What do you think about "e-soaring"?

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EzyBuildWing

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Agree with Post 1639 and 1640......great vids..... elevates flying into an Art Form.......become an "eGliding" artist. Could be every pilot's goal.
Really liked the "Cloudstreet" trailer.....
NZ proximity beach-gliding looks awesome..... Stefan Langer is an artist!

 

John.Roo

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henryk

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"
Clear advantages

The change from a two-blade folding propeller, patented by Reiner Stemme for the S10 series, to a new three-blade design provides elfin with clear advantages. Its propeller is not only optimized for electric propulsion but works now at significantly lower noise levels with slower revolution still delivering sufficient thrust. As the aircraft’s nose cone has received a nearly rounded shape, vibration levels have been lowered further. The propulsion system is perfectly positioned at the front tip of the aircraft where it usually unfolds maximum thrust efficiency on single engine aircraft.
"
=significantly lower NOISE levels=big achivement for GLIDER !

"auer" solution seems better=

=NO nose cone shifting, only light ring movement...
(hand shifted).

=2 x 2 blade folding propellers (CR Diff., reactionless ,low noise )
 

John.Roo

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Stemme is a "Rolls-Royce" between motorgliders - really beautifull TMG.
However see two small problems - weight and... price.
Stemme has outstanding performance, high price and high maintennance costs.
Elfin (electric Stemme project) is using modified airframe so I don´t expect that weight will lower. And price.... well in case they will use certified batteries etc. and announced range extender I expect that price will probably rise oved 400K USD (it is arround 350K USD for Rotax version We Fly: Stemme S12).

If you want to reduce production costs of electric airplane in EU you have to make light one seater.... is that simple ;)

P.S.
... for example something like this ;)

... or this one...
 
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EzyBuildWing

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Facet Opal was super-simple/small/light, with a 30 kW Rotax 447......Ir weighed 240 lbs empty(no fuel), and 660 lbs MTOW........cruise 250km/hr and absolute range with 62 gallons of fuel was quoted as approx 3500 miles...... had retracts.
It looked absolutely fantastic. in flight..... maybe ideal for electrifying?
40 kW Zero motor for zoom-climb, then some eSoaring....

 

John.Roo

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=exellent aircraft,
but not a glider...(low AR , L/D).

Kaspers BKB1-A tailles glider seems more optimal= AR=10, L/D=30...


=can fly in "reverse" direction!!!
Facet Opal, Kaspers BKB1-A... are interesting projects.
However this are not airplanes suitable for "e-glider mission".

Why?
"E-glider" should be something like "flying electric bike".
It means konstruction you know with new features making your pilot´s life easier and adding "fun factor".
As I mentionned before - perfectly suitable is for example Axel / Gekon. Lite airframe, easy to fly, possibiity of electric propulsion and looking like airplanes you know.
Don´t forget that young pilots are a bit affraid to fly new looking airplanes (flying wings, tandem wings etc.). And retired glider pilots are very conservative - they have been flying all life with gliders with tail surfaces and they don´t want to learn something new.
Therefore I do comparizon with electric bicycles.
"Normal" bicycle is known - everybody can use it.
"Electric / pedelec" bicycle has been something new, but as it has practically similar way of use it became very popular. Is adding "fun factor" ;)
It is important to keep eye on acceptable price - again good comparizon with electric bicycle.
Electric bicycle is not cheaper than "normal" one, however is "affordable".

Actually I see one important problem to solve.
Batteries safety.
I personally still beleive that well designed battery is safe.
However experience from electric cars (issues with electric Volt or burned Tesla cars) are adding new requirements to design of battery for small electric airplane.
1) is necessary to separate each cell - in case one cell starts to burn the "neighboring" cells must stay safe. This is (by the way) new requirement for airplane batteries in Germany.
2) battery pack needs to be easy removable to allow charging and storage out of airframe. I was not real fan of this solution, but is very possible that this will be requested by aeroclubs to alow hangaring beside of other airplanes. It will also increase safety requirements for connectors.
3) each battery pack will require really good monitoring (temp. sensors, BMS etc.).

Positive is that light "e-glider" needs only small battery.
5-6 kWh is a reasonable minimum.
5-6 kWh = weight of 25-30 kg and 2x 15 kg should be OK for manipulation.

Sample of scalable 3 (3,2) kWh battery packs available in Germany from Geiger engineering

Battery pack.jpg
In US is available for example system from Aerolite EV-103

Both systems were mentionned here before and I suppose that capacity will improve in future. However parameters of both systems are OK even with actuall generation of cells 👍
 

EzyBuildWing

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OK......best configuration for proximity-soaring eGlider is conventional/conservative "Plain vanilla" with fuse and tail, and with L/D >30....... and eMotor/eSustainer means no "propeller-anxiety" and no "ICE-anxiety"....... winch-launch and self-launch capable......
What's cheapest eGlider that satisfies these criteria?
Maybe a Lippisch Storch, or a Kasperwing or maybe the GRP Swift?
 

John.Roo

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OK......best configuration for proximity-soaring eGlider is conventional/conservative "Plain vanilla" with fuse and tail, and with L/D >30....... and eMotor/eSustainer means no "propeller-anxiety" and no "ICE-anxiety"....... winch-launch and self-launch capable......
What's cheapest eGlider that satisfies these criteria?
Maybe a Lippisch Storch, or a Kasperwing or maybe the GRP Swift?
Well... you pointed reason of this discussion.
They are existing ultralight gliders, but their mission is highest possible performance.
Suitable types are for example GP gliders, Apis, Silent... however their price range si higher.

As I wrote I - I have nothing against light constructions Kasperwing or Lippish Storch.
However I definitelly prefer composite construction (long lifetime of airframe, no problem with humindity etc.).
Actually I know only few prototypes in lower performance / price range.
I still keep my eye on Axel / Gekon (even if Gekon seems to be aiming for higher L/D), Sagitta and maybe French Exel (by the way... electric version of Exel is using LiFePO cells, unfortunatelly production is probably stopped).
 
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