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

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

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

On Wednesday, November 28, 2018 at 3:53:44 PM UTC-7, Luka Žnidarši� 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!

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

I bought into a LAK17BFES in the spring. Once the batteries were back from
LZ I have had a great time flying it in a mixture of XC and ridge flying.

The engine start is as easy as advertised and has taken some of the stress
away from some low level ridge running this autumn certainly! With a young
family the thought of a muddy field and the retrieve I probably wouldn't
have flown!

Anyway, I'm 6ft 2 and fit in the LAK fine. It seems to run pretty well
with V2s etc but when the lift gets weak it seemed to lose out a bit to the
JS1 I have been flying with (although Matt is a better pilot than I am -
but don't tell him I said that).

I can't talk about the "over the other side of the pond" issues relating to
transport but it is a thumbs up for the LAK/FES system so far in the 6
months I have owned one.







At 14:34 30 November 2018, wrote:
Good morning to all from a very grey and mushy Montreal,

I want to thank everyone for posting and sharing their experiences with
tho=
se 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
e=
ver there was an authority on this advancement in green and very compact
pr=
opulsion, 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
c=
ommunity, my concerns are mainly to do with support of these high
capacity
=
storage devices once they reach foreign shores, far from the factories of
b=
oth 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
fell=
ow 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
th=
is technology, as their long distance flights attest to, and they do not
se=
em 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
comp=
lete the investigation into the cause of the fires, issuance of the
emergen=
cy 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
batte=
ry replacement, not to be found anywhere across North America. Now, it is
a=
ll 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,
'Da=
ngerous Goods' under the act of the same name as set forth by various
membe=
rs if IATA, including Canada.=20

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
sa=
ilplane is worthy of my consideration? The next time a problem with the
sto=
rage 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
co=
me to my rescue with a replacement battery, if only a temporary or loaner
u=
nit, 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
g=
et 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
l=
eft unattended on chargers for extended periods of time.......I digress,
th=
is 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
sen=
d 'muy-rapido-express-now-or-better-yet-yesterday' replacement units when
M=
urphy pays a visit? Surely, if the combined efforts of LAK, GP,
Schempp-Hi=
rth, Silent, and yes, LZ Design, can't provide for support of a these
stora=
ge units, either by way of replacement units, or handling of defective
unit=
s, or preferably both, the effort of marketing this development in North
Am=
erica will, I dare say, be 'rather difficult'.=20

Thank you all again, and I look forward to more informative rebuttal.=20

John Hebert

OK, since you asked for rebuttals, how about this...?

How many FES equipped sailplanes are in North America?Â* How many
replacement batteries do you think would be a reasonable number to be
stored/maintained here?Â* Who will provide the time, labor, shop/storage
space to maintain these units?Â* What is their shelf life?Â* 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.Â* 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.Â* 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

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?

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

Very good perspective, Matt.Â* 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