Seems like Flettner is a brand name in this case.

Related? I asked the question from their website - let’s see if they answer.
How about some “future-news” of the past:
Here we go again: Maersk, Shell, Norway, blah blah blah…
Get it? “Norsepower” instead of “horsepower”? Get it? huh? huh? huh?

The word is spelled “pique”

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Did he say “The Selsam Maelstrom”?
Man, that looks like a lot of power going down the drain.
Reminds me of the Niagara River right before the falls…
Don’t fall in! :slight_smile:

I’m about done with this format. Spent the time to write to the Flettner Ventilator Company to respond to Pierre but was not allowed to “reply” after 3 replies. By a machine. I find the floormat-format of this forum to be too cumbersome for easy use.
Such a fixation on “categories” that it’s nearly impossible to even find a thread from the day before. Also as we know, endless talk takes a lot of time, without necessarily producing anything. Well here is the response from Flettner Ventilator:
Hello Doug,

Thank you for your email.

Yes, Anton Flettner’s inventions and patents are used by our company Flettner Ventilator Ltd.

The Magnus effect is part of the technique used.

I hope this information helpds?
Please visit for more information on our company and its history.

Met vriendelijke groet, best regards, Mit freundlichen Grüßen

Pascal Lenferink

Business Manager
Flettner Ventilator Ltd
Tel: +44 (0)1908 698903
GSM: +44 (0) 7908 909012

Thats hardly a Magnus effect in use there? Im just seing a VAWT driving a fan?

…bringing the number back to zero…

Magnus rotors are efficient with both a high spin ratio (2 to 4) and a low wind speed, avoiding a too high tangential speed which increases by the cube. A high wind speed and a high spin ratio lead to a huge power consumption overcoming the delivered power. A spin ratio of 4 with 15 m/s wind speed is to forget. It is a reason why Magnus rotors are not massively developed.

From theory and also some experiments I made, the Sharp rotor is probably better for AWE at least for high winds.

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Yeah, that’s what I was thinking: Sharp rotor, although the sausage shape is easier to build and maybe lighter. I just wonder if either is better than an airfoil. Anyway, just goes to show how few ideas are ever even tried.

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I can be partially wrong.

To be fair, one could probably make an inflatable sharp rotor as well, it would just have some more complexity to the build

Anytime you deviate from a sphere or cylinder (round shape), with regard to inflated, lighter-than-air structures, you reduce the contained volume (buoyant lift) while increasing the material (mass) required for the envelope. This was a big red flag for one of the most highly-publicized AWE projects ever, still featured in new articles about AWE (shows how much the authors understand), what was it called again? MIT? Donut? You know,

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Yeah, just saw something called a «Bat» in here: Estimation of energy production in aerial systems of Wind Energy

I never consider lighter than air, I dont believe its a viable option. If you need to go that route use something that is 24/7 airborne but using energy from the ground instead

I’ve seen several press-release-news-of-the-future stories of major shipping companies signing up for trial installations of “Norsepower” flettner/magnus rotating cylindrical sails. The general tone of these press-releases is “if it works out we’ll buy many more”.
Here’s one for a Ferry whose route is crosswind in both directions, predicted to reduce emissions by 4-5%.

This has the flavor of something that is not going to work out.

  1. Sounds like 4-5% is a best-case scenario;
  2. Does that even include the power to rotate the sails?
  3. What about the extra weight? Will the extra weight slow the vessel? How much?
  4. What about the extra cost?
  5. What about the added complexity?
  6. What about heeling?
  7. What if the typically-optimistic estimates of 4-5% energy savings are high?
  8. How much would they have to slow the vessel to save that same 4-5% of fuel? 2% slower?
  9. If the estimates of fuel savings are low, might they save the same lower percentage by slowing the vessel 1%?
  10. I’d love to see the world’s ships using less fuel, but by this point, how many similar press-release-news-of-the-future stories regarding new, experimental methods for wind energy have we seen? How many have come true?
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I hear you. Though:

My reference to an almost success was debunked bu wikipedia (Buckau). Even so, there are flettner ships in use apparently saving 25% fuel. (Saving 25% when you need to cut 100% is also a strange way of approaching global warming, but thats a different story). So it seems it’s enjoying some limited success and at least a lot of the hyped up prototype projects that you like so much…

Good article. Here’s the meat of it:
" The ship had proved inefficient on these voyages, with the power consumed by spinning 15m tall drums being greatly disproportionate to the propulsive effect when compared with conventional propellers. As the system could not compete economically, Flettner turned his attention to other projects and the rotors were removed.[8]"

This is saying you get less propulsion from the spinning sails than if you just put the same power into a regular propeller. If they worked well, you can bet Flettner would not have removed them from the ship.

And the section discussing “Saving 25%”, if you read carefully, is owned by a wind turbine company (Enercon) and they say “up to 25%” (compared to same-sized conventional freight vessels)"

That is two qualifiers to 25%. My guess is they are not counting the energy used to spin the cylinders, hence an illusion of “up to” 25%. Up to means “less than”, which could be only 5% or even zero or minus 5%!.

I’ll tell you what I think is going on here: In this climate of borderline insanity with people doing backflips to see who can appear to be the most politically-correct and carbon neutral, people are doing whatever it takes to have even the appearance of “making a difference”. It’s not the actual making of a difference that counts, since few people can figure out whether they actually ARE making a difference, but the emotion-based illusion of making this “difference”.

