Talk:Ducted fan

I removed the sentence which implied 'high-bypass ducted fans ... are optimized for high-speed flight.' Based on the actual use of turbofans in the US military aircraft, high-bypass turbofans are found in a handful of combat aircraft (A-10 Warthog being one of them, with a bypass ratio of ~ 8:1.) The supersonic fighters F14, F15, F16, F18, and Mig-29 all use low-bypass ( < 0.8:1) turbofans. High-bypass turbofans are more efficient (than pure jet-engines) at high subsonic velocities.

anonymous (68.122.56.147) - 07/10/2005

"An unshrouded propeller is limited since their tip speeds approach the sound barrier at lower rpms." Shouldn't it say higher RPMs? -(Simm 11:41, 28 April 2006 (UTC))


 * I believe it should read 'lower rpms than an equivalent shrouded propeller'. ericg ✈ 16:36, 28 April 2006 (UTC)

Kinds of ducted fans
This article makes the assumption that the only ducted fan is an airplane propulsive device. Ducted fans are a very common high-efficiency cooling fan design. For instance, almost all PC cooling fans are a simple form of ducted fan.

Should there be a separate page on the more common use of 'ducted fan' to refer to these air movers, or should there just be a short bit added to the front of this article that would mention other uses of the term? Loren.wilton (talk) 02:56, 11 March 2008 (UTC)
 * I expanded this article to include ventilation fans and the term jet fan.   Comfr (talk) 03:16, 23 March 2019 (UTC)

Many fictional aircraft have used ducted fans, for example the GDI Orca VTOL, or the GIJOE Dragonhawk transport, or the RDA Gunships in avatar. So when people think of a ducted-fan they think of aircraft. —Preceding unsigned comment added by 24.99.68.169 (talk) 13:54, 7 July 2010 (UTC)

RC Aircraft Speed Claims
Can we get a reference for the 200mph speed claim? Perhaps that is meant to be a scale speed? JPelham (talk) 13:59, 24 April 2012 (UTC) I know that 100mph is "pretty fast" for a model aircraft, but entirely achievable, and that would be a scale speed on the order of 1000mph. I can't back up the 200mph claim, but 200mph scale speed would be rather banal

Contradiction
"Ducted fans are favoured in VTOL aircraft such as the Lockheed Martin F-35 Lightning II, and other low-speed designs such as hovercraft for their higher thrust-to-weight ratio." "At low speeds, the presence of the duct may create more drag than extra thrust, and therefore its comparative advantage to an open prop is canceled."

Without qualification, these two statements would seem to contradict one another; suggesting that low speed use is both favorable and a disadvantage. —Preceding unsigned comment added by 74.131.162.68 (talk) 02:24, 18 December 2008 (UTC)

Two different definitions of "Low speed". The first talks about aircraft that move too slowly to generate lift with a wing. High-efficiency ducted fans are used to keep these vehicles afloat. The second talks about lowering the speed of the fans themselves, which ducted fans don't do well. — Preceding unsigned comment added by 99.23.24.249 (talk) 14:16, 6 February 2013 (UTC)

"Ducted Fan" vs. "Ducted Propeller"
See "Ducted propeller": 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 "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≈)".

Discussion please at "Talk:Ducted propeller" (keeping it at one position). --129.247.247.239 (talk) 09:27, 1 February 2012 (UTC)

Casting a reader's vote in favor of retaining the Pro/Con section
Dear ducted fan editors,

I would like to humbly cast a vote in favor of retaining the pro/con style of that section (contrary to the general Wikipedia aversion to that format). I sought out this article specifically for such a comparison and was well served by what I found.

I read the Wikipedia argument against that format which seems to assume that a pro/con section necessarily implies contention. I disagree. The pro/con section in the ducted fan article is a concise expression of relative tradeoffs in different applications with different objectives.

Just my little vote.

Andy

P.S. Do not hesitate to remove this comment after you have seen it. Thanks. — Preceding unsigned comment added by 76.90.95.158 (talk) 02:50, 22 January 2014 (UTC)

Tip speed limits, Reynolds number and maximum rotational speeds
One of the key reasons for using a ducted fan is its ability to increase Reynolds number within the duct, thus to increase the rotational speed before the tip speed becomes supersonic (a typical hard limit on propeller performance - propellers don't operate well with supersonic tips). Yet neither of these are mentioned in the article. Instead the article claims that rotational speeds are increased solely because there are more blades (untrue) and that they're shorter (which might be a mechanical construction virtue, but isn't an aerodynamic one). Andy Dingley (talk) 10:29, 5 February 2018 (UTC)
 * "One of the key reasons for using a ducted fan is its ability to increase Reynolds number within the duct". Do you have a source which explains this statement? Thanks.Pieter1963 (talk) 00:49, 19 July 2018 (UTC)