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What do you think about "e-soaring"?

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John.Roo

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=electric is cheaper,NO need in music !
K7 has "skid" so at the beginning of aerotow you need higher static thrust. Important is to start to move :)
With electric propulsion you can use peak power for first few seconds to start to move faster. Glider pilot needs at the beginning to build up speed quickly to be able to control glider with ailerons.
But please don´t expect that electric aerotowing is silent. I already mentionned before - noise is produced by prop. For really silent aerotowing would be necessary to have some special low rpm but high efficient prop probably with bigger diameter.
It is difficult to find suitable product when is requested adjustable / feathering / two blade prop.
Adjustable - to keep efficiency as high as possible (torque / rpm)
Feathering - I suppose that in this thread we like soaring :)
Two blade - during soaring I prefer to have prop in horizontal position. In case of problem with propulsion and emergency landing out of fied you save you blades :) But ok, also three blade prop could be acceptable....
 

John.Roo

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The CR flight solution probably give a lot ot thrust, but I really need in flight adjustable and featherign prop :)

Info from EMRAX manuals shows that to achieve best efficiency you have to stay in specific area of torque vs RPM and with our range of speeds this will be achievable only by variable pitch prop (+ feathering or folding - we are in soaring thread) :)

Efficiency EMPRAX 188.jpg
 

John.Roo

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=yes,for glider towing mashine, not a soaring one...
You are right - for tow plane could be an option. However pilots are interested in universal options and I don´t want to allow to pilots to change props :) You would be surprissed how many pilots are able to change the prop without to think about CG :)
 

John.Roo

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That is true :)

I can understand that "real glider pilot" takes his flying like a challenge. I don´t think that he is "fighting with nature" - he is more "cooperating with nature" because is using free energy of sun, cumulus clouds and wind.
But glider needs to takeoff to some altitude - so at the begining you must add energy to this challenge. And here we are - you can burn fuel in tow plane, you can burn fuel or electric energy in winch system or you can burn fuel or electric energy in self launch propulsion system. Unfortunatelly places for glider gravity takeoffs are very rare :)
Glider pilot must make many very specific decissions based on actual meteo situation and his experience. And also based on his safety. Knowleadge that he has sustainer system on board affects risk pilot is willing to take. That is logical. Problem is that with combustion engine retracted behind cockpit he must make decission about when to abort fligth too high. Glider pilot flying with "pure glider" has tendency to "fight" till the last moment or to don´t take risk of outlanding and use "conservative tactisc". Electric sustainer can be started at lower altitude and "ignition" is fast. Negative - weight of battery (even higher battery weight if is self launch system). Weight is for glider pilot good only in specific conditions and ideally is removable - water ballast. So conservative glider pilots takes propulsion weight a bit like "necessary evil".
And I would really like to change this point of view - at least between new generation of young glider pilots :cool:
ASAH9702.jpg
 
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PiperCruisin

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TwinHybrid.jpg
I tried presenting this to a group of sailplane enthusiasts. I never found the slightest interest from them so I gave up on it. Bought a Cherokee and moving on.
 

henryk

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sailplane enthusiasts.
=sailplane,glider should have high L/D ...

-two moters (drag elements) is not optimal solution...?

=iff foldable propellers (into fuselage) ?
 

John.Roo

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View attachment 99480
I tried presenting this to a group of sailplane enthusiasts. I never found the slightest interest from them so I gave up on it. Bought a Cherokee and moving on.
Hello!
Seems that concept with two small motors is popular.
1595658993126.png
In case of EASA / FAA certified glider is modification difficult - only holder of type certificate can allow such a modifications.
In homebuilds world is your limitation only your imagination :) .... and money...
If you use electric propulsion you can use multiple motor design (at least in Czech Republic). The only condition is that in case of failure of one motor the other one much switch off automatically (reason is that UL/LSA pilots are not trainer for asymetric thrust).
So now you can go ahead :)
 

Jay Kempf

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Hello!
Seems that concept with two small motors is popular.
View attachment 99498
In case of EASA / FAA certified glider is modification difficult - only holder of type certificate can allow such a modifications.
In homebuilds world is your limitation only your imagination :) .... and money...
If you use electric propulsion you can use multiple motor design (at least in Czech Republic). The only condition is that in case of failure of one motor the other one much switch off automatically (reason is that UL/LSA pilots are not trainer for asymetric thrust).
So now you can go ahead :)
That is a great idea for a glider installation like that. Just shut both down on failure of one and have emergency procedures that are same as for glider. I like it.
Dual motor installation is just that but this installation with smaller props on a very long wingspan and tail volume probably wouldn't be bad on one engine anyway. The dual pusher folder set up allows conventional tail which is good. This could be a kit added to any conventional glider as long as there was a very good procedure for mounting and it is much safer than retractable motors. There is no dangerous draggy transition while you are in trouble already due to altitude decay too far from the intended landing target.
 
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John.Roo

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To stay "glider like", there is also the solution tested for the "Euroglider" :
Two small pylon over the trailing edge of the wing with rearward folding props.

Drawback of e-genuis and sunseeker duo configuration is that the vertical tail plane and tail cone must be heavily reinforced (so only possible on new designs), and have quite long power cables (both problems add lots of weight). Also, with all this weight "behing", you would need batteries under your feet, or move the wing rearward (of course they used the second solution, again possible only on new designs).
From the 2kg of copper I installed in my FES glider, I believe Egenius has at least 10kg of power cables in the tail...

The problem with the Euroglider configuration is that it is not legal yet (expect on the prototype to help convince french regulators that there is no problems)...
Euroglider team is only working to adapt CS22 (certified gliders) application in France, forgetting about ather countries and other reglulation (CS-VLA, ultralights...) that are much more potential to see the developpement of new planes with this configuration...
1595703316633.png
The idea on picture is not mine.
Exian posted this picture - it is Euroglider project :)
 

henryk

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Mar 8, 2010
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krakow,poland

=similar, comfortable, BUT LOUDLY ! (propellers in TURBULENT flow ...)

PS=who was hear italian aircraft PIAGGIO ?

 
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