What do you thing about "e-soaring"?

Discussion in 'Soaring' started by John.Roo, Dec 5, 2013.

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  1. Jan 31, 2014 #21

    JenDAG

    JenDAG

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    Hello Martin,
    I thought that main point is use wind turbine as air brake. Then aditional drag of RAT is not problem, but of course it has weight penaly.
    Using motor/generator is best weight solution.

    Main key is efficiency drop of dual purpose propeller* if it is small or not significan in real life then go for it.
    Windward goes for dual purpose featherable prop on DuchHawk for Etlantic project (Etlantic One | Electric Airplane crossing Atlantic | Project , CAFE Foundation Blog — Information and discussion from the Comparative Aircraft Flight Efficiency (CAFE) Foundation.) so efficiency drop should be reasonable low.
    If so, I would go for variable pitch mechanical foldable prop (not naturaly as on FES) which folds into recess at fulelage skin, similar to Composit Airplanes -, for drag reduction during soaring.
    (links taken from https://www.homebuiltairplanes.com/forums/soaring/5888-folding-feathering-propellers.html)

    If you are not happy with dual poupose compromise then I would use two props for one motor/generator, one naturaly foldable for propulsion and one radialy foldable (could be translation movemet only) for generator mode.

    I'm living only 2:45h from Usti/O (Kralupy/V, Praha) and sometimes I visit Hradec K so we can meet at LKUO, but unfortunately I'm F* bussy at the moment.
    March or April should be more "relax", so if you will be still intereted in we can meet.

    Any news about PhoEnix project to share?
    Last news what I catch were Rozhovor: Martin.

    Best regards,
    Honza
    *(I'm not proppeller guru so I can't give you advice about it, but it is nice job for fluid mechanics heads from CVUT, VUT or UK MatFyz, I'm pure mechanical design engineer as controls system, landing gears, etc on Raven 257/Corvus 1F my last aero job, now big engines 2MW and more)
     
  2. Jan 31, 2014 #22

    saini flyer

    saini flyer

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    It is easy to talk about folding props than getting your hands on one... atleast for me!
    The S10 is out of question just on the price point and the VIVA guys never reply to emails .....

    The VIVA design is no longer owned by Composite aircrafts. It is the eVIVA now from Yuneec. So, does anyone know about the availability and pricing on the folding prop between 60-120 HP? Topaz has looked at this for a long time too and did'nt find any. The FES guys did email me back but their prop can only load 22KW power and the price is a few thousand euros for the combination prophub+prop.

     
  3. Jan 31, 2014 #23

    JenDAG

    JenDAG

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    I know about Topaz's need of "high" power foldable prop, I went thru all foldable prop thread, but I don't know about any manufacturer for his power range.
    This is caused by my opinion that folding props are relativaly new and rare in airplanes, not as in RC models, and they are used for sailplanes which not required so much powerful engine, where 22kW is enough. Each manufacturer developed own folding system to suit they own needs because there is no mass market for it at the moment as for normal fixed props. So if you need foldable hub you need to design, manufacture and test your own [​IMG], link to hub in foldable prop thread is good starting point. But this thread is not about foldable props, isn't it?

    Main poits are:
    is it possible to design efficient enough dual purpose propeller, if so foldable of featherable? - I vote foldable.
    could you regenerate reasonable amount of enegy during descent? - I think so.
    what is the gliding performance drop when regenerate, is it worth it? - I would like to know the answer.

    Regards,
    Honza
     
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  4. Feb 2, 2014 #24

    John.Roo

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    Hello dear friends,
    for 60 hp foldable prop you can contact WoodComp. Long time ago we produced prototype of foldable prop for HKS engine.
    But it was “forward folding” system (I thing Carat use similar on). For what airplane/engine you need foldable prop?

    I would personally also prefer folding prop. The only problem is that I also need to have possibility of in-flight adjustable blades.
    And this is real technical problem… therefore we have adjustable and feathering version.


    News in PhoEnix project?

    Since I “burned” motor during ground testing no news… Now we are producing new electric motor and definitely we will need new controller.

    And my dream is to begin on 18 meters wing extension for “Ultimate PhoEnix” version
    J
    “Two props” design sounds interesting. Season is slowly coming and I would love to make much more flight tests this year.
    With answers to all questions (glider ratio with/without regen, efficiency etc…) will be possible to go forward.


    Best regards!
    Martin

     

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  5. Feb 2, 2014 #25

    henryk

    henryk

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    -my fellow is working at S-10 like foldable propeller,but with electric\homemade\ motor...
    at first for JANTAR1 glider,but it is universal system.
     
  6. Feb 2, 2014 #26

    saini flyer

    saini flyer

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    John, I dod not see any mention of a folding prop on their website. The Carat is good for 50HP so looks like it is a custom job unless Henryk's buddy has a solution.



    I always thought that an electricmotor is essentially a great fit as you do not have to mess around with the whole constant speed prop issue ....but I guess that is not the case ... what am I missing :ermm:

    Can you give some more details of this prop design, size, pitch, for which powerplant, size of spinner. How will the air intake for rotax work with this?
    The S-10 does is as it has no issues with any cooling ducts etc upfront but if your engine is tractor.... :ponder:
     
  7. Feb 2, 2014 #27

    henryk

    henryk

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    -it is NOT for for IC ,but for electric motor in the nase...

