FES vs Gas Engine – Finding a Thermal?

[V1[_4_]]

While reading the FES article in June Soaring (yes, I’m behind in my reading), I noticed the author’s comment about searching for a thermal while FES was running, then shutting down FES as he started to climb. This is a topic I don’t 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 readings that it seemed pointless to try to determine if I was flying into rising air, so I just climbed first, then shut down the engine and started a thermal search.

My question – do others have experience to share about their ability to find thermals while a sustainer or self-launcher (either gas or electric) was running? If electric has an advantage here, this could reduce the run-time needed and conserve “fuel�.

- Frank

[Bruce Hoult]

On Thursday, August 24, 2017 at 11:29:01 PM UTC+3, V1 wrote:
> While reading the FES article in June Soaring (yes, I’m behind in my reading), I noticed the author’s comment about searching for a thermal while FES was running, then shutting down FES as he started to climb. This is a topic I don’t 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 readings that it seemed pointless to try to determine if I was flying into rising air, so I just climbed first, then shut down the engine and started a thermal search.
>
> My question – do others have experience to share about their ability to find thermals while a sustainer or self-launcher (either gas or electric) was running? If electric has an advantage here, this could reduce the run-time needed and conserve “fuel�.

I've only had ten or so flights in a Grob 109, but on as far as I can recall every one of them we shut down the engine once established in lift ... in some cases in thermals, or often in ridge lift just after (barely) clearing the trees at the end of the strip (which was on a plateau).

[Dave Nadler]

On Thursday, August 24, 2017 at 4:29:01 PM UTC-4, V1 wrote:
> My question – do others have experience to share about their ability to
> find thermals while a sustainer or self-launcher (either gas or electric)
> was running?

Sure, but it depends a lot on the glider and power plant.
In Antares I normally reduce power just after take-off down to 400-500fpm climb.
When I feel the first thermal, I make a circle to be sure.
If pretty sure, bring the power all the way back but do not shut down.
If I'm climbing one turn, I retract motor.
Typical altitude about 1000 ft, for example:
https://www.onlinecontest.org/olc-2.0/gliding/flightinfo.html?flightId=-1855578239
or a bit lower, with a brief boost after initial shutdown:
https://www.onlinecontest.org/olc-2.0/gliding/flightinfo.html?flightId=-1769203627
Try this in most motor-gliders and you'll kill yourself.

In ArcusM it is more difficult to feel the thermal, but in any case one
needs to go much higher for a safer shut-down (typically climb to 2500ft).
A thermal helps here but you still have to do the cool-down cycle and
plummet-mode during retraction (sometimes takes a couple tries).
And because of the plummet factor your search area is severely restricted
by the need to be close-in for an emergency return on failure.

In my prior motorglider was really hard to feel the thermals, and again
being gas powered with severe plummet mode, had to always go a lot higher.

> If electric has an advantage here, this could reduce the run-time needed
> and conserve “fuel�.

Absolutely, but ONLY if:
- there is lift near the launch point, and
- traffic permits low-level thermalling (while always maintaining
a safe emergency return plan).

Hope that helps!
Best Regards, Dave

[Dan Marotta]

It's pretty easy in the Stemme with the triple probe mounted to the
front of the nose cone, in front of the propeller.Â* All the soaring
instruments work as designed without interference from the prop. BTW,
the Stemme (used) costs less than the Arcus AND you can take a friend! :-D

On 8/24/2017 2:28 PM, V1 wrote:
> While reading the FES article in June Soaring (yes, I’m behind in my reading), I noticed the author’s comment about searching for a thermal while FES was running, then shutting down FES as he started to climb. This is a topic I don’t 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 readings that it seemed pointless to try to determine if I was flying into rising air, so I just climbed first, then shut down the engine and started a thermal search.
>
> My question – do others have experience to share about their ability to find thermals while a sustainer or self-launcher (either gas or electric) was running? If electric has an advantage here, this could reduce the run-time needed and conserve “fuel�.
>
> - Frank
>

--
Dan, 5J

[JS[_5_]]

Doesn't everyone with a SLSP do this every flight?
Worked fine in the ASH26E. CAI302 with electronic TE.
Seat of the pants input is useful too.
Vibration? That's for two-stroke users.
Jim

[Scott Manley[_2_]]

I fly an Alisport Silent 2 Electro (FES capable of self-launch).

