Story ID: 326UberNBAA17
Uber Plans uUban eVTOL Network
By: Mark Huber
Caption: Such a network can reduce noise, congestion and emissions, says Uber.
Word Count: 887
Uber plans to launch demonstration urban electric vertical takeoff and landing (eVTOL) networks in Dallas and Dubai by 2020 and is working with Bell, Embraer, Aurora, Pipistrel and Mooney to develop air vehicles and related technologies. It said it will welcome other manufacturers into the network as well. Uber is partnering with ChargePoint to develop network vehicle charger stations. The vehicles will have stringent requirements for safety, noise and emissions; be expected to have a range of at least 60 miles and a maximum speed of 150 mph; be durable enough to fly 2,000 hours per year; and have direct operating costs of $1.32 per passenger mile or less, which Uber points out is less than the variable cost of car ownership.

Uber first made the case for urban vertical flight last year in a widely distributed white paper titled, “Fast-Forwarding to the Future of On-Demand Urban Air Transportation.” The widespread deployment of such a system, according to Uber, would reduce congestion, save time and bring overall infrastructure costs below those for ground-based transportation. “This isn't going to be easy,” acknowledged Uber chief product officer Jeff Holden, “but it can be done sooner rather than later.”
Technology Changes Under Way
Holden said the key to getting the network in place is “radically changing the type of aircraft we're manufacturing here and doing it at mass scale.” Those aircraft would incorporate distributed electric power (DEP) propulsion and fly-by-wire controls as a means of improving speed, efficiency, redundancy, reliability and safety while reducing noise and emissions. “Helicopters won't work because of noise, cost and energy efficiency, speed limitations. Combustion engines are only 23 percent efficient while electric motors are 92 percent efficient. A fixed-wing design with electric (DEP) gives you a 10 times efficiency improvement over a rotorcraft with a combustion engine. Helicopters also have single points of failure, and you need to maintain them extremely carefully and do teardowns at a high frequency and that translates into high operating costs,” he said. The aircraft would initially be piloted, then optionally piloted, and eventually be able to fly throughout the network fully autonomously.

Holden said working with NASA and the FAA will be critical in developing the network. It is partnering with NASA and the FAA to develop and test scheduling and separation methods to ensure safe flight. “We're going to have a lot of these aircraft in the air, particularly when you combine them with drones. NASA is going to be a tremendous partner to make this a reality.”

Uber has hired NASA veteran Mark Moore as director of aviation engineering. Moore said the network is going to require the air vehicles to have “precise digital datalinks” on board for real-time deconfliction data to be communicated among vehicles. The amount of deconfliction required could be substantial. Holden said Uber's modeling suggests a demand for up to 200,000 air trips per day in the demonstration cities.

Several OEMs have already developed and flown scaled vehicles while others have a distinct vision of what those vehicles will look like. Bell Helicopter's Scott Drennan, director of engineering innovation, said his company's design would be robust enough to fly 2,000 hours per year, be “modular, adaptable and scalable”; be able to use a variety of powerplants; have both civil passenger and military logistics applications; and likely be certified under the powered lift category (FAR 21.17B).

In April, Aurora Flight Sciences flew a one-quarter-scale prototype vehicle based on the XV-24 aircraft that it is developing for the military. The Aurora design features separate propulsion systems for hover and cruise and uses eight distributed lift rotors mounted on booms and one main aft-mounted propulsor along with a main wing and three lifting surfaces. Once the aircraft transitions past the stall speed (40 mph) in cruise flight, the lift rotors shut down. Airbus A3 (the company's Silicon Valley arm) said subscale versions of the Vahana tiltwing eVTOL have already flown and that a full-scale version would fly by year-end. The goal is for production aircraft to be autonomous and to be equipped with low-altitude ballistic recovery system (BRS) parachutes. Carter Aviation Technologies has partnered with Mooney to develop a four- to six-seat vehicle that uses Carter's slowed-rotor compound design and cruises at 175 mph. Carter CEO Jay Carter pointed out that the high-inertia main rotor is always turning and in effect functions as a main parachute while providing directional control all the way down to the ground in the event of an emergency.

Earlier this year, German start-up Lilium conducted a successful unmanned flight of the two-seat Eagle prototype eVTOL jet. The design features 36 low-vibration electric jet engines mounted to wings via 12 moveable flaps, which are pointed downward on takeoff and landing to provide vertical lift but gradually transition to the horizontal to provide forward thrust. The engines are shielded to protect each other from the impact of uncontained failure. They have a small fan diameter and limited drag and feature a simple design of two bearings, one shaft and simple rotors. The design of the aircraft makes it easy to maneuver during transition flight, a key advantage in an urban environment, notes Lilium CEO Daniel Wiegand. “We can fly curves during climb and descent,” he said. The aircraft has a range of approximately 186 statute miles and top speed of 186 mph.