    =its a pity=detailes solution is patend pending.\in fligt S10-like,but another=simpler=folding methode!\
     
  8. Feb 2, 2014 #28

    John.Roo

    John.Roo

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    Nothing to do with e-soaring, just one beautifull actual photo from Klaus Ohlmann.
    Without engine over Mt. Everest....
    Congratulations and best regards to Himalaya dear friend!
     

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  9. Feb 2, 2014 #29

    henryk

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    Last edited: Feb 2, 2014
  10. Feb 3, 2014 #30

    JenDAG

    JenDAG

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    It's just technical problem and it has technical solution, chalenging one but possible.


    It will go for 600g MTOW class or it could stay in 450kg MTOW class?

    Thanks, but it is also chalenging and still it has weight penalty and added mechanism complexity.
    It is more back up solution what I "pre-designed"
    if dual purpose propeller will have to big efficiency drop.

    Honza


     
  11. Feb 3, 2014 #31

    henryk

    henryk

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    =electric motor/generator can work in both directions+90 deg.blades rotation change from
    drive to windmilling regime...
     
  12. Feb 4, 2014 #32

    ultralajt

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    I propose that you took a propeller blade in your hand (any prop..real one or just a small RC model) and check again your change from drive to windmilling regime.
    You will see, that you cant have both, no mather how you turn the propeller blade....no matter the pitch rotation or direction of turns.

    If propeller is "normal" made for the plane propulsion, then rotating the pitch blade angle for 90° it really could became a windmill blade and it will rotate the main shaft in oposite direction. But looking closely on the propeller blade local airfoil angle of attack it is a mess!! The pitch distribution along the prop blade is totally wrong. So, such propeller acting as a windmill will have very mad efficiency. Using such thing on a glider with intensions to "harvest" energy from glider while thermalling, you will braking the glider more, than "harvested" energy worth.

    I will make a drawing to represent more graphically what I am talking about:

    prop-windmill-dellusion.jpg

    Try to draw vectors of two remained drawings for yourself... :)
    Simple rotating of the blade wil not work. You must change also the twist (local change of blade airfoil AoA). Such propeller dont exist yet.
    "Ivoprop" was somehow capable of small change of the twist by elastic blade structure and a torsion steel shaft from root to tke blade tip, but it was "ground" adjustable only, and change was really smal compared with what we are talking about to change from drive to windmill.
    As we are talking about efficiency, any deviation from the ideal could be usseless.

    Mitja
     
    Last edited: Feb 4, 2014
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  13. Feb 4, 2014 #33

    henryk

    henryk

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    =IVOPROP=twist change circa +- 10 deg,by in hub electromotor too...
     
  14. Feb 4, 2014 #34

    ultralajt

    ultralajt

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    But you need more than 10° and this will challenge the design of the blade.. probably not worth to do as it will rise complexity and cost.
     
  15. Feb 4, 2014 #35

    henryk

    henryk

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    http://www.ivoprop.com/images/inflightpartspic.jpg

    http://www.rotaryforum.com/forum/attachment.php?attachmentid=50127&d=1223275450

    Both models utilize the same carbon / graphite fiber blades with stainless steel leading edges. The blades are capable of pitch change 3 to 17 degrees on the tips or inches of helix advancement from 18" to 52".

    =sum attitude =circa 20 degrees...
     
  16. Feb 4, 2014 #36

    John.Roo

    John.Roo

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    Hello dear friends,
    first of all - I am very glad we are discussing.
    It is interesting to see your opinions and new points of view.

    For JenDAG – PhoEnix is calculated for MTOW 600 kg (Czech ELSA).

    Actually we have Empty Weight 276 kg (without batteries) and 326 kg (with 8kWh battery pack).

    Of course is VFR equipped, radio installed and with ballistic rescue system.


    And now about the “windmilling” prop….
    I don´t understand the picture with propeller profile.
    When flying without power we don´t change rotation direction and we also don´t change prop angle settings (90°).
    For better imagination - is the same situation like when you want to restart combustible engine in-flight without starter.
    When you fly fast enough, prop starts to rotate (the same direction like when driven by power from engine) and you only switch ignition on….

    Yes, I agree you can have profile more optimized for generator or more for power, however it is not necessary to change rotation direction.


    I thing that if energy “harvesting” can be interesting in case of cars recuperation during braking (seems that Tesla solved this problem somehow) we have to try it.
    If will be used only during descent for landing – still make sense to test it.

    Maybe we will only leave prop turning when plane is on ground (nose against wind direction = real windmilling)
    J

    Best regards!
    Martin
     
  17. Feb 4, 2014 #37

    henryk

    henryk

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    =the 5m/s wind and 1m^2 OPTIMAL propeller<50 W electric power...

    BTW=blade pitch for feasering="0",
    for propelling="-",
    for windmilling="+".
     
    Last edited: Feb 4, 2014
  18. Feb 4, 2014 #38

    JenDAG

    JenDAG

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    Does anyone have time to web search for more info about Windward propeller etlantic to Tackle the Atlantic – Both Ways!?

    Martin, I think that your success is staying on your availability and quality of fluid mechanics analysis for prop blades, other things like folding and pitch setting mechanisms are "just" a cream on the top of cake.
    Fingers crossed for your project.

    Some news from e-soaring:
    Silent 2 Electro Certified in Germany

    Honza
     
  19. Feb 5, 2014 #39

    henryk

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  20. Feb 5, 2014 #40

    John.Roo

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