China's TCab E20 eVTOL prototype is making regular transition flights
Shanghai's TCab Tech has become one of China's leading eVTOL contenders, claiming it's now made many test flights validating its 50-percent scale prototype E20 air taxi design in vertical lift and hover mode, as well as transitions to winged cruise flight.
The E20 is an interesting take on a five-seat electric VTOL aircraft, a kind of halfway measure between tilt-prop vectored thrust designs like the Joby S4 and lift and cruise designs like Autoflight's Prosperity. A large pair of gull wings rise off the top of the cabin, and halfway along them are a pair of four-blade lift props, capable of splitting and aligning themselves longitudinally for minimal drag in forward flight.
Further out on the main wings sit a pair of large five-blade tilting props, and the remainder of the wing tips are fixed to the propulsion nacelles such that they tilt along with them. Back toward the tail is a second, shorter, forward-angled wing, which terminates in another set of tilting nacelles with large five-bladed props on them.
Four tilting props, then, and two that are set for lift only and low-drag cruise. A reduction in complexity, perhaps, from designs like the Joby S4, although it seems that it comes with a cost in terms of top speed and range. TCab claims the E20 will only go as fast as 260 km/h (162 mph) where Joby has already clocked more than 330 km/h (205 mph) in the air, and TCab is only promising some 200 km (124 miles) of range against Joby's 241 km (150 miles).
Mind you, these are still perfectly useful figures to bring to the table. Unlike eHang, which is already performing autonomous demonstration flights with passengers on board and inching towards full certification any day now, TCab is going with a pilot and four passengers.
The company has built at least one full-sized "engineering verification machine" – but it's also flown several sub-scale prototypes. It saw rapid progress in 2021, with a 25-percent scale demonstrator completed in August, which had completed "hundreds" of transition tests by October. By December 2021, TCab had a 50-percent scale model in the air with a 6-meter (19.7-ft) wingspan.
Now, the company says it's done dozens of flight tests taking this 50-percent scale prototype through the tricky process of transitioning to winged cruise flight and back again. This version of the E20 also introduced increased control options for the flaps in cruise flight, as well as adding "variable collective pitch," which we take to mean that the tilting props can now vary the pitch of their five blades.
All of this appears to make TCab one of China's most advanced eVTOL companies, and the only one we're aware of thus far to have demonstrated this kind of progress on a vectored-thrust design. Definitely a company to keep an eye on as the intercontinental race for eVTOL supremacy heats up.
Check out the transition flight video below. Annoyingly, it doesn't give us a close-up of the tilt mechanism engaging, but it does give a good sense of how quickly these things will accelerate when the propulsion systems begin to tilt.
Source: TCab Tech via Electric VTOL News
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Great to see more of them in the works !