# Toroidal Propellors
**URL:** https://foil.zone/t/toroidal-propellors/17518
**Category:** Propulsion System (Motor, Gears)
**Created:** [February 8, 2023, 10:33pm UTC](https://foil.zone/t/toroidal-propellors/17518 "2023-02-08T22:33:07Z")
**Posts on this page:** 20
**Page:** 2
### Author:  [@Larsb](https://foil.zone/u/Larsb)
#### Post date: [February 13, 2023, 8:20pm UTC](https://foil.zone/t/toroidal-propellors/17518/22 "2023-02-13T20:20:18Z")
Can’t post files here, one of the online places.
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### Author:  [@SoEFoil](https://foil.zone/u/SoEFoil)
#### Post date: [February 13, 2023, 10:30pm UTC](https://foil.zone/t/toroidal-propellors/17518/23 "2023-02-13T22:30:05Z")
> [@Larsb](#):
>
> haven’t got enough to do 50 iterations to get something worth it.
Unfortunately, I’m afraid we don’t have much choice but trial and error. That’s what the drone builders are doing with the toroidal prop. I think that starting from the FR prop scaling down the prop surface by 40 to 50% in chord and replicating the blade could be a good start.
On the toroidal prop side, here is an impressive 5 min design (Feb. 05 2023):
[ ](https://www.youtube.com/watch?v=UWoXFdRhPKc)
… but there is an obvious data problem at the moment (Feb 08 2023):
[ ](https://www.youtube.com/watch?v=Tg2NnXx8qyY)
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### Author:  [@Louvicar](https://foil.zone/u/Louvicar)
#### Post date: [February 14, 2023, 10:38am UTC](https://foil.zone/t/toroidal-propellors/17518/24 "2023-02-14T10:38:16Z")
Hi, do you think it could be possible to design a retractable toroidal propeller?
Especially for e-foils whose propulsion is stopped once they reach the open sea.
We’re working on a project with my engeneering school
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### Author:  [@Larsb](https://foil.zone/u/Larsb)
#### Post date: [February 14, 2023, 11:53am UTC](https://foil.zone/t/toroidal-propellors/17518/25 "2023-02-14T11:53:51Z")
Yes, seems like it.
Looking at the sharrow prop it seems to breach some of the common propeller design rules. First blade has higher pitch than second?
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### Author:  [@Larsb](https://foil.zone/u/Larsb)
#### Post date: [February 14, 2023, 12:49pm UTC](https://foil.zone/t/toroidal-propellors/17518/26 "2023-02-14T12:49:36Z")
Uploaded STL here: [https://grabcad.com/library/65161-65162-loop-propeller-dia-138mm-1](https://grabcad.com/library/65161-65162-loop-propeller-dia-138mm-1)
Step file seems to take forever to convert. might crash so it’ll have to come later.
It’s 138mm outer diameter, for 65161/65162 threaded shaft motors with 4mm prop pin.
I didn’t try it so don’t ask me how good it is 🙂
The prop was adapted from the 200mm thinginverse prop linked earlier in this thread
I tried to measure pitch, i get it to be 3.2" and p/d ratio is 0.6. You normally find the best efficiency around p/d=1 and the foil shape is distorted. I don’t think it’s likely to be good.
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### Author:  [@sharrow](https://foil.zone/u/sharrow)
#### Post date: [February 14, 2023, 4:16pm UTC](https://foil.zone/t/toroidal-propellors/17518/27 "2023-02-14T16:16:26Z")
Thank you Lars for sharing, but again, in my opinion the thingiverse prop is not correct designed according to the original sharrow prop. because the string is bend the wrong way. Does anyone understand what I mean? Or do you think it makes no difference?
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### Author:  [@Larsb](https://foil.zone/u/Larsb)
#### Post date: [February 14, 2023, 4:31pm UTC](https://foil.zone/t/toroidal-propellors/17518/28 "2023-02-14T16:31:15Z")
I switched it in the updated model and i agree the thinginverse prop was wrong. It should make a difference but i think it anyway looks like a poor design. No good foil sections, no good prop.
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### Author:  [@sharrow](https://foil.zone/u/sharrow)
#### Post date: [February 14, 2023, 5:04pm UTC](https://foil.zone/t/toroidal-propellors/17518/29 "2023-02-14T17:04:42Z")
The strings needs to get more pitch and more bending I think. If we can get a exact copy from the original only scalled down in size, I think it will do the same results. I would print and test it. hear you can see the shape better.
> **[\#SharrowPropeller | “I absolutely love my new Sharrow Propeller! Everyone out...](https://www.facebook.com/100069830268305/videos/536384181681376/? __so__ =permalink)**
>
> “I absolutely love my new Sharrow Propeller! Everyone out at the lake and the marina is talking about it. Another customer purchased a prop for his boat...
