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Re: [AWECS] Re: Open Source AWE Automation?

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  • dave santos
    Doug,   Re: Smart AWE: No one still seriously proposes a basic winch as the power device: capstans & fairlead levers work better. A smart winch   is
    Message 1 of 29 , Apr 16, 2011
      Doug,
       
      Re: Smart AWE: No one still seriously proposes a basic winch as the power device: capstans & fairlead levers work better. A "smart winch"  is mostly for launching & landing, playing the kite in just the right way. Its just like landing an airplane, you adjust the approach angle continuosly & land right in the cradle. Take off is even trickier, & the winch agent will be talking to the kite agent (smart kite) trying for early launch, which might be a short tow on a dolly wheels. There's zillions of ideas at play. The opposite of smart is (?).
       
      The rotor is a fine device that we both champion, especially the autogyro principle. Keep in mind the linear relation between high performance & control demand, & also that everything this forum concerns is basicaly a kite, with common physics. Why debate the kite when you soon get to compete against it in field tests?
       
      Re: Fear of Fabric (Membraphobia): Its true that no one love sails like a sailor, just let them show what rags can do,
       
      daveS
       

       
    • Robert Copcutt
      Doug, Your warning is heard but I have not seen your alternative suggestion in enough detail to be convinced that it should be pushed as a global standard.
      Message 2 of 29 , Apr 16, 2011
        Doug,

        Your warning is heard but I have not seen your alternative suggestion in
        enough detail to be convinced that it should be pushed as a global
        standard.

        Cranes, lifts (elevators) and fishing boats use winches. They do wear
        but a well made system should last long enough to be economical. At
        least with AWE there is no need to get to the top of a tall tower to do
        that servicing.

        Again, fabric is still used in many applications. Covering the blades of
        turbines on a tower may not be the best plan because of difficulty of
        access. The system I am thinking of does not have these access problems
        because the airborne wing will be easily docked for repair as soon as a
        problem develops.

        Turbines all need a system for turning out of the wind when it gets too
        strong. They still rarely achieve a capacity factor better than 25%. AWE
        could do a bit better than this by having different sized wings for
        different conditions. That eases the durability requirement of the
        fabric. It also means the wings need to be cheap and using fabric should
        help with this too.

        Robert.


        On Sat, 2011-04-16 at 16:09 +0000, Doug wrote:
        >
        > Dave S.:
        > Smart Kite? Smart Winch?
        > "Beware developing a "standard" for a dead-end platform"?
        >
        > Since wind energy uses a rotor that's the same as a gyrocopter rotor,
        > why would you be talking about kites? You warn against developing
        > "dead-end platforms" - Why aren't you talking about gyrocopter rotors?
        > Do you not know that winches have not proven capable of steady-state
        > reliable, economical electrical power generation? Is there an example
        > of any successful wind energy system that uses a winch to extract the
        > power? Do you truly believe this is likely, considering the wear on a
        > winch, juxtaposed with the requirement for 20 years of low-maintenance
        > operation?
        >
        > Is not a cloth "kite", or anything made of cloth, already a
        > long-proven dead-end platform with regard to wind energy? Is this not
        > already well-known for about 100 years now? And before that for 1000
        > years even the cloth sails were just coverings for an airfoil-shaped
        > wood framework. Tethered triangular cloth kites went out of style for
        > wind energy 1000 years ago. Let's build on what's already known, not
        > start from scratch as though we're just beginners. We don't have
        > another 1000 years to repeat the same mistakes, do we? It's time for
        > the next generation of turbines, that has to build on the last
        > generation of turbines, not go back a few generations.
        > :)
        > Doug S.
        >
      • dave santos
        Robert,   Professional pessimism was meant in the special sense of, say, a cautious sea captain pondering a bold course, or like Daedalus & Icarus.   Its
        Message 3 of 29 , Apr 16, 2011
          Robert,
           
          "Professional pessimism" was meant in the special sense of, say, a cautious sea captain pondering a bold course, or like Daedalus & Icarus.
           
          Its true that kite-killing will become less frequent at larger scales (large arrays), but the back-up need may remain.
           
          No one else is doing it, so you should seriously undertake to draft the central plan you describe, it would be welcomed,
           
          daveS
           
           
           
        • Dave Lang
          FWIW, regardless of what Doug may claim about winch-reliability, the folks at Markey Winch in Seattle (I think they have about 60% of the world marine winch
          Message 4 of 29 , Apr 16, 2011
            Re: [AWECS] Re: Open Source AWE Automation?
            FWIW, regardless of what Doug may claim about winch-reliability,
            the folks at Markey Winch in Seattle (I think they have about 60% of the world marine winch manufacturing trade), quote MTBF's of 40 YEARS!

            DaveL




            At 10:16 AM -0700 4/16/11, dave santos wrote:
             
            Doug,
             
            Re: Smart AWE: No one still seriously proposes a basic winch as the power device: capstans & fairlead levers work better. A "smart winch"  is mostly for launching & landing, playing the kite in just the right way. Its just like landing an airplane, you adjust the approach angle continuosly & land right in the cradle. Take off is even trickier, & the winch agent will be talking to the kite agent (smart kite) trying for early launch, which might be a short tow on a dolly wheels. There's zillions of ideas at play. The opposite of smart is (?).
             
            The rotor is a fine device that we both champion, especially the autogyro principle. Keep in mind the linear relation between high performance & control demand, & also that everything this forum concerns is basicaly a kite, with common physics. Why debate the kite when you soon get to compete against it in field tests?
             
            Re: Fear of Fabric (Membraphobia): Its true that no one love sails like a sailor, just let them show what rags can do,
             
            daveS
             

             

          • Grant Calverley
            Markey Winch in Seattle also make a smart winch for tugs that dock monster LPG tankers. The dynamic wavy offshore conditions would snap lines on dumb winches.
            Message 5 of 29 , Apr 16, 2011
              Markey Winch in Seattle also make a smart winch for tugs that dock monster LPG tankers. The dynamic wavy offshore conditions  would snap lines on dumb winches.  We saw it demonstrated.  It generates up to 1 MW of power that gets dumped into electric heat on the outbound stroke and is a regular winch on the inbound. You can have one for 800 grand and they last 40 years.
               

              Grant Calverley
              360-378-6186



              On Sat, Apr 16, 2011 at 1:40 PM, Dave Lang <SeattleDL@...> wrote:
               

              FWIW, regardless of what Doug may claim about winch-reliability,
              the folks at Markey Winch in Seattle (I think they have about 60% of the world marine winch manufacturing trade), quote MTBF's of 40 YEARS!

              DaveL




              At 10:16 AM -0700 4/16/11, dave santos wrote:
               
              Doug,
               
              Re: Smart AWE: No one still seriously proposes a basic winch as the power device: capstans & fairlead levers work better. A "smart winch"  is mostly for launching & landing, playing the kite in just the right way. Its just like landing an airplane, you adjust the approach angle continuosly & land right in the cradle. Take off is even trickier, & the winch agent will be talking to the kite agent (smart kite) trying for early launch, which might be a short tow on a dolly wheels. There's zillions of ideas at play. The opposite of smart is (?).
               
              The rotor is a fine device that we both champion, especially the autogyro principle. Keep in mind the linear relation between high performance & control demand, & also that everything this forum concerns is basicaly a kite, with common physics. Why debate the kite when you soon get to compete against it in field tests?
               
              Re: Fear of Fabric (Membraphobia): Its true that no one love sails like a sailor, just let them show what rags can do,
               
              daveS
               

               


            • Joe Faust
              http://markeymachinery.com/history.asp Markey Machinery
              Message 6 of 29 , Apr 16, 2011
              • Uwe Fechner
                Hi, as some of you will know, we are implementing an automated kite power system at TU Delft. This is not an easy task. I support the idea of open source kite
                Message 7 of 29 , Apr 16, 2011
                  Hi,

                  as some of you will know, we are implementing an automated kite power system at TU Delft.
                  This is not an easy task. I support the idea of open source kite power automation. Some
                  ideas:
                  - as communication protocol for the inter-operation of equipment of different groups
                    I suggest to use the CAN aerospace protocol:
                    ( http://www.stockflightsystems.com/index.php?option=com_content&task=view&id=13&Itemid=53 )
                    Advantages:
                    - cheap
                    - reliable
                    - freely available standard
                    - quite easy to implement
                  - we use the following software components:
                    - Linux
                    - Xenomai (to make Linux hard real-time capable)
                    - RTNet for real-time communication between the computers on the ground
                    - Orocos as middle-ware, to implement distributed, real-time, agent-based control systems
                    - C++
                    - MISRA C++ coding standard for secure C++ software

                  I think, that the high security requirements of aviation are not needed for kite based HAWP systems,
                  because kites are very safe, as long as you are able to cut the main power cable in case of a control
                  system failure.

                  This are all the ideas, I currently want to share with you.

                  Hope to see you in Leuven.

                  Regards:

                  Uwe Fechner, TU Delft

                  On 15.04.2011 17:30, dave santos wrote:
                  Robert,
                   
                  Below is an attempt to put the Open Source AWE issue in proper perspective,
                   
                  daveS
                   
                  ===================================
                   
                  AWE Automation Open Source development in in an infant stage, but soundly proceeding on the principle of knowledge sharing. To advance further, consider three classic models of high-tech Open Source; the PC architecture, the Web (Internet Protocol with HTML), & Linux. These are standards whose consensual adoption allow developers to create interoperable resources without paying royalties. In the case of the PC it required an "800lb Gorilla", IBM, to create a hardware standard & release it to the Public Domain. In the case of the Web, first the underlying Internet Protocol was developed within the US government & released, then a "hero hacker" developed a presentation layer for a "World Wide Web" & gave it to the world. In the last case, Linux was the software adaptation of Unix, the gold standard of operating systems, to the PC harware platform, with powerful synergistic results. The lesson of these models is the power of free consensual standards. For AWE Automation we have many partial standards to build on. Aviation culture is a highly developed set of norms, with FAA & ICAO regulations as a core set of game rules. We will draw on computer technology standards to develop avionics that ultimately conform to FAA/ICAO standards.
                   
                  Our special job is to define AWE-specific standards to allow interchangeability of components, for example, where one developer's smart kite naturally works with another developer's smart winch, & both work with a third developer's flight planning & operations software. This is the work of many years & we have just begun. Expect a "pastiche" phase of many disconnected resources. There are many functional modules certain to find wide use. A simple example is the is the digital control of the classic analog hobbyist servo. A more ambitious component is a parser of automated weather data. The Tethered Aviation Concept of Operations (TACO)  draft current on this forum is a special example of an emerging consensual AWE standard.
                   
                  A cautionary note: Beware developing a "standard" for a dead-end platform. Winning standards are those wisely chosen to have a long life that can even become "immortal".

                • Theo Schmidt
                  Doug schrieb: ... ... Wind turbine sailboats use the rotor *either* unbraked in the autogyro mode as a sail, *or* as a turbine connected to a load. I m
                  Message 8 of 29 , Apr 20, 2011
                    Doug schrieb:
                    ...
                    > Since wind energy uses a rotor that's the same as a gyrocopter rotor, why
                    > would you be talking about kites?
                    ...

                    Wind turbine sailboats use the rotor *either* unbraked in the autogyro mode as a
                    sail, *or* as a turbine connected to a load. I'm wondering if this would be any
                    different with AWE. I.e. a rotor would be *either* a kite *or* a turbine.
                    Presumably a rotor could do both at the same time, but would it be better to use
                    multiple rotors?

                    Theo Schmidt
                  • Pierre BENHAIEM
                    It seems that SkyMill Energy, Inc. shows a reel-out scheme where the autogyro is towing the drum working the ground generator,that like a kite (in reel-out
                    Message 9 of 29 , Apr 20, 2011
                      It seems that SkyMill Energy, Inc. shows a reel-out scheme where the autogyro is towing the drum working the ground generator,that like a kite (in reel-out scheme).Rotokite Sequoia | Patents and Rotokite could be defined as a sort of autogyro being a set of two opposite soft kites.In contrast the autogyro in Sky wind power (flygen,not reel-out) works both as kite and turbine.

                      PierreB

                      http://flygenkite.com


                      > Message du 20/04/11 14:36
                      > De : "Theo Schmidt"
                      > A : AirborneWindEnergy@yahoogroups.com
                      > Copie à :
                      > Objet : Autogyro and turbine mode [was: Re: [AWECS] Re: Open Source AWE Automation?]
                      >
                      >  

                      > Doug schrieb:
                      > ...
                      > > Since wind energy uses a rotor that's the same as a gyrocopter rotor, why
                      > > would you be talking about kites?
                      > ...
                      >
                      > Wind turbine sailboats use the rotor *either* unbraked in the autogyro mode as a
                      > sail, *or* as a turbine connected to a load. I'm wondering if this would be any
                      > different with AWE. I.e. a rotor would be *either* a kite *or* a turbine.
                      > Presumably a rotor could do both at the same time, but would it be better to use
                      > multiple rotors?
                      >
                      > Theo Schmidt
                      >


                    • Robert Copcutt
                      Dave S, Oh well, I walked straight into that one! I am happy to start off with a document that explains my thinking but in the spirit of open source I think it
                      Message 10 of 29 , Apr 20, 2011
                        Dave S,

                        Oh well, I walked straight into that one! I am happy to start off with a
                        document that explains my thinking but in the spirit of open source I
                        think it should become a collaborative effort.

                        Robert.


                        On Sat, 2011-04-16 at 10:33 -0700, dave santos wrote:
                        >
                        > Robert,
                        >
                        >
                        > No one else is doing it, so you should seriously undertake to draft
                        > the central plan you describe, it would be welcomed,
                        >
                        > daveS
                        >
                        >
                        >
                      • dave santos
                        Robert,   Its lately become clear that the open source AWE movement is the biggest & most dynamic player, so your initiative is timely. Count on wide group
                        Message 11 of 29 , Apr 20, 2011
                          Robert,
                           
                          Its lately become clear that the open source AWE movement is the biggest & most dynamic player, so your initiative is timely. Count on wide group support of your effort to draft a common open-source AWE R&D plan. A suggestion is to fully integrate academia & base core findings on direct comparative testing by multiple independent parties.
                           
