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#81
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Which 18m FES sailplane to buy?
Dne sreda, 28. november 2018 05.01.09 UTC+1 je oseba 2G napisala:
On Tuesday, November 27, 2018 at 12:22:06 PM UTC-8, wrote: On Tuesday, November 27, 2018 at 2:26:46 PM UTC-5, Matt Herron (Sr) wrote: Hi John: I'm 5'7", so I can't help you on fit. But I found both the LAK17 and the Mini completely comfortable, and I think there was extra room beyond my personal dimensions. The 17 and the Mini essentially have the same fuselage, so if you've ever sat in a 17, you would probably find the Mini about the same fit. As for batteries, I assume one could get support through US/Canadian distributor, but my guess is that any serious repairs would have to come from LZ in Slovenia. As you probably know, LZ recalled all FES batteries for inspection and upgrade following the two battery fires. Here's what I wrote about that issue for Soaring: In accordance with a Modification Bulletin issued by the European Aviation Safety Agency (EASA), the LAK factory has reinforced the battery pack housing with flame retardant fiberglass, installed an independent fire warning system, and added a safety valve smoke vent to the battery compartment cover. The FES system has been with us for about eight years now. During this time some 180 gliders have been fitted with the engine, either as self-launch or sustainer. /There have been no reported engine failures in flight./ However, there have been two fires involving the lithium polymer battery packs at the heart of the FES system. One happened during a landing in the UK and was extinguished after the pilot exited the glider safely. The pilot reported that one of the battery packs had previously been dropped, which could have damaged one or more of the lithium cells. The other fire occurred in a trailer where the batteries had been stored with the units still connected, a big “no no“ according to FES maintenance manuals. While the exact cause of the fires has not been determined, any fire involving lithium batteries can be extremely serious – these units pack a lot of energy and must be handled with respect. In response to the fires, LZ Design, the Slovenian manufacturer of the FES system, has recalled all the battery packs for disassembly and inspection. LZ is checking for the suspected presence of small metal shards, a possible by-product of machine work on the battery case cover. Since the individual lithium cells are housed in plastic bags rather than hard cases, if a shard were present it would be possible for it to migrate during battery usage and penetrate a lithium cell, potentially causing a short and a resulting fire. After each inspection is complete, LZ re-installs all the lithium cells in a solid matrix of silicon gel, which should correct the problem. Regards, Matt Herron 3 fires. One in the US UH I went to the FES presentation in Reno this year. I was unimpressed in the resolution of the fires that have occurred (I am an electrical engineer), especially in not acknowledging the third fire. My advice is to wait until the root cause of these fires has been conclusively identified. Having a parachute (as one friend of mine opined) is not an adequate backup plan. Tom Dear Tom, I think you did not listening carefully, as it was mentioned. The problem with 3rd fire was that owner of the glider was informed and asked by the factory not to use his batteries. So this this 3rd fire could be easily avoided, but he could not resist to use his batteries. This happened when we already had a solution and it was part of the same problem, which could be easily avoided. Regards, Luka |
#82
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Which 18m FES sailplane to buy?
Hi Luka,
thanks for joining this discussion. While refurbishing the batterypacks you have seen all these packs after years of use. Do you think, that these swarf were causing the fires? Or what do you think was the root cause of the fires? greets Lukas |
#83
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Which 18m FES sailplane to buy?
