Talk:Slowed rotor

To-do list:

• streamline gallery to show aircraft in same position, from same viewpoint, to show similarities and differences
• missing aircraft - which ones? (lack of independently verified data?)
• missing numbers for Rotodyne, lacks data, says Harris 2003 page A-179
• better Mu drawing
• expand tech for different aircraft types,
• more drag theory

TGCP (talk) 18:33, 16 May 2014 (UTC)

Bo 46 - slowed or not ?

It seems the Bölkow Bo 46 slowed the advancing blade tip and speeded up the retreating blade tip, so they both had about the same airspeed, even when the helicopter went quite fast. The rotor shaft RPM was about constant. I don't know if this means it was a slowed rotor aircraft ? TGCP (talk) 16:37, 18 May 2014 (UTC)

Other candidates

• The Lockheed XH-51 may or may not be considered an aircraft with slowed rotor - its rotor speed was 95.5% at 263 knots while diving slightly, and 91% at 223 knots in level flight. "RESEARCH IN MANEUVERABILITY OF THE XH-51A COMPOUND HELICOPTER" TGCP (talk) 07:38, 28 August 2014 (UTC)

List of rotorcraft

What does this list add to the article? Every gyrodyne, winged autogyro and compound helicopter uses the principle, so this list is hopelessly incomplete. But make it bigger and it loses any structure, and hence any value. Is there anything in it that needs to be kept to help the rest of the article make sense? — Cheers, Steelpillow (Talk) 17:11, 4 April 2020 (UTC)

Have you seen references that describe a significant slowing of the rotor inflight in other rotorcraft than the ones in the list? I would say the cutoff for inclusion is around 90% of nominal rotor RPM - more than that, and they are not meaningfully slowed. TGCP (talk) 21:15, 4 April 2020 (UTC)

That misses the point. I think the list should be deleted. Harris for example is clear that the principle has long been used in fast rotorcraft design, indeed is necessary for any fast rotorcraft. Yes he discusses examples, but they illustrate or carry the text, and we should take the same approach. — Cheers, Steelpillow (Talk) 04:31, 5 April 2020 (UTC)

I am just asking if anything in it is worth working into the rest of the article first. — Cheers, Steelpillow (Talk) 11:33, 5 April 2020 (UTC)

Removing the list has made comparison difficult, and overview is reduced. That has made the article less useful for the reader, although the text edits have improved the article. TGCP (talk) 15:09, 5 April 2020 (UTC)

What value to the reader did any of that bring? — Cheers, Steelpillow (Talk) 15:52, 5 April 2020 (UTC)

It's unfortunate if you can't see the combination of overview and detail the list brings. The uniform display of speed, L/D and Mu numbers show both the model variety and energy aspects (via L/D) of the different applications of Slowed Rotors. If more numbers were available, they would increase clarity, unfortunately those numbers are hard to come by - probably for commercial reasons.

The common autogyro such as MTOsport 2017 (section 2) does have variable rotor speed between 200-550, but that is at a much lower speed and thus not high Mu. It has a maximum L/D of just 4, and maximum Mu of 0.61. It could be shown as comparison, but does not display the slowed rotor aspects of high speed where retreating blade stall and transonic tip speed are to be handled via higher Mu. The enclosed Calidus would be marginally better, but also not displaying the significantly different airflow of Slowed Rotor. Aircraft that show high Mu would be notable, as requested above. TGCP (talk) 17:46, 5 April 2020 (UTC)

I find all that a bit muddled. When I looked at the list, all I saw was a pile of stuff that added nothing to the article because it lacked accompanying commentary. More numbers would make the jumble even more obscure. Nobody cares whether type X had higher Mu, or greater L/D, than Y unless the reasons for it are significant. By contrast, a useful commentary can, and should, stand on its own, it does not need to reference such a list. Breaking out the chronological periods was the simplest and most obvious step in that direction. Your comments on the MTOsport belong in the topic below. — Cheers, Steelpillow (Talk) 19:05, 5 April 2020 (UTC)

The context could be better, yes. The importance of high L/D via high Mu is in the article, albeit only a few sentences; regarding rotational speed and fuel consumption, yielding longer operating time, including at high speed. That connection could be improved.

