What do you thing about "e-soaring"?

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

Help Support HomeBuiltAirplanes Forum by donating:

  1. Dec 5, 2013 #1

    John.Roo

    John.Roo

    John.Roo

    Well-Known Member

    Joined:
    Oct 8, 2013
    Messages:
    227
    Likes Received:
    164
    Location:
    Letohrad / Czech Republic
    Dear friends,

    In my “New Member Introduction” thread I mentioned one idea – “E-soaring as possible new competition class”. And I really would like to know your opinion.
    I personally believe that in future will rise little bit special competition class. You can see that electric systems (like FES for example) installed in gliders are already powerful enough to allow TakeOff. And then you have still some capacity for return to home airfield. But you can also use a little bit of powerto “increase” glider ratio. PhoEnix for example needs about 8 kW of power for horizontal flight. Adding just 2-4 kW you will not keep horizontal flight, but you significantly decrease rate of descent = increase “glider ratio” (I am not sure if I can use term “glider ratio” with powered flight).
    Of course then they come technical questions like - batteries with the same capacity for all e-gliders? Battery capacity depending somehow on Empty/Gross weight of e-glider? Bonus for capacity saved (measured after landing)? Etc.. however, this questions are just technical details.


    Main possible advantages:

    · Increased safety – you can use batteries and remaining capacity to go home/near airfield in case of emergency

    · No tow planes

    · Pilots can use different strategy how to manage the power

    · At the end (maybe) cheaper – you can achieve high L/D on “normal” gliders not increasing span and making “supergliders - expensive open class prototypes”

    And if we go even more to the future, one all above written is just first step. Later we can try to regen energy in thermals “windmilling” propeller and charging batteries in flight (electric motor can work like generator). This is something not possible for combustible engines :)
    Then is added one more tactical decision for pilot – spent time to recharge a little bit battery or gain altitude and go forward…


    Just dreaming with my morning coffee dear friends…


    But what you thing about this idea?

    Best regards!

    Martin
     
    dcstrng, Jan Carlsson, henryk and 2 others like this.
  2. Dec 5, 2013 #2

    Birdman100

    Birdman100

    Birdman100

    Well-Known Member

    Joined:
    Jun 12, 2013
    Messages:
    807
    Likes Received:
    186
    Location:
    Novi Sad, Vojvodina
    Like your idea very much!

    Especially that with windmilling in thermals. All that would add much more flying options during competitions, thus making tactics much more complicated. These competitions could be held in more diversity of places so increasing popularity of the sport(?)
     
  3. Dec 5, 2013 #3

    Jon Ferguson

    Jon Ferguson

    Jon Ferguson

    Well-Known Member

    Joined:
    Dec 15, 2011
    Messages:
    827
    Likes Received:
    382
    Location:
    Harpers Ferry, WV
    I like your idea too, it sounds like a lot of fun.
     
  4. Dec 5, 2013 #4

    Brian Clayton

    Brian Clayton

    Brian Clayton

    Well-Known Member

    Joined:
    Dec 7, 2012
    Messages:
    1,042
    Likes Received:
    529
    Location:
    Ivey, Ga and Centerville,Tn
    I have problems finding enough extension cords.....
     
  5. Dec 5, 2013 #5

    autoreply

    autoreply

    autoreply

    Moderator

    Joined:
    Jul 8, 2009
    Messages:
    10,732
    Likes Received:
    2,542
    Location:
    Rotterdam, Netherlands
    As they found out during the Green Flight Challenge, actually flying a glider, instead of a powered electric plane sometimes is faster...

    More span has and will probably always be the cheapest way to increase performance. A typical 3m extra span adds maybe 700-1000 euro's to the price of a racing class ship. You can't even buy a prop for that kind of money, let alone a single solar cell.

