Toroidal Propeller Download EXCLUSIVE

A toroidal propeller is a type of propeller that is ring-shaped with each blade forming a closed loop. The propellers are significantly quieter at audible frequency ranges where humans are not susceptible to sensitivity, between 20 Hz and 20 kHz, while generating comparable thrust to traditional propellers. In practice, toroidal propellers reduce noise pollution in both aviation and maritime transport.[1]

In the centuries after Archimedes invented the Archimedes' screw, developments of propeller design led to the torus marine propeller, then described as a propeller featuring "double blades". It was invented in the early 1890s by Charles Myers from Manchester affiliated with Fawcett, Preston and Company.[2] The design was successfully trialed on several English steam tugboats and passenger ferries at the time.[3]

Toroidal Propeller Download

Download 🔥 https://urloso.com/2y3IZj 🔥

In the 1930s, Friedrich Honerkamp patented a toroidal fan,[4] and Rene Louis Marlet patented a toroidal aircraft propeller.[5] The marine propeller was patented again in the late 1960s by Australian engineer David B. Sudgen affiliated with Robbins Company of Seattle.[6] Overall, the relevant Cooperative Patent Classification category, B63H1/265 Blades each blade being constituted by a surface enclosing an empty space, e.g. forming a closed loop, features over 150 patents in 120 years worldwide as of 2022.[7]

The technology was adapted for fluid dynamics in the 2010s by Gregory Sharrow with twisted loops instead of traditional blades. He patented propellers that addressed issues with rotary propulsion through the reduction of tip captivation and vortices to increase performance in boats. Sharrow Marine argued that the benefits of lower fuel consumption, higher efficiency and reduced noise are even greater in water.[8] Its MX propeller was recognized as one of Time magazine's "Best Inventions of 2023" for being more efficient and quieter than standard boat propellers.[9]

The design distributes vortices generated by the propeller along the entire shape of the propeller, which means that noise is distributed and damped more quickly without requiring components that add weight to increase overall power.[8] It has similarities with the closed wing, which is annularly shaped and therefore distributes the vortices generated along the entire shape instead of just at the tip. This decreases the probability that the spinning propeller will catch onto objects or cut surfaces.[10]

Toroidal propellers are most commonly used by the aviation and maritime industries on drones and boats with thrusts comparable to multirotor drone propellers. Due to its audible frequency, the propellers have also been associated with Quiet Take Off and Landing protocols and stealth aircraft. Unmanned aerial vehicles such as Amazon Prime Air, valkyrie drones, collision-tolerant drones and cargo drones have also been considered for use.[10]

However, as engineers learn more about aerodynamics and attempt new experiments, propellers are evolving to more complex shapes. These feature multiple blades, high sweep angles, blade tip devices and other features to optimise performance in different conditions.

Coincidentally, already in 2012, US engineering company Sharrow Marine also developed a toroidal propeller for boats; they have demonstrated it to be more efficient and quieter than traditional marine propellers.

This phenomenon is not unique to propeller blades, which are essentially rotating wings. The wing of a plane also experiences this phenomenon. Engineers have done much research on wingtip devices that can minimise this.

Even though the basic propeller shape has remained the same since its invention, many propeller blade designs have been put forward. To test these, engineers need to perform design trade-off studies. Some of these approaches have been tested to try and make helicopter blades and drones more efficient and less noisy.

Well-designed toroidal propellers may have advantages in specific operating conditions, such as dense fluids or a specific range of speeds. However, the question remains as to how a toroidal propeller compares to a well-designed traditional propeller for the same conditions.

Previous optimisation studies have been conducted, some of which even use machine-learning techniques to identify suitable geometries. Engineers are also trying to make propellers that sound less annoying, by considering how humans perceive sound.

When it comes to using toroidal propellers for drones, their heavier weight will also have implications on the responsiveness and stability of the drone. This is critical when operating in windy and turbulent conditions such as windy weather.

For devices designed to revolve, however, there's been little in terms of revolutionary design changes for an awfully long time; prop-driven aircraft still use twisted-aerofoil bladed props similar in design to the bamboo-copters Chinese kids were enjoying 2,400 years ago, with surprisingly slim gains in efficiency over the wooden props the Wright brothers developed in wind tunnels in 1903. Boats still use screw-style propellers, variants of which can be found as far back as the 1700s.

