Talk:Anton Flettner

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"Magnus Effect" that is, the force generated by wind on a rotating cylinder, is a strong force that is tangential both to the wind direction, and the axis of the cylinder.

  See: Baughman's Aviation Dictionary and Reference Guide - Copyright 1942, by 

Harold Baughman.

  Anton Flettner did research in hydrodynamics, and then aerodynamics at Goettingen Germany. Most of his reseach papers therefore, were written in German.

An excellent reference however, was published in English as a translation. The book is rare to find, but can be found in larger research libraries, and the Library of Congress.

  The excellent reference is:
          Anton Flettner
      The Story of the Rotor 
 From the German " Mein Weg zum Rotor"
  Published by: F.O. Willhofft
               68 Beaver Street
                  New York 
                    1926
  Copyrite  1926   F.O Willhofft

 It is the only good English reference on both Magnus Effect research, and the career of Anton Flettner prior to WW2.

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Another article written by misguided fanboy?

The portion on rotor ships is really disingenuous. It quotes Popular Science - never a very reliable source about the impact of proposed technology - from 1925. We certainly have not seen this amazing revolutionary technology reshape the world of shipping... He simply failed when he tried. The fact that it appears to have promise and is being tried in a few ships suggests he might have really been onto something, but it's simply novel at this point, not yet revolutionary... There's been no revolution. Fitzhugh (talk) 06:02, 8 June 2019 (UTC)

I'm not going to edit the page but the gee-whiz treatment of this topic in the introduction does not meet any sort of encyclopedic standards, especially since the outsized 1925 Popular Science claims have not been substantiated by actual experimentation with a modern rotary sail ship. Much more modest power savings are reported. As per the obvious, the technology would be dominant if there were not attendant disutilities. 0x69494411 18:18, 27 December 2020 (UTC)

@Fitzhugh, 0x69494411: The Anton Flettner article includes photo of the Buchau rotor ship from 1924, which can be visually compared to E-Ship 1, completed August 2010. Today, Marine Traffic (click on MMSI no. in WP article about that ship) shows E-Ship 1 reported: 9 hours ago it was sailing in West Mediterranean on course 262 ° at a bit under 12 knots.

Because of that (and more, see citation below) I disagree that Flettner's idea (and execution of 1924) was a failure, but he might have been premature then, of businessmen of that time (and later time) short- or too narow-sighted. It was also not intended for today, it was intended for that time when last commercial sailboats still existed, but were uneconomic mostly because of manpower needed; advantage of Buchau's rotating sails was drastic reduction of manpower to manage the sails.

For quoting popular Science - it is quoted in the 2 volume publication, prepared by the Borg/Luther Group, for Naval Sea Systems Command Department of the Navy, with the title "The Magnus Effect - an overview of it's past and future practical applications". This source estimates the commercialization in 1925 probably failed because of then cheap fuel and economy crisis. About discontinuing the development in 1985 (see p.100):

In spite of this promising performance and over the protests of the general manager of Steering Systems Incorporated, the directors of TBW Industries chose to discontinue further development of Magnus effect steering systems. One possible explaination for this decision might be that patent protection was nearly impossible. Because of the W. Roos patent of 1929, cylindrical rudders were in the public domain . (see Chapter 4)

Currently, google shows TBW Industries at 59 Victory Ln, Los Gatos, CA 95030, USA, permanently closed... I am adding this citation where it would do some good. The Flettner article should be expanded by info from, and supported by this source. If someone can do before I get time, (s)he's welcome. Marjan Tomki SI (talk) 11:20, 11 September 2024 (UTC)

After a more thorough (but not complete) look into the source in question, some additional thoughts.

• This source was peer-reviewed (by US Navy) before having been made available, but both authors were inventors and developers of devices using Magnus Effect, so probably at least a little biased.
• Historical material referred to in the source shows that no reasonably reliable mathematical modelling for predictions of effects of different aspects of designs were found at the time. Experiments (with models, wind tunnels, or full size ships etc.) were the only reliable way to extrapolate changes in variables (size from model to full size, water or wind speed, speed of rotation etc.) to the Every formula I looked into seemed just the search of the best approximation possible at the time.
• At the time, there was not (at least economically) available computer power for modelling with e.g. Navier–Stokes equations calculations (even when they were initially introduced and developed by those two between 1822 (Navier) to 1842–1850 (Stokes), they and their successors are still developed; e.g. Hannah Fry's doctoral thesis was from that), which IMO would give better understanding and predictions. But when I listened to a course on Physcs of Sailing (for future and current licenced teachers for sailing on Faculty of Sports), lecturer still talked about Venturi effect on sails and aircraft wings, which is reasonably accurate for pipes and not even quantitatively good estimate for sailing. I was older than the other attendees and didn't want to disrupt at the time (the goal was to get good teacher and trainers for sailing, not embarrass the lecturer). When I listened to the Physics of Sailing course (by different lecturer of the same faculty, and by Zoom because of COVID-19 regulations in 2020, he mentioned Napier - Stokes equations, but the scope was not on the details and by Zoom I did not pursue at the time.
• I discussed fluid dynamics problem with some physicists and mathematicians: dealing with Napier Stokes equations need (at lest 3D) matrix (actually tensor - if I recall correctly, matrix is a 2D tensor, but term matrix is more known to laymen) of interrelated partial differential equations, that needs substantial computing power, which was not available (for acceptable price) half a century ago (e.g. 1980). At that time such computations were used almost only for meteorology (similar fluid dynamics problem) and things related to war and weapons.
• I recently asked people who build, and some at least partly design (mostly for sports, but not exclusively) small vessels, if they have SW that can do hydrodynamic calculations. Of those that answered, all outsource that task. They do hydrostatic calculations and tests, they also seem to do some dynamics of distribution of forces (e.g. on mast, keel, rudder, standing rigging of the boats in waves, but I didn't see the calculations), but not full hydrodynamics. I didn't yet have the opportunity to see how that part of fluid dynamics modelling is done by a program a designer uses (or, more probably, program plugin). Ten years or so ago, I did optimization of a computer for a student of ships design to be able to run design SW, but had no time to look into it. Now he owns a sailing school, and has no more need for such (supposedly expensive) SW.

Conclusion: Didn't find sources for definite, exact answers for a lot of things here, yet (and may not live til I do). From Flettner and related articles, I'll use this source for the data that support claims about Flettner (together with other sources), e.g. power needed for Buchau Flettner sail ship etc. That seems consistent (and it was peer reviewed). With review of Magnus effect related patents, the comparison of weak and strong points of proposed solutions in patents can be interesting, too. Marjan Tomki SI (talk) 08:36, 12 September 2024 (UTC)