Talk:Ducted propeller

Air/Sea

See Ducted Fan: Am I understanding correctly that "ducted propeller" is the in-water type, while the in-air operating object is called Ducted Fan ? Or what is the difference?

Problem comes from german wikipedia: Article "de:Mantelpropeller" translates to "Ducted propeller", but is linked to "Ducted fan".
People are arguing about
"a fan (Turbofan) (blade ) is not a propeller because a propeller bases on generating Aerodynamic force/Lift (force) (Airfoil), while a Turbofan blade works mainly with impulse and bare Acceleration of the air (no frontward ≈aerodynamic lift≈)". --129.247.247.239 (talk) 09:21, 1 February 2012 (UTC)

If someone is claiming that a "screw thingy" of either form is accelerating a fluid backwards but with no forward thrust, then they need to look at Newton's third law again.

Ducted fans and ducted propellers are ontologically overlapping (i.e. we can't define them apart in a robust fashion), but we agree the "water / air" split as a simple convenience, as we do need to be able to make two articles with two distinct names. Andy Dingley (talk) 10:28, 1 February 2012 (UTC)

Other than the name, ducted propellors and ducted fans are the same thing. Dude6935 (talk) 03:02, 6 September 2012 (UTC)

By linguistic convention, they're used in different media: incompressible liquids and compressible gases.

Different Reynolds numbers for the different media mean that their blade shapes are then different. Andy Dingley (talk) 09:50, 6 September 2012 (UTC)

That is quite wrong. There is no such linguistic convention in aeronautics. The terms are interchangeable and engineers will often mix them in the same paragraph. The term "ducted propulsor" is also sometimes used. The key factor for disambiguating air and water is that "ducted fan" is not used in marine parlance. — Cheers, Steelpillow (Talk) 19:45, 21 March 2022 (UTC)

Duplicate table

I merged Kort nozzle here, and that article had an aerodynamics diagram that appeared to mostly duplicate the one here. I've included it here for reference.

Circulation around Kort nozzle

dT = Thrust dL = Lift	pu: Negative pressure po: Positive pressure

D O N D E groovily Talk to me 04:04, 18 March 2012 (UTC)

Physics

I still believe the physics explanation is incorrect. One purpose of the duct is to reduce circulation. Circulation is a loss in efficiency, not an advantage. The duct allows the fan (propeller) to see cruise-like conditions even at zero velocity. This reduces tip losses. There are always many different explanations for the physics of lift/thrust, but I believe the circulation explanation is obviously flawed. Drawn from Ducted Fan Design Volume 1 Millenial Year Edition - 2001 by F Marc de Piolenc & George Wright Jr. Dude6935 (talk) 02:44, 6 September 2012 (UTC)

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"Wheels"?

Under the heading "Advantages and disadvantages", the fourth paragraph states "...ice or any other floating object can become jammed between the wheel and nozzle, locking up the wheel. Fouled wheels in Kort nozzles are much more difficult to clear than open wheels". (emphases added) What is meant by "wheels"? The subject is "propellors". Could this be the result of a translation error? Bricology (talk) 19:29, 23 October 2021 (UTC)

@Bricology I did some research on this. http://www.vac-u-boat.com/Old_River_Bills_Site/Wheels&Korts.htm suggests that there is a tradition, perhaps arcane, to interchange propellors with wheels in this area. Who knew? Fiddle^Timtrent Faddle^Talk to me 20:05, 23 October 2021 (UTC)

Very interesting, but you can't just introduce a jargon term in the middle of an article without explanation. I'm changing it to "propeller", for consistency throughout the article. --BjKa (talk) 13:32, 21 November 2023 (UTC)

rotating?

The article currently says: "a marine propeller fitted with a non-rotating nozzle".
So what's a rotating nozzle then? Do those even exist? I feel what is trying to be conveyed here, is the fact that the shroud surrounding the propeller is fixed to the housing that bears the propeller. (I can't find a good way to put it succinctly either.) The problem I see is that Kort nozzle assemblies are often mounted so they can pivot - as the article states, to act as the primary steering mechanism instead of a conventional rudder. Could this not be described as "a rotating nozzle"? Therefore I feel a wording is necessary that doesn't confuse the layman right in the very first sentence of the article. --BjKa (talk) 13:24, 21 November 2023 (UTC)