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### Author:  [@hovav](https://foil.zone/u/hovav)
#### Post date: [February 15, 2023, 7:12am UTC](https://foil.zone/t/toroidal-propellors/17518/30 "2023-02-15T07:12:08Z")
Hi Lars and thank you so much for sharing this !
Would it be too much to ask you to share the step file or the fusion360 \*.f3d file ?
Thank you.
Hovav
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### Author:  [@Larsb](https://foil.zone/u/Larsb)
#### Post date: [February 15, 2023, 7:19am UTC](https://foil.zone/t/toroidal-propellors/17518/31 "2023-02-15T07:19:51Z")
I work in Catia so no fusion file, step conversion crashed, the million triangles remaining from the original stl was tough on my computer
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### Author:  [@Larsb](https://foil.zone/u/Larsb)
#### Post date: [February 15, 2023, 8:51am UTC](https://foil.zone/t/toroidal-propellors/17518/32 "2023-02-15T08:51:13Z")
I checked the videos, the first video, no airfoil sections so not really an interesting propeller. It’s a great first though, I’m impressed that it flew so well even with a square section
That second video was a different story… i think he misinterpreted the MIT video, a classic fluff piece, being the sales pitch to him personally as an invester. What a waste of air, for him and for us.
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### Author:  [@Gazman79](https://foil.zone/u/Gazman79)
#### Post date: [February 15, 2023, 9:06am UTC](https://foil.zone/t/toroidal-propellors/17518/33 "2023-02-15T09:06:17Z")
Thanks Lars for the reworked prop, hopefully it’s a starting point for some testing.
It printed OK, I printed it hot to give it chance for layers to bond better but this means clean up will be harder,
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### Author:  [@Larsb](https://foil.zone/u/Larsb)
#### Post date: [February 15, 2023, 9:44am UTC](https://foil.zone/t/toroidal-propellors/17518/34 "2023-02-15T09:44:00Z")
This’ll be interesting! 👍
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### Author:  [@Larsb](https://foil.zone/u/Larsb)
#### Post date: [February 15, 2023, 11:40am UTC](https://foil.zone/t/toroidal-propellors/17518/35 "2023-02-15T11:40:21Z")
I modeled a loop prop from scratch based on a Caeses prop, it really shows how far from the original prop designs the Sharrow is.
To keep a more classic prop with foil shapes and angles correctly the loop gets quite large and there is little to no thrust created by the loop… I think it needs to be tweaked a lot.
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### Author:  [@Jezza](https://foil.zone/u/Jezza)
#### Post date: [February 15, 2023, 12:42pm UTC](https://foil.zone/t/toroidal-propellors/17518/36 "2023-02-15T12:42:34Z")
> [@Louvicar](#):
>
> do you think it could be possible to design a retractable toroidal propeller?
It’s always possible to design one, but you’ll have a terrible drag point on a folding toroidal prop.
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### Author:  [@Gazman79](https://foil.zone/u/Gazman79)
#### Post date: [February 15, 2023, 1:29pm UTC](https://foil.zone/t/toroidal-propellors/17518/37 "2023-02-15T13:29:16Z")
Getting there, I could see the inconsistencies with the aerofoil so I filled with superglue and sanded to smooth the profile
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### Author:  [@Toto44](https://foil.zone/u/Toto44)
#### Post date: [February 15, 2023, 3:24pm UTC](https://foil.zone/t/toroidal-propellors/17518/38 "2023-02-15T15:24:28Z")
and now go! We want to see 500W at 30Km/h
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### Author:  [@sharrow](https://foil.zone/u/sharrow)
#### Post date: [February 15, 2023, 3:51pm UTC](https://foil.zone/t/toroidal-propellors/17518/39 "2023-02-15T15:51:16Z")
I am looking forward to the results, but already shared my point of view and tipps. Soon we’ll get first trial and error, keep going. And thank you for the work so far.
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### Author:  [@Gazman79](https://foil.zone/u/Gazman79)
#### Post date: [February 15, 2023, 3:52pm UTC](https://foil.zone/t/toroidal-propellors/17518/40 "2023-02-15T15:52:57Z")
Lol, I would imagine it will struggle to reach 20kmh because of the low pitch. It will be running a lot faster rpm but hopefully a lot less load. Maybe!
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### Author:  [@SoEFoil](https://foil.zone/u/SoEFoil)
#### Post date: [February 15, 2023, 8:33pm UTC](https://foil.zone/t/toroidal-propellors/17518/41 "2023-02-15T20:33:42Z")
Here is something outside the patent scope: the one-foot Sharrow prop blade.
Who said a Sharrow prop blade needs to be bound on two points to the hub ?
Advantage: the blades fold inside the air bubble behind the propeller hub where there is little water and therefore little drag …
Food for thought : my hitech prototype 😉
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