If faced with the facts, the politically-correct rationale is typically “Well, we’re raising awareness”. So, as we often see, even projects that end up using MORE fossil fuels are lauded and worshipped, as long as they look like they might use slightly less fuel. And after spending all that money to create this illusion, the companies know better than to tell people it doesn’t really save any fuel. They just pull out a figure indicting some minor savings and then quickly change the subject. It’s more about illusion, emotion, and public relations than anything else.
Did you know people have built a wind turbine using flettner rotors as blades? Yup, they apparently must have sucked too. Not that sucking is a bad thing for an airfoil,since that is how they work, but, well, you know what I mean. :slight_smile:

There are significant differences between Flettner rotors used for vessels and that for AWES, as the first are appropriate only for some wind directions and undergo the cantilever effect while the second can be inflatable, are held by both ends, and face the wind. So different results can be expected. But the power consumed is comparable and can be very high for too high spin ratios. For AWES a spin ratio of 2, perhaps 3, could be a limit.

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As a comment to what you are saying about creating an illusion of being environmentally friendly: The Norwegian state just awarded $260 mill to AN OIL COMPANY to create (not install, but actually develop new tech) windmills. These windmills will supply power to OIL PLATFORMS for the next decades.

We are doomed as a species.

(Let me just state that this is a satirical post. Though my general opinion should be clear, the actual decision about this funding is a complex one, and I’m sure it was done with only the best intentions)

If it produces usable power at a good price, better than burning even more fuel.
Hywind uses the ballast-stabilized spar-buoy floating wind turbine foundation that I invented. See Figs. 14-20 of my Euro Patent:
Do you realize the oil industry controls the environmental movement? It keeps them in a monopoly position by restricting drilling, otherwise oil would be so cheap nobody could make a profit. They also control politics - watch the financial channel where they talk bout how the only reason oil prices haven’t collapsed is Venezuela and Iran, two of the largest producers, have been shut down via a revolution and sanctions. Coincidence?
Tallak you have to realize something my grandmother once told me:
There is ALWAYS, and has always been, a doomsday scenario being promoted, always looming in the background, but it never actually happens, so stop worrying. For all you know, the carbon is staving off another glacial cycle. It’s a known fact the planet is now greener than it was a few decades ago, from satellite photos. When I was a kid, it was 1) nuclear war, and 2) overpopulation (we were not supposed to be able to grow enough food for more people). They had us hiding under our desks at school. Today the doomsday scenario is all about temperature. They depend on kids like you going into panic-mode, since you haven’t already been through ten previous “we’re all gonna die!” scenarios yet… Give it a few years and it will be all about robots, disease, mosquitos, meteors, drones, or something else - maybe even cooling. I know, you laugh, but just wait and see. What I’m more concerned about is spending my life inventing wind turbines and having a major developer using the idea I paid to develop and have published. We’ve had a patent issued in the U.S. based on the documented fact I invented the only floating wind turbine foundation in commercial use today, U.S. Patent 10,024,307 Floating Marine Wind Turbine. Currently looking to sell the patent. We’re auctioning off the deepwater offshore locations in California next year. If you know any decision-makers at Equinor, please have them contact me.

I just ran across this patent to stow a shipboard flettner / magnus rotor.
The problem?
The tall cylinder causes air drag when not in use, slowing the vessel and/or causing more fuel to be burned. The promoters of the magnus sails don’t say anything about the extra weight of not only the cylinders, but the weight of the rotary support structure, which must be strong enough to survive storms, the weight of the drive motors with gearing, and the weight and expense of whatever setup is required to provide the power to run the drive motors.
Why don’t we see any ship trying simple (regular) sails, even in a limited way? My guess? Regular sails would seem like giant step backwards. Sails are old-news, and sound boring, with no “Professor crackpot” sexiness from which to generate exciting “look how green we are” press-releases. Nonetheless, I’ve always wondered why oceangoing ships do not have auxiliary sails. Regular sails require no significant power to operate, weigh less, and are easier to stow away for storms or times of no wind, and when stowed would cause no drag. When I saw the fact that these cylinders actually slow the vessel by causing air drag when there is no wind, I realized that weighs strongly against their wide adoption. More fake-future-news, being promoted by people with the very best of intentions, is my best guess. As with kite-ships, probably better proven as advantageous in small craft before getting too far into convincing ship operators to spend millions of dollars with these “raising awareness” symbolic projects destined to be quietly dismantled like Flettner’s original rotor-sail demo ship, once the hype has served its purpose. If someone truly has a better way to sail a boat, I say prove it in the existing field of sailboats and sailing, maybe show you can win some races, or go home.

Very good points… Flettner may be a dead end for ships…

Wrt doomsday scenarios: In the 80s we had acid rain, and no doubt it did considerable damage to ecosystems here in Norway. Humanity managed to deal with that one. But it was looking quite bleak for Norway at one point. These are facts, we must not just forget that there was real chance of doing substantial damage here.

Now we have global warming. Though I would very much like to take the «happy go lucky» stance you do, and as I respect that you have come to different conclusions on the severeness, for me i see both good and very bad outcomes of this. Both are possible. The odds of the bad one coming true is way too high, and people are showing a fantastic inability to act on the problem.

So when (if) the bad outcome is real, we can look back at how the Norwegian government «saved» us by giving money to the oil companies so they could extract oil more cheaply…

Sorry for going off topic. We might start a new thread on global warming, but it’s better I think to stick to AWE, much more interesting

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Here’s that patent I mentioned: