devdazed Posted at 2-7 11:10
I think the pocket on top should move downward as well as the pocket on bottom by 0.1mm maybe.  The length of the hole is accurate to the smooth part of the screw, but the lip on the bottom see below picture.  the threads should clear the bottom of the lip so when tightened its not clamped on.

I don't know that my printer can handle much thinner, maybe if thinner then going to SLA might be better.

Oh wow, 30% longer?
The online model I found must not be correct at that rate!

Can you measure what the standard prop length is from the center of the hole out to the tip?

Lost Somewhere Posted at 2-7 11:41
Oh wow, 30% longer?
The online model I found must not be correct at that rate!

roughly 65mm

Looks like MIT is trying to get credit for something that already existed for years.  The Sharrow Propeller™ was invented by Gregory Sharrow and is the first major advancement in propeller technology since the 1830s.  
https://www.sharrowmarine.com/

devdazed Posted at 2-7 12:44
roughly 65mm

Ok, these have deeper counter bores, and are 65mm long. They're also about 1.46g instead of 1.7g, depending on material.
Rotor STL

Lost Somewhere Posted at 2-6 11:38
Hey, if you're really curious and want to try printing more. Here's a link to some M3P double toroid props.
No guarantee they will work as I haven't printed them and tried them out. But if you want to be the Guinea pig, be my guest. They are 1.7g each, 3.4g for a pair. You need to print 4 sets of these parts. I made them thicker and heavier than they were, just to help with strength.
STL File

IshidaEd Posted at 2-7 20:47
[view_image]

That's the old one. Someone tried it, gave me some updates to make, and I already posted a new one if you really want to try it. I didn't want more people making one that wasn't optimal.

devdazed Posted at 2-7 09:45
also, using PLA they are clocking in at 3.6 grams for the pair (although with enough post-processing I may be able to shave off 0.2 grams.  I wonder if we reduce the surface area of each blade by half if it will produce similar lift to the stock ones with lighter weight?

If I FDM some of them I think I'll use PETG, should be more flexible.

ok, getting closer.  we need to drop the pocket down more.  Maybe the same distance as the bottom pocket is deep?  also it is still about 10mm longer than the stock prop, not sure if that was intentional or not.  

also, i noticed some abnormalities after printing and thought it was my printer but then saw the same things in the slicer, not sure if its the slicer of it is in the STL

devdazed Posted at 2-8 11:12
also, i noticed some abnormalities after printing and thought it was my printer but then saw the same things in the slicer, not sure if its the slicer of it is in the STL

[view_image]

Hi,
Any chance your slicer scaled the part up?
I set the size from hole to tip to exactly 65mm, so it shouldn't be larger than the standard one.
If it did scale up then that would be the reason that the hub is also thicker than it should be, since I took about 0.25mm off of that thickness from the first one, so I would have hoped it would spin freely now.

Your slicer is probably doing what it can, the blade is likely just so thin that it's skipping out in those regions and making a jagged edge. I guess I could put a larger radius on your STL so that it removes more of that fine edge.

Let me know what you find on your slicer scaling. Then if you find it was scaled up, but still has issues slicing the thin spots, I'll make you an update if you still want to try. There are more and more people making videos on toroidal props. The latest one today has lots of great data with everything graphed. From my flow simulation the double lobe are much better than the triple lobe, but that still doesn't mean they are better than a normal prop.

Great effort in general by the community on looking into these.

Lost Somewhere Posted at 2-8 12:18
Hi,
Any chance your slicer scaled the part up?
I set the size from hole to tip to exactly 65mm, so it shouldn't be larger than the standard one.

ok, I think that the scaling issue is definitely part of the problem.  It didn't get rid of the abnormalities but it almost fixed the tightness issue.  They aren't totally free moving but i don't think it's something that the RPMs won't be able to overcome.  I printed one pair for fitment and ran a test, it didn't error out and tried to take off but the other 3 props had much more lift so it tilted.  I'm going to print the other 3 pairs and try to do another test.

devdazed Posted at 2-8 17:14
ok, I think that the scaling issue is definitely part of the problem.  It didn't get rid of the abnormalities but it almost fixed the tightness issue.  They aren't totally free moving but i don't think it's something that the RPMs won't be able to overcome.  I printed one pair for fitment and ran a test, it didn't error out and tried to take off but the other 3 props had much more lift so it tilted.  I'm going to print the other 3 pairs and try to do another test.

Do you want me to take just a hair more off the countersink?
Do you want a larger radius so it's not as thin at the trailing edge?