Dne sreda, 28. november 2018 13.08.23 UTC+1 je oseba napisala:
Hi Luka, thanks for joining this discussion. While refurbishing the batterypacks you have seen all these packs after years of use. Do you think, that these swarf were causing the fires? Or what do you think was the root cause of the fires? greets Lukas Hi Lukas, Based on our initial tests and final tests from AAIB (they made also vibration test) where metal swarfs were placed between the cells and pressed together, we do not think that swarfs were the reason of thermal runaway as it was my initial theory. Our inspection of the cells during refurbishing process of battery packs further excluded swarfs as the reason. After all the work on battery packs, it seems to me that that root cause might be galvanic corrosion at pouch cell edges, which appeared in some special circumstances. We isolate all pouch cell edges and installed additional isolation material between the cells. Cells are now installed into new housing, which is fully non-conductive and much stronger. We doubled thickens of walls as we found out that many packs were mechanically damaged. New housing is high temperature resistant, to prevent housing failure in worst case of thermal runaway. We tested new arrangement with intentionally created internal shortcut at 50% level of charge and at 100% level of charge. In each test case there was no fire anymore, and new housing withstand the pressure. And we did much more than that. New SS housing for further protection during transportation of battery packs, become standard equipment. As we received many packs fully charged we introduced also FES discharger assistant as standard equipment etc. It is getting late, so I need to get some rest now, so that tomorrow I can do some more work regarding further FES development and improvements Kind regards, Luka |
#84
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Which 18m FES sailplane to buy?
On Wednesday, November 28, 2018 at 3:53:44 PM UTC-7, Luka Žnidaršič wrote:
Dne sreda, 28. november 2018 13.08.23 UTC+1 je oseba napisala: Hi Luka, thanks for joining this discussion. While refurbishing the batterypacks you have seen all these packs after years of use. Do you think, that these swarf were causing the fires? Or what do you think was the root cause of the fires? greets Lukas Hi Lukas, Based on our initial tests and final tests from AAIB (they made also vibration test) where metal swarfs were placed between the cells and pressed together, we do not think that swarfs were the reason of thermal runaway as it was my initial theory. Our inspection of the cells during refurbishing process of battery packs further excluded swarfs as the reason. After all the work on battery packs, it seems to me that that root cause might be galvanic corrosion at pouch cell edges, which appeared in some special circumstances. We isolate all pouch cell edges and installed additional isolation material between the cells. Cells are now installed into new housing, which is fully non-conductive and much stronger. We doubled thickens of walls as we found out that many packs were mechanically damaged. New housing is high temperature resistant, to prevent housing failure in worst case of thermal runaway. We tested new arrangement with intentionally created internal shortcut at 50% level of charge and at 100% level of charge. In each test case there was no fire anymore, and new housing withstand the pressure. And we did much more than that. New SS housing for further protection during transportation of battery packs, become standard equipment. As we received many packs fully charged we introduced also FES discharger assistant as standard equipment etc. It is getting late, so I need to get some rest now, so that tomorrow I can do some more work regarding further FES development and improvements Kind regards, Luka Impressive! |
#85
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Which 18m FES sailplane to buy?
Good morning to all from a very grey and mushy Montreal,
I want to thank everyone for posting and sharing their experiences with those of us who are looking at buying some type of FES equipped sailplane down the road. Please keep this thread going with your own impressions on this most fascinating technological development. I especially want to thank Luka for jumping in and sharing the latest in 'forensic' battery research. If ever there was an authority on this advancement in green and very compact propulsion, it surely is him and his company. And while I am sensitive to the many challenges of developing this technology and bringing it to soaring community, my concerns are mainly to do with support of these high capacity storage devices once they reach foreign shores, far from the factories of both the glider, power plant AND battery manufacturers, in a galaxy far, far away....... From the sidelines of my club this past soaring season, I watched two fellow members and LAK 17b FES owner enjoy their 21m toy....WITHOUT the benefit of that rather expensive FES option. Now, these two fellows hardly need this technology, as their long distance flights attest to, and they do not seem hampered by the LAK (lack, get it?) of FES in the slightest, even under weak soaring conditions. However, even after you factor in the time to complete the investigation into the cause of the fires, issuance of the emergency Airworthiness Directive on the storage device, design and implementation of the manufacturer's supported battery box modification, I still find it very disturbing that these customers, after having spent some considerable coinage on this technology, were left high and dry without a suitable battery replacement, not to be found anywhere across North America. Now, it is all very nice for you folks living in Europe to simply send the defective or recalled units back from whence they came, but when a lithium device here is declared 'defective', it is essentially treated for what is, to wit, 'Dangerous Goods' under the act of the same name as set forth by various members if IATA, including Canada. So then, as this technology matures and improves every year, sometimes at a snail's pace, at others, leaps and bounds, my question is really a simple one, and back to the essence