    Yes, modern open-class ships are very expensive. But that has little to do with the class. It's the eternal chain-reaction:
    Add engine=>more wing to carry that weight=>heavier fuselage, longer tail boom=>even bigger wing=>wing needs extra panels to fit in trailer=>more weight=>more span=>heavier tail=>

    Well, you see where that's ending ;-)

    For me, most of the sport is exactly the challenge of flying fast/far by using the weather/terrain. Opening up power would take all that challenge away. Not that a turbo/self-launcher wouldn't be nice..
     
    Matt G. likes this.
  6. Dec 5, 2013 #6

    Topaz

    Topaz

    Topaz

    Super Moderator Staff Member

    Joined:
    Jul 30, 2005
    Messages:
    13,848
    Likes Received:
    5,469
    Location:
    Orange County, California
    +1. This sums it up neatly for me, too. I love the idea of a self-launcher, or even a towed sailplane with a sustainer motor. Both allow me to explore lift that I might not look into without some kind of backup to get me up-and-away if it doesn't pan out. A self-launcher allows me to fly whenever I want, not just when a tow is available. As a self-employed person, sometimes holes open up in my schedule that don't necessarily coincide with my soaring club's operations schedule.

    But the reason soaring is fun is that it's a challenge. When I was training in powered airplanes, for the most part I found flying them pretty boring after my skills let me handle the airplane more-or-less competently. I've never been one to find fun or challenge in hitting a waypoint exactly on-time or making sure my pattern was at this airspeed and that altitude on this leg, and another set of precise numbers on the next. I don't want to be a machine. I don't disparage someone who likes that kind of flying - different strokes for different folks, to be sure - but it's not for me.

    Being able to "dial in" however much "lift" I want at any point in the flight just takes away a lot of the fun for me. Autoreply quite accurately pointed out why Open-Class sailplanes are so hideously expensive. It's a cascade effect.

    More interesting to me than "e-soaring" would be the mostly non-represented lower end of the soaring spectrum: Micro-lift gliders and wringing the highest possible performance out of, say, a Part-103 compliant homebuilt sailplane (see the SparrowHawk) seems like a better way to keep the costs "down" and the fun "up".

    Not saying "e-soaring" is a bad idea. I'm just saying that it doesn't suit me personally.
     
    Last edited: Dec 5, 2013
  7. Dec 5, 2013 #7

    Birdman100

    Birdman100

    Birdman100

    Well-Known Member

    Joined:
    Jun 12, 2013
    Messages:
    807
    Likes Received:
    186
    Location:
    Novi Sad, Vojvodina
    Auto & Topaz,
    That hypothetical new e-class wouldnt diminish the importance of other existing sailplane classes.
    They would still be out there, with pure non-powered gliders, e-soaring would be just another "option".

    You, Auto, stated that folded prop adds about 2% to overall drag, that is reduction from L/D =51 to 50! And of course there is still room to improve all that, aerodynamics (about prop and its folded position), as well the electronics.
    At the other side I feel that (if we fix the span) gliders came to a point of aerodynamic perfectness and it seems there is no much way to improve performance even more without some new revolutionary ideas.
     
    Highplains likes this.
  8. Dec 6, 2013 #8

    Topaz

    Topaz

    Topaz

    Super Moderator Staff Member

    Joined:
    Jul 30, 2005
    Messages:
    13,848
    Likes Received:
    5,469
    Location:
    Orange County, California
    Of course. But the OP asked what "we" thought about the idea. I don't think "e-soaring" shouldn't happen or is somehow a bad thing. I just said that it's not for me.
     
  9. Dec 6, 2013 #9

    ultralajt

    ultralajt

    ultralajt

    Well-Known Member

    Joined:
    May 10, 2009
    Messages:
    1,566
    Likes Received:
    750
    Location:
    Slovenia
    Windmilling while themal soaring? Khmm... :ponder:

    First of all, ordinary popeller made for propulsion is way different shape as it is usual windmil propeller blade.
    So use of the same propeller for both applications demands a prop with variable pitch. For windmilling the blade should pitch up for ~90° from nomal and the direction of motor shaft rotation became opposite. BUT the twist distibution along the blade length (local AOA) became WRONG! How to change wrong pitch distribution on a solid prop blade?
    Solving that problem is quite a challenging task. Maybe even impossible to make it practical, light and efficient for usage we talking about.

