Talk:Propeller (aeronautics)/Archive 1

Archive 1

Expansion notes

Needs a section on construction methods, also some ideas of things to cover:

• Ground adjustable props
• Alpha/Beta range
• Disc solidity (why we have 2,3,4,5 and 6 bladed props)
• Mention of tractor/pusher props and handing.
• Aero factors - Effective pitch, geometric pitch, slip.
• Size conventions - Diameter and pitch.
• Prop de-icing/anti-icing methods
• Propeller companies
• Prop synchronization
• Blade tracking (checking for bent blades)
• Balancing/vibration

Just some thoughts!! Nimbus (Cumulus nimbus floats by) 19:26, 26 January 2010 (UTC)

Would also be nice if a copy-editing inclined person could have a go at removing the 'somes' and 'manys' that have been inherited here. Nimbus (Cumulus nimbus floats by) 19:58, 26 January 2010 (UTC)

Equations, especially Torque

I have seen the equations on the Propeller page, but I think that this section is rather important and should be improved in this article. I for one am interested in the amount of torque a motor & propeller assembly will apply on an aircraft. For example quadrotor helicopters seem to use this effect for yawing. The propeller page says:

Q = \rho V_a^2 D^3 \times f_q \left(\frac{ND}{V_a}\right)

But f_q is completely unexplained, and I'm also wondering how V_a can be determined. I'm also a bit surprised that the propeller's weight(distribution) doesn't appear in the formula. 213.39.191.246 (talk) 17:34, 11 March 2010 (UTC)

Contra-rotating propellers

There are duplicate sections on Contra-rotating propellers. Could an expert pick one or merger them. Im not an expert or a member for that matter, so Im leaving it. Thanks. 76.244.162.154 (talk) 06:09, 29 May 2010 (UTC) Sandy

If you look a little closer you will note that one section is for contra-rotating propellers (two propellers rotating in opposite directions on the same shaft) and another for counter-rotating propellers (single propellers on multi-engine aircraft that rotate away or toward each other), two quite different features. Cheers Nimbus (Cumulus nimbus floats by) 06:17, 29 May 2010 (UTC)

Reverse Pitch and Electric Governors

In the reverse pitch section, I've included the fact that the rotation of the engine itslef doesn't reverse. I felt it was worth noting, since a lot of people get confused about this, and think that during reverse thrust it is the engine that reverses its rotation.

Also, in the variable pitch section, It might be intersting to mention that when the use of electric governors started to spread after WWII, they caused many incidents in which, because of a failure or misconstruction of the governor, the angle of attack of the blades flattens inadvertently during high power operations (mostly during the take off run), causing the propeller to reach very high speeds and consequently to disintegrate (I don't know if this phenomenon has a specific name in English - in Portuguese, it's called "disparo de hélice", which would mean "propeller blowout"). Because of this problem, electric governors almost disapeared form the aviation industry during the second half of the 20th century. Nowadays, they are slowly regaining acceptance from pilots and manufacturers.

189.15.204.135 (talk) 16:59, 1 July 2010 (UTC)

Which could all be added (with references) to the propeller governor article, it does need expanding. Nimbus (Cumulus nimbus floats by) 22:05, 1 July 2010 (UTC)

"disparo de hélice" - the English term for this is a "runaway propeller" or "propeller overspeeding". IIRC, it was mainly the US that went in for electrically-controlled propellers, e.g. the Curtiss Electric series. The UK preferred hydraulically-operated ones, such as those by Dowty and Rotol, although de Havilland made propellers under licence from Hamilton Standard.

