[deugtniet]

I watched the video, and only (maybe) saw STOL, not VTOL.

Looks like they use two Dyson style fans for propulsion, which means the fan blades are on the inside of the fuselage, could be very interesting for an urban environment, as there is less risk of hitting something with your blades.

That being said, they mention a gas turbine is necessary for propulsion, so it probably won't be quiet enough for urban envirnoments

[MrDunham]

Deep in the article it mentions a 15 dB reduction in noise compared to a turboprop at the same thrust.

Unfortunately, though, they don't give hard numbers… If that's 120 dB versus 135 dB it's still too loud for urban environment. But 105 dB versus 120 would make a huge difference and likely be tolerable for a city if it's kept to landing pads on skyscrapers.

[nradov]

Putting landing pads on skyscrapers is mostly a fantasy. There are only a few such pads today. They can't easily be added to existing buildings because the roofs are already used for antennas and climate control machinery. Weight is an issue. And even relatively quiet aircraft are going to annoy tenants on the top floors.

[ChrisMarshallNY]

> STOL

I suspect the "V" is still "in theory," because it probably relies on those fans being rotated, and it looks like the ones in the demonstrator are fixed.

Once the rotation happens, a lot more factors come into play, and those problems are not new (see "Osprey").

I think that SCRAMJet engines also use fluid dynamics, in a similar manner.

[philip1209]

An issue with both the Osprey and the VTOL F-35 is that they each have two engines involved in VTOL. So, if one engine fails - then the plane becomes unbalanced and probably flips over. (That's why the F-35 has auto-ejection [1])

This technology is interesting because, if you can have one engine involved in VTOL (like the Harrier) but vector the thrust easily, then an engine failure during takeoff or landing can avoid spinning the plane.

[1] https://www.thedrive.com/the-war-zone/the-f-35b-can-eject-it...

[danbruc]

From looking at their website [1], it looks to me like they are just using a jet turbine and routing the air through pipes to those ring-shaped outlets.

[1] https://jetoptera.com/technology/

[JPLeRouzic]

Thanks for the link. I have a question. They say:

"The energy required to propel our smallest aircraft at 200 mph for 30 minutes is 100 kWh. This energy can be provided by 26 kg of jet fuel or 600 kg of modern Li-ion batteries."

Is really "26 kg of jet fuel" comparable to "600 kg of modern Li-ion batteries"?

Thanks!

[tleb_]

A UAV is still dangerous around people even with no blades involved; a falling UAV is enough to kill. This is a real issue that companies (startups and giants from the domain) are trying to solve, which is required for unmonitored UAV in urban areas to start getting legally accepted (at least in France).

[giantg2]

Ballistic parachutes have been around for a long time. I wonder if they can use that with an audible alarm to eeduce the likelihood of a person strike.

[elif]

It's funny to me that the plane is driven by a compressor turbine but they are calling it "blade less"

Maybe there's a new way to build compressors I don't know about?