FES vs Gas Engine – Finding a Thermal?

With the FES, the vario still shows sensible readings but will show
positive proportional to the power you've put in if the motor is
running. So you'll see climb rate going up in thermals (and down in
sink), and you can sort of guess there's a thermal there - reduce
power, see what happens. There's so little penalty to stopping the
motor and re-starting anyway, just whirl a little knob.

Now, if the FES controller and the vario (both LX) talked to each
other and we could have the vario FES-compensated, that'd be
pretty cool..!

You could even imagine a "get me home" mode which tried to
maintain altitude by adjusting power - so you could slow in lift and
extend the range.


At 20:28 24 August 2017, V1 wrote:
While reading the FES article in June Soaring (yes, I=E2=80=99m
behind in
m=
y reading), I noticed the author=E2=80=99s comment about
searching for a
th=
ermal while FES was running, then shutting down FES as he
started to
climb.=
This is a topic I don=E2=80=99t recall seeing discussed in any
FES vs gas
=
comparisons.

In my Solo-powered Ventus 2cxT, my experience has been that the
vibration
(=
and possibly disturbed airflow) caused so much wild gyration in the
vario
r=
eadings that it seemed pointless to try to determine if I was flying
into
r=
ising air, so I just climbed first, then shut down the engine and
started
a=
thermal search.

My question =E2=80=93 do others have experience to share about
their
abilit=
y to find thermals while a sustainer or self-launcher (either gas or
electr=
ic) was running? If electric has an advantage here, this could
reduce the
r=
un-time needed and conserve =E2=80=9Cfuel=E2=80=9D.=20

- Frank

My experience in the Electro mirrors Scott's, although he seems to be better at centering the low thermals than I! I'm usually closer to 30% battery used for a self launch.

On Friday, August 25, 2017 at 12:46:05 PM UTC-4, Tony wrote:
... I'm usually closer to 30% battery used for a self launch.

In Antares 20E (without charge+) I'm typically around 15% used.
Obviously depends on ballast load and how high...

On Friday, August 25, 2017 at 11:00:09 AM UTC-5, Shaun Murdoch wrote:


You could even imagine a "get me home" mode which tried to
maintain altitude by adjusting power - so you could slow in lift and
extend the range.


Best "get me home" mode is to shut off the motor and climb in the lift. :-)

Steve Leonard

At 18:09 25 August 2017, Steve Leonard wrote:
On Friday, August 25, 2017 at 11:00:09 AM UTC-5, Shaun Murdoch
wrote:


You could even imagine a "get me home" mode which tried to
maintain altitude by adjusting power - so you could slow in lift and
extend the range.


Best "get me home" mode is to shut off the motor and climb in the
lift.
:-)

Steve Leonard


:-)

Here in the UK, at the end of the day - when you need the FES, nature
isn't always enough... but it helps!

On Friday, August 25, 2017 at 2:00:07 PM UTC-5, Shaun Murdoch wrote:

:-)

Here in the UK, at the end of the day - when you need the FES, nature
isn't always enough... but it helps!

And sometimes, the FES isn't enough, either. Right, Tony? :-)

Steve Leonard

Twice in my FES career I have not been able to make it back home during a self retrieve. One after a self launch here in Kansas and the second turnpoint of a 300km triangle got washed out. The other time on the day of my day win last month in Hungary, where the last thermal of the day was 100km downwind of home.

Both times the FES got me to an airport where I was then able to get an Aerotow retrieve.

Alisport is working on an extra battery pack for the wings that will double the range and make it less likely that you will have the same experience as me

So, instead of, "the wind died" to a none sailplane pilot, you could say, "the battery died!"
Really leave them confused........;-)

BTW, great job by you and your team mates at that contest. Made us proud.

With my Ventus 2cxm, a pneumatic switch allows the tail TE probe to be switched to Static for the powered climb, which gives a jitter-free vario needle, which while not TE, allows thermals to be clearly recognized and circled in. When at a safe altitude and in a thermal, I stop the engine while continuing the same circle. I have fitted the optional engine brake, which allows the prop to be rapidly stopped from windmilling. I immediately start the prop retracting (I ignore the recommended (high-drag) cool down with prop extended) but after retraction I leave the doors open for a minute for muffler cooling. This minimizes the high-drag retraction period.

Another comment: the only vicious and totally-unexpected spin entry I ever have had in the normally-predicable ventus 2cxm, was when I got too slow while waiting for the prop to stop windmilling (before I fitted the engine brake). A characteristic to remember if trying an inflight start.

Another comment: the only vicious and totally-unexpected spin
entry I ever...

Well that sounds horrible! Are pylon powered sailplane
manufacturers required to demonstrate spin recovery with the
engine out and stopped?

Not flown a Ventus M of any type but this looks like another
example of poor systems design. If the engine retraction sequence
consists of switching off ONE switch (e.g. DG808) or moving one
lever (Antares) then the pilot has nothing to do but control the
airspeed. Many of these other self launch/turbo retract systems
look like an invitation to "finger trouble".