The MTOsport is an example of why such aircraft are not suitable (low MU) for this article or the list despite having very variable rotor speed, and how gyrodynes etc. in general can be considered for the article - whether they employ the SR principle. The numbers show that, if they are available, as requested above, but text is a good addition. That's why merely referring to a source saying "slowed rotor was considered for XH-51" is vague, because we don't know to which degree. The L/D diagram on page 9 by Duda/Pruter is how the difference would show itself (substituting the red airplane curve for an SR), but the high L/D at high speed are not indepedently verified for SR (yet?) other than XV-1. We use numbers to distinguish other categories, such as Truck classification. TGCP (talk) 21:48, 5 April 2020 (UTC)

Current layout is a mess of stats that are incredibly difficult to parse since they have been taken out of the table layout. Either the table needs to be reconstructed or the stats need to be removed altogether. I'd prefer the latter since anyone looking for this level of detail should probably be researching elsewhere anyway. Retswerb (talk) 01:30, 12 February 2022 (UTC)

Those numbers are the core of the matter, and are difficult to display in a meaningful way. They are best understood in comparison with conventional helicopters. But yes, the current layout is a mess when no longer in table layout. TGCP (talk) 01:56, 14 February 2022 (UTC)

Having some examples is of definite value, but per WP:NOTSTATS I think we are deep in the weeds on details here. Retswerb (talk) 22:24, 26 February 2022 (UTC)

Suggestion: the list of aircraft have a MU between 0.6 to 0.95, whereas the helicopters are 0.3-0.5 , this can be summarized and compared. TGCP (talk) 00:11, 27 February 2022 (UTC)

I'm not sure I follow. Also if the Carter PAV is actually at 1.13, doesn't that contradict the previous statement that no experimental knowledge exists for mu > 1.0? Retswerb (talk) 01:27, 27 February 2022 (UTC)

The MU number is one of the differentiators between technologies, like the Mach number differentiates between subsonic aircraft and supersonic. As mentioned above, Truck classification is another example of how numbers are used to define categories.

The 1.13 number was measured by the manufacturer (similar to car manufacturer numbers), not public, so it may or may not be included in that group. TGCP (talk) 13:47, 27 February 2022 (UTC)

Criteria for inclusion

See the Lockheed XH-51 example above; it only reduces RRPM to 91%, barely different from helicopters. Quantifying that number shows the difference. If the rotor is not really slowed, it is not a slowed rotor aircraft. TGCP (talk) 09:18, 5 April 2020 (UTC)

What we editors think about actual facts is neither here nor there. Reliable sources bear out that the XH-51 was part of a significant programme to utilise the phenomenon. That is the only criterion which matters. Of course the article should discuss it, but only in that context. — Cheers, Steelpillow (Talk) 11:32, 5 April 2020 (UTC)

Application is notable. We apply more notability to efforts that have become airborne than paper projects. And even more to production aircraft such as Boeing 737 (such has not happened for these aircraft). The slowed rotor part of the XH-51 programme does not seem to have had practical application. Did it improve theory/development for other programmes? If so, that can be notably added to the text, but its flying parameters are not suitable in the main list (perhaps in the comparison section). The PCA-2 expanded the knowledge for slowed rotor, and as such had notable impact on other aircraft. Its parameters show a high Mu and high L/D for its age. TGCP (talk) 14:38, 5 April 2020 (UTC)

Unexplained text

This sentence, and similar ones do not adequately explain the numbers, nor the relevance to the design.

"In forward flight the power to the rotor was reduced to about 10%. 166 knots (191 mph; 307 km/h). 0.6. 120 to 140 60% \ 40%."

And the refs are piling up within the sentence making it harder to read.GraemeLeggett (talk) 08:45, 18 May 2023 (UTC)

References