Gyrocopter rotor instead of canvas sail ?

Discussion in 'Hydrodynamics and Aerodynamics' started by CocoonCruisers, Mar 22, 2019.

  1. Angélique
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    Angélique aka Angel (only by name)

    It's actually a harbor light, which is there a lateral mark of the region A*, harbor lights are usually much smaller than lighthouses.

    (* in the picture (of Saint-Malo) it's red on the starboard side while going to sea)

    P.S. - She looks much smaller here, L 30.5 m (100') × B 12.80 m (42') . . .
    [​IMG]
     
    Last edited: Mar 30, 2019
  2. Angélique
    Joined: Feb 2009
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    Location: Belgium ⇄ The Netherlands

    Angélique aka Angel (only by name)



    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

    Energy ObserverThe Vessel

    ‘‘ Built in Canada in 1983 by the naval architect Nigel Irens, under the supervision of the navigator Mike Birth, it was a maxi catamaran (sailing) which has left its mark on the evolution of multi-hull boats. Originally 24.38 meters long, it has been lengthened four times and today measures 30.5 meters long by 12.80 meters wide. ’’

    It's the ex: Formule Tag, ENZA New Zealand, Royal & SunAlliance, Team Legato, Doha, Spirit of Antigua, Daedalus, with quite a bit of racing history and victories, and quite some famous skippers in her racing days; Mike Birch, Peter Blake, Robin Knox-Johnston, Tracy Edwards, Tony Bullimore, to name just a few of them.

    ‘‘ Under the name Enza in 1994: Jules Verne Trophy (new record around the World), skippered by Peter Blake and Robin Knox-Johnston, in 74 days, 22 hours, 17 minutes and 22 seconds, with an average speed of 12 knots. ’’
     
    Last edited: Mar 30, 2019
  3. CocoonCruisers
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    CocoonCruisers Junior Member

    Yes Dejay, it seems they can produce a bit of side force (90°), and not just a 180° drag that adds up to the rest of the wind drag like Angélique is describing if i understand right. Some guy turned that into an RC plane:

    It seems to be very inefficient though, like everything about vertical axis wind turbines (not talking flettner here, but about ones designed to generate torque).
    Peak power of the ones in Energy Observer is only 1kW each, where a horizontal one comparable in cross section or material usage would put out at least 3 times as much.
    95% of the boat's energy comes from the 25kWp solar array.

    They look cool though, and their symbolic character aligns well with the missions of this project: Greenwashing, tax-paid fun-project tinkering for french nuclear engineers, groupiedom relative to the actually cool guys in french composites and ocean racing engineering ;) (Oops, no offense intended, i hope nobody here is involved in that project. I can understand them well and wish them every luck, part of me also found that project kind of cool. On an other hand, i'm somewhat prestressed because of former involvement in the naughty french energy lobbying wars, and this fits EDF/CEA's usual alibi scheme so well ... and also because i found it a little sad to cut up such a nice sailboat just to reenact the demonstration of less effective technologies, that have all been proven more thoroughly elsewhere decades ago, including in France.)
     
    Last edited: Mar 30, 2019
  4. CocoonCruisers
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    CocoonCruisers Junior Member

    Cool to see how you put things into perspective one more time. I love that systemic approach ;
    but we can be smart recombining what exists, and will get a lot of favourable winds with today's automation possibilities ... and knowledge sharing :)

    I'd see two distinct use cases then:

    - One requiring precise positioning, plus some power reserves for whatever tugging/pushing role, or just to still be able to hold station when there is a bit of current . We'll face two problems then: the direct upwind or dead downwind capacities can be achieved. But as far as i can extrapolate from the 'Blackbird' writeups, it seems that there would be little power left to do meaningful work. And what happens in a calm ? I fear we'd quickly get into scenarii where we'd also rely quite heavily on stored energy.

    - One requiring looser positioning , as for communications networks, oceanographic measurements etc, where relying on a (rotary) lifting surface seems good enough. The automation opportunities apply to that too: tacking 100 times a day is annoying for a human, but not for a computer. A smallscale PTO for electricity or aircon would probably be included in such a scenario too, but one would not get into compromises between a 'torque' rotor and a 'lift' rotor design. Am i right then in assuming that we'd only want to go for the complexity of the 'gearing' approach (high torque transmission, gearbox etc) in the not-all-that-likely case that it would provide better VMG ?

    +1 for that name!
     
    Last edited: Mar 30, 2019
  5. Angélique
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    Angélique aka Angel (only by name)

    Besides that, new materials and new techniques can overcome old barriers, sometimes making old ideas working better nowadays, and despite the old phrase I think there's still room for new inventions in sailing and yacht design. Sharing (thought) experiments and doing it together with the rest of the world is one of the wonders of the internet which will accelerate the process of innovation . . :)
     
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  6. Dejay
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    Dejay Senior Newbie

    Thanks! So many interesting effects regarding aerodynamics.

