Seattle-based startup Jetoptera is designing propellerless vertical take-off and landing (VTOL) vehicles that will make the future of urban aviation quieter, safer and faster. What’s more, the US Air Force is very curious.

The proportion of the world’s population living in cities is expected to rise from the current 50 per cent to nearly 70 per cent by 2050, meaning that already crowded city streets are likely to become even more congested. To free people from traffic, dozens of companies are planning VTOL vehicles that could quickly fly passengers through cities like an airborne Uber.

Rethinking the drive

Like helicopters, most VTOLs under development still use propellers to generate the thrust needed to fly. Although the rotating blades of VTOL variants are generally smaller and quieter than the single large blade of helicopters, they still generate noise that can be disturbing.

The Jetoptera takes a different approach, replacing traditional rotating propellers with a propulsion system called a “Fluidic Propulsion System” (FPS), which it describes rather plastically as “a bladeless fan on steroids”, Big Think wrote.

According to Jetoptera’s description, this system sends small amounts of compressed air through rearward-facing vents inside a ring-shaped engine. The Coanda effect causes this air to create negative pressure, which sucks ambient air into the front of the engine.

As a result, the amount of air discharged at the rear of the thruster is up to 15 times more than the compressor pumps. The engines can be positioned so that this air pressurises the ground during take-off and then rotates during level flight to propel the VTOL forward.

Based on research funded by the US Department of Defense, Jetoptera’s system is “the quietest propulsion method in the sky,” the company claims. “In places like New York, Los Angeles and London, you wouldn’t hear our aircraft until it approached from a distance of about 200 feet (60 metres),” Jetoptera CEO and chief technology officer Andrei Evulet told Future Flight trade portal earlier.

We need a better battery

Unlike many VTOL startups, Jetoptera has not committed to making its flying cars electric-powered. Current plans are to rely on gas turbine generators, meaning the vehicles might one day ease ground traffic, but they wouldn’t help solve the climate crisis.

“We are dubious about the energy source. Although batteries are one promising source, battery technology is simply not advanced enough at this stage. We don’t want to become winged batteries. We need to be able to transport cargo and eventually people. So if we want an electric-powered aircraft, somebody has to invent a better battery,” Evulet explained to My Edmonds News last year.

Jetoptera is currently developing several vehicles equipped with its FPS, including a two-seat commuter VTOL, the J-2000. A quarter-scale model of this aircraft has already flown in 2019, reaching a top speed of 144 km/h. They expect the full-size version to have a range of 320 kilometres, a top speed of 320 km/h and a payload capacity of between 200 and 360 kg.

Jetoptera is also developing a VTOL for the US Air Force, which is expected to reach speeds of around Mach 0.8 (982 km/h), which is about as fast as a commercial jet airliner. A small-scale model of this design is undergoing wind tunnel testing, and Jetoptera expects to have a flight-ready demonstrator by 2025. The project is well under way, with aerospace and defence giant Northrop Grumman (which developed the B-21 Raider stealth superbomber, for example) also on board.

“These working models will allow us to test airframe and propulsion system designs. We hope to have more prototypes capable of carrying people by 2026,” said Evulet.

Source: BigThink