                          Good luck with an important task,
                           
                          daveS
                           
                           

                           
                        • Grant Calverley
                          Hi Theo and Pierre, Autogyros or Gyrogliders, wind turbines and helicopters are all related but are quite different. With a wind turbine the blade angle of
                          Message 12 of 29 , Apr 20, 2011
                            Hi Theo and Pierre,
                            Autogyros or Gyrogliders, wind turbines and helicopters are all related but are quite different.  With a wind turbine the blade angle of attack (AOA) tends to be negative (below 0 degrees). This negative angle directs the lifting force of the airfoil more into torque. With a helicopter the AOA is positive (above 6 or 8 degrees) Most of the force is directed to lift but of course needs to be powered around with a motor. An Gyroglider is the exact middle with a AOA from 2 to around 6 degrees.  The middle third of the rotor acts like a wind turbine and add torque and rotation to the system. The outer 1/3 of the disc act like a helicopter and adds lift.  The torque and the lift magically balance each other. The variable is the rotors RPM which goes up and down with the wind speed or the amount of wind collected.  (the rotor discs AOA or how much it is tipped into the wind)
                             
                            The problem as I see it, is a airfoils lift goes up or down as a function of the square of the wind speed. (actually cubed in theory).(this is true up to the point of the airfoils drag rise as it gets close to Mach 1, but that is another issue unique to rotors).  With concepts like Skywind power or Doug S. Super Turbine (TM) they are taking torque out of the autogyro rotor. Doing that they are slowing the rotor down and loosing lift by the square.  This is like stealing the goose the laid the golden egg and adds an complex control balancing act.  How much lift can you steal by tapping the torque of an gyroglider rotor before you fall out of the sky?. (the answer is not very much, if you ask a aurogyro pilot who has touched the rotor break in flight, not a recommended maneuver. Freeflight and tethered flight are quite different so it is not a perfect example.) One could say reeling out by 1/3 windspeed does the same thing with the ground gen, cross wind maneuvering helps bring some of the lift back.  (However, there is a big limiter to cross wind power and that is tether drag, which also goes up by the square (cube?) as the speed increases.  Having 2 to 4 tethers really adds killer drag. To fly fast, say 200mph like Makani or Ampex you need a short single tether under 1000 meters or the tether drag will be overwhelming. (I don't buy that they are only flying low because of the FAA)  At jet steam altitudes gentle shunting crosswind maneuvers can help with gyrogliders up to a point where they begin be a detriment due to the drag caused by the long fast moving tether.
                             
                            Letting the rotor free spin and find its natural RPM there is no concern about over speeding the generators so that control problem is not an issue. Also changing from wind turbine to helicopter and back as Joby, Skywindpower and Makani are proposing can be done but is very complicated with helicopter style swash plates, motor/generators and such.  If they are to work for months at a time without maintenance this mechanical complexity is an issue. The pure Gyroglider uses a bearing and some simple hinges in the hub making in mechanically robust concept working in almost pure tension.
                             
                            Concepts like the rotokite, Jobys latest auto rotation style patent, and other twin kites will work well at low line angles, low in the sky. From 0 to 45 degrees. Basically they are just working like a big tethered downwind wind turbines.  The same could be said for Makanis circle looping kites.  To go above 45 degrees they kind of need that middle third of a rotor adding torque into the system so it can drive the outer third back into the wind.  Also the hub (not just a tether connection between kites) is an  important component.  There is desymmetry of lift in a rotor.  The hub helps transfer torque generated on one side to the other keeping the system in balance. This I have learned this is critical especially at the start up.
                             
                            If you are satisfied with working 500 to 1000 meters with tether angles low to the ground (under 45 degrees) most of these concepts will work fine.   To go higher to the jetstream levels you need to get your single tether above 45 degrees or your line length gets crazy long and adds too much drag. We have found the gyroglider rotor with a ground gen is one way you can do that.
                             
                            The biggest question in the end is ROI.  If your ROI is 2x what a HAWT is, is there enough profit for the risk the investor takes or would the prudent investor just invest in twice as many HAWT and accept a lower more stable return.  With the SkyMill Gyroglider we are seeing a preliminary 4x improvement in ROI over HAWT in select locations. We find this very encouraging.
                             

                            Grant Calverley
                            360-378-6186



                            On Wed, Apr 20, 2011 at 6:11 AM, Pierre BENHAIEM <pierre.benhaiem@...> wrote:
                             

                            It seems that SkyMill Energy, Inc. shows a reel-out scheme where the autogyro is towing the drum working the ground generator,that like a kite (in reel-out scheme).Rotokite Sequoia | Patents and Rotokite could be defined as a sort of autogyro being a set of two opposite soft kites.In contrast the autogyro in Sky wind power (flygen,not reel-out) works both as kite and turbine.