    Ok so considering the autorotating / windmill hybrid that tspeer suggested, for an autonomous vessel that is a really cool idea. Would it be more or less efficient than a solar powered vessel?

    For station keeping you wouldn't need a big battery since you mostly only move when there is wind. That would seem to be a big bonus already, it can basically convert any wind forces acting on it into surplus energy while keeping position. I figure how much energy is left would just depend on efficiency of the turbine and on drag / weight.

    Solar is cheap and easy but you'd need batteries to correct position at night or on cloudy days. Maybe for an autonomous vessel that is negligent though. You would also have less maintenance.

    I'm not sure what I'd do with an autonomous vessel in the middle of the ocean but I want one now!
     
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  7. Angélique
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    Angélique aka Angel (only by name)

    Generating subtitles on YouTube . . . .
    YouTube subtitles.jpg

    Clicking symbol 1 will generate subtitles, symbol 1 red underlined means subtitles are on.
    Clicking symbol 2 gives the option to select a language for the subtitles, and to change the speed of the video, and more.

    As stated in post #32 the boat already sailed around the world within 2½ months in a non stop trip on 100% wind energy, that was a quarter of a century ago.
     
    Last edited: Apr 5, 2019
  8. CocoonCruisers
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    CocoonCruisers Junior Member

    Why choose actually ? To me it sounds hugely complementary.

    Perhaps you just stepped onto one more advantage to the rotary sail: it facilitates usage of the roof for a solar array by doing away with the rope & boom etc clutter, and it lets way more light through than a canvas sail.
    The only thing to be careful about is the impact of shading on whole strings of solar panels: you don't want half the field shut down because of the shade on one panel (Single-panel chargers / inverters that limit this risk are available these days though)
     
  9. Dejay
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    Dejay Senior Newbie

    If you could change the angle of attack of the rotor and have symmetric wing profiles (?) you could also rotate the turbine 180° to the wind in order to minimize shading. Kite sails with automatic control would be even better against shading.

    But yeah, MPPT per panel. And with a wind turbine you'd need a rather wide vessel anyways for stability, so that would give you ample space for solar panels and probably a surplus. But the wind turbine makes it so that you at least don't drive so you don't need a large battery to store energy for propulsion.

    But it's a question of what would be cheaper and lighter, just solar with a battery or a wind turbine with added structure.
     
  10. tspeer
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    tspeer Senior Member

    No. They can only be used to provide power that drives something else for propulsion. A horizontal axis rotor is quite different in that regard.
     
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  11. tlouth7
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    tlouth7 Senior Member

    So what controls does an autogyro yacht need? Could it be made to self-feather (e.g. by having the azimuth axis in front of the rotor axis)? If so, is a conventional mainsheet that pulls the "sail" to windward of feathering sufficient?

    Thinking about it, in order to tack in a conventional way the rotor pitch (or direction of rotation?) would have to switch as you pass through head-to-wind.
     
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  12. dinoa
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    dinoa Senior Member

    The rotor tip path plane would have to swivel through 360 degrees on an axis parallel to the mast. About 12 degrees angle of attack of the rotor disc to the relative wind would give best L/D and 90 degrees would give the highest drag with the rotor in parachute mode running before the wind. The simplest control would be with a 2 bladed rotor on a see-saw hinge mounted to the mast.[​IMG]A[​IMG]

    The mast would swivel for control. The torque tube shown in plans would be attached to the mast but offset to allow the disc to "flap" through about +-10 degrees on the see-saw (teeter) hinge to compensate for dis-symmetry of lift over the disc due to rotor tip speed difference between advancing and retreating blades. Tacking would involve swiveling the mast through about 70 degrees to present the other side of the disc to the wind, running would require 90+. Reverse flow through the disc would result in rapid decay of rotor RPM; a situation to be avoided.
     
    Last edited: Apr 1, 2019
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  13. Dejay
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    Dejay Senior Newbie

    "rotor in parachute mode running before the wind" I think the idea for downwind was to change gear and use the propeller int he water to drive the rotor to push against the wind. So it could actually go faster downwind than the wind.
     
  14. dinoa
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    dinoa Senior Member

    Gyroplane rotors autorotate and are not connected to the drive train. Thrust is provided by a separate engine driven propeller.

    [​IMG]
     

  15. tlouth7
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    tlouth7 Senior Member

    It seems to me that you could do away with the teeter hinge on a sailing gyro because asymmetrical lift (between the top and bottom halves of the disk) is not inherently a problem.

    What is the situation that would result in the rotor stopping? You say reverse flow but I thought it was excessive angle of attack (between the airflow and the rotor disk). Edit: I see what you are suggesting, having a fixed pitch rotor and swinging it all the way round like a square rigger or kite (in which case the mast has to swivel by more than 180 degrees between tacks).

    Edit: Further to the point above about asymmetrical lift, could this be used to advantage by having the high lift advancing blade at the bottom of the disk, thus reducing heeling moment? This would be similar to having twist in a conventional sail.
     
    Last edited: Apr 2, 2019
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