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Re: [AWECS] Kite Carousel Mechanical Design

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  • dave santos
    Caro Massimo, I agree that autonomous kite flight must eventually reach the reliability you propose (of general aviation), but its strange to hear a
    Message 1 of 15 , Jan 6, 2011
      Caro Massimo,
       
      I agree that autonomous kite flight must eventually reach the reliability you propose (of general aviation), but its strange to hear a wonderful claim that its already come true. Even human-expert kite-pilots lose control of their wings, particularly in turbulent high or low conditions. You seem to be the only one experiencing & claiming kite reliabilty; perhaps its chance, somebody has to be the luckiest of the hundred or so experimenters. I crash all the time, but deliberately pushing the envelope, to make up for the fact that i only have ~3000 "technical" flight hours. Also, my smaller kites live faster & reveal freak failure modes sooner. Maybe your weather & simulation settings are milder than the conditions others experience. Don't you have any state-sensor uncertainty or actuator-bandwidth limitations?
       
      After decades of following robotics & controls, i know of no reliable automation system comparable to the kite application. All successful mass automation seems to only be low-dimensional mostly linear control, including autopilots/avionics. So what successful autonomous control applications have you identified as comparable to the kite problem?
       
      A circular track does contain a downwind-upwind displacement comparable to reeling. True, that a lever/crank rated to gigawatt scale will be fairly short, but thats good, as its the ratio of its length to the carousel's large diameter that provides a high step-up. But the KiteLab variant is a far smaller wheel than yours. Its a nice win if a "little" carousel, with the kites anchored around it, can do the same job,
       
      Saluti,
       
      daveS
       
       
       

      From: KITE GEN / Ippolito <m.ippolito@...>
      To: AirborneWindEnergy@yahoogroups.com
      Cc:
      Sent: Thursday, January 6, 2011 12:41:02 PM
      Subject: Re: [AWECS] Kite Carousel Mechanical Design

       

      Dear Dave,
      It is quite easy to align problems and doubt, less easy is look for, find and check solution.

      I disagree with your common sense axioms, the control science today is able to produce systems much more effective than human control.
      It is possible to stabilise a condition where a system crash, can only occurs in system failure conditions, both mechanical or electronics, but this is addressable by a well known procedure, adopted i.e. in aviation.
      The world is plenty of controls that cleverly do their job 24/7/365, but we typically become aware that something is automatically controlled only in case of failure. 

      Your statement saying  "a small cyclonic gust could affect the fly" reveal me that you never simulated in real time the fly of a controlled kite with the full lines management. I've certainly simulated, but also directly piloted for almost 1000 hours and implemented the first simple control on a real machine, called the mobilegen or KSU.
      The (double) tethered fly have the same reliability of a normal plane fly with additional opportunities, for example it is easy to get out quickly from a stall condition with a small reeling-in pulse or is available the side-slip manoeuvre to quickly get out from trouble, and more, the fly recovery after the side-slip offer a guaranteed successful upshot.

      I agree that it could be counter-intuitive, but the wind has a little importance in the manoeuvring precision, the kite could fly at 60 - 120(*)  m/s and the reference wind is 6-10 m/s,  a wind intemperance, including gusts, could at the maximum fluctuate few ten meters around the controlled path.     

      The solution to conduct to a central crank, assuming that you want to produce energy at a lower cost, will carry expensive problems in terms of mechanics and electrical machinery, Sorry for my bold opinion, but this was our early design then after a lot of thinking and brainstorming we abandoned that solution for the most credible, cheap, light, modular and technologically feasible ring.

      Massimo Ippolito

      (*) Belgian experimental C shaped kite, in aluminium foil (NCB)



    • Pierre BENHAIEM
      Massimo, Thank you for your precious indications and the compliment. About single/double line: I could not imagine such an explain.By chance it could be
      Message 2 of 15 , Jan 7, 2011
        Massimo,

        Thank you for your precious indications and the compliment.

        About single/double line:
        I could not imagine such an explain.By chance it could be positive for a furthering automatic version of the two lines
        Manual Flygen  (Youtube) for loading (model airplane,laptop...) batteries and also,with a quick launch of market as model airplane,to create a synergy with high-scale AWECS allowing an acceleration of their development.

