We heard you loud and clear in the KZfaq comments-you all wanted to catch the pure sound of our latest Whisper plane, without the extra tunes added. Well, guess what? We're all ears! Here it is, straight-up Whisper audio goodness, no distractions included! Let's dive into the sound of soaring together! 🎵✈ kzfaq.infoMeLD_w3ZNwU?feature=share

Decibel meter would have been nice

I suggest a decibel meter in the cockpit, with old prop, and new.

In a video that is promoting noise reduction, the music is not helpful🤷🏼‍♂️

Cut the music

Please for the love of god and everything that is good in the world.... can you just leave the music out. Its cheap, its for teenagers, and its distracting.

I am VINDICATED by this new propeller !! Some 20 years ago or so I designed a simple wooden prop with bent inward tips of about 15 degrees, it was about 9 or ten inches and I meant to buy the electric motors to test between it and a straight planar prop but I never got around to it, I believe I left it with my dad because I made a smaller one for me. I hope he still has it because MY house burned down and I lost almost everything I owned. I would have been happy with ten to fifteen percent improvement in thrust with a given amount of power, but your tests show about 25% more thrust and that makes me very happy. I am glad someone perfected this design and now it can be used with electric planes also to extend their range.... and I don't have to use my time to manufacture them because Mr. Catto is doing it better than I could have imagined and with a much larger knowledge base in the physics behind it.

Don’t do the music

I always like to see new tech, but with a prop... there is a lot more than just static thrust. Did the climbout change? Did the cruise speed change? Did the fuel consumption change? And, since the vid is about a "Quiet" prop.... you should have had a Db meter inside, and outside the plane.

My god. Came to hear the prop but all I hear is MUSIC!!!!

A lot of good feelings about the success of the prop but very few facts to support that. How many decibels quieter? What was the speed difference? Climb difference? How much does it weigh? I think the NR prop has better static trust with an 80hp. Maybe altitude? The prop looks amazing, it would be nice to know if outperforms other props. Thank you for the video.

Ground testing is fun to see, but the airflow during flight is obviously very different. Optimal pitch increases with air speed. With the same throttle position, 5500rpm on the ground is going to result in much higher rpm in flight.

Wow. Those blades are so clearly inspired by Ludwig Prandtl's second formulae and the bell curve lift distribution. All to reduce tip vorticies.

I would like to have heard a low flyover with the old prop and then with the new prop. Cool design...wish you much success.

Can't hear anything with that music. Keep it out!

That is a very quiet propeller! Well done to Mr. Catto.

It's great to see you guys encouraging sound reduction. There are industry-standard sound tests you can run - that would be very helpful to share as well.

I look forward to when we can order the upgraded blades for the Tsi airmaster prop!

Cool! Can you scale the down to drones?

I've been looking into quieter drone propellers. There are some interesting designs out there that move the blade tip vortex out of phase between the blades.

Time to update the POH limitations😂

We've been wiating for a Prandtl based prop for years now - glad to see/hear one flying! Now I need one in a constant speed hub for our C182A!

Daniel Raymer and Craig Catto .... Two legends there

Craig Catto is a wizard! A legendary prop designer and great guy all-around!

Well done Craig. It looks logical to me, and that reduction in noise with increase thrust is a huge benefit. I love the simplicity of the fine adjustment mechanism for all three blades at once. Cheers from Sydney, AU.

Im glad to see yall are finding uunique solutions to the Torrance problems

I had intended to watch a bit at the start and skip to the end but I watched the whole video 😃😃

You really need to try the Eprop super smooth and super quite and 2.5kg in weight...better on the gearbox and will produce the best performance for a Rotax as it has been totally designed for the Rotax engines. Everyone with a Eprop is super happy. Try one..if you dont like it they give you a full refund

Perfect. Finishing up the Vans and I'm buying this.

Awsome to see as a pilot my self. This prop is in mew bourn stage to. 2024 and out it will get so damn much better ❤❤❤

Wonderful ! All about performance and if noise goes down that is a rediculous byproduct ! Cool little aircraft - Have fun and as always , be xtra safe - because it’s more fun ! 😊 We do this because it’s fun and serves the people ! See ya - DeBary , Florida .

Excellent! You're only a step away from having a plane that's so quiet, some people will suspect -- and complain -- that it's a UN spy plane.

Seeing Torrance airfield makes me so homesick... Great prop design!

you guys should invite the Torrance city council to come see your guys's quieter airplane

Awesome. I'm almost ready to order my TSI kit, and I'm excited for when this prop is available.

Awesome video guys.

Great work/engineering Catto

Mis más sinceras felicitaciones a los que desarrollan mejoras tecnológicas para la aviación.

Have you guys considered testing toroidal props? They seem to be outstanding. You should've had a decibel meter to determine the amount of the sound difference.

That was an improvement. Now to see how durable it is.

I'm so glad to see other people leave comments about horrible music being edited into videos. I can't figure out why so many KZfaqrs think that they need the music. 99% of the time it is annoying, distracting and makes me not want to watch the video.

