https://newatlas.com/aircraft/cyclotech-cyclorotor-noise

CycloTech reveals outdoor noise level from its CycloRotor propellers
By Loz Blain
June 07, 2023

Voith-Schneider CycloRotors are capable of vectoring thrust nearly instantly
in 360 degrees, while rotating at a constant rate
Voith-Schneider propellers are capable of vectoring thrust nearly instantly
in 360 degrees, while rotating at a constant rate
Cyclotech
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View gallery - 5 images

Having received permission from Austrian authorities to begin outdoor flight
testing on its remarkable CycloRotor-propelled technology demonstrator,
CycloTech has announced noise testing results for its 360-degree thrust
vectoring propulsion barrels.

CycloTech is one of very few companies looking beyond the humble propeller,
pitch-controllable rotor or ducted fan to provide thrust for electric VTOL
aircraft and drones. Instead, it uses a series of spinning barrels.

These CycloRotor barrels are known as Voith-Schneider propellers, and they
spin at a reasonably constant rate when an aircraft is off the ground,
rather than needing to constantly speed up and slow down like the propellers
on a drone do to keep it balanced in changing wind conditions.

Instead, the walls of the barrels are a series of blades, and these blades
can be pitch-controlled throughout the rotation of the barrel, allowing for
near-instant changes in the magnitude and direction of thrust through 360
degrees.
Cyclotech | Cyclogyro Principle

Blade pitch control is handled by a central hub that works a bit like the
swashplate in a helicopter; when it's moved off-axis, it changes the pitch
of all blades as the barrel rotates, such that the thrust remains constant
when the hub is staying still.

One advantage of this kind of idea is that it doesn't necessarily require
electric motors spinning the barrels, because it doesn't need massive
amounts of instant torque to stabilize an aircraft. You could run the thing
on combustion engines, and presumably make yourself a much longer-endurance
aircraft.
CycloTech First Flight

Progress hasn't exactly been at lightning speed here. CycloTech made the
first tethered flights (above) with its 83-kg (183-lb) technology
demonstrator more than a year and a half ago, and since then, it's been
radio silence apart from a super-weird cargo drone concept it put together
in conjunction with Japanese delivery company Yamato.

But there are two bits of recent news worth mentioning. Firstly, in March,
CycloTech announced it had received permission from Austro Control, the
Austrian aviation safety authority, to start flying the demonstrator
outside.

“The Operational Authorization for the outdoor flight test campaign is a
major milestone and will be key to demonstrate the CycloRotor technology to
the aviation world.” said Deva Harsha Yarramshetti, Flight Test Engineer at
CycloTech, in a press release.
The tech demonstrator has now been given the nod for outdoor flight testing
The tech demonstrator has now been given the nod for outdoor flight
testingCyclotech

And now, the company says it's completed an extensive outdoor noise testing
campaign for the propulsion system at the Wels General Aviation Airport in
Austria.

Noise is crucial to eVTOL aircraft designs. If they're going to democratize
vertical flight and become the ubiquitous air taxis of the world, they need
to be vastly quieter and cheaper than helicopters. So CycloTech stuck a
propulsion barrel on a test stand and took a bunch of readings, reporting
that "the CycloRotor generates a sound pressure level of 59 dBA at a
distance of 100 meters (328 ft), which is equivalent to the level of a
typical conversation between two people."

It's hard to put this result in context, though. For starters, the barrel
was mounted on a vertical axis, so the thrust couldn't be vectored downward
like it'd typically be in any eVTOL aircraft. Secondly, it's not clear which
direction it was vectored toward relative to the microphone array.
An array of microphones set up for acoustic testing
An array of microphones set up for acoustic testingCyclotech

Thirdly, well, there was only one of them, where a full-sized eVTOL aircraft
will probably run six or eight for the sake of redundancy. And it was also a
fairly small one – presumably, the CR-42 CycloRotor, whose maximum thrust of
253 N (~57 lbf) is nowhere near what each of a Joby S4's big tilting
propellers put out.

We bring up the S4 because back in May last year, Joby became the first
eVTOL company to release genuine noise figures for a full-size air taxi
prototype. Working with a team from NASA, Joby measured the S4 from the same
100-m distance as CycloTech, and found over more than 20 takeoff and landing
cycles, the noise level from its six large propellers never rose over 65
dBA.
Cyclotech's 83 kg technology demonstrator aircraft, set up for thrust
testing on a vertical pole
Cyclotech's 83 kg technology demonstrator aircraft, set up for thrust
testing on a vertical poleCyclotech

So while the CycloTech system is much earlier in development than the Joby
aircraft, it seems reasonable to estimate that the CycloRotor propulsion
barrels are likely to prove significantly noisier than regular ol'
propellers once scaled up to full air taxi size – assuming that this is
where this kind of tech will end up.

Check out the noise testing in the video below, which remarkably contains no
audio from the tests. The first flight video above, however, lets you listen
in a bit.
Outdoor Noise Test Campaign | VIDEO

Source: CycloTech
View gallery - 5 images
Tags
AircraftCyclorotorsElectric AircrafteVTOL

5 comments

obert June 8, 2023 03:53 AM
One wonders what problem does it try to solve. Helicopter is complicated but
efficient, drones are inefficient but simple and cheap. This is complexity
of 4 helicopters in one, neither simple nor efficient.
reader June 8, 2023 06:18 AM
Tip speed is lower so noise will be lower.
JamesFeeney June 8, 2023 08:33 AM
I saw something like this for a boat propeller system. Could this be
modified to catch wind energy (the opposite of propelling)?
Towerman June 8, 2023 09:30 AM
@Robert
There is no problem and it is efficient, the drums don't require a lot of
energy to turn compared to other propulsion methods the technology has
already been proven. Its a ingenious concept.
Towerman June 8, 2023 09:34 AM
Yes its no secret. Though i prefer concepts like Joby and Skai. I have a
sweet spot for the cyclorotor. It just looks Right. I cant wait for it to
commercialize. And there is no doubt whatsoever that it will pioneer a niche
market in its own right ! Please keep us updated Loz