        About storage,two different purposes:
        1) The availability you indicate :" ...Christina Archer and Ken Caldeira (Global Assessment of High-Altitude Wind Power) opinion  (build interconnecting devices that are geographically dispersed via ground-based transmission lines)...",also in response to a precedent remark by Dave North towards the necessity of great amounts of storage.
        2) Temporary small storage (hydraulic installations,supercapacitors...)for smoothing the production for a good quality of produced electricity before connexion to the grid.For reel-out systems it can be necessary because of the irregularity of produced power (the same for flygen,listen the variation of sound on Manual Flygen),and also to compensate the retrieval phase.A farm of reel-out allows avoiding a part of the temporary storage with global management of one farm.But Carousel configuration,with its continuous move of conversion system,takes a great advantage:a smoothing device is not needed.

        Pierre Benhaïem     





        > Message du 06/01/11 19:11
        > De : "KITE GEN / Ippolito"
        > A : AirborneWindEnergy@yahoogroups.com
        > Copie à :
        > Objet : Re: [AWECS] Re: Kite Carousel Mechanical Design
        >
        >  

        > Sorry, before I wrote an erroneous data, the passive phase of the KG Stem is one third the active instead is 2/3,
        > perhaps the big effort to read my English hide me the errors I'm introducing :-)
        >
        > Pierre,
        > Congratulations you are proposing the most interesting questions I ever received all gathered together.
        >
        > About the parasitic forces:
        > Considering a rope pitch mean angle of 45 degree and a mean yaw angle of 45  the tangential force is the cosine product, then half of the line forces.
        > I do not consider parasitic force, the radial resistance is promptly converted in kite speed, and the vertical component is useful to slight lift the carousel poles in order to activate a damping effect clipping all the forces exceeding the design requirement. The weight of the pole or mast is calibrated to actively counteract the vertical component. In the Carousel movie is difficult to see but a guy cable assert the tangential counterforce on the must.
        >
        > About the single/double line:
        > Let me introduce an analogy of signal theory domain, please consider the control actuation of the kite (line length differential), like an information transmission.
        > What are the problems affecting this signal communication?  One issue could be the delay or better defined the round trip time, the other could be the noise superimposed over the sent information.
        > The delay isn't an issue, the propagation time on the dyneema or vectran lines is about 200 millisecond/km, and the feedback to close the round trip is practically zero because the sensors aboard, are radio linked (light speed) to the ground control. In 200 millisecond the kite fly for 10 - 20 meters in a kilo-metric airspace volume.
        > The noise isn't again an issue, the two lines act as a balanced transmission media, the symmetrical information flow on the lines in phase opposition (antiphase) and the common mode noise is cancelled.
        > So in my opinion the claim of the need to actuate close to the kite is again a free and false intuition due to an insufficient methodic investigation.
        > Two lines from the security and safety point of view, are instead a paramount aids to pay with a very slight drag increment. 
        >
        > About Storage:
        > May be, I have missed some previous discussion, but let me know why, the Christina Archer and Ken Caldeira (Global Assessment of High-Altitude Wind Power) opinion  (build interconnecting devices that are geographically dispersed via ground-based transmission lines), isn't any more valid?
        > 200 km of distance to mutual extend the AWECS availability up to 95%, could be a very good result, nuclear reactors have an availability of 90%.
        > In my opinion this is a very effective solution to mitigate the concern about the wind intermittency.
        > Energy storage isn't any more an issue, really.
        > The atmosphere is an huge capacitor of 3000-4000 TWh of energy always available and permanently auto-recharged.
        >
        > thank you
        > Massimo Ippolto
        >
        >
        >
        >
        >
        >  
        >
        >
        >
        > On 06/01/2011 12.57, Pierre BENHAIEM wrote:

        Massimo,
        >
        > The shown "train" version of Carousel on the beautiful video lets an important diminution of strengths on the structure in rapport to the first version with "levers".
        >
        > As you know with figure-eight (or others)kites deliver a good tangential force (that producing torque),and also variable bad axial (towards the top) and radial (towards sides) forces according to the angle of flight in rapport to the horizontal plan and to the ring direction.Its not a great problem if angles are not too high.But with a reel-out/in system (Stem) it is possible to avoid parasitic forces with a good permanent orientation of the moving part of the ground station according to the path of kite.
        >
        > For electric production Carousel has the great advantage of continuous and regular motion:a temporary storage (different of furthering needed great storages) is not necessary;it is not the case for reel-out because 1) cyclic irregularity of power according to kite position in the flight window 2) retrieval phase with motor production;compensation between unities can limit the problem but it seems that a temporary storage will be necessary.
        >
        > You pointed on your patents the double use (power,steering) of winches with losses,that from reel-out in rapport to Carousel where the winches are only for steering.Several questions:is it possible to make a good control with very long lines?Other technologies like Skysail or TuDelft an Ampyx advocate a single line and steering control near the kite?
        >
        > David North makes a good remark for possible perturbation of the grid with wind energy and indicates the necessity of great storage (for example why not pumping-turbinage).Morever no grid could support enormous variations from GW scale AWECS.
        >
        > So are AWECS impossible for great amounts of energy?
        > Yes and no.
        >
        > Why not for a complete global change of policies where coal plants would work as energy storage for adjustments (a little like in German where wind is about 20% and coal 80% but with reverse proportions).For this way competitor solar energy would become a friend as (enough) predictive energy.
        >
        > So GW scale AWECS like Carousel should be presented into another definition of global energy mix for 2050.
        >
        > At World Energy Congress Fatih Birol (IEA) gave a favorable answer to my question about HAWE.In some papers he indicates a necessary "revolution" because of depletion of fossil sources.
        > A good thing if you can work with him.
        >
        > PierreB  
        >
        >
        >
        >
        >
        > Message du 06/01/11 09:16
        > > De : "KITE GEN / Ippolito"
        > > A : AirborneWindEnergy@yahoogroups.com
        > > Copie à :
        > > Objet : Re:[AWECS] Re: Kite Carousel Mechanical Design
        > >
        > >  