Lost Somewhere Posted at 2-8 17:27
Do you want me to take just a hair more off the countersink?
Do you want a larger radius so it's not as thin at the trailing edge?

Probably couldn't hurt to take a bit more off the countersink.  If you want to increase the radius I can see if the slicer will like it better, not sure how that will affect the dynamics of it though.

devdazed Posted at 2-8 17:29
Probably couldn't hurt to take a bit more off the countersink.  If you want to increase the radius I can see if the slicer will like it better, not sure how that will affect the dynamics of it though.

OK, give me a few minutes.
It shouldn't affect the edge much since you already can't print it out to the thinnest part of the edge, so at least what it can print should be a bit more smooth and even.

devdazed Posted at 2-8 17:29
Probably couldn't hurt to take a bit more off the countersink.  If you want to increase the radius I can see if the slicer will like it better, not sure how that will affect the dynamics of it though.

OK, Here's the latest revision that should be better with the minimum size of an FDM.
Let me know if the slicer likes it better.

Double Prop STL 3

Lost Somewhere Posted at 2-8 17:41
OK, Here's the latest revision that should be better with the minimum size of an FDM.
Let me know if the slicer likes it better.

This looks better in the slicer. I'll print some out and see how they look.

Quadmovr is always doing cool stuff. From 3d printing to demonstrated flights:

EDIT: Oops, sorry, I see this was already posted.

devdazed Posted at 2-9 08:16
This looks better in the slicer. I'll print some out and see how they look.

I printed a couple pairs of the new ones. They need far less in the way of supports, which makes them easier to post-process.  I threw on pair on the Mini with stock props on the other 3 arms.  It was able to stay more-or-less stable in hovering.  I'm printing the rest now and will try with all 4 pairs.

Ok, I finally got all 4 pairs printed, post-processed and installed. I tried a test run and there were no errors, but they weren't generating enough lift to get the drone off the ground.  It was barely just enough to where it would move slightly, but not actually lift.  I ensured they were all installed properly as I didn't feel any airflow above it and plenty of airflow below each of the props.  so not sure where to go from here. It was much quieter for what it's worth, sounded like a fast blowing fan.

devdazed Posted at 2-10 12:07
Ok, I finally got all 4 pairs printed, post-processed and installed. I tried a test run and there were no errors, but they weren't generating enough lift to get the drone off the ground.  It was barely just enough to where it would move slightly, but not actually lift.  I ensured they were all installed properly as I didn't feel any airflow above it and plenty of airflow below each of the props.  so not sure where to go from here. It was much quieter for what it's worth, sounded like a fast blowing fan.

Oh, sad!
Well, I guess it needs a lot more pitch angle. I'll have to make another update.
You've put in a lot of effort, and still no satisfying results.

Not sure it's worth trying more.
I put a greater angle on them to try to get more lift.
I'll be back in about a week, so I can do the testing then.
But if anyone is interested it's here.
Props Rev4

Lost Somewhere Posted at 1-29 19:53
It is quiet. I was mostly curious to design and try something really unique. I like the bright color, and the quieter the better, I'll keep these in mind. Thanks

I do also like that the toroidal ones don't have a sharp tip. Not as good as a prop guard, but still a lot better than nothing and they don't add hardly any weight compared to a prop guard.

less noise, safer are worth it benefits.  would make a good alternative to ducted drones if it doesn't have to be that safe.

but per other attempts to print their own...there's a lot of nuances to the design

Zbip57 Posted at 2-5 09:58
https://www.youtube.com/watch?v=UWoXFdRhPKc

Impressive.
But the toroidals seem much noisier.

Following the MIT Study, I'm fairly certain DJI and others will be giving this a hard look and eventually releasing their own versions. Even with the "low noise" props now available, the noise is still a big factor. I'd certainly be interested for use on my Mavic 2S.

This guy does some insane flying with home made toroidal props, but they are noisy compared to the second multi-blade fan props.

The guy on YouTube flying a DJI FPV with printed toroidal blades, the noise is deeper...actually more noise

https://youtube.com/shorts/Df32lrVy5os?feature=share

Watch some youtube vids. A few vids of drone with 3D printed ones in action. They are impressive!  Alot of boomers here don't like change. Don't listen to them. Try these props out for yourself. Hopefully DJI is doing R&D on these propellers and will have them avialible for their drones in the near future. I mean, if I was a billion dollar company, I would. But I'd rather put 8 blade props on my Mavic. Very quiet and effieceint for slow speed and  hovering.