    Okay, by simplifying the prop, using symetrical blade airfoil and a blade without twist is doable, but the efficiency of that blade is ridiculous low.


    Regarding windmilling in thermals to charge batteries, we loose plenty of energy (efficiency of the prop, generator, chager, battery) and the gain is not so big that it could beat just extract that nature energy by pure soaring. We should take in concern whole cyle (thermal soaring gaining altitude in the thermall, and gliding to the next thermal)

    Mitja
     
  10. Dec 6, 2013 #10

    autoreply

    autoreply

    autoreply

    Moderator

    Joined:
    Jul 8, 2009
    Messages:
    10,732
    Likes Received:
    2,542
    Location:
    Rotterdam, Netherlands
    If it were a success.Which I highly doubt, see above reasoning.

    The FAI has had a long and distinguished list of failed new classes, I presume this would just be the next one.
    And twice that at high speed.
    Not sure about that one, but all the current classes are certainly nonsensical. Microlight, 13.5, std, 15M, 18M, 20M twins, 850 kg class. Commercial interest, forces new classes, but then manufacturers create sub-optimal models that do fairly well in multiple classes...
     
  11. Dec 8, 2013 #11

    John.Roo

    John.Roo

    John.Roo

    Well-Known Member

    Joined:
    Oct 8, 2013
    Messages:
    227
    Likes Received:
    164
    Location:
    Letohrad / Czech Republic
    Thank you – it is very interesting for me to see your opinions dear friends.

    The idea of to use power of lift is not that new as it looks like. I was thinking about that idea during designing of PhoEnix. Friends (glider pilots) asked me – why you don’t use regeneration of energy during descent. “Windmill prop” instead of use airbrakes and recharge batteries. Well if this will work during landing, why not in thermal lift? Therefore we produced our own propeller with not standard profile of blades and adjustable (instead of folding). Of course mechanically adjustable and with feathering possibility. With help of our friend Google I found also study from 2007/2008 about Regenerative Soaring Theory. Nobody so far approved/refused if it is possible. I had a plan to start series of tests, but not done so far… Flying with prototype means to go forward step by step (latest step was permission to retract the gear and make flights from one airport to other airport). During ground tests was easy to get a lot of energy (test done with our prop installed on roof of my car driving on normal roads with different speeds). But only after series of measurements during flight testing can be done final decision – YES makes sense because recharged capacity vs recharge time is reasonable / NO power we get is low and it would take too much time in one thermal… And since dreaming about what if result is YES I was thinking about possible impact in “normal private” soaring or “competition” flying.
    Big issue is safety factor. Most of RC KIT builders experience is that that LiPo cells are dangerous not during standard discharge (standard means 1-2C) but during quick recharge. Also is necessary to find out how this way if not really continuous recharging will affect life of cells….
    However, first of all we have to find out simple answer - is the efficiency of “thermal recharging” good enough for “normal” use or not?
    Best regards!
    Martin

    P.S.
    Link to Regenerative Soaring Theory
    http://www.howfliesthealbatross.com/Regen electric flight.pdf
    Wow - 2011 upgrade - I have to read it :)
     
  12. Jan 7, 2014 #12

    kennyrayandersen

    kennyrayandersen

    kennyrayandersen

    Well-Known Member

    Joined:
    Jun 7, 2011
    Messages:
    68
    Likes Received:
    6
    Location:
    Ft. Worth TX
    I've thought a bit about this and it would be nice to self-launch an Carbon Dragon-type light sailplane. The interesting thing for me might be a 10 minute launch with a 5 minute reserve so that you may not have to lug much battery. Unfortunately, I think the cost for most e-systems that I've seen is quite high IMO. Similarly, with a very light (nearly foot-launch-able) sailplane it might be possible to use a large model airplane ICE for much less money, assuming you are just trying to get the job done; however, restarting the ICE might be problematic (although that might be able to be worked around as well).
     
