Best option for electric self starting glider

The last few comments on this thread are a really not useful. Each aircraft fits a specific mission. There has been mentioned of needing redundant engines, needing hours of engine operation time, etc, etc. We are not flying airplanes, they are gliders first with motors to allow either take-off or the abilty to sustain.

There is no right answer, each fits the needs of the pilot. Some may want a few miles of sustaining (traditional turbo or non-launching FES), some may want just enough to launch, some want both, snd some want redundant systems so they can fly out of reach of safe landing sites.

Each design is a compromise and ultimately has to fit the needs of the owner. There is no right or wrong design. Arguing over which one is better is like arguing over which flavor of ice cream is better.

2G wrote on 4/13/2020 9:19 PM:
On Monday, April 13, 2020 at 7:48:51 PM UTC-7, Eric Greenwell wrote:
2G wrote on 4/13/2020 5:54 PM:

Electric gliders won't cut it when you have to motor a was to the lift, like at Williams. Once, Jim Leedy and I motored from KRLD to Mt. Rainier in his Taifun to get to the wave lift.

The Williams case is one I considered before choosing the Jeta. On the map, it
looks like about 20 NM the to hills to the west. Most electric gliders have that
much range; eg, the Gp15 Jeta with the large battery could launch, motor the 20
miles, and still have about 55-60 NM range left. The small battery would only have
30-35 nn range left, though. The AS34 would have about 45 NM range left after
motoring from Williams to the hills; the miniLak FES also about 45 NM, maybe more.

Everyone knows the gasoline powered self-launchers all have powered ranges that
exceed the best electric range, but that is irrelevant for most of the people
buying an electric glider. They want to eliminate the tow and dramatically
increase their chances of getting home, and the electric glider gives them what
they want. If you dream of flights that require hours of power, or airfields that
don't have electricity, you must stay with gasoline.

--
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

The launch has to be 4kft, min and the distance is more like 22nm. And what if the lift is further into the hills? And what if you have a headwind? And if you don't connect you don't have a glide back to Williams. The same thing goes for Minden. The margins are either non-existent or too thin for my tastes. Of course, you could always get a tow. In fact, save the cost of a FES and fly a pure glider.

There are several ways to deal with your worst case scenario:
1) don't fly on a difficult day
2) take a 5 mile, 4000' tow, leaving plenty of reserve to return to Williams
3) accept the possibility you might have to land at Antelope Valley
4) own a GP15: motor the 25 NM to 4000', and have 45-50 NM range left.

For 4), there no worries about getting back to Williams with that 10 knot tail
wind, 2500 agl height where you gave up trying to connect. The AS34 and miniLak
should be OK, too. Connecting with difficult lift will be easier in the electrics:
run at low power while searching around until you find something, turn it off, and
5 seconds later you are flying a glider again. Maybe not quite so easy in the
AS34, with it's more conventional pylon.

The fact is, most people do not fly where a lot of range is required, and most are
currently flying gliders with ZERO powered range (pure gliders). To these pilots,
the range of current electric gliders is very appealing. Think about it: if
maximum range was the crucial factor in selecting a motorglider, we'd all be
flying Stemme S10s! Right, Dan?

--
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

On Tuesday, April 14, 2020 at 2:14:17 AM UTC-4, Tim Taylor wrote:
The last few comments on this thread are a really not useful. Each aircraft fits a specific mission. There has been mentioned of needing redundant engines, needing hours of engine operation time, etc, etc. We are not flying airplanes, they are gliders first with motors to allow either take-off or the abilty to sustain.

There is no right answer, each fits the needs of the pilot. Some may want a few miles of sustaining (traditional turbo or non-launching FES), some may want just enough to launch, some want both, snd some want redundant systems so they can fly out of reach of safe landing sites.

Each design is a compromise and ultimately has to fit the needs of the owner. There is no right or wrong design. Arguing over which one is better is like arguing over which flavor of ice cream is better.

I'll describe the requirements I am trying to satisfy for me with my project. I suspect this is much like many but obviously not all.
1) The glider needs to be practical for one person to assemble in a reasonable period of time without heavy lifting. This means a ship that is not more than about 100 lb heavier than it's similar non powered counterpart.
2) Self launch capability with acceptable margins. I am using a takeoff distance of 900 feet, off pavement, and climb rate of at least 400 feet per minute. Ability to fly off unpaved surface knowing takeoff distance will increase.
3) Battery capacity for a 2000 foot launch and 2500 feet reserve to save and get home or to a safe airport.
4)System must have sufficient motor cooling to allow high power settings long enough to get to a safe altitude before power reduction.
5) Practical charging. In my project the battery can be removed for charging away from the glider.
6) Existing proven airframe.
This is my "Wednesday afternoon" ship for when I have no tow pilot.
FWIW
UH

There is another 2 seater side by side 20mtr electric in the works and they claim the basic version is ok for competitions.



http://www.reinerstemme.aero/

Muttley

On Monday, April 13, 2020 at 10:00:45 PM UTC-7, 2G wrote:
On Monday, April 13, 2020 at 9:49:26 PM UTC-7, wrote:
On Monday, April 13, 2020 at 9:37:18 AM UTC-7, Duster wrote:
Any opinions on the Taurus Electro? Side-by-side, pylon, self-launch, trailer option for solar array charging, etc. They claim the profile of the cockpit/fuselage acts like a lifting body.