Lost Somewhere Posted at 1-30 11:01
Oh awesome, you're the guy I need!
I'm a mechanical nuclear pharmaceutical engineer so I make no claim to know aeronautics.
Like you said, the toroidal design is sort of like having 4 blades at each motor instead of 2. So if they have the same pitch and length and width, then the lift will be a lot more and it will spin slower but take more power. However, if I make the pitch a little less and the blade a little narrower, it might be closer to the original. If it doesn't work well, and I don't expect the first set to be perfect, then I can adjust any of the 3 parameters so that I can get back to the same RPM and lift. The idea is that it will be quieter, but I don't know if it will end up more or less efficient in the end, the losses are likely higher, and some noise reduction might just be from spinning slower. But they claim this design reduces noise, so I assume that should be at the same RPM, but who knows. It's fun to try.

Where'd you get the STL file for the drone?

(Double post)

devdazed Posted at 2-10 12:07
Ok, I finally got all 4 pairs printed, post-processed and installed. I tried a test run and there were no errors, but they weren't generating enough lift to get the drone off the ground.  It was barely just enough to where it would move slightly, but not actually lift.  I ensured they were all installed properly as I didn't feel any airflow above it and plenty of airflow below each of the props.  so not sure where to go from here. It was much quieter for what it's worth, sounded like a fast blowing fan.

OK, so I got my Rev 4 printed and running. Not bad actually! They were just a little tight so they didn't float on the pins, and the pin size was a little loose. So there are a couple really minor changes I should make.

Zoooom Posted at 2-13 20:22
This guy does some insane flying with home made toroidal props, but they are noisy compared to the second multi-blade fan props.

https://youtu.be/UWoXFdRhPKc

So, the one I printed had almost exactly the same noise as the standard prop. Granted the printed one wasn't sanded or coated with some glossy clear coat, and it still had just a couple little rough points from the supports. But overall pretty good for something home made.

The first picture is the standard prop and the second is the toroidal one.

Beta5K Posted at 2-22 11:55
Where'd you get the STL file for the drone?

I think it's this one.
https://www.printables.com/model/325447-dji-mini-3-pro-drone

LV_Forestry Posted at 1-30 03:53
They are not really toroidal propellers on your screenshot. You're more likely to knead bread dough with it than hope to fly a drone.

A toroidal propeller is more of a 4-blade propeller on which 2 ends are joined to try to eliminate or reduce the turbulence that forms at the end of the blade and generates a lot of noise.

It flew pretty well. I'll try to upload a video to youtube and then post a link.

WernerD Posted at 1-30 08:49
(I have a degree in aeronautics. Just saying.)
These are very interesting, indeed. Would love for somebody to try them out with the Mini3 but I fear simply creating some and bolting them onto the Mini 3 will not work. As somebody said before, these propellers should be seen as 4 blade props with extra long blades (wing tips increase the effective wing span). Hence I would expect that the rpms must be approx half of what the Mini 3 operates normally.
If I am right, that would require adjusting the motor control software.

Flew well, I'll try to post a few second video of it taking off.

WernerD Posted at 1-31 01:27
One more thing, again, like somebody else said before me. I do not understand the geometry of your props given the screenshots. To me they look like a ring. No increased pitch closer to the axis, the wing depth seems to be constant, no wing-shaped profile. It looks like a cement mixer, not a propulsion device on the pictures.
I am not sure a proper and efficient form can even be designed without a fluid dynamics software. As approximation I would take the existing Mini 3 props and "bend" the tips 90° up. Then take the same pair with wingtips bent down. Then connect the two pairs in the CAD software so they merge at the wing tips and at the axis via parallel transformations and without changing the pitch.
[view_image]

I just posted some pics of the print, you can see better what the profile is.

devdazed Posted at 2-10 12:07
Ok, I finally got all 4 pairs printed, post-processed and installed. I tried a test run and there were no errors, but they weren't generating enough lift to get the drone off the ground.  It was barely just enough to where it would move slightly, but not actually lift.  I ensured they were all installed properly as I didn't feel any airflow above it and plenty of airflow below each of the props.  so not sure where to go from here. It was much quieter for what it's worth, sounded like a fast blowing fan.

Here's the video link.

Lost Somewhere Posted at 2-22 20:11
Here's the video link.

https://youtu.be/DVq7PSdUdHs

Nice work ! Have you noticed a reduction in noise?

LV_Forestry Posted at 2-22 21:49
Nice work ! Have you noticed a reduction in noise?

Not really, the sound profile images are above.

Lost Somewhere Posted at 2-22 19:25
Flew well, I'll try to post a few second video of it taking off.

[view_image]

I am impressed! Well done!

Those look cool