I take off with full power, climb to a safe altitude, pull the gear up, reduce power to about 80%, and then cruise-climb looking for a thermal. When I find one, I start circling and continue to run the motor. This gets me up into the stronger part of the thermal more quickly.

When it is obvious the thermal is doing most of the lifting, I shut down the motor. With the FES, the shutdown is automatic after dialing the motor down below 1000 RPM (a couple counter-clockwise turns on the rheostat). The motor controller takes over, electronically brakes the motor/prop to a stop, and the blades fold back aerodynamically. The controller then positions the blades along side the fuselage by pulsing the motor.

I simply continue to work the thermal.

On any decent soaring day, I use about 20% of the battery capacity to launch and climb into a thermal, leaving 80% in reserve in case I do something stupid.

On more than one occasion, I have restarted the FES in flight when a thermal didn't pan out. One one flight, I had launched a little too early in the day and needed to restart/re-climb four times before the day started working. Fortunately, starting and stopping the FES is as simple as turning the volume up/down on a radio, minimizing pilot workload to near zero.

The pitot/TEC probe on the Silent 2 Electro is mounted high on the vertical stabilizer, clear of (above) the prop wash.

[[email protected]]

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.

[Tango Whisky]

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.

[Dave Walsh]

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

[Dave Nadler]

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

[Shaun Murdoch]

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
>
>

[Tony[_5_]]

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.

[Dave Nadler]

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...

[Steve Leonard[_2_]]

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

[Shaun Murdoch]

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!

[Steve Leonard[_2_]]

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

[Tony[_5_]]

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 :)

[Charlie M. (UH & 002 owner/pilot)]

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.

[[email protected]]

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.

[Dave Walsh]

>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".

[[email protected]]

On Saturday, August 26, 2017 at 12:15:08 PM UTC+2, Dave Walsh wrote:
> >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".

I've heard dozens of stories of pilots outlanding their motor gliders when the engine wouldn't start, to discover on the ground that they'd forgotten to switch the fuel on.

At some point you have to ask - is this a pilot problem or a design problem?

[[email protected]]

There is a need for a fuel shut off valve. But it's a pilot problem if the pilot

A) Doesn't do a short engine run of say 30 seconds before leaving gliding distance of the home airport.

B) Chooses to close the fuel valve in flight unless there is a serious need to.

C) Chooses to pass on the opportunities to use and follow checklists.

At some point better design isn't going to save those who can't or won't take steps to protect themselves or who wait until they have run out of time by getting too low.

[Dave Nadler]

On Saturday, August 26, 2017 at 6:15:08 AM UTC-4, Dave Walsh wrote:
> >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?

All pylon-drive machines suffer some degradation of tail effectiveness
because of the pylon wake, much worse with a big radiator as in gas
powered machines. The V2cm in plummet-mode is not real stable in yaw
with much reduced elevator and rudder authority, and I was specifically
warned to be extremely careful with this configuration...

[Dave Nadler]

On Saturday, August 26, 2017 at 8:23:08 AM UTC-4, wrote:
> I've heard dozens of stories of pilots outlanding their motor gliders
> when the engine wouldn't start, to discover on the ground that they'd
> forgotten to switch the fuel on.
>
> At some point you have to ask - is this a pilot problem or a design problem?

It is a design problem. A start checklist that seems quite trivial on the
ground becomes unmanageable when you're low, dehydrated, hot, stressed,
exhausted, trying to stay in save position for safe landing when the motor
doesn't start...

I worked with manufacturer and ILEC on this some years back.
The fuel shut-off is required for certification, even though
far more accidents have been caused by fuel valve in wrong position
than fire incidents (fire is why shut-off is required).
Work-around is fuel shut-off that normally remains "on", as is
done in ArcusM for example. That's not possible on some older
designs (for example, fuel can siphon through carb when motor
is in retracted position - don't ask me how I know).

Ergonomic design is not so easy!
The newer systems are MUCH better, but still leave room for screw-up...