        > > Pierre,
        > > You're right on the two geometrical parameters, but the specific power of the Carousel is several times more than reel out/in system and in terms of energy is even better.
        > >
        > > Reeling out method imply to waste some wind speed to reach the operational force and then the the excess wind will progressively produce energy.
        > > Carousel is fully operative with the base wind speed, in case of stronger wind the Carousel modulate reducing the airspace path effectiveness.    
        > > The reeling in/out cycle affect the generation continuity, the active phase is roughly limited to a third of the time.
        > > Power is Velocity  * Force, The Stem configuration is prominent in force to energy conversion, Carousel in speed to energy.
        > > More speed imply less relative force, smaller ropes, smaller control winches, better aerodynamic of the wing and ropes, more structural lightness, much more ERoEI. 
        > > Better aerodynamic imply lower base (nominal) wind speed, this extend dramatically the yearly availability.
        > > In the Stem the control winches pilot the kites and produce energy, in the Carousel the alternator ring produce the energy and the winches pilot and manage the kites operations, a further gain in efficiency, durability and  ERoEI.
        > >
        > > Stacked kites aren't the better solution, it is required an active attitude trimming that continuously adapt the array behaviour,
        > > the aerodynamic improvement approach based on a single wing is in my view, is the most effective.
        > > pls. have a look of the Carousel offshore in this movie (minute 6.20)  
        > > http://www.youtube.com/watch?gl=IT&v=HMQwYkZEaMk
        > >
        > > The ERoEI of Stem configuration is certainly much lower than the Carousel, but in any case is still huge: 350 
        > >
        > > Massimo Ippolito
        > >
        > > On 06/01/2011 0.36, Pierre Benhaiem wrote:

        It seems that the three ratios of land,space area and space volume occupation/power are identical for KiteGen Carousel and farms of KiteGen Stem (reel-out),and also for other systems like OrthoKiteBunch...For example on a vertical plan of swept area you have one kite or one array of kites for Carousel;and for a Stem-farm the same vertical plan is divided into two or more successive sections,that for an identical total length of tethers*.  Other subject,questions for Carousel:is not it a problem for an array of kites that the speed of kites in the top are higher when figure-eight are realized?The total length of such an array could be calculated according to an estimation of wind gradient?  PierreB   Note*:the ratio of land occupation/power,generally good for AWECS, is not the only one.It is necessary to take into account the whole (space) area according to the length of tethers and the variability of wind direction,and also the space volume which is taken from aer ial circulation.      --- In AirborneWindEnergy@yahoogroups.com, dave santos  wrote:   
        The well-known KiteGen Carousel concept involves teaming up multiple     
        stacks of "pumping" phased power kites to turn a giant turntable. There are two major challenges to resolve; first there is the need to keep the kites clear of each other & the ground, for if they foul a terrible mess can result; & second, the "grunt" power of kites & a slowly moving carousel is far from the high-speed rotation practical electrical generators require.   
        Both KiteLab & the Guangdong AWE group have figured out that one can     
        run radiating cableways from a central location to allow properly spacing any number of kites to all contribute power together. In particular KiteLab envisions a sort of central sunken crank-&-wheel carousel, like a giant unicycle laid on its side, with many kite-driven cables fanning-in from acros the kitefield to drive the crank. The carousel would turn with great power, but at low rpm. The rim of the carousel wheel would carry large generators turning at high rpm as "planetary gears". One might make such a super wheel as a cheap earth-banked high-speed circular train track with circling COTS TGV (bullet train) engines in regenerative-braking mode (motoring to get up to speed), or large industrial generators custom-set as planetary wheels, the rim driven by torque transmitted by wire rope spokes from the hub & crank, just like the unicycle model. The crank would be built   
        like a large steel-truss side-drawn bridge.  What a sight such a carousel in operation would be! This concept also     
        applies to tapping coastal ocean currents & scales to the very limits of civil & mechanical engineering, to multi-gigawatt output comparable to the largest power projects.   
        CoolIP      
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        > >
        >