                            PierreB

                            http://flygenkite.com


                            > Message du 20/04/11 14:36
                            > De : "Theo Schmidt"
                            > A : AirborneWindEnergy@yahoogroups.com
                            > Copie à :
                            > Objet : Autogyro and turbine mode [was: Re: [AWECS] Re: Open Source AWE Automation?]

                            >
                            >  

                            > Doug schrieb:
                            > ...
                            > > Since wind energy uses a rotor that's the same as a gyrocopter rotor, why
                            > > would you be talking about kites?
                            > ...
                            >
                            > Wind turbine sailboats use the rotor *either* unbraked in the autogyro mode as a
                            > sail, *or* as a turbine connected to a load. I'm wondering if this would be any
                            > different with AWE. I.e. a rotor would be *either* a kite *or* a turbine.
                            > Presumably a rotor could do both at the same time, but would it be better to use
                            > multiple rotors?
                            >
                            > Theo Schmidt
                            >



                          • Pierre BENHAIEM
                            Hi Grant, Great post.What is your opinion about this: Furthermore, as the cable becomes more aligned with the vertical the cable drag increases, requiring
                            Message 13 of 29 , Apr 21, 2011
                              Hi Grant,

                              Great post.What is your opinion about this:"Furthermore, as the cable becomes more aligned with the vertical the cable drag increases, requiring larger kites to compensate." ,p.12 Long-Term Laddermill Modeling for Site Selection - kyoto ... .
                              Can be it a problem for a very long cable near the vertical (even without or little crosswind motion)?
                               
                              PierreB 




                              > Message du 20/04/11 20:30
                              > De : "Grant Calverley"
                              > A : AirborneWindEnergy@yahoogroups.com
                              > Copie à :
                              > Objet : Re: Autogyro and turbine mode [was: Re: [AWECS] Re: Open Source AWE Automation?]
                              >
                              >  

                              >

                              Hi Theo and Pierre,

                              Autogyros or Gyrogliders, wind turbines and helicopters are all related but are quite different.  With a wind turbine the blade angle of attack (AOA) tends to be negative (below 0 degrees). This negative angle directs the lifting force of the airfoil more into torque. With a helicopter the AOA is positive (above 6 or 8 degrees) Most of the force is directed to lift but of course needs to be powered around with a motor. An Gyroglider is the exact middle with a AOA from 2 to around 6 degrees.  The middle third of the rotor acts like a wind turbine and add torque and rotation to the system. The outer 1/3 of the disc act like a helicopter and adds lift.  The torque and the lift magically balance each other. The variable is the rotors RPM which goes up and down with the wind speed or the amount of wind collected.  (the rotor discs AOA or how much it is tipped into the wind)

                              The problem as I see it, is a airfoils lift goes up or down as a function of the square of the wind speed. (actually cubed in theory).(this is true up to the point of the airfoils drag rise as it gets close to Mach 1, but that is another issue unique to rotors).  With concepts like Skywind power or Doug S. Super Turbine (TM) they are taking torque out of the autogyro rotor. Doing that they are slowing the rotor down and loosing lift by the square.  This is like stealing the goose the laid the golden egg and adds an complex control balancing act.  How much lift can you steal by tapping the torque of an gyroglider rotor before you fall out of the sky?. (the answer is not very much, if you ask a aurogyro pilot who has touched the rotor break in flight, not a recommended maneuver. Freeflight and tethered flight are quite different so it is not a perfect example.) One could say reeling out by 1/3 windspeed does the same thing with the ground gen, cross wind maneuvering helps bring some of the lift back.  (However, there is a big limiter to cross wind power and that is tether drag, which also goes up by the square (cube?) as the speed increases.  Having 2 to 4 tethers really adds killer drag. To fly fast, say 200mph like Makani or Ampex you need a short single tether under 1000 meters or the tether drag will be overwhelming. (I don't buy that they are only flying low because of the FAA)  At jet steam altitudes gentle shunting crosswind maneuvers can help with gyrogliders up to a point where they begin be a detriment due to the drag caused by the long fast moving tether.

                              Letting the rotor free spin and find its natural RPM there is no concern about over speeding the generators so that control problem is not an issue. Also changing from wind turbine to helicopter and back as Joby, Skywindpower and Makani are proposing can be done but is very complicated with helicopter style swash plates, motor/generators and such.  If they are to work for months at a time without maintenance this mechanical complexity is an issue. The pure Gyroglider uses a bearing and some simple hinges in the hub making in mechanically robust concept working in almost pure tension.

                              Concepts like the rotokite, Jobys latest auto rotation style patent, and other twin kites will work well at low line angles, low in the sky. From 0 to 45 degrees. Basically they are just working like a big tethered downwind wind turbines.  The same could be said for Makanis circle looping kites.  To go above 45 degrees they kind of need that middle third of a rotor adding torque into the system so it can drive the outer third back into the wind.  Also the hub (not just a tether connection between kites) is an  important component.  There is desymmetry of lift in a rotor.  The hub helps transfer torque generated on one side to the other keeping the system in balance. This I have learned this is critical especially at the start up.