[Jonathan St. Cloud]

Really wish the Lange or Lange type, electrical propulsion system was more widely adopted, for both self launch and sustainer, looks like a great design. I see Schemp-Hirth does offer an electrical Arcus on their web site, but have heard they can not deliver a glider with the the E motor. Schleicher is offering an electric sustainer with the new ASG-32 and the video of an FES ASW-27 self launching was amazing.


On Saturday, August 26, 2017 at 6:58:17 AM UTC-7, Dave Nadler wrote:
> On Saturday, August 26, 2017 at 6:15:08 AM UTC-4, Dave Walsh wrote:
> > >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?
>
> All pylon-drive machines suffer some degradation of tail effectiveness
> because of the pylon wake, much worse with a big radiator as in gas
> powered machines. The V2cm in plummet-mode is not real stable in yaw
> with much reduced elevator and rudder authority, and I was specifically
> warned to be extremely careful with this configuration...

[Dave Nadler]

On Saturday, August 26, 2017 at 9:30:12 AM UTC-4, wrote:
> ...it's a pilot problem if...
> At some point better design isn't going to save those who can't or
> won't take steps to protect themselves or who wait until they have run
> out of time by getting too low.

The rate of incidents and accidents clearly shows it is not just a pilot problem.
Perhaps better training and respect for the problem could help,
but reality of the pilot population and incident rate says its design problem...

[Dave Nadler]

On Friday, August 25, 2017 at 5:28:52 PM UTC-4, Tony wrote:
> Twice in my FES career I have not been able to make it back home
> during a self retrieve....

Hasn't happened to me yet in Antares in over 1200 hours.
Did my first trailer retrieve recently in Uvalde; wall of water between
me and home, plus no confidence it would clear before dark...
Only once previously did I land out (again T-storms), but after the
storms passed I dried it off, took off, and flew home. Really annoyed
the other pilots that landed with me ;-)

Lowest I've ever had the battery pack was around 25% after
a long self-retrieve.

http://wingsandwheels.com/class/classified.php?id=685

[[email protected]]

Not the answer for everybody, but try a jet!

https://youtu.be/HQVWCASrZyw

[Dave Nadler]

On Saturday, August 26, 2017 at 12:43:51 PM UTC-4, wrote:
> Not the answer for everybody, but try a jet!

I think all of my buddies with jet (JS) have had at least one failure.
None of these contraptions is 100% or even close.
Plan A is always landing.
If it starts, be delighted.
WHEN it DOES NOT start, just finish the landing.

Be safe out there,
Best Regards, Dave

[[email protected]]

I think all of my buddies with jet (JS) have had at least one failure.
None of these contraptions is 100% or even close.

None of the "sustainer" jet engines are much more than slightly upgraded "toy" R/C engines, with only partially developed Engine Control Units. I am not surprised at the reliability issues, as Bob Carlton and I used these in a jet powered Alisport Silent on the airshow circuit from 2005 to 2008. We carried four engines to make sure we had two operational at any time.

After switching to the PBS TJ-100, a true Mil-Spec turbine with total FADEC control, the problems disappeared. PBS has been manufacturing turbines since the sixties (or before), with much of their product geared toward Auxiliary Power Units for Soviet fighter aircraft and helicopters, (L-39 and L-59 Albatros and Mi-8, among others). After the collapse of the Soviet Union, the engine was redesigned into a pure turbojet, as well as a turboshaft and turboprop, with more sophisticated materials and a vastly enhanced computer controller.

PBS is a large company in the Czech Republic, with over 1,200 employees in a very modern manufacturing facility. They build turbine machinery for everything from hydroelectric power generators to small aircraft. Over 300 employees work in the aircraft division. More than 700 PBS TJ-100 engines are in the field, on everything from target drones to manned aircraft like Bob's airshow planes.

Since 2008, Bob has installed the PBS TJ-100 on his Salto airshow glider, a TesT-14 two seat glider (retractable engine configuration). Sonex Aircraft Inc. has sold over ten subSonex kits, with at least five flying and about five BD-5 aircraft are on the airshow circuit using the PBS-TJ100 engine. We are currently completing the installation of the PBS-TJ-100 in a third Arcus airframe.

