UAM, Urban Air Mobility - Dette er en av dem, et av veldig mange typer - AW&ST

New Look For TF-2 As Terrafugia Matures Urban Aircraft Design Guy Norris Terrafugia, the Massachusetts-based developer of the Transition roadable light sport aircraft, is close to finalizing the design of its ambitious follow-on project, the TF-2 passenger and cargo vertical-takeoff-and-landing urban air mobility (UAM) vehicle. Unlike most other UAM designs unveiled so far, the TF-2 extends the roadable aircraft concept by integrating the flying vehicle with an attachable, drivable four-passenger or cargo pod that can carry up to 1,200 lb. on ranges up to 185 mi. at 125 kt. Terrafugia, which was acquired in 2017 by China’s Geely Group, believes the air and ground vehicle combination could offer significantly increased utility over dedicated air vehicle designs. ·         Revised TF-2 lift-plus pusher design features six rotors and two puller props ·         Original high tailplane replaced by inverted twin vertical tails on extended booms The TF-2 is targeted at type certification in 2023, says Terrafugia, which is evaluating the design with a flying scale model. A full-scale vehicle should begin flight test by the end of next year. Certification will be under the FAA’s simplified Part 23 rules. The craft will use a piston or gas turbine engine to generate electric power to drive multiple rotors. With the company having earlier studied tiltrotor designs, the TF-2 is now defined with a simpler lift-plus pusher configuration that appears to be more practical for faster development. “We are comfortable with the design, and we know the way going forward,” says Hakan Apell, business development and marketing director for Terrafugia. "But you never know, if something pops up with the tiltrotor concept then it could be back. But as for now, we are concentrating all our development around lift-push."

The revised TF-2 now features tip-mounted puller props and added lift fans on extended booms. Credit: Guy Norris/AW&ST

The radically revised configuration replaces four electric-powered lift rotors in the original design with six slightly smaller units mounted on two extended booms. The fuselage-located single pusher propeller of the earlier configuration is also replaced with two wingtip-mounted electric puller propellers, while the gas turbine providing power for the vehicle’s propulsion system occupies the former site of the pusher propeller in the upper aft fuselage. The design changes, which removes the potential danger to ground personnel of the earlier concept’s aft-mounted propeller, also ducts engine exhaust up and away from the tail area.

Building on a design feature of its tiltrotor concept, the new-look TF-2 has inverted twin vertical tails that double as aft landing legs. The arrangement replaces the original design that mounted the tails on extended booms and joined them with a high-mounted horizontal tailplane. The revised configuration also lowers the positioning of the fuselage, integrating the body with a high wing and more closely integrating the cockpit and removable aft cabin section.

The new TF-2 configuration includes inverted vertical tails that double as aft landing legs. Credit: Guy Norris/AW&ST

Details of the revised TF-2 emerged at the recent National Business Aviation Association meeting in Orlando, Florida, where Terrafugia was officially taking orders for the Transition following its reemergence under new ownership. “We have a unique vehicle coming to the market now, and it’s actually happening,” says Apell. “[The Transition] is a taste of the future. It is time to revolutionize the aerospace industry.” Parts for the first production Transitions are already being manufactured, says Terrafugia CEO Chris Jaran. Initial deliveries are set to begin in late 2019, but the first few vehicles will be retained primarily for training and leasing. Wider distribution of vehicles for general use will follow in the early 2020s, he says. The Transition features a hybrid-electric power system to drive the wheels on the ground, while extra “boost” power will be available in flight from its LiFePO4 (Lithium iron phosphate chemistry) battery. Propeller power is provided by a fuel-injected Rotax 912iS piston engine. Plans call for the Transition to be manufactured in China, with final assembly and completion in the U.S. Terrafugia has also added a BRS Aerospace airframe parachute system to a suite of safety devices for the Transition, which must meet both airworthiness and ground-vehicle regulatory standards. The parachute system, which will be deployable by ballistic rocket from a container behind the cockpit, will be standard equipment along with automobile safety features such as crumple zones and rearview cameras.