of the original post, which FES/Self-Launch sailplane is worthy of my consideration? The next time a problem with the storage unit is encountered, and let us be frank, problems WILL be encountered, even if it isn't traceable to a design or manufacturing flaw, who will come to my rescue with a replacement battery, if only a temporary or loaner unit, to at least see me through the very short gliding season in my region? Batteries in service, even with the best of care, have a hard life. They get dropped. The get left outdoors by the trailer or vehicle, in the sun and the rain. They get left on cold concrete floors or in trailers. They are left unattended on chargers for extended periods of time.......I digress, this has all been covered before, and there are very clear directives issued by Luka and others on what NOT to do with these batteries whilst in service, but mistakes still happen. What I don't understand, or much less accept, is how come there are no provisions here, ANYWHERE in North America, to send 'muy-rapido-express-now-or-better-yet-yesterday' replacement units when Murphy pays a visit? Surely, if the combined efforts of LAK, GP, Schempp-Hirth, Silent, and yes, LZ Design, can't provide for support of a these storage units, either by way of replacement units, or handling of defective units, or preferably both, the effort of marketing this development in North America will, I dare say, be 'rather difficult'. Thank you all again, and I look forward to more informative rebuttal. John Hebert |
#87
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Which 18m FES sailplane to buy?
OK, since you asked for rebuttals, how about this...?
How many FES equipped sailplanes are in North America?* How many replacement batteries do you think would be a reasonable number to be stored/maintained here?* Who will provide the time, labor, shop/storage space to maintain these units?* What is their shelf life?* Do you get my drift? I don't believe it would be economically feasible to have replacement/loaner batteries stored around the world though that would seem to me to be ideal.* A better approach, IMHO, would be to reduce or eliminate all of these ridiculous regulations which make it impossible to move these things around economically.* But figure the odds on changing regulations... On 11/30/2018 7:34 AM, wrote: Good morning to all from a very grey and mushy Montreal, I want to thank everyone for posting and sharing their experiences with those of us who are looking at buying some type of FES equipped sailplane down the road. Please keep this thread going with your own impressions on this most fascinating technological development. I especially want to thank Luka for jumping in and sharing the latest in 'forensic' battery research. If ever there was an authority on this advancement in green and very compact propulsion, it surely is him and his company. And while I am sensitive to the many challenges of developing this technology and bringing it to soaring community, my concerns are mainly to do with support of these high capacity storage devices once they reach foreign shores, far from the factories of both the glider, power plant AND battery manufacturers, in a galaxy far, far away....... From the sidelines of my club this past soaring season, I watched two fellow members and LAK 17b FES owner enjoy their 21m toy....WITHOUT the benefit of that rather expensive FES option. Now, these two fellows hardly need this technology, as their long distance flights attest to, and they do not seem hampered by the LAK (lack, get it?) of FES in the slightest, even under weak soaring conditions. However, even after you factor in the time to complete the investigation into the cause of the fires, issuance of the emergency Airworthiness Directive on the storage device, design and implementation of the manufacturer's supported battery box modification, I still find it very disturbing that these customers, after having spent some considerable coinage on this technology, were left high and dry without a suitable battery replacement, not to be found anywhere across North America. Now, it is all very nice for you folks living in Europe to simply send the defective or recalled units back from whence they came, but when a lithium device here is declared 'defective', it is essentially treated for what is, to wit, 'Dangerous Goods' under the act of the same name as set forth by various members if IATA, including Canada. So then, as this technology matures and improves every year, sometimes at a snail's pace, at others, leaps and bounds, my question is really a simple one, and back to the essence of the original post, which FES/Self-Launch sailplane is worthy of my consideration? The next time a problem with the storage unit is encountered, and let us be frank, problems WILL be encountered, even if it isn't traceable to a design or manufacturing flaw, who will come to my rescue with a replacement battery, if only a temporary or loaner unit, to at least see me through the very short gliding season in my region? Batteries in service, even with the best of care, have a hard life. They get dropped. The get left outdoors by the trailer or vehicle, in the sun and the rain. They get left on cold concrete floors or in trailers. They are left unattended on chargers for extended periods of time.......I digress, this has all been covered before, and there are very clear directives issued by Luka and others on what NOT to do with these batteries whilst in service, but mistakes still happen. What I don't understand, or much less accept, is how come there are no provisions here, ANYWHERE in North America, to send 'muy-rapido-express-now-or-better-yet-yesterday' replacement units when Murphy pays a visit? Surely, if the combined efforts of LAK, GP, Schempp-Hirth, Silent, and yes, LZ Design, can't provide for support of a these storage units, either by way of replacement units, or handling of defective units, or preferably both, the effort of marketing this development in North America will, I dare say, be 'rather difficult'. Thank you all again, and I look forward to more informative rebuttal. John Hebert -- Dan, 5J |
#88
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Which 18m FES sailplane to buy?
