air was founded in November 2016, initially to pursue the eVTOL air taxi market. “But we started to understand more about the probable time frame to get through certification with a passenger-carrying aircraft that was autonomous, so decided we could build a similar aircraft for cargo initially and have an entry to market that would be ready much quicker,” says David Merrill, CEO and co-founder. Elroy’s cargo UAV is a tandem-wing design, with a cargo pod under the central fuselage, six propellers for vertical lift under twin booms and a pusher prop for forward flight. The vehicle has a 150-lb.-cargo capability, but is designed to scale up. The company is targeting government customers as well as logistics companies “This requirement of 150 lb. of payload and about 150 mi. of operational radius is at the intersection of the Venn diagram where they could both use the system and find it useful,” he says. Examples include express logistics “from places where you’ve got either terrain that makes a truck route impossible or you have truck routes that are inefficient,” says Merrill. He cites a 100-mi. route from a depot to a customer, with few other stops along the way. “So you’ve got a truck that spends half a day driving out to one customer, offloading 25-50 packages, picking up from that customer and driving all the way back. It uses a lot of time, and the truck is carrying mostly air.” Flying that kind of route makes sense, he says, particularly with the ground robotics Elroy plans for loading and unloading. The aircraft will automatically pick up the packed pod, fly the mission, deposit the pod at its destination and pick up another. “We don’t need a lot of people involved,” says Merrill. As with Natilus, Elroy foresees one pilot in command being responsible for a fleet of aircraft. Elroy is building a subscale prototype to validate the aerodynamics and controls. But the company has already tested a full-scale “Aluminum Falcon” prototype of its lift system—rotors, motors and controllers—on a truck-mounted rig at Half-Moon Bay Airport, south of San Francisco. This enabled Elroy to measure lift and noise, the latter important because the aircraft is expected to operate in urban areas. The expected lift per rotor was achieved, and noise was only “a couple of dB” above ambient, he says. The rotors are variable pitch. This allows a larger diameter, so they spin more slowly, which reduces noise. “And, most important, it gives us more options on the supply chain for motors,” Merrill says, noting eVTOLs with fixed-pitch rotors need “pretty beefy” motors. Ground testing of the subscale aircraft is to begin in early March, with Elroy hoping for a first flight by late March. The full-scale aircraft is to follow by late summer. Based on the regulatory environment, Elroy is targeting domestic government customers first, then overseas, then domestic commercial cargo. “Optimistically, we will be flying initial customers for the government in 2021,” says Clint Cope, vice president of engineering and co-founder, but deliveries could begin earlier to overseas customers. Sabrewing is taking a different route to market. As a first step, it is building the Draco-2, a 65%-scale demonstrator designed to fly 5,000 nm, as an entrant in the Pacific Drone Challenge. To win, the 30-ft.-span aircraft must fly 4,500 nm nonstop, unrefueled and unmanned from Sendai in northeast Japan to Moffett Field in Silicon Valley. Japan’s iRobotics is the other contender. But the Draco-2 is also the prototype for a full-scale unmanned cargo aircraft, the Wyvern, that Sabrewing plans to develop. This will be similar in size, cost and speed to the Cessna 208 Caravan and Quest Kodiak, but with almost double the payload, says CEO Ed De Reyes. The Wyvern will be hybrid-electric, with dual gasoline engines driving generators that power eight fans mounted in four ducts. The full-scale aircraft will be VTOL (the Draco-2 is not). “That’s how we intend to capture the market,” says De Reyes. “It will do a super-short takeoff with a large payload, then land vertically at its destination. It will serve the same market as the [Cessna] 208 and Kodiak, flying 200-800 nm to drop into remote villages.” Sabrewing has 18 sponsors onboard for the Challenge, supplying materials and equipment for the Draco-2. These include Tencate for the composites, Cobham and Inmarsat for satcom, Cloud Cap Technology for the autopilot and Attollo Engineering for the lidar sensor, part of a sense-and-avoid system that includes an Iris Automation camera system and uAvionix automatic dependent surveillance-broadcast. “We have everything we need to build the air vehicle, except the main sponsorship,” says De Reyes. Sabrewing is building a wind-tunnel model, the Draco-1, after which work on the aircraft will begin. Initial testing is scheduled for the fall in Warm Springs, Oregon. Distance testing is to be conducted from Dutch Harbor, Alaska, to Tillamook, Oregon, both part of the Pan Pacific UAS Test Range Complex. The company expects to attempt the Challenge flight in late fall 2019.