I sanded them and that reduced the noise and some higher pitch frequencies a little more.

What I'd really like to see is an STL modded for a Phantom 4 I can print.... I just can't find any anywhere and I continue to thrash my Phantom. She keeps running and I've been wanting to test a few double-toroidal  props.

Hi, To be continued? will there be a crash test?

Just found this video about the manufacturing process of the boat props. Not relevant to this discussion but interesting.

Ken weighs in .

KLRSKIR Posted at 3-14 06:47
Ken weighs in here.

Nice!
I think my design was thicker and SLA print was better than FDM. It was certainly a lot stronger than what they were showing just flopping around.

Lost Somewhere Posted at 3-14 07:00
Nice!
I think my design was thicker and SLA print was better than FDM. It was certainly a lot stronger than what they were showing just flopping around.

I would definitely agree.

I like your's more, also.

why? to what end?

Is this allowed on helicopters?

The Saint Posted at 1-29 19:45
the m3p is already very quiet; however, may i suggest: https://www.masterairscrew.com/products/dji-mini-3-pro-stealth-upgrade-propellers-x4-red

The master airscrew stealth props are garbage. They're extremely brittle, production quality is trash, they are way to loose on the propeller shafts, and the noise difference is not noticeable what so ever. At least with the set I had tried. Lots of reviews say they're garbage and I should have listened. Stay away, far away from them.

djiuser_HXdzkKgLnGrO Posted at 3-19 16:34
The master airscrew stealth props are garbage. They're extremely brittle, production quality is trash, they are way to loose on the propeller shafts, and the noise difference is not noticeable what so ever. At least with the set I had tried. Lots of reviews say they're garbage and I should have listened. Stay away, far away from them.

well, at least they look good.

where can I get these

seraphic Posted at 3-15 02:12
Is this allowed on helicopters?

Helicopter blades rely on an affect called rotor flapping to mitigate the lateral differential in lift caused by one blade advancing into the wind and one blade retreating. Basically one blade droops increasing lift and the other blade flexes upward reducing the lift surface. These blades are probably a little too rigid and would require a dual rotor/counter rotation system.

Lost Somewhere Posted at 2-23 17:08
I sanded them and that reduced the noise and some higher pitch frequencies a little more.

Can I make a suggestion. I don't have the CAD skills for this, but it seems to me that spinning mass is a bigger problem than overall mass. How about a tapered, or even hollow design that reduces the spinning mass by removing mass from the rotor tips. Then using a high strength resin, look into the medical/dental resins that are extremely high strength by comparison to standard consumer resins. (they just cost a lot more)

Tflo Posted at 7-11 09:42
Helicopter blades rely on an affect called rotor flapping to mitigate the lateral differential in lift caused by one blade advancing into the wind and one blade retreating. Basically one blade droops increasing lift and the other blade flexes upward reducing the lift surface. These blades are probably a little too rigid and would require a dual rotor/counter rotation system.

Never heard of rotor flapping, but in the industry we called cyclic.

https://www.eclipseaviation.com/ ... g-you-need-to-know/

Burt37 Posted at 7-11 16:14
Never heard of rotor flapping, but in the industry we called cyclic.

https://www.eclipseaviation.com/the-cyclic-control-on-a-helicopter-everything-you-need-to-know/

The way I learned it is that cyclic control is related to changing the thrust vectors by applying force to the articulating arms via swash plates. This changes the angle of attack of each rotor as it enters different parts of the rotors cycle/rotation. This is a separate effect from rotor flapping. Cyclic control allows for directional control of the thrust generated by the lift disk. In a quad copter this is accomplished by increasing or decreasing the rotational speed of different rotors at the corners of the quad copter. In a single rotor system you have to change the angle of attack in different regions of the lift disk. Blade flapping is what makes an "Even" lift disk or equal thrust on all parts of the lift disk during forward flight. This is also one of the speed limiting factors of rotary wing aircraft. At some forward velocity the relative velocity of the retreating blade to the atmosphere is Zero, while the advancing rotor is moving very fast relative to the surrounding atmosphere, this would generate one sided thrust only and the helicopter would flip, lose control and crash. This of course occurs at lesser velocities as well, but the up-tilt of the advancing rotors generates large vortices at the rotor tip canceling out the lift effect for a large portion of the rotor thereby reducing lift/thrust on the advancing rotor; on the retreating rotor the rotor tip dips due to a decrease in lift/thrust as the rotational velocity of the rotor slows relative to the atmosphere. This creates a larger lift surface on the retreating rotor increasing the lift/thrust. This why single rotor systems always utilize highly flexible rotors.