While I sypathize with Dan Marotta's point of view (and emphatically with John Hebert's) , I think a small dose of reality salts may be in order here.
1) Defective Lythium batteries are a SERIOUS fire hazard! And Lythium fires can be extremely intense. Would you want to schedule your trans Atlantic filght on an aircraft that due to “changing regulations” was carrying those defective batteries in its cargo hold? How would you feel if you were the captain of a container ship? Wonderful though those batteries are, they are still probably the Achellies Heel of the FES system. 2) The FES system (which I firmly believe to be the future of motor gliding) is still in its infancy. How large is the current FES customer base in North (South?) America? As that base expands, it may be reasoable to expect dealors to stock a limited supply of loaner batteries, Right now, probably not. 3) We all owe a debt of gratitude to the folks at LZ Designs for creating a remarkable advancement in glider power. Since it's inception the FES system has already gone through three design enhancements. And since Luca and his folks seem intent on further design improvements (rather than just sitting back and enjoying their profits), I think we can expect much innovation in a few short years. What will FES be like in ten years? |
#89
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Which 18m FES sailplane to buy?
AFAIK, there was no swapping batteries in Europe either, during the "crisis". All batteries were declared not-airworthy. The sailplanes could only fly as pure gliders.
I was deeply impressed by how short has been the time it took Luka to analyze the faults and then provide a solution, then have it approved by the authorities and finally return the FES systems to service. There are so many examples of much longer delays, lasting up to many years, for relatively simpler problems like (for example) the propeller hub failures on the Solo 2350C engine system as fitted to Antares and DG1000T. In many if not all aspects, auxiliary powered gliding has always been a bag of problems. That said, all my sailplanes are/were fitted with engines. Aldo Cernezzi |
#90
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Which 18m FES sailplane to buy?
Very good perspective, Matt.* Points that I did not consider.
On 11/30/2018 12:42 PM, Matt Herron (Sr) wrote: While I sypathize with Dan Marotta's point of view (and emphatically with John Hebert's) , I think a small dose of reality salts may be in order here. 1) Defective Lythium batteries are a SERIOUS fire hazard! And Lythium fires can be extremely intense. Would you want to schedule your trans Atlantic filght on an aircraft that due to “changing regulations” was carrying those defective batteries in its cargo hold? How would you feel if you were the captain of a container ship? Wonderful though those batteries are, they are still probably the Achellies Heel of the FES system. 2) The FES system (which I firmly believe to be the future of motor gliding) is still in its infancy. How large is the current FES customer base in North (South?) America? As that base expands, it may be reasoable to expect dealors to stock a limited supply of loaner batteries, Right now, probably not. 3) We all owe a debt of gratitude to the folks at LZ Designs for creating a remarkable advancement in glider power. Since it's inception the FES system has already gone through three design enhancements. And since Luca and his folks seem intent on further design improvements (rather than just sitting back and enjoying their profits), I think we can expect much innovation in a few short years. What will FES be like in ten years? -- Dan, 5J |
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