                              If you are satisfied with working 500 to 1000 meters with tether angles low to the ground (under 45 degrees) most of these concepts will work fine.   To go higher to the jetstream levels you need to get your single tether above 45 degrees or your line length gets crazy long and adds too much drag. We have found the gyroglider rotor with a ground gen is one way you can do that.

                              The biggest question in the end is ROI.  If your ROI is 2x what a HAWT is, is there enough profit for the risk the investor takes or would the prudent investor just invest in twice as many HAWT and accept a lower more stable return.  With the SkyMill Gyroglider we are seeing a preliminary 4x improvement in ROI over HAWT in select locations. We find this very encouraging.


                              Grant Calverley
                              > 360-378-6186
                              >
                              >
                              >
                              >

                              On Wed, Apr 20, 2011 at 6:11 AM, Pierre BENHAIEM <pierre.benhaiem@...> wrote:
                              >

                               

                              > It seems that SkyMill Energy, Inc. shows a reel-out scheme where the autogyro is towing the drum working the ground generator,that like a kite (in reel-out scheme).Rotokite Sequoia | Patents and Rotokite could be defined as a sort of autogyro being a set of two opposite soft kites.In contrast the autogyro in Sky wind power (flygen,not reel-out) works both as kite and turbine.
                              >
                              > PierreB
                              >
                              > http://flygenkite.com
                              >
                              >
                              >

                              > Message du 20/04/11 14:36
                              > > De : "Theo Schmidt"
                              > > A : AirborneWindEnergy@yahoogroups.com
                              > > Copie à :
                              > > Objet : Autogyro and turbine mode [was: Re: [AWECS] Re: Open Source AWE Automation?]


                              > >
                              > >  

                              >

                              > > Doug schrieb:
                              > > ...
                              > > > Since wind energy uses a rotor that's the same as a gyrocopter rotor, why
                              > > > would you be talking about kites?
                              > > ...
                              > >
                              > > Wind turbine sailboats use the rotor *either* unbraked in the autogyro mode as a
                              > > sail, *or* as a turbine connected to a load. I'm wondering if this would be any
                              > > different with AWE. I.e. a rotor would be *either* a kite *or* a turbine.
                              > > Presumably a rotor could do both at the same time, but would it be better to use
                              > > multiple rotors?
                              > >
                              > > Theo Schmidt
                              > >

                              >


                              >

                              >


                              >
                            • Grant Calverley
                              Hi Pierre, This is really a Dave Lang question but I will try and make some sense of it. I think it might be that the sentence is a bit out of context or
                              Message 14 of 29 , Apr 21, 2011
                                Hi Pierre,
                                This is really a Dave Lang question but I will try and make some sense of it.
                                 
                                I think it might be that the sentence is a bit out of context or perhaps a translation problem. It is not very clear to me either.
                                 
                                What I think they  may be referring to a fixed length of tether.  Call it 1000 meters long.  If you look a both extremes, a horizontal 1000 meter long tether and a vertical 1000 meter long,  the vertical one will have much more form drag and similar surface drag then the one that is laying down horizontal, it experiences only surface drag and a very tiny tiny bit of form drag.
                                 
                                In the same paragraph you have these sentences which make sense if you consider the mix of form and surface drag the tethers are experiencing.

                                "It shows that for a fixed cable angle, increasing the kite altitude leads to a decrease in performance. This is due to the increase in cable length and therefore cable drag." (= more form drag and more surface drag) "Similarly, fixing the kite altitude and increasing the cable angle results in an increase in cable length and decrease in performance. " (= almost the same form drag plus more surface drag)

                                I may be reading this wrong still.

                                Grant


                                 
                                On Thu, Apr 21, 2011 at 12:44 AM, Pierre BENHAIEM <pierre.benhaiem@...> wrote:
                                 

                                Hi Grant,

                                Great post.What is your opinion about this:"Furthermore, as the cable becomes more aligned with the vertical the cable drag increases, requiring larger kites to compensate." ,p.12 Long-Term Laddermill Modeling for Site Selection - kyoto ... .
                                Can be it a problem for a very long cable near the vertical (even without or little crosswind motion)?
                                 
                                PierreB 


                                .


                              • Pierre BENHAIEM
                                Hi Grant, Thank for the explain.Following another question:is form drag really identical if the vertical (sine) is the same for two tethers in comparison but
                                Message 15 of 29 , Apr 22, 2011
                                  Hi Grant,

                                  Thank for the explain.Following another question:is form drag really identical if the vertical (sine) is the same for two tethers in comparison but the length of one tether is higher and so its angle is closer to the horizontal?It seems a component of negative lift could be integrated due to the angle in front of wind (the question is for all sort of AWECS).Simulations and experiments of tether drag according different (static,or crosswind with variations of angle,and also according to possible profiles of tether) configurations remains a big field of research.