Catto nails it again. Great company, don't blame the FBO's music on him!

Hello Jean aka "Dassie" ! Greetings from Corrie Snr here in the RSA!👌👌👍👍

Even I could hear the difference, sweet.

What tools should i use to design my propeller? 360 ? Or just foam or wood models?

Reckon if the leading edge had nodules on it leading into V patterns similar to what is on the bypass cowling in newer jet engines coupled with a winglet on the tip will give the ultimate in quietness. The challenge is there is nothing like that available to my knowledge. So now is the time to get one developed, built and tested.

Beautiful prop. Mr Catto knows his stuff. Outstanding results. Decibel count would have been nice. Lose the music. It contributed nothing in fact it was a distraction.

Noticed that on the first test with the DUC prop, the prop spinner was on. I think for a valid test, the spinner must be on in ALL tests and the winds must be documented to be the same

Love that prop. Finally someone improving prop design. Not being an engineer I have always wondered why the exhaust of an airplane is dumped right in front of the cockpit? Why not add 5 or 10 lbs of exhaust pipe past the cockpit to lower the cockpit noise level. The 1 negative that I do see is the parasite drag. The rubber hangers used in the automotive field could work for support. Also the exhaust pipe could be designed to help scavenge the exhaust gases vs creating back pressure so that could help increase the power. IMHO. I'm sure this has been tried but I have never seen it, not that I have seen everything.

The prop on the Joby electric has a similar tip shape.Hopefully it'll work even better at higher Mach numbers

Like most have said use a decibel meter and it would be nice if you added charts to visually show the differences in thrust, sound, speed, and rpm. I wonder what would happen in a contra-rotating setup with these blades?

I wish you would have used one of your other Slings to give us a real time comparison! One during run up and one on the fly over test. But amazing technology and video, thanks

Does Sling Pilot Academy have any plans to test a CS prop on a HW or TSI with gthe 916 engine?

Hell yeah

Frequency response graph as well as dB level?

Inspection of Blackhawk helicopter blade tip uses the same idea. The blade has a dog tooth about one blade cord inboard. Generates a vortex rotating opposite the tip vortex. I can understand the noise reduction, but can’t understand why doubling the vortexes increases efficiency.

old school here. do you not safety wire prop bolts anymore?

The military could use this technology on there tail rotors to cut the noise. That's where the most prop noise comes from on a standard design helicopter.

I wonder if you could redesign the rotor on an autogyro to make the gyro use less gas at a faster flight

It would have been nice to have db readings using a "conventional" prop vs the new prop...

seems kool :)))

make sure that when you install an experimental prop to have all your friends and hangers on stand in line with it during testing run up

Little boys on Christmas morning ! Ha - 😅. Cool stuff !

Amazing! The Catto Blade reminds me of the similar design used in new airline industry engine like the GE-E90 that has and provides all the properties the catto blade has efficiency, power, fuel savings and noise reduction!

Is there a way to use 'Noise Cancellation' (like military helicopters)?

What is the net efficiency improvement?

What regulatory regime are you operating under which allows you to test fly like that? Where I am everything would be bogged down in paperwork for months!

It would be interesting to see the performance difference of a prop change on a WW2 fighter.

Variable pitch propellers went out with the B. of Britain, Dowty-Rotol constant speed props were found to be better. Your tests are conducted at ground level, but Spits and Mustangs achieved their fastest speeds at about 15,000 - 20,000 ft. Would this new prop perform well at altitude?

Would be nice of you to at least mention astonishing Paul Lipps propeller that Catto made for Lipps as an inspiration for the "new" propeller that resembles propellers used on little photography drones for more than a decade. Now if you can rmake similar 1909 Olmsted propeller that I think inspired Paul Lipps, that would be nice.

It would be nice to measure the difference in the cruise speed and fuel consumption, also the noise level can be measured using any mic

Insane result so is the music

If I owned an airplane and was looking for an "advanced prop"....based on this video...I would keep looking.

How would a propeller designed from a Sycamore seed work?

I snapped 2 motorcycle tie-downs when lifting an elk out of my truck with a forklift. I’d worry about that strap recoiling into the prop if the hook bends. I have no idea how much elasticity there might be in that strap, but this would be an expensive way to find out.

A set of numbers at the end would be nice.

Sounds reasonable, zero lift at the tip, less noise. Where is the decibels meter? Where is the summary chart? Noise, Static Thrust, Climb Rate...

How about the prop's performance at cruise speed? There is more to a prop than pulling a truck and noise.