Variable pitch

I think the "feathering" propellers are the same as the 2-mode variable pitch (not constant speed !) propellers (read article section). Thus, having 2 seperate sections is wrong. 91.182.16.165 (talk) 12:15, 2 August 2010 (UTC)

The headers are part of the 'Propeller control' section, variable pitch, feathering and reverse pitch describes three different modes of propeller control (not the type of prop itself necessarily). Are you thinking of a 'Controllable pitch' propeller? This would be a non-constant speed, two-position (fine pitch/coarse pitch) with the ability to feather and often operated manually directly by the pilot? Nimbus (Cumulus nimbus floats by) 22:54, 2 August 2010 (UTC)

Propeller spinner

I was surprised to find no mention of the propeller spinner (the aerodynamic cone). Some WP articles use the term, but I found no description or history. Chris the speller ^yack 04:46, 23 September 2011 (UTC)

Strictly a spinner is not part of the propeller, to work it in here would need a paragraph, a mention in the lead and a redirect creating. Lesser aircraft parts have their own article so there is probably room for a spinner (aircraft) article assuming we can find enough material from reliable sources. I can bring it up at WT:AETF and see what can be done. Cheers Nimbus (Cumulus nimbus floats by) 19:24, 23 September 2011 (UTC)

How do propellers work?

Could someone add an explanation of how propellers work in actually propelling the plane forward eg: with a section on how the airflow generated by the propeller creates lift? Preferably something that is simple in language, understandable by someone with a passing interest in the subject? Might want to look at a HowStuffWorks article, if one exists, as a starting point. Thanks! EaswarH 02:43, 4 January 2012 (UTC) — Preceding unsigned comment added by Easwarno1 (talk • contribs)

It's a fair point. Could be added to the lead as it's not really long enough for the size of the article. Nimbus (Cumulus nimbus floats by) 07:16, 4 January 2012 (UTC)

Dubious claim for impetus to develop feathering propellers

I think the statement that feathering props were developed for fighters is wrong. I cannot think of any single-engine aircraft with a feathering prop, other than self-launching gliders, and AFAIK feathering props first appeared on multi-engine transport and bomber aircraft. YSSYguy (talk) 00:39, 10 August 2012 (UTC)

I agree, that sentence is uncited so it could be removed. Should state the need for feathering in its place which I think is for drag reduction on multi-engined aircraft (asymmetry) and to prevent further engine/airframe damage by stopping rotation (windmilling) of a mechanically failed engine. Nimbus (Cumulus nimbus floats by) 06:35, 10 August 2012 (UTC)

I've just been through the edit history for Propeller (marine), which is the parent for this article, and that entire paragraph was added unreferenced in June 2007. On that basis, and pending no further input or disagreement, I will remove the sentence in a few days' time. YSSYguy (talk) 07:42, 10 August 2012 (UTC)

I saw YSSYguy's edit summary and agreed. I deleted the offending sentence and subsequently saw this thread on the Talk page. The consensus seems to be that the sentence detracts from the value of the article so I don't think my deletion was seriously premature. Dolphin (t) 11:34, 11 August 2012 (UTC)

The fully-feathering propeller was developed because when propellers were two-bladed most twin-engined aircraft could stay in the air with one engine stopped, however as propellers gained more blades, first three, then four blades, the drag produced by a stopped propeller was so much greater that many twins could not remain in the air at high weights. — Preceding unsigned comment added by 95.149.247.9 (talk) 12:50, 9 February 2018 (UTC)

Merger proposal

I propose that Single blade propeller be merged into this article as it is merely a variant of aircraft propellers and holds little notability for a stand-alone article and is superfluous.--Petebutt (talk) 00:35, 31 October 2012 (UTC)

• weak oppose There is far more to say about propellers than any single article can achieve. As the single blade propeller is quite so esoteric, I see it as entirely appropriate to keep it separate. I'd like to see it expanded to cover the single-bladed wind turbines though. Andy Dingley (talk) 01:06, 31 October 2012 (UTC)
• Oppose The main aircraft propeller article is laid out per summary style with headers and links to the related sub-articles underneath, have not checked if the single-blade article is linked, it should be if not. There is another use of single blade aircraft propellers which is not mentioned there, control line FAI speed models, I'd like to know why they are used over a two-bladed propeller, when I find a source I will add this. Nimbus (Cumulus nimbus floats by) 23:29, 31 October 2012 (UTC)
• Support - three lines of text and a single overly large picture (with a portion of it duplicated to fill space) don't make a notable article - and the main page isn't even close to being overly long. In any case the mechanics of single blade props can best be covered with other propellers where it will if anything help explain how props work, and useage is extremely limited. We don't have an article on three bladed props so why does a single blade prop warrant one? FWIW (aside from simplifying storage) single blade props are used for the same reason you'd use a three bladed prop instead of a 5 bladed prop - which is better discussed on this page.NiD.29 (talk) 15:41, 1 November 2012 (UTC)
• Oppose Single blade propellers are not commonly, or even occasionally used in aircraft. The concept of single bladed propellers is based on the assertion that fewer blades results in a more efficient propeller, which is simply not supportable, it being impossible for all other factors to be equal. A very long stretch would justify this claim at very slow airspeeds, such as in motorgliders (the only aircraft where single blade propellers have ever been used). Altaphon (talk) 03:15, 7 April 2013 (UTC)