                                  Note:the kite helping to carry the tether and situated above the kite power DaveS mentions as a solution can be a problem during reel-in phase.

                                  PierreB



                                  > Message du 22/04/11 01:06
                                  > De : "Grant Calverley"
                                  > A : AirborneWindEnergy@yahoogroups.com
                                  > Copie à :
                                  > Objet : Re: Autogyro and turbine mode [was: Re: [AWECS] Re: Open Source AWE Automation?]
                                  >
                                  >  

                                  >

                                  Hi Pierre,

                                  This is really a Dave Lang question but I will try and make some sense of it.

                                  I think it might be that the sentence is a bit out of context or perhaps a translation problem. It is not very clear to me either.

                                  What I think they  may be referring to a fixed length of tether.  Call it 1000 meters long.  If you look a both extremes, a horizontal 1000 meter long tether and a vertical 1000 meter long,  the vertical one will have much more form drag and similar surface drag then the one that is laying down horizontal, it experiences only surface drag and a very tiny tiny bit of form drag.

                                  In the same paragraph you have these sentences which make sense if you consider the mix of form and surface drag the tethers are experiencing.

                                  "It shows that for a fixed cable angle, increasing the kite altitude leads to a decrease in performance. This is due to the increase in cable length and therefore cable drag." (= more form drag and more surface drag) "Similarly, fixing the kite altitude and increasing the cable angle results in an increase in cable length and decrease in performance. " (= almost the same form drag plus more surface drag)

                                  I may be reading this wrong still.

                                  Grant


                                  >  

                                  On Thu, Apr 21, 2011 at 12:44 AM, Pierre BENHAIEM <pierre.benhaiem@...> wrote:
                                  >

                                   

                                  > Hi Grant,
                                  >
                                  > Great post.What is your opinion about this:"Furthermore, as the cable becomes more aligned with the vertical the cable drag increases, requiring larger kites to compensate." ,p.12 Long-Term Laddermill Modeling for Site Selection - kyoto ... .
                                  > Can be it a problem for a very long cable near the vertical (even without or little crosswind motion)?
                                  >  
                                  > PierreB 
                                  >
                                  >
                                  >

                                  .


                                  >

                                  >
                                • Grant Calverley
                                  Now this really is a Dave Lang question. Tether dynamics are very complicated. I think the core question is the form drag of an ellipse (cross section of the
                                  Message 16 of 29 , Apr 22, 2011
                                    Now this really is a Dave Lang question. Tether dynamics are very complicated.  I think the core question is the form drag of an ellipse (cross section of the the sloped tether) the same as a circle if they both have the same width projected to the wind.  Then you add in the extra surface drag, lift, and lift induced drag and the downward windage on the sloped tether .   Or you go fly a kite like Dave Santos suggests and get out your fish scales and seek what you can find out.
                                    Grant Calverley
                                    360-378-6186



                                    On Fri, Apr 22, 2011 at 1:41 AM, Pierre BENHAIEM <pierre.benhaiem@...> wrote:
                                     

                                    Hi Grant,

                                    Thank for the explain.Following another question:is form drag really identical if the vertical (sine) is the same for two tethers in comparison but the length of one tether is higher and so its angle is closer to the horizontal?It seems a component of negative lift could be integrated due to the angle in front of wind (the question is for all sort of AWECS).Simulations and experiments of tether drag according different (static,or crosswind with variations of angle,and also according to possible profiles of tether) configurations remains a big field of research.

                                    Note:the kite helping to carry the tether and situated above the kite power DaveS mentions as a solution can be a problem during reel-in phase.

                                    PierreB



                                    > Message du 22/04/11 01:06

                                    > De : "Grant Calverley"
                                    > A : AirborneWindEnergy@yahoogroups.com
                                    > Copie à :
                                    > Objet : Re: Autogyro and turbine mode [was: Re: [AWECS] Re: Open Source AWE Automation?]
                                    >
                                    >  

                                    >

                                    Hi Pierre,

                                    This is really a Dave Lang question but I will try and make some sense of it.

                                    I think it might be that the sentence is a bit out of context or perhaps a translation problem. It is not very clear to me either.

                                    What I think they  may be referring to a fixed length of tether.  Call it 1000 meters long.  If you look a both extremes, a horizontal 1000 meter long tether and a vertical 1000 meter long,  the vertical one will have much more form drag and similar surface drag then the one that is laying down horizontal, it experiences only surface drag and a very tiny tiny bit of form drag.

                                    In the same paragraph you have these sentences which make sense if you consider the mix of form and surface drag the tethers are experiencing.