There are 4 Electro's in the USA and about a dozen Rotax powered. I've flown a Rotax-powered one for about 10 years, but only have a few flights in an Electro. It flies like an older generation, lightly loaded 15 meter ship. Lots of fun soaring, but not for unhandicapped competition or records.

The company's objective in designing the electric version was to have it achieve the same performance, at the same price, as the gas powered. I understand that the electric will climb slightly faster (bigger prop, IIRC), and the price probably isn't that much more than the Rotax version. I think the empty weight is similar, though the batteries consume a lot of space.

But the run time, like all of the electrics, is the big difference. I think Pipistrel used to advertise 6,000' of climb on a charge, though that was a while back and they probably have better numbers today. (The Rotax powered version has a max fuel capacity of something like 14 gallons (with dual tanks). I have only the single tank configuration, but have never had "range anxiety" with probably over an hour of run time, should it be needed.. (Typical flight has 5-7 minutes for initial launch and another 5-10 minutes of run time if I need a relight, and I would guess that the Electros have a similar profile.))

The solar trailer for the Electro is quite cool. You can park at an unelectrified gliderport, and the sun charges the battery array in the trailer. Then you hook-up your Taurus overnight and recharge the on-board batteries. Rinse and repeat.

Pipistrel has a big lead over others in actual, in-the-field application and improvements vs. projected and theoretical systems. If they elected to market their systems in a higher-performance sailplane I think they would have a superior product.

For VFR cross country flight the FAA requires you to have a 30 minute fuel reserve. Note that electric gliders don't even have 30 minutes of run time, let alone a reserve. All this discussion assumes running the battery totally flat - no reserve WHATSOEVER and perfect battery performance (no degradation for temperature or age). This is an unacceptable level of even token, lip-service safety. GIVE ME A BREAK!

Tom

That must be because airplane pilots think slower than helicopter pilots?

The pure glider never has any fuel reserve (molecules or electrons), yet
they go cross country all of the time.Â* Are you suggesting that flying
cross country in a pure glider is illegal?

On 4/13/2020 11:00 PM, 2G wrote:
On Monday, April 13, 2020 at 9:49:26 PM UTC-7, wrote:
On Monday, April 13, 2020 at 9:37:18 AM UTC-7, Duster wrote:
Any opinions on the Taurus Electro? Side-by-side, pylon, self-launch, trailer option for solar array charging, etc. They claim the profile of the cockpit/fuselage acts like a lifting body.
There are 4 Electro's in the USA and about a dozen Rotax powered. I've flown a Rotax-powered one for about 10 years, but only have a few flights in an Electro. It flies like an older generation, lightly loaded 15 meter ship. Lots of fun soaring, but not for unhandicapped competition or records.

The company's objective in designing the electric version was to have it achieve the same performance, at the same price, as the gas powered. I understand that the electric will climb slightly faster (bigger prop, IIRC), and the price probably isn't that much more than the Rotax version. I think the empty weight is similar, though the batteries consume a lot of space.

But the run time, like all of the electrics, is the big difference. I think Pipistrel used to advertise 6,000' of climb on a charge, though that was a while back and they probably have better numbers today. (The Rotax powered version has a max fuel capacity of something like 14 gallons (with dual tanks). I have only the single tank configuration, but have never had "range anxiety" with probably over an hour of run time, should it be needed. (Typical flight has 5-7 minutes for initial launch and another 5-10 minutes of run time if I need a relight, and I would guess that the Electros have a similar profile.))

The solar trailer for the Electro is quite cool. You can park at an unelectrified gliderport, and the sun charges the battery array in the trailer. Then you hook-up your Taurus overnight and recharge the on-board batteries. Rinse and repeat.

Pipistrel has a big lead over others in actual, in-the-field application and improvements vs. projected and theoretical systems. If they elected to market their systems in a higher-performance sailplane I think they would have a superior product.
For VFR cross country flight the FAA requires you to have a 30 minute fuel reserve. Note that electric gliders don't even have 30 minutes of run time, let alone a reserve. All this discussion assumes running the battery totally flat - no reserve WHATSOEVER and perfect battery performance (no degradation for temperature or age). This is an unacceptable level of even token, lip-service safety. GIVE ME A BREAK!

