FES vs Gas Engine – Finding a Thermal?

As a facilities, RC electric and automotive guy, beyond depleted batteries or really crappy wiring, the "no run" on electric is likely magnitudes better than any gas.
Regardless of FES or pylon.

The electric motor is a ton less, but current battery tech (no pun intended) makes the gas/electric swap (for similar power) a wash. The batteries take a lot of weight, but it's closer to fuselage centerline so the CG effect is limited.

Cost, well, how is it certified and how open is your aviation authority?
Engineering, like marriage, there is give and take, nothing is perfect. Make the best decision you can, live with any potential downside.

I don't think that there will be much drag from the erected but not turning pylon and prop of the GP 14/15 design. The blades are folded backwards and the pylon looks pretty aerodynamic. I think it is a brilliant concept - with the added benefit of being a self launcher rather than a sustainer. If the GP 15 was more advanced through the certification and a more known design I would be waiting for one now instead of for a Solo engines self launcher.

In my Solo 2350 powered 29E, I find it quite possible to recognize a thermal even though everything is vibrating and the vario readout is very nervous.. I try to circle with a constant speed and if the vario constantly is positive and I still have the impression (seat of the pants input) I'm in a thermal after 2 or 3 turns, I shut off the engine.

Of course only if situation (altitude, landout situation) permits.

Le vendredi 25 août 2017 08:37:15 UTC+2, a écritÂ*:
In my Solo 2350 powered 29E, I find it quite possible to recognize a thermal even though everything is vibrating and the vario readout is very nervous. I try to circle with a constant speed and if the vario constantly is positive and I still have the impression (seat of the pants input) I'm in a thermal after 2 or 3 turns, I shut off the engine.

Of course only if situation (altitude, landout situation) permits.

With my Ventus cM, I do exactly the same. I judge the quality of the thermal by the reading of the integrator value (and my seat pans); the TE probe sits in the propwash (haven't seen the necessity for a pneumatic switch during the last 10 years...) which makes the realtime vario reading fairly useless.

I'm with Dave Nadler on this; it's pretty easy to sense when
the Antares 20E is in a thermal even with the engine running.
Never flown a FES.
With a bit of practice sensing the thermal in the all-vibro-Solo
powered DG808 was possible too. I never bothered though,
just climb 5000+ feet, switch off and set off searching.

Dave N: Be interesting to know what on earth "plummet
mode" is in the Arcus M?

Dave Walsh

On Friday, August 25, 2017 at 10:15:06 AM UTC-4, Dave Walsh wrote:
Dave N: Be interesting to know what on earth "plummet
mode" is in the Arcus M?

Plummet-mode is when engine is extended and not running.
Not exciting in Antares or FES, a bit more so with turbos.
Exciting in gas-powered pylon self-launchers (engine/radiator drag).
ArcusM is not too bad - about 500fpm.
Some motorgliders are more like 800fpm which definitely focuses one's attention.

Planning for plummet-mode is especially important for safety during:
- departure route
- powered flight between landable areas
- shut-down activities
These engines have a very high failure rate and its truly exciting to have
a failure on departure - you better have your response planned in advance.
Power-plant retraction is also failure-prone, so advance planning about
when to give up and restart or land is advisable...

Hope that's clear!
Best Regards, Dave

Dave Nadler wrote on 8/25/2017 7:29 AM:
On Friday, August 25, 2017 at 10:15:06 AM UTC-4, Dave Walsh wrote:
Dave N: Be interesting to know what on earth "plummet
mode" is in the Arcus M?

Plummet-mode is when engine is extended and not running.
Not exciting in Antares or FES, a bit more so with turbos.
Exciting in gas-powered pylon self-launchers (engine/radiator drag).
ArcusM is not too bad - about 500fpm.
Some motorgliders are more like 800fpm which definitely focuses one's attention.

Planning for plummet-mode is especially important for safety during:
- departure route
- powered flight between landable areas
- shut-down activities
These engines have a very high failure rate and its truly exciting to have
a failure on departure - you better have your response planned in advance.
Power-plant retraction is also failure-prone, so advance planning about
when to give up and restart or land is advisable...

Fortunately for Schleicher self-launchers, the "plummet mode" Dave describes does
not exist. Glide ratio for my ASH 26 E is about 20:1 in the pattern with the pylon
up and gear down. It feels like I'm flying Blanik - nothing to worry about, and
the practical effect of landing with the pylon up means I use somewhat less
spoiler than with the mast retracted. Gliders with the "engine on a stick", like
PIK 20E, are strongly affected when the pylon is up.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf

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

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!