  13. Jan 8, 2014 #13

    Aircar

    Aircar

    Aircar

    Banned

    Joined:
    Feb 20, 2010
    Messages:
    3,567
    Likes Received:
    367
    Location:
    Melbourne Australia
    As noted this is not a new idea but yet to be put into operation --maybe one or two prototypes had tried such a thing . I published a paper in 1971 predicting the idea of storing energy other than by height (using the aeromill concept before it had a name --Paul MacCready published in Technical soaring on regenerative soaring in the 80s or thereabouts . NASA tested wing tip turbines on a related vein -recovering lost energy from tip vortex ,

    A propeller can be turned into a wind turbine by reversing the whole unit along a 'spanwise' axis --we used to retrieve a target drogue using a windturbine mounted on an external arm (Royal Australian Navy target practice contract ) --the camber has to face aft for this use of course.

    With an energy extractor you can stay in the strong lift band of a thermal and/or stay out of cloud if that is not legal or otherwise and allows to increase the effective rate of climb (presuming a reversible electric motor as generator and a light battery system --lithium air or aluminium air are the theoretical best but not sure about recharging feasibility. With a 'dribble' of power and no noise or vibration it would allow for supership performance without the extremes of handling and cost -- outlawing laminar flow airfoils on the basis that they confer an unfair advantage or require expensive construction would be just as 'pure' as outlawing a little other 'anti drag' .
     
  14. Jan 8, 2014 #14

    kennyrayandersen

    kennyrayandersen

    kennyrayandersen

    Well-Known Member

    Joined:
    Jun 7, 2011
    Messages:
    68
    Likes Received:
    6
    Location:
    Ft. Worth TX
    it would seems that energy is energy. if I'm regenerating the battery I'm extracting that from the system, so I'm decending faster, not gaining az much altitude, or trading speed etc. there is no free lunch!
     
  15. Jan 8, 2014 #15

    John.Roo

    John.Roo

    John.Roo

    Well-Known Member

    Joined:
    Oct 8, 2013
    Messages:
    227
    Likes Received:
    164
    Location:
    Letohrad / Czech Republic
    Absolutely right - in regen mode you are increasing drag of airplane significantly. It means your sink ratio will increase due to drag of windmilling prop. But this is "sponzored" by the thermal. I don´t think so you can really recharge during descent – too short time. But during day you may enter to strong thermal 4-5m/s for example. When you reach cloud base you stay there and with the same speed at the same altitude only with a lot higher descent rate you windmill your prop. With descent rate same like thermal lift you start to exchange energy of cloud to the energy in battery maintaining the same altitude.
    Main and most important question is – what efficiency of system we can reach? Makes sense to stay in thermal or “jump” to the other one?Maybe development of solar panels will solve the question and better will be to cover wing with solar panel and slowly recharge during whole flight.So far efficiency of solar panels is very poor, another problem is profile of wing not allowing to have the same angle for all solar cells and… well you can see how sophisticated system is for example Solar Impulse.Second step is how to use “extracted” energy. With small energy sponsoring (electric motor spinning prop and using 2-3 kW) you can increase “glider ratio”. It is little bit like to “climb higher then cloud base” J

    Health, happiness and only perfect landings in 2014 dear friends!



     

    Attached Files:

  16. Jan 8, 2014 #16

    bmcj

    bmcj

    bmcj

    Well-Known Member HBA Supporter

    Joined:
    Apr 10, 2007
    Messages:
    12,966
    Likes Received:
    4,910
    Location:
    Fresno, California
    What conclusions did they draw from this? Vortex energy is lost energy, and disruption (energy extraction) of the vortex has potentially beneficial effects (like the winglet does). Can you truly reduce the vortex by extracting energy, or does your extractor just break up one big vortex into many smaller ones of equal detriment?