Tom

--
Dan, 5J

True dat, Eric.

For me the Stemme's range is only used to reposition to another soaring
location as I don't have a trailer.Â* That money is better spent on other
toys.Â* The big down side to the Stemme for me is it's limitation to
paved runways.Â* I know a lot of them are flown off of grass fields, but
there are none of those where I fly.Â* Gravel is also pretty much out of
the question, again for me, due to the cost of a propeller.

On 4/14/2020 7:17 AM, Eric Greenwell wrote:
2G wrote on 4/13/2020 9:19 PM:
On Monday, April 13, 2020 at 7:48:51 PM UTC-7, Eric Greenwell wrote:
2G wrote on 4/13/2020 5:54 PM:

Electric gliders won't cut it when you have to motor a was to the
lift, like at Williams. Once, Jim Leedy and I motored from KRLD to
Mt. Rainier in his Taifun to get to the wave lift.

The Williams case is one I considered before choosing the Jeta. On
the map, it
looks like about 20 NM the to hills to the west. Most electric
gliders have that
much range; eg, the Gp15 Jeta with the large battery could launch,
motor the 20
miles, and still have about 55-60 NM range left. The small battery
would only have
30-35 nn range left, though. The AS34 would have about 45 NM range
left after
motoring from Williams to the hills; the miniLak FES also about 45
NM, maybe more.

Everyone knows the gasoline powered self-launchers all have powered
ranges that
exceed the best electric range, but that is irrelevant for most of
the people
buying an electric glider. They want to eliminate the tow and
dramatically
increase their chances of getting home, and the electric glider
gives them what
they want. If you dream of flights that require hours of power, or
airfields that
don't have electricity, you must stay with gasoline.

--
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

The launch has to be 4kft, min and the distance is more like 22nm.
And what if the lift is further into the hills? And what if you have
a headwind? And if you don't connect you don't have a glide back to
Williams. The same thing goes for Minden. The margins are either
non-existent or too thin for my tastes. Of course, you could always
get a tow. In fact, save the cost of a FES and fly a pure glider.

There are several ways to deal with your worst case scenario:
1) don't fly on a difficult day
2) take a 5 mile, 4000' tow, leaving plenty of reserve to return to
Williams
3) accept the possibility you might have to land at Antelope Valley
4) own a GP15: motor the 25 NM to 4000', and have 45-50 NM range left.

For 4), there no worries about getting back to Williams with that 10
knot tail wind, 2500 agl height where you gave up trying to connect.
The AS34 and miniLak should be OK, too. Connecting with difficult lift
will be easier in the electrics: run at low power while searching
around until you find something, turn it off, and 5 seconds later you
are flying a glider again. Maybe not quite so easy in the AS34, with
it's more conventional pylon.

The fact is, most people do not fly where a lot of range is required,
and most are currently flying gliders with ZERO powered range (pure
gliders). To these pilots, the range of current electric gliders is
very appealing. Think about it: if maximum range was the crucial
factor in selecting a motorglider, we'd all be flying Stemme S10s!
Right, Dan?


--
Dan, 5J

On Tuesday, April 14, 2020 at 10:16:57 AM UTC-7, Dan Marotta wrote:
The pure glider never has any fuel reserve (molecules or electrons), yet
they go cross country all of the time.Â* Are you suggesting that flying
cross country in a pure glider is illegal?

On 4/13/2020 11:00 PM, 2G wrote:
On Monday, April 13, 2020 at 9:49:26 PM UTC-7, wrote:
On Monday, April 13, 2020 at 9:37:18 AM UTC-7, Duster wrote:
Any opinions on the Taurus Electro? Side-by-side, pylon, self-launch, trailer option for solar array charging, etc. They claim the profile of the cockpit/fuselage acts like a lifting body.
There are 4 Electro's in the USA and about a dozen Rotax powered. I've flown a Rotax-powered one for about 10 years, but only have a few flights in an Electro. It flies like an older generation, lightly loaded 15 meter ship. Lots of fun soaring, but not for unhandicapped competition or records.

The company's objective in designing the electric version was to have it achieve the same performance, at the same price, as the gas powered. I understand that the electric will climb slightly faster (bigger prop, IIRC), and the price probably isn't that much more than the Rotax version. I think the empty weight is similar, though the batteries consume a lot of space..

But the run time, like all of the electrics, is the big difference. I think Pipistrel used to advertise 6,000' of climb on a charge, though that was a while back and they probably have better numbers today. (The Rotax powered version has a max fuel capacity of something like 14 gallons (with dual tanks). I have only the single tank configuration, but have never had "range anxiety" with probably over an hour of run time, should it be needed. (Typical flight has 5-7 minutes for initial launch and another 5-10 minutes of run time if I need a relight, and I would guess that the Electros have a similar profile.))