"Propellers, as we know, are pretty loud," says Dr. Thomas Sebastian, a senior staff member in the Lincoln Lab's Structural and Thermal-Fluids Engineering Group. "And we can look at wings to see how that works. Back when people were coming up with all kinds of crazy ideas for airplanes in the early 1900s and during World War 2, there were a couple of designs that were basically these ring wings. So I wondered what it would look like if you took a ring wing and turned something like that into a propeller."

"We came up with this initial concept of using a toroidal shape, this annular wing shape, to hopefully make a quieter propeller," Sebastian continues. "I had an intern of mine, who was just absolutely phenomenal, run with the idea. He took the concept and created a bunch of iterations using 3D printers."

Indeed, they sound more like a rushing breeze than a propeller, making a much less intrusive sound. Anecdotally, according to the team, a drone running these props makes a level of sound roughly as annoying as a regular drone about twice as far away. Have a listen in the video below:

"The key thing that we thought was making the propellers quieter, was the fact that you're now distributing the vortices that are being generated by the propeller across the whole shape of it, instead of just at the tip," says Sebastian. "Which then makes it effectively dissipate faster in the atmosphere. That vortex doesn't propagate as far, so you're less likely to hear it."

In terms of drawbacks, these are fairly complex shapes, so they're much harder to manufacture than standard props using cheap and easy injection molding. They're probably the sort of thing you need to get 3D printed. But even if they double or triple the price of propellers, these are a low-cost part of a drone and the overall impact might not be that tough on the hip pocket.

It's unclear at this stage whether designs like this might be relevant at a larger scale, replacing traditional propellers on fixed-wing aircraft, or indeed on electric VTOL air taxis. The latter already appear to be significantly quieter than helicopters, but if they end up flooding the urban airspace with fast, cheap, green aerial transport, every decibel of noise will count when it comes to public and regulatory resistance. The question there, really, is what kind of frequencies these larger props will occupy in the audio spectrum, and whether the toroidal props shift the sound in a human-friendly direction.

Indeed, the company says this is a propeller you can stick on more or less any outboard motor, then blast along at 30 mph (48 km/h) quietly enough to have a conversation on board without raising your voice. Remarkable stuff.

Sharrow is already selling its toroidal props, CNC machined to fit a wide range of common outboard motors from most major manufacturers. The drawback here is price; they cost US$4,999 a pop regardless of which model, where a regular propeller might go for closer to US$500. But again, this is a pretty small component in the overall cost of many boats, and given their voracious appetite for fuel, the outlay may well pay for itself in short order as well as making the ride a lot more comfortable for the people on board, bystanders, and for marine life under the surface.

What do you think of a Toroidal propeller on an airplane? I realize it could be significantly heavier so I would have to be carbon fiber, but would it be worth the noise reduction? Potential speed gains?

Another interesting tid-bit is that electric planes really aren't much quieter than gas airplanes because most the noise comes from the propeller. This is what Steve Bertorelli claimed anyway, no personal experience.

I'm not seeing a way to make it variable pitch. As far as making it lighter, it sure looks that it has twice as many blades as a standard propeller. the smallest configuration would have two loops and each loop has two blades connected at the ends. the only way to lighten it would be to reduce the diameter. I don't think it would give enough thrust at a smaller diameter.

Jets are a bit different , For t/o and cruise operation we are full power and anything less and we lose efficiency (BSFC). You cant really compare them to prop aircraft and their engines because of the fact that if you try to reduce RPM with a fixed pitch prop You can only change it so much on account of the air flow eventually windmilling the propeller. This does happen in a turbojet/turbofan, but not at the lower speeds of a piston Fixed propeller. While different, the underlying mechanics are the same in the jet engine vs FP piston and until a Fixed pitch propeller is being driven by the air and not the engine, these two setups operate the same... reduce engine power, reduce RPM and reduce thrust. However once past the 0 thrust threshold in a Fixed prop setup, the prop begins to create massive amounts of drag and the RPM is kept high (way above idle). In a jet the drag does not increase much and the RPM's of the fan/core are able to drop to very low RPM. The only difference with a CS prop is that instead of reducing RPM, we reduce torque. Once again, after the 0 thrust point is hit, the propeller begins to create a lot of drag. 2351a5e196