Hey, you asked for a suggestion of what to make quieter on your plane? I dunno if this is reasonable, but.... what if you somehow measured your exhaust manifold pressure, since straight off the block, your exhaust gasses are basically some sort of percussive phenomenon. Then, armed with that recording of the status quo, you somehow enlist the CFT expertise of Catto and his staff. Then iterate over some sort of exhaust design that in no way restricts the exhaust gas outflow, but somehow does a secret sauce to the exhaust gasses, so that by the time they exit, they have become no more than a smooth, laminar flow, and just happen to be at the ambient air pressure, whilst having a velocity matching your IAS? 🤣 As a suggestion, I intend for it to come across as ridiculous. I would think that meeting those criteria would make your exhaust inaudible, and your crew of inventors who made it that way, would suddenly be defense contractors, never having applied for the job! Whether this is good news or bad news, I don't see that happening, but you can certainly say that my suggested goals are "aspirational." Meaning you can aim for that perfect result, and, should you attain 3-5% toward that goal, you would have a decent result. Get halfway there and, boy howdy, you might forget to shut the engine down due to not hearing it, anymore. 🤣 Here are a couple of thoughts that might help: look into how "shotgun" style directional microphones are designed. Although the lateral arrays of holes seem like baffles, their purpose is actually to allow off-beam sound (i.e., sound from sources to the sides) to enter the microphone in a pattern that causes it to destructive interfere with itself. Maybe the corresponding method of handling exhaust gas is to do something like divert it into a few channels, then cause it to travel slightly different lengths in the channels, until you merge those channels back together in a large-bore outflow channel. The hope there being that the percussive wavefront (the "p's in pow" in the "pah-pah-pah-pah-" rhythmic exhaust sound) could be delayed by different amounts, so that the pressure peak of some channel will be mixing with the low-pressure valley of some other. If, at any given time, every "pow" is mixed with every "ah" then instead of "pah-pah-pah-pah-" it might sound like "------" instead! The tricky bit might turn out to be: figuring out how to adjust the destructive interference, to match your RPMs, as you transition through the flight regimes. Maybe the "channels" would need to be made similar to the inner workings of an accordion, with a mechanism that changes musical keys to keep it harmonious. I suggest this as an example only because I have no idea what is inside an accordion! In other words, it's food for thought, if you consider Twinkies food. Here's another completely unverified spatially for you: Exhaust gas is hot, and takes up more volume than the ambient air. If you can cool it somehow, it would, of course, shrink back a bit closer to ambient density. Considering that it was the expansion of hot gasses that made the piston move, and then was exhausted as the "p in pow" sound, causing the exhaust gas to have cooled at some point after the cylinder, and before it is finished being exhausted, should get you a little bit closer to the "b in bow" or the "v in vow." Set your sights on the "m in mao," and... uh, let's just say we Americans are still dreamers. So a thought might be to 3d print a new exhaust manifold. Don't change anything much, except add internal and external "heat sink" fins. Or, go really to an unproven, and possibly dangerous extreme, by flowing your avgas through narrow "coolant loops" in the exhaust manifold. Transferring exhaust gas heat to the pre-ignition fuel, just immediately prior to compression and the spark could have beneficial results! You might get more efficiency, more power, quieter exhaust, and radiant skin. You would want to watch out for: dieseling, pre-ignition, premature detonation, chunks of motor getting blown out, engine bursting into flames, shutdown procedure now includes fire department step, and in-flight stalling due to fuel lines now all coked up and congested from it. So, this is an idea I emphasize might be terrible. On the other hand, it might be great. I have no idea. Maybe those ideas are most useful for triggering you to have better ideas that supplant them. If so, my work here is done! Good luck, guys! I will be looking forward to your progress toward silence in propeller-driven aircraft.

What is the story with the music?! This is not a gym workout session... why is there no sound dB measurement (even with the phone)?? One frame with summary charts comparison before and after

Propellers have one purpose ONLY and that is to keep the pilot cool , you would notice the pilot overheating and sweating a lot when the propellers stop spinning

Interesting

What airport is that?

Now you have to redesign the exhaust , Get the noise level down to match a Honda Gold wing Touring Bike.

So was the only benefit a quieter plane? Please let me know so I can see if I want one of these vs my Whirlwind.

Reminds me of the Prandtl wing.

A toroidal fan blade. Manufacturing a toroidal blade and the certification by the FAA is the difficult part.

How can I buy one for my Rotax 914 ? 😊

So what's the speed difference??

Comparison results could be done using a Toroidal Propeller ???!!!

Can you mount that on an electric motor?

Love you guys as achievements I hear planes going over head you can’t hear yourself think that was awesome the difference I’ve always had touchy ears I hate it when some motorbike or semi with allowed tires in the open exhaust thanks that everybody else wants to hear that noise you can hear them a mile before they get here in a mile after their past I imagine if someone lived by an airport they would appreciate your guises achievements God bless

What happens if a rock nicks the prop?

Is there a constant-speed version?

what in hadies is the tail pipe

I certainly hope all prop blades are the same pitch ! I got ya tho - Roger .

When will we see Tubeculs on the leading edge, Shark skin on all surfaces , and zig zag owl trailing edge? Just Tubeculs give 20% extra lift and efficiency imagine the rest?

Looking more & more like air boat props evolving for 🤔 20 yrs now

Before and after comparison would be nice. Maybe two planes following each other. And as others suggested, decimal meters.

One problem…the plane plays the music ONLY when the new props are installed