In our personal experience with these aircraft, over 750 inflight engine starts have occurred with no failures. Of course, reliability comes from the engineering experience the PBS company has demonstrated, and that doesn't come cheap.

As Dave pointed out, reliability of the Arcus M powerplant and retraction system is somewhat "failure prone." The PBS-TJ-100 engine and Desert Aerospace retraction system has been extremely reliable, but it comes at a high price.

[krasw]

sunnuntai 27. elokuuta 2017 0.08.34 UTC+3 Dave Nadler kirjoitti:
> On Saturday, August 26, 2017 at 12:43:51 PM UTC-4, wrote:
> > Not the answer for everybody, but try a jet!
>
> I think all of my buddies with jet (JS) have had at least one failure.
> None of these contraptions is 100% or even close.
> Plan A is always landing.
> If it starts, be delighted.
> WHEN it DOES NOT start, just finish the landing.
>
> Be safe out there,
> Best Regards, Dave

I've heard also that starting a jet (also JS) is far from foolproof. Apparently you have to sit trough whole start-abort-cycle and attempting restart takes very long time.

[Soartech]

>my experience has been that the vibration (and possibly disturbed airflow) caused so much wild gyration in the vario readings that it seemed pointless to try to determine if I was flying into rising air, so I just climbed first, then shut down the engine and started a thermal search.

Hi Frank,
My ApisM is equipped with a pneumatic toggle switch that disables the rear-fin-mounted Total Energy probe. It is vital that you have this. It completely eliminates the wild vario readings so that you can detect thermals and circle in them with the engine on. This greatly boosts your climb rate and you get to shut off the engine much quicker. When the engine is retracted just flip the switch and you are back to TE mode.

[Jonathan St. Cloud]

At the 18 meter Nationals in Uvalde this month one would imagine there were multiple in air-starts. The only one I had heard of that did not start was the jet on a Jonkers. Having owned several lawn mower sustainers, I wonder if it is feasible for a sustainer electric pylon, or would the weight be effectively the same as a self launch?

On Sunday, August 27, 2017 at 12:38:53 AM UTC-7, krasw wrote:
> sunnuntai 27. elokuuta 2017 0.08.34 UTC+3 Dave Nadler kirjoitti:
> > On Saturday, August 26, 2017 at 12:43:51 PM UTC-4, wrote:
> > > Not the answer for everybody, but try a jet!
> >
> > I think all of my buddies with jet (JS) have had at least one failure.
> > None of these contraptions is 100% or even close.
> > Plan A is always landing.
> > If it starts, be delighted.
> > WHEN it DOES NOT start, just finish the landing.
> >
> > Be safe out there,
> > Best Regards, Dave
>
> I've heard also that starting a jet (also JS) is far from foolproof. Apparently you have to sit trough whole start-abort-cycle and attempting restart takes very long time.

[Eric Greenwell[_4_]]

Jonathan St. Cloud wrote on 8/27/2017 2:58 PM:
> At the 18 meter Nationals in Uvalde this month one would imagine there were multiple in air-starts. The only one I had heard of that did not start was the jet on a Jonkers. Having owned several lawn mower sustainers, I wonder if it is feasible for a sustainer electric pylon, or would the weight be effectively the same as a self launch?
>
Schleicher provides the ASG 32 EL, an electric sustainer version of the ASG 32.


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

http://soaringsafety.org/prevention/Guide-to-transponders-in-sailplanes-2014A.pdf

[Dave Nadler]

On Sunday, August 27, 2017 at 5:58:39 PM UTC-4, Jonathan St. Cloud wrote:
> ...I wonder if it is feasible for a sustainer electric pylon, or would
> the weight be effectively the same as a self launch?

A huge % of the weight of electric is in the battery.
As the electric motor is relatively light, might as well do self-launch...

[Eric Greenwell[_4_]]

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/motorgliders/publications/download-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/Guide-to-transponders-in-sailplanes-2014A.pdf

[Eric Greenwell[_4_]]

wrote on 8/26/2017 5:23 AM:
> On Saturday, August 26, 2017 at 12:15:08 PM UTC+2, Dave Walsh wrote:
>> 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".
>
> I've heard dozens of stories of pilots outlanding their motor gliders when the engine wouldn't start, to discover on the ground that they'd forgotten to switch the fuel on.
>
> At some point you have to ask - is this a pilot problem or a design problem?

