The MIT Lincoln Laboratory is developing near-silent toroidal propellers!

[Christophe]

Have you seen a military submarine propeller in use?

I think it's a part of their "anatomy" that we try very hard to keep secret

Their precise form is secret defense yes but they are not toroids...at least not until the Kursk generation...

[Macro]

Their precise form is secret defense yes but they are not toroids...at least not until the Kursk generation...

in 30 years there has been little progress .... Nothing but cell phones ...

[Remundo]

intuitively it seems to me that the toroidals will "rub", there is a kind of large frontal surface which pushes the air, therefore which generates drag.

[Christophe]

Yeah, that also seems suspicious to me... and on my personal experience of the stream, there was almost no torque on it...
And like a propeller it's more or less reversible. I have serious doubts about all the claims on the web...

After that, it's not a flat toroid like the 2023 models...

I think the advantage is more in sound reduction than performance...despite the "super awesome" curves above.

Alright, I'm going to do some testing.

ps: I can't find the model in question on the site anymore...

[Christophe]

Their precise form is secret defense yes but they are not toroids...at least not until the Kursk generation...

in 30 years there has been little progress .... Nothing but cell phones ...

Yes, certainly, but it takes 20 years to budget and manufacture a new type of submarine...

[Macro]

So the kourk generation is a fifty-year-old conception...

50 years... When we see the advances in aerodynamics that you have made on your trailer in 5 weeks...

[Christophe]

50 years... When we see the advances in aerodynamics that you have made on your trailer in 5 weeks...

Rather the 70s but ok, I bow...you win!

[Flytox]

Well shit, I'm stupid !!

Come to think of it, I already printed one a toroidal helix for testing in my stream 2 years ago...I had found this model on https://www.thingiverse.com/ well before MIT communicated on it suddenly!

I just found the 3D print in my "archives", the toroidal is 225 mm and the classic 200 mm.

thoroidale_hydro.jpg

Well comparatively in the stream...despite its 25 mm more on the diameter...the toroidal, this is big shit!

The torque was much lower than the other for the same water speed!

So I'm less motivated to do aero tests...

Is it with a surface finish like in the photo that you are going to do the test? Usually we find very "smooth" profiles. I know of a few exceptions but this is only done in very specific areas and on aero centrifugal spinning wheels.

[Christophe]

The other model had the same surface finish...

[Christophe]

I prepared the 3D printing of a 3-blade toroid in 250mm and 10mm thick. This corresponds in overall dimensions to a classic test propeller that I have on hand.

I had to make some 3D modifications at the level of the axis of connection to the motor so that the bore corresponds and crush according to Z because by default the toroidals are quite thick!

Original dimensions of this model: 204, 202, 15 (good already it was not symmetrical )
Dimensions of the printed part: 225, 225, 10

Otherwise, I haven't quite understood the direction of rotation yet: unlike a conventional propeller, it looks like it's reversible?
Good cold I would say that I printed one that will perform better in the sense trig...

The print is in progress...