Tflo Posted at 7-12 10:10
The way I learned it is that cyclic control is related to changing the thrust vectors by applying force to the articulating arms via swash plates. This changes the angle of attack of each rotor as it enters different parts of the rotors cycle/rotation. This is a separate effect from rotor flapping. Cyclic control allows for directional control of the thrust generated by the lift disk. In a quad copter this is accomplished by increasing or decreasing the rotational speed of different rotors at the corners of the quad copter. In a single rotor system you have to change the angle of attack in different regions of the lift disk. Blade flapping is what makes an "Even" lift disk or equal thrust on all parts of the lift disk during forward flight. This is also one of the speed limiting factors of rotary wing aircraft. At some forward velocity the relative velocity of the retreating blade to the atmosphere is Zero, while the advancing rotor is moving very fast relative to the surrounding atmosphere, this would generate one sided thrust only and the helicopter would flip, lose control and crash. This of course occurs at lesser velocities as well, but the up-tilt of the advancing rotors generates large vortices at the rotor tip canceling out the lift effect for a large portion of the rotor thereby reducing lift/thrust on the advancing rotor; on the retreating rotor the rotor tip dips due to a decrease in lift/thrust as the rotational velocity of the rotor slows relative to the atmosphere. This creates a larger lift surface on the retreating rotor increasing the lift/thrust. This why single rotor systems always utilize highly flexible rotors.

Wow... I always knew there was a reason I stuck to fixed wing!

Fascinating things those rotorcraft, but the aerodynamics are just toooooo complicated. And to think that Da Vinci is credited with coming up with the idea when all he did really was stick an Archimedes screw on top of a bike! He had no idea of what it was going to really take to make one of those things fly and be controllable.

And as for auto-gyros - well, they are just witchcraft, surely.

No Original Thought Posted at 7-12 12:41
Wow... I always knew there was a reason I stuck to fixed wing!

Fascinating things those rotorcraft, but the aerodynamics are just toooooo complicated. And to think that Da Vinci is credited with coming up with the idea when all he did really was stick an Archimedes screw on top of a bike! He had no idea of what it was going to really take to make one of those things fly and be controllable.

Apparently, Archimedes saw the screw first time in Egypt... He didn't invented. He just took the idea back to Greece.

Reference:

https://en.wikipedia.org/wiki/Archimedes%27_screw

But I still remember that day when I was able to hover at 20cm from the ground for the first time with my JR Ergo 60 converted to Z230... I still have it... Surely it is a lot harder than fly a quad, but the reward is also much, much greater...

grabcad.com/library/mini-3-pro-toroidal-props-1

Has anybody made progress with this effort?  

I have a resin 3d printer that can go down to 0.05mm resolution, and would be willing to print a version that's targeted to the finer resolution.

theGleep Posted at 10-20 13:54
Has anybody made progress with this effort?  

I have a resin 3d printer that can go down to 0.05mm resolution, and would be willing to print a version that's targeted to the finer resolution.

Making progress. I bought a nice little resin printer and have been iterating. The extra drag of 4 surfaces instead of 2 often causes the motors to overheat. So retrofitting for the mini 3 is tricky. They would be better on a custom drone with properly matched motors.

The Saint Posted at 1-29 19:45
the m3p is already very quiet; however, may i suggest: https://www.masterairscrew.com/products/dji-mini-3-pro-stealth-upgrade-propellers-x4-red

These "stealth" props don't do a thing. I ordered 2 sets of them for my mini pro 3 and it makes no difference whatsoever. Was really bummed, but now I have extra props...so yay.

djiuser_jAOWCPcU60pF Posted at 11-18 15:06
These "stealth" props don't do a thing. I ordered 2 sets of them for my mini pro 3 and it makes no difference whatsoever. Was really bummed, but now I have extra props...so yay.

Yeah mostly for the color.

i dont know how this mit place claims to have invented this prop design in 2017 but in the 1930's Lois Marlet patent pended toridial aircraft proppellers it was even recognized by the R and D 100.  go on Wikipedia, and look up Toridial propellers.  looks like MIT had somebody else do their homework for them before they were even born

Lost Somewhere Posted at 1-29 19:12
Engineers at MIT seem to think it's a good idea to try.
https://hackaday.com/2023/01/28/toroidal-propellers-make-drones-less-annoying/

they been using these props on aircraft since the 1930's

I expect more robustness for crashes against very hard objects with this round propeller.