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  1. John.Roo

    What do you think about "e-soaring"?

    Thanks for detailed info 👍 Seems that best way is to follow your recommendation ;) "Honestly probably less work to build your own BMS than test someone else’s undocumented one enough to trust it."
  2. John.Roo

    What do you think about "e-soaring"?

    Yes I can... everyday I see arctile about fire of electric car (scooter, mobile during charging etc...). Fire of electric airplane would be very interesting for media....
  3. John.Roo

    What do you think about "e-soaring"?

    Good BMS is definitelly important - I agree. So far I have been using active BMS only during charging. During flight has been BMS monitoring temp of cells (not each cell, just paralelly solded packs). And in first prototype we had BMS in charger and separated temp sensors in battery case...
  4. John.Roo

    What do you think about "e-soaring"?

    Battery modules from BESTGO.... also interesting. Weight of battery 88,8 V nominal, 74 Ah (set from 4x 22,2 V packages) is 34,4 kg. https://www.bestgobattery.com/battery-modules.html
  5. John.Roo

    What do you think about "e-soaring"?

    Evwest is in US also offering interesting batteries.... https://www.evwest.com/catalog/product_info.php?cPath=4&products_id=481&osCsid=0796473dd8af2c09a961e1f4a9f4d8a5 Pitty that most interesting battery packs (above mentionned LG Chem and Tesla Smart) are not available...
  6. John.Roo

    What do you think about "e-soaring"?

    By the way... This looks like interesting offer.... I fount it on one Czech web with second hand parts. New pack from Hyunday Ionic - 2.41 kWh for 250 USD. Here are details about used cells...
  7. John.Roo

    What do you think about "e-soaring"?

    Thanks to very interesting post from addaon would be good to open one more question about batteries... It is better to use less bigger cells or more small cells? Some time ago I had very interesting discussion with engineers from Skoda automotive and they told me that they prefere large cells to...
  8. John.Roo

    What do you think about "e-soaring"?

    Very good observation 👍 Reason is simple - in the "middle" video was inside other pilot - much lighter than me. In third video (from different day) I had light tail wind and due to my weight I had CG position far in the front. So after we added more weight in the tail ;)
  9. John.Roo

    What do you think about "e-soaring"?

    Wow - you have definitely much more experience 👍 Our first electric airplane had LiFePO cells, but we quickly changed battery to Li-Po cells (year 2010/2011). Most of flights I did with 27S 5P (pouch cells 11 000 mAh, 3,7 V nom). Than we bought controller for higher voltage and I did some...
  10. John.Roo

    What do you think about "e-soaring"?

    Interesting 👍 For weight calculation I used this cell... https://shop.gwl.eu/LiFePO4-cells-3-2-V/ELERIX-LIFEPO4-battery-cell-Prismatic-3-2V100AH.html?cur=2 Peak discharge current 2C - 200 A for 30 sec. Max. discharge current 1C - 100 A. For horizontal flight I need 5 kW of power and for safe...
  11. John.Roo

    What do you think about "e-soaring"?

    I agree 👍 Idea was to show weiht difference and think about positives and negatives of both technologies. I would say that if weight penalty is acceptable (like in or case) than is better to use LiFePO cells - especialy in amateur homebuild conditions. However I have to answer one more...
  12. John.Roo

    What do you think about "e-soaring"?

    Students from Toronto University produced really flying prototype. But still not practically usable - during takeoff they needed help of tow car and flight was only short. Unfortunatelly videos you posted are not showing any practical advantage of "flaping wings". On first one we see glider...
  13. John.Roo

    What do you think about "e-soaring"?

    Good point 👍 No, it is only comparizon of weight of "pure cells" with +- same capacity. Prismatic LiFePO cells are easier to connect and only 18 cels are used. To have same capacity would be necesary to sold together 510 Li-Ion VTC6 cells = much more work (and possibility of mistake). For...
  14. John.Roo

    What do you think about "e-soaring"?

    Off topic..... One of most beautiful Czech glider 🤗 Aerobatic LF-107 Lunak (kite / hawk) General characteristics Crew: one Length: 6.78 m (22 ft 3 in) Wingspan: 14.27 m (46 ft 10 in) Wing area: 13.38 m2 (144.0 sq ft) Aspect ratio: 15.22 Empty weight: 205 kg (452 lb) Gross weight: 310 kg...
  15. John.Roo

    What do you think about "e-soaring"?

    LiFePO cells are more safe in compare with LiIon cells. Unfortunately they are also more heavy... So what would be weight difference? For example this 100 Ah cell... 18 cells = 18 x 3,2 V = 57,6 V (nominal) Voltage range / cell = 2,5 - 3,65 V Battery voltage range 45 - 65,7 V Capacity = 57,6...
  16. John.Roo

    What do you think about "e-soaring"?

    Nice dokument.... 👍 "When Dreams Take Flight is a film about dreams and dreamers, a film about people who are willing to risk life and limb to follow their hearts and chase a dream that has existed since the dawn of man. Watch as Todd Reichert, a student from the University of Toronto, trying...
  17. John.Roo

    What do you think about "e-soaring"?

    When e-Genius has been "only" battery powered, they did also nice flights 👍 Interesting info at the end of video.... First flight - 325 km distance and 40 kWh of energy has been used. Flight back - 365 km distance and 43 kWh of energy used. During both flights they flown at 4 000 m altitude...
  18. John.Roo

    What do you think about "e-soaring"?

    Henryk you know perfectly what means to fly 3-4 km in "ground efect" - you flown personally many times with hang glider ;) I can only repeat that in year 1866 even 30 meters flight would be great success. Article says that he was "jumping from bell tower" and during his last flight he crashed...
  19. John.Roo

    What do you think about "e-soaring"?

    Well.... every country has some legends. It they are true or not is difficult to say. I personally believe that in this case is really possible that pilot did some succesfull "jumps" or "short flights". Jan Wnek did his tests during practically same years like Otto Lilienthal. I can imagine that...
  20. John.Roo

    What do you think about "e-soaring"?

    That is possible.... maybe they used special solar panels... that would explain why is not "serial" produced Sunseeker Duo. However hybrid like e-Genius is not using any special technology. I hope that at least Elfin will make soon first flight....
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