Which 18m FES sailplane to buy?

On 11/27/18 9:01 PM, 2G wrote:
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


The third fire was disclosed in one of the papers I read, it was about
40 pages on the testing and corrective actions that were being taken.

It did strike me as random shotgunning of fixes, replacing the carbon
fiber battery cases with fiberglass would seem to be minimally effective
for a lithium fire. Improving the terminal insulation, when terminal
insulation had no apparent involvement in the fires, may not do
anything. Hard to argue with an improved fire detection system, but
does nothing to prevent the fires.

-Dave