Missing Link

In the External Links section, the "HOWTO adjust a propeller correctly" is a broken link. It sounds useful so please would the provider re-route it ? Thanks. Darkman101 (talk) 08:38, 3 November 2012 (UTC)

I have removed it - wikipedia is not an instruction manual. MilborneOne (talk) 19:21, 3 November 2012 (UTC)

Dubious statement about angles

The article says, "Changes to a propeller's efficiency are produced by a number of factors, notably adjustments to the helix angle(θ), the angle between the resultant relative velocity and the blade rotation direction, and to blade pitch (where θ = Φ + α) . " I see a number of problems with this:

• The article doesn't define α which I assume is "angle of attack".
• The article doesn't define Φ which I assume is "blade pitch angle".
• Therefore is it not true that Φ = θ + α ?
• The above also implies that helix angle and blade pitch can be "adjusted" independently - is that true? Burninthruthesky (talk) 10:59, 5 December 2012 (UTC)

I've now found a reference. I'll update the article. Burninthruthesky (talk) 11:57, 5 December 2012 (UTC)

Erm, it needs more work. Unfortunately the new language isn't much better. The angles are a small part of the picture; one really must address the whole concept of keeping the airflow attached to the airfoil over the range of speeds and AOA, and preventing losses due to formation of tip vortices etc. etc. I will look for an appropriately simple reference describing propeller efficiency, which will depend on another simple reference on terminology of pitch. It's all in Weick from 1930 but not in a paragraph or two. Altaphon (talk) 03:29, 7 April 2013 (UTC)

Earliest propeller?

In his 1768 Théorie de la vis d'Archimède, Alexis-Jean-Pierre Paucton suggested the use of one airscrew for lift and a second for propulsion. This is nowadays called a gyrodyne, but more to the point here does it mark the invention of the aircraft propeller? — Cheers, Steelpillow (Talk) 14:31, 14 October 2013 (UTC)

aircraft propeller blades vs wind turbine blades

My understanding is that aircraft propeller blades and wind turbine blades are subject to very similar physical aerodynamics, are designed using the same engineering design tools, and are built from the same materials using more-or-less the same processes.

Which Wikipedia article is a good place to describe the differences between them? --DavidCary (talk) 17:06, 19 March 2014 (UTC)

Rotor blades, of both helicopters and autogyros, fan blades and gas compressor and turbine blades also share many of these characteristics. I'd suggest that any article comparing types should encompass all, or at least most, of these. A fundamental division of function is between those that convert axial flow into torque vs. those that convert rotary motion into axial force, with the autogyro being unique in that the one rotor kind of does both simultaneously. The generic engineering term is "rotor", and here we are dealing with bladed rotors for power transfer in gaseous media. Before diving into an article, I'd make sure I had a good reference to the discussion. Otherwise it will be just another lousy and incoherent page of PoV ramblings sandwiched between referenced tidbits. — Cheers, Steelpillow (Talk) 17:55, 19 March 2014 (UTC)

Actually that makes very little difference. The biggest differences are 1) Are they in free air or not? (a turbine or compressor blade that's one of many stages between fixed stators is significantly different to one in an unguided stream in open air) and 2) What's the Reynolds number, i.e. the airspeed (and also the pressure). The size and scaling of wind turbines vs aircraft makes a lot of difference for the materials design, but the gas dynamics is really just a scaling exercise from the same principles. Andy Dingley (talk) 18:56, 19 March 2014 (UTC)

Propeller trivia?