                                    "It shows that for a fixed cable angle, increasing the kite altitude leads to a decrease in performance. This is due to the increase in cable length and therefore cable drag." (= more form drag and more surface drag) "Similarly, fixing the kite altitude and increasing the cable angle results in an increase in cable length and decrease in performance. " (= almost the same form drag plus more surface drag)

                                    I may be reading this wrong still.

                                    Grant


                                    >  

                                    On Thu, Apr 21, 2011 at 12:44 AM, Pierre BENHAIEM <pierre.benhaiem@...> wrote:
                                    >

                                     

                                    > Hi Grant,
                                    >
                                    > Great post.What is your opinion about this:"Furthermore, as the cable becomes more aligned with the vertical the cable drag increases, requiring larger kites to compensate." ,p.12 Long-Term Laddermill Modeling for Site Selection - kyoto ... .
                                    > Can be it a problem for a very long cable near the vertical (even without or little crosswind motion)?
                                    >  
                                    > PierreB 
                                    >
                                    >
                                    >

                                    .


                                    >


                                    >



                                  • benhaiemp
                                    I am trying different systems including small rotor from http://thehelicopterkite.tripod.com/ http://thehelicopterkite.tripod.com/ . Launching of such a rotor,
                                    Message 17 of 29 , Dec 26, 2014
                                      I am trying different systems including small rotor from http://thehelicopterkite.tripod.com/ .

                                      Launching of such a rotor, and also rotors from http://en.wikipedia.org/wiki/Autogyro 

                                      is difficuft, while launching a propeller is far more easier. 

                                      And SkyMill autogyro-like works cyclically by reel-in/out method needing some level of depower during reel-in phase.So I have some questions:

                                      • Is depower assured by variation of pitch of blades or aoa of disk ?
                                      • Is depower assured by stopping  or slowind down the rotor, and if it is, how is it possible to alternate cyclic (even partial) launching et slowing down?
                                      • Other

                                      PierreB

                                      http://flygenkite.com 

                                       

                                    • dave santos
                                      Pierre asked: - Is depower assured by variation of pitch of blades or aoa of disk ? - Is depower assured by stopping  or slowind down the rotor, and if it
                                      Message 18 of 29 , Dec 26, 2014
                                        Pierre asked: "
                                        • Is depower assured by variation of pitch of blades or aoa of disk ?
                                        • Is depower assured by stopping  or slowind down the rotor, and if it is, how is it possible to alternate cyclic (even partial) launching et slowing down?"

                                        Yes, either collective pitch or disc AoA can be used for depower. SkyMill began in favor of AoA modulation,  to avoid the mechanical complexity of a collective-pitch hub, but this can change if desired.

                                        Stopping  the rotor for low drag retract is a possible new idea that you pose here. A single "two-blade" rotor would have very low drag in a "javelin mode", so it could be a real contender in reeling circles. Many AWES autogyro cycles and operational modes are possible. SkyMill is supposedly active in stealth-mode, so its not publicly known what cycles and modes they are down-selecting.


                                        On Friday, December 26, 2014 3:32 AM, "pierre.benhaiem@... [AirborneWindEnergy]" <AirborneWindEnergy@yahoogroups.com> wrote:


                                         
                                        I am trying different systems including small rotor from http://thehelicopterkite.tripod.com/ .
                                        Launching of such a rotor, and also rotors from http://en.wikipedia.org/wiki/Autogyro 
                                        is difficuft, while launching a propeller is far more easier. 
                                        And SkyMill autogyro-like works cyclically by reel-in/out method needing some level of depower during reel-in phase.So I have some questions:
                                        • Is depower assured by variation of pitch of blades or aoa of disk ?
                                        • Is depower assured by stopping  or slowind down the rotor, and if it is, how is it possible to alternate cyclic (even partial) launching et slowing down?
                                        • Other
                                        PierreB
                                         


                                      • joe_f_90032
                                        http://www.ushawks.org/forum/viewtopic.php?p=8722&sid=717030de2919f8dfa02a9c1b58cfd408#p8722by RickMasters
                                        Message 19 of 29 , Dec 26, 2014

                                          Postby RickMasters » Wed Dec 03, 2014 4:34 am

                                          This was supposed to make parachutes obsolete. :lol: 
                                          Image
                                          Image
                                          Image
                                          Image
                                          Tests began at Ringway of the Mk.III in June 1942, with towed flights of around four minutes ending in controlled 
                                          landings. A totally free landing followed. The Rotachute was then towed behind a Tiger Moth until it, but not the tow aircraft, achieved takeoff. Further flights led eventually to towed air launches, the Rotakite reaching altitudes of up to 3,900 ft., and reaching 93 mph and flight duration of up to 40 minutes.
                                          http://www.fiddlersgreen.net/models/Air ... -Jeep.html

                                          That's a sink rate of less than 100 fpm!
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