        >
      • mmarchitti
        Dave, modern combact aircraft like Typhoon are intrinsically unstable: even in a straight and level flight in calm weather condition, they cannot be controlled
        Message 3 of 15 , Jan 7, 2011
          Dave, modern combact aircraft like Typhoon are intrinsically unstable: even in a straight and level flight in calm weather condition, they cannot be controlled only by human input, without the aid of a flight control system and computer.

          --- In AirborneWindEnergy@yahoogroups.com, dave santos <santos137@...> wrote:
          >
          > Caro Massimo,
          >
          > I agree that autonomous kite flight must eventually reach the reliability you propose (of general aviation), but its strange to hear a wonderful claim that its already come true. Even human-expert kite-pilots lose control of their wings, particularly in turbulent high or low conditions. You seem to be the only one experiencing & claiming kite reliabilty; perhaps its chance, somebody has to be the luckiest of the hundred or so experimenters. I crash all the time, but deliberately pushing the envelope, to make up for the fact that i only have ~3000 "technical" flight hours. Also, my smaller kites live faster & reveal freak failure modes sooner. Maybe your weather & simulation settings are milder than the conditions others experience. Don't you have any state-sensor uncertainty or actuator-bandwidth limitations?
          >
          > After decades of following robotics & controls, i know of no reliable automation system comparable to the kite application. All successful mass automation seems to only be low-dimensional mostly linear control, including autopilots/avionics. So what successful autonomous control applications have you identified as comparable to the kite problem?
          >
          > A circular track does contain a downwind-upwind displacement comparable to reeling. True, that a lever/crank rated to gigawatt scale will be fairly short, but thats good, as its the ratio of its length to the carousel's large diameter that provides a high step-up. But the KiteLab variant is a far smaller wheel than yours. Its a nice win if a "little" carousel, with the kites anchored around it, can do the same job,
          >
          > Saluti,
          >
          > daveS
          >
          >
          >
          >
          >
          > From: KITE GEN / Ippolito <m.ippolito@...>
          > To: AirborneWindEnergy@yahoogroups.com
          > Cc:
          > Sent: Thursday, January 6, 2011 12:41:02 PM
          > Subject: Re: [AWECS] Kite Carousel Mechanical Design
          >
          >
          >  
          > Dear Dave,
          > It is quite easy to align problems and doubt, less easy is look for, find and check solution.
          >
          > I disagree with your common sense axioms, the control science today is able to produce systems much more effective than human control.
          > It is possible to stabilise a condition where a system crash, can only occurs in system failure conditions, both mechanical or electronics, but this is addressable by a well known procedure, adopted i.e. in aviation.
          > The world is plenty of controls that cleverly do their job 24/7/365, but we typically become aware that something is automatically controlled only in case of failure. 
          >
          > Your statement saying  "a small cyclonic gust could affect the fly" reveal me that you never simulated in real time the fly of a controlled kite with the full lines management. I've certainly simulated, but also directly piloted for almost 1000 hours and implemented the first simple control on a real machine, called the mobilegen or KSU.
          > The (double) tethered fly have the same reliability of a normal plane fly with additional opportunities, for example it is easy to get out quickly from a stall condition with a small reeling-in pulse or is available the side-slip manoeuvre to quickly get out from trouble, and more, the fly recovery after the side-slip offer a guaranteed successful upshot.
          >
          > I agree that it could be counter-intuitive, but the wind has a little importance in the manoeuvring precision, the kite could fly at 60 - 120(*)  m/s and the reference wind is 6-10 m/s,  a wind intemperance, including gusts, could at the maximum fluctuate few ten meters around the controlled path.     
          >
          > The solution to conduct to a central crank, assuming that you want to produce energy at a lower cost, will carry expensive problems in terms of mechanics and electrical machinery, Sorry for my bold opinion, but this was our early design then after a lot of thinking and brainstorming we abandoned that solution for the most credible, cheap, light, modular and technologically feasible ring.
          >
          > Massimo Ippolito
          >
          > (*) Belgian experimental C shaped kite, in aluminium foil (NCB)
          >
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