In 1921, William Hall of Imperial Oil & Walter Johnson, handyman with Hudson's Bay Company, hand-carved two props for Imperial's Junkers-Larsen JL-6s, using oaken sleigh boards & glue made from moose parchments. It took them 8 days, & the props were essentially flawless when finished. So says Stephen Payne in Canadian Wings (Douglas & McIntyre, 2006), p.58. (Since I can't find a place on the page for it, it's here, to record the sheer coolness of it. ;p ) TREKphiler ^{any time you're ready, Uhura} 21:44, 21 December 2014 (UTC)

There was an article on this in an issue of Aeroplane Monthly in around 1973-4. — Preceding unsigned comment added by 95.149.247.9 (talk) 12:45, 9 February 2018 (UTC)

Propeller efficiency

The article says Wright's propeller 82%, modern propeller 90% and a well-designed propeller 80% at best. These values, taken at face value with no knowledge of propeller performance, seem to contradict. Is anyone able to add suitable qualifying, and sourced, explanations which tell the reader that propeller technology hasn't gone backwards? Pieter1963 (talk) 20:55, 22 March 2018 (UTC)

Certainly needs fixing. According to A.C. Kermode; The Mechanics of Flight, Eighth edition, Pitman 1972, pp. 135, 143-4, a propeller's efficiency varies during the flight regime, with a maximum efficiency of just over 80%. He defines efficiency as the power output to the air over the power input from the engine. The sources cited in the article do not appear to actually define efficiency, despite discussing it at length and giving equations for lots of other things. Nor do they look particularly reliable. Hope this helps. — Cheers, Steelpillow (Talk) 22:15, 22 March 2018 (UTC)

Thanks for that. I have found 2 reliable-looking sources that say Wright's was about 68% so that seems to be going in the right direction, will edit. As you say, an efficiency value doesn't mean much without adding extras like flight speed. Many articles on propellers have a plot which shows this so it would be good to add one here but that is beyond me.Pieter1963 (talk) 15:21, 24 March 2018 (UTC)

very small pitch angle

"Very small pitch and helix angles give a good performance against resistance but provide little thrust" I'm trying to learn a bit about propellers using this article. I'm not sure what is trying to be put across here so think it should be reworded to explain what actual operating condition this applies to. Any inputs or shall I just have a go myself?Pieter1963 (talk) 20:30, 28 March 2018 (UTC)

Airspeed

Re, "re-reverted "only" to "most", since e.g. the Tu-95 flies 20% faster than the "about 480 mph" with high reliability (though loud)": I would prefer the article clarified the top speeds of prop-driven aircraft, rather than implying some are supersonic. Burninthruthesky (talk) 06:34, 17 July 2018 (UTC)

A strange link

{{convert|480|mph|km/h nmi/h|0|abbr=on|lk=on}} 480 mph (772 km/h; 417 nmi/h) It is very strange and not very useful/informative to link nmi/h, nautical miles per hour, to speed. Peter Horn User talk 19:11, 26 August 2018 (UTC)

Eureka {{convert|480|mph|km/h kn|0|abbr=on|lk=on}} 480 mph (772 km/h; 417 kn) Peter Horn User talk 19:18, 26 August 2018 (UTC)

Propeller dangers

Should there be a section about propeller safety and the dangers they can present? 'cause they can inflict injury to anyone or anything that gets too close. They're like weapons!184.186.4.209 (talk) 05:02, 26 December 2018 (UTC)

If someone finds a reliable, published source for the information you have described, it could possibly be incorporated. However, your description sounds like something appropriate in an instruction manual but not in an encyclopaedia. Wikipedia is not an instruction manual - have a look at WP:NOTMANUAL. Dolphin (t) 09:59, 26 December 2018 (UTC)

Blade twist nonsense

The claim that blade twist is applied in order to reduce the angle of attack with increasing radius appears to be wrong. Angle of attack has nothing to do with the relative fluid velocity increasing with increasing radius. I believe the intent of the twist is to actually reduce angle of attack with increasing radius in order to have a uniform load along the blade. That is because with the lift proportional to the square of the speed, the force at the outer radii would be very large. — Preceding unsigned comment added by 208.107.114.11 (talk) 19:31, 19 May 2021 (UTC)