    Yes, but up to a point (altitude), there may be more potential in just riding the thermal to a higher altitude rather than trying to store the energy electrically.

    Bruce :)
     
  17. Jan 9, 2014 #17

    Aircar

    Aircar

    Aircar

    Banned

    Joined:
    Feb 20, 2010
    Messages:
    3,567
    Likes Received:
    367
    Location:
    Melbourne Australia
    Bruce - look up the NASA wing tip turbine papers -- it certainly works for migrating birds but I have no idea what they concluded offhand, --secondly the strength of a thermal varies greatly as a function of height (the difference between the 'outside' air temp and the thermal --ie the ambient air and the lapse rate variation with height --determines ROC of the air --better to stay in the highest updraft rather than stooge around in the dregs at the inversion or work the weak lift down low.

    And as to not gaining anything from extracting in descent --we often pulled airbrakes at 7 or 8000 ft in club gliders after using up your alloted hour --that energy could be recouped with an aeromill.
     
  18. Jan 9, 2014 #18

    John.Roo

    John.Roo

    John.Roo

    Well-Known Member

    Joined:
    Oct 8, 2013
    Messages:
    227
    Likes Received:
    164
    Location:
    Letohrad / Czech Republic
    Just to explain small misunderstanding…The idea is to climb to cloud base. Without windmilling you can reach that altitude with optimal glider performance. Because there is no way to go higher (enter to cloud is not standard procedure) and thermal is strong, you can start to keep the same altitude and gain some energy exchanging lift in to the speed and brake down by windmilling = maintaining the same altitude and the same speed. This means my “climb higher than cloud base”. Sorry for my English J
    And about the descent using windmilling like brake….Yes, in case you go down from 7-8T feet then makes also sense. I was counting with normal comeback when pilots are at about 1 000 ft when arriving. Even less due to their high end glider computers J
    Anyway I would love to try it. In 2013 I had problems with regulator and at the end I damaged the motor in September. Now I am trying to involve some Aeronautical or Electrotechnical University - they have professional testing systems possibility. The main question will be – real efficiency of whole system. If we take optimistic values like 70% efficiency of propeller and 70% efficiency of electric motor in generator mode we have only 50% together. Then efficiency of recharge system… etc.
    Best regards!
    Martin
     
  19. Jan 18, 2014 #19

    JenDAG

    JenDAG

    JenDAG

    Active Member

    Joined:
    Apr 26, 2012
    Messages:
    36
    Likes Received:
    8
    Location:
    Czech
    Martin,
    it should be better to use for propulsion oprimized propeller, ideally foldable like Stemme prop. or RC models, and as air brakes use Ram Air Turbine (RAT) with optimized windmill propeller?

    Honza
     
  20. Jan 27, 2014 #20

    John.Roo

    John.Roo

    John.Roo

    Well-Known Member

    Joined:
    Oct 8, 2013
    Messages:
    227
    Likes Received:
    164
    Location:
    Letohrad / Czech Republic
    Hello Honzo,
    definitely good idea.
    Question is again efficiency + weight.

    The reason why I would like to have system “all in one” (motor working in generator mode using the same prop) is the weight.
    But true is, that well designed NACA air intake (probably with doors) leading air flow into tunnel with small generator would be able to give energy with good efficiency.Typical RAM (small turbine operating outside fuselage) will increase drag, however is again about efficiency. I wish to have possibility to cooperate with University or specialist in this project J
    Stemme is “Rolls-Royce” between motorgliders. Problem is only price and maintenance costs. In case of separated generator option would be probably easiest, „cleanest” and cheaper way to fold the prop along fuselage – like FES system.

    Anyway – thanks for your comment.
    If you are based not so far from LKUO we can meet to discuss
    J

    Best regards!

    Martin
     

Share This Page



arrow_white