The solar trailer for the Electro is quite cool. You can park at an unelectrified gliderport, and the sun charges the battery array in the trailer. Then you hook-up your Taurus overnight and recharge the on-board batteries. Rinse and repeat.

Pipistrel has a big lead over others in actual, in-the-field application and improvements vs. projected and theoretical systems. If they elected to market their systems in a higher-performance sailplane I think they would have a superior product.
For VFR cross country flight the FAA requires you to have a 30 minute fuel reserve. Note that electric gliders don't even have 30 minutes of run time, let alone a reserve. All this discussion assumes running the battery totally flat - no reserve WHATSOEVER and perfect battery performance (no degradation for temperature or age). This is an unacceptable level of even token, lip-service safety. GIVE ME A BREAK!

Tom

--
Dan, 5J

In a glider, you only need about 6000 ft AGL at all times. That's about 30 minutes till you hit the dirt.

That's about what I try to maintain, flying in the Sierra/Great Basin. The valleys are around 4000 MSL, and below about 10,000 you are beginning the think about landing sites.

On Tuesday, April 14, 2020 at 1:00:45 AM UTC-4, 2G wrote:
On Monday, April 13, 2020 at 9:49:26 PM UTC-7, wrote:
On Monday, April 13, 2020 at 9:37:18 AM UTC-7, Duster wrote:
Any opinions on the Taurus Electro? Side-by-side, pylon, self-launch, trailer option for solar array charging, etc. They claim the profile of the cockpit/fuselage acts like a lifting body.

There are 4 Electro's in the USA and about a dozen Rotax powered. I've flown a Rotax-powered one for about 10 years, but only have a few flights in an Electro. It flies like an older generation, lightly loaded 15 meter ship. Lots of fun soaring, but not for unhandicapped competition or records.

The company's objective in designing the electric version was to have it achieve the same performance, at the same price, as the gas powered. I understand that the electric will climb slightly faster (bigger prop, IIRC), and the price probably isn't that much more than the Rotax version. I think the empty weight is similar, though the batteries consume a lot of space.

But the run time, like all of the electrics, is the big difference. I think Pipistrel used to advertise 6,000' of climb on a charge, though that was a while back and they probably have better numbers today. (The Rotax powered version has a max fuel capacity of something like 14 gallons (with dual tanks). I have only the single tank configuration, but have never had "range anxiety" with probably over an hour of run time, should it be needed.. (Typical flight has 5-7 minutes for initial launch and another 5-10 minutes of run time if I need a relight, and I would guess that the Electros have a similar profile.))

The solar trailer for the Electro is quite cool. You can park at an unelectrified gliderport, and the sun charges the battery array in the trailer. Then you hook-up your Taurus overnight and recharge the on-board batteries. Rinse and repeat.

Pipistrel has a big lead over others in actual, in-the-field application and improvements vs. projected and theoretical systems. If they elected to market their systems in a higher-performance sailplane I think they would have a superior product.

For VFR cross country flight the FAA requires you to have a 30 minute fuel reserve. Note that electric gliders don't even have 30 minutes of run time, let alone a reserve. All this discussion assumes running the battery totally flat - no reserve WHATSOEVER and perfect battery performance (no degradation for temperature or age). This is an unacceptable level of even token, lip-service safety. GIVE ME A BREAK!

Tom

- I guess I should never venture out flying my motorless (pure) glider, since it has no fuel reserve at all! :-)

2G wrote on 4/13/2020 10:00 PM:
Note that electric gliders don't even have 30 minutes of run time, let alone a reserve. All this discussion assumes running the battery totally flat - no reserve WHATSOEVER and perfect battery performance (no degradation for temperature or age). This is an unacceptable level of even token, lip-service safety. GIVE ME A BREAK!

Actually, several of them do exceed 30 minutes run time; eg, the Jeta with the
large battery has a nominal 150km range under power. That's at about 100kph,
yielding a 90 minute run, and a few minutes longer if you include the launch and
climb to 2500' AGL. The AS34 has a similar run time, the miniLak about 60 minutes,
plus launch time.

The discussion does not assume running the batteries totally flat; eg, the GP15
battery is limited to a 90% discharge to greatly extend it's life. Of course,
temperature and age will affect performance, as it can with gasoline gliders.
Electrics do have an advantage at high density altitudes: their power remains
constant, unlike a gas engine.

As for safety, most motorglider pilots know the engine is to be treated as a
convenience, and not an insurance policy. Like a pure glider, we should always be
within gliding reach of a safe landing place.

--
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