# What do you think about "e-soaring"?

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#### henryk

##### Well-Known Member
towing...
R912 ?
or=
"
So very glad to see they managed to make the dream a reallity: An electric tow plane "-YT...

#### John.Roo

##### Well-Known Member
Well.... I did already succesfull glider aerotowing with electric Phoenix...

... but on the video is aerotowing with Phoenix with 100 hp Rotax
It was one of my first aerotows with Phoenix. In glider was experienced pilot and very good glider designer Christian Brondel from company Stralpes.

#### John.Roo

##### Well-Known Member
"Rolls Royce" between motorgliders...
However I really don´t like the idea of 120 kg (264 lb) bateries behind pilots.
But what I like is the range extender - 60 kg / 30-35 kW sounds good.

And this is also interesting:
"The elfin design ist a complete new development and does not base upon the existing S10. REINERSTEMME.aero GmbH, the present company of Dr. Reiner Stemme, is not connected to STEMME AG."
Not based on Stemme S10? Really?

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#### blane.c

##### Well-Known Member
HBA Supporter
"Rolls Royce" between motorgliders...
However I really don´t like the idea of 120 kg (264 lb) bateries behind pilots.
But what I like is the range extender - 60 kg / 30-35 kW sounds good.

And this is also interesting:
"The elfin design ist a complete new development and does not base upon the existing S10. REINERSTEMME.aero GmbH, the present company of Dr. Reiner Stemme, is not connected to STEMME AG."
Not based on Stemme S10? Really?
That statement does seem a stretch.

I think it should perform well normal, when something "poops the bed" I am more curious.

#### henryk

##### Well-Known Member
Stemme S10?
-my Fellow constract S10 like E-drive (in JANTAR 1),
with modyfication=only small ring is moved back for propeller retraction...

=nase is on "normal" place=lower drag when propeller is workong.

#### John.Roo

##### Well-Known Member
I hope they will release more details about the Elfin range extender.

"The 60 kilogram (132 pound) under-wing mounted internal combustion engine and generator setup can deliver 30-35 kW continuously."

#### John.Roo

##### Well-Known Member
I am sorry - this post will be not about airplanes, however I definitelly love this brilliant idea

#### henryk

##### Well-Known Member
love this brilliant idea
-Yes !
but today it is impossible=NO so strongwomans !!!

#### blane.c

##### Well-Known Member
HBA Supporter
I hope they will release more details about the Elfin range extender.

"The 60 kilogram (132 pound) under-wing mounted internal combustion engine and generator setup can deliver 30-35 kW continuously."
View attachment 106508
So they may sell more of these than gliders?

It must be complete with fuel tank?

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#### blane.c

##### Well-Known Member
HBA Supporter
-Yes !
but today it is impossible=NO so strongwomans !!!
Looks nice for "still waters" put a lite chop on the water and test it.

#### John.Roo

##### Well-Known Member
So they may sell more of these than gliders?

It must be complete with fuel tank?
According to infro from web is in pod only range extender and fuel tank is integrated in the wing.

Looks great, just the price....
"New Stemme S12 has U.S. price from $349,000 to$369,000."
.
And that is price for Rotax Stemme... so lets wait how much will costs electric Elfin version and how much will costs the range extender.

#### henryk

##### Well-Known Member

=Elektro Fliegers ...

#### blane.c

##### Well-Known Member
HBA Supporter
So because of the weight in the empennage the fuselage can be shorter?

#### EzyBuildWing

##### Well-Known Member
Dragonfly Rancher crop-sprayer can carry 42 gallons (420 lbs) of liquid-spray. So presumably 420 lbs of batteries could replace the liquid-spray for an hour or so of inexpensive e-Flying. Check out the vid:

#### henryk

##### Well-Known Member
for an hour or so of inexpensive e-Flying.
=low L/D=low Energy Efficiency=BIG accu...

#### John.Roo

##### Well-Known Member
So because of the weight in the empennage the fuselage can be shorter?
Depends on more details... but generally you are right.
CG range must be kept in right position. You have to consider also area of stabilizer and elevator and position of pilots etc.

#### John.Roo

##### Well-Known Member
Dragonfly Rancher crop-sprayer can carry 42 gallons (420 lbs) of liquid-spray. So presumably 420 lbs of batteries could replace the liquid-spray for an hour or so of inexpensive e-Flying. Check out the vid:
Generally you really can use weight reserve for a big battery
I suppose that 420 lg is weight of liquid. You will use electric motor and electric motor is lighter than ICE - another weight reserve. And there is also some reserve for fuel.

But too heavy battery is also not good so you have to decide:
- how much power you need for takeoff
- how much power you need for hoorizontal flight at requested cruise speed (ideally at best L/D speed)
- typical flight profile (how long do you want do fly, how many takeoffs etc.).
- do you wan to fly alone or with co-pilot
- and probably most important question... how much money you want to spent

And from all that informations you get basic specification of electric propulsion system you need

#### John.Roo

##### Well-Known Member
E-Spyder
"Flightstar e-Spyder
Electric aircraft development of the Spyder in conjunction with Yuneec International of China. Equipped with a Yuneec Power Drive 20 20 kW (27 hp) electric motor and two 28 lb (13 kg) lithium-polymer battery packs which provide a 40 minute endurance. First flown in July 2009. Qualifies as a US single seat ultralight with an empty weight of 253 lb (115 kg)."

#### John.Roo

##### Well-Known Member
Small hybrid propulsion.... interesting