If the glider is a Schleicher self-launcher, it's a pilot problem. The valve
should be left open in flight. I leave mine open all the time on my ASH 26E, even
on the ground. It's main purpose is to keep fuel from getting to the engine if
there is a fire. The only time I shut it is during the annual, when it's tested.

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

http://soaringsafety.org/prevention/Guide-to-transponders-in-sailplanes-2014A.pdf

[krasw]

maanantai 28. elokuuta 2017 5.36.30 UTC+3 Eric Greenwell kirjoitti:
> If the glider is a Schleicher self-launcher, it's a pilot problem. The valve
> should be left open in flight. I leave mine open all the time on my ASH 26E, even
> on the ground. It's main purpose is to keep fuel from getting to the engine if
> there is a fire. The only time I shut it is during the annual, when it's tested.
>

Maybe it should read "fuel emergency shutoff" with red knob, instead of "fuel valve", if that is the real use of it.

[firsys]

On Thursday, August 24, 2017 at 4:29:01 PM UTC-4, V1 wrote:
> While reading the FES article in June Soaring (yes, I’m behind in my reading), I noticed the author’s comment about searching for a thermal while FES was running, then shutting down FES as he started to climb. This is a topic I don’t 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 readings that it seemed pointless to try to determine if I was flying into rising air, so I just climbed first, then shut down the engine and started a thermal search.
>
> My question – do others have experience to share about their ability to find thermals while a sustainer or self-launcher (either gas or electric) was running? If electric has an advantage here, this could reduce the run-time needed and conserve “fuel�.
>
> - Frank

On the PIK I have a standard TE probe going to
a gust filter and then the Winter vario.

This is good enougt with the engine running
to evaluate a thermal.

JMF

[[email protected]]

On Sunday, August 27, 2017 at 5:58:39 PM UTC-4, Jonathan St. Cloud wrote:
> At the 18 meter Nationals in Uvalde this month one would imagine there were multiple in air-starts. The only one I had heard of that did not start was the jet on a Jonkers. Having owned several lawn mower sustainers, I wonder if it is feasible for a sustainer electric pylon, or would the weight be effectively the same as a self launch?
>
I'm working on conversion of ASW-24E from Rotax shaker to pylon mounted electric as I write this. Weight change will be about 8 lb and CG move forward..
UH

[[email protected]]

On Friday, August 25, 2017 at 11:46:05 AM UTC-5, Tony wrote:
> 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.

My experience is similar to Tony's. I usually climb to 1000 at about 70% power then dial back to sustainer level 4 KW searching for the 1st thermal then center the thermal until I climb to 2000 then shut down. A good day I will have 70% battery left. On a bad day 50%

There is no plummet mode with the FES

[Dave Walsh]

Not sure an electric "engine on a stick" is sensible as a new
design for a get you home (turbo) glider - all the drag and
complexity of the erection mechanism/doors etc. Surely the
FES route make much more sense - simpler, less drag, more
efficient.
Of course if you already own a Rotax/Solo shaker stick engine
it might be attractive (outside of EASA land) you lucky
Americans.

When the engine on a stick fails the drag is very dependant on
the individual sailplane: it's not just the engine & pylon there's
often a big radiator too. From recollection the DG400(&PIK20E)
was about 14:1; the DG800B/C a bit better, a previous post
gives 20:1 for the ASH26E; the Antares 20E (no radiator) is
30:1.

Dave Walsh

[Charlie M. (UH & 002 owner/pilot)]

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.

[[email protected]]

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.

[Dave Walsh]

At 09:27 30 August 2017, wrote:
>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
>a=
>nd 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
>la=
>uncher.

>I think the crucial word here is "concept". Be interesting to
see just how close the real thing is to their website projections;
if they're even close it will be an interesting ship.
Is it just me who thinks the GP product range naming is weird
and confusing? Build a 13.5m glider and call it GP14; build a
15m glider powered by electricity and cal it a GP 15 JETA?
Did their marketing team once work for Mercedes or is this all
home grown.