What do you think about "e-soaring"?

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John.Roo

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ePipistrel training-school aircraft at Popham UK.......longer wing for soaring could maybe be fitted?
Interesting numbers....


I also wonder why they didn´t used aiframe from Pipistrel Sinus.
Sinus has 15 m wing and exactly the same fuselage incl. possibility to have taidragger or tricycle gear.
1653450714806.png
Sinus L/D is 27:1 = higher in compare with Alpha Electro / Virus (17:1 or 15:1).

The only reason could be the wing strength.
If I remember well, Sinus had MTOM range between 472,5 kg (UL version) to 544 kg (LSA version).
But MTOM 544 kg is not enough for installation of their electric propulsion...
1653451154104.png
 

Sraight'nlevel

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I also wonder why they didn´t used aiframe from Pipistrel Sinus.
Sinus has 15 m wing and exactly the same fuselage incl. possibility to have taidragger or tricycle gear.
View attachment 125802
Sinus L/D is 27:1 = higher in compare with Alpha Electro / Virus (17:1 or 15:1).

The only reason could be the wing strength.
If I remember well, Sinus had MTOM range between 472,5 kg (UL version) to 544 kg (LSA version).
But MTOM 544 kg is not enough for installation of their electric propulsion...
View attachment 125803
I am wondering why IAI Heron UAV can fly 52 hours, but Velis just 1 hr tops ?
 

John.Roo

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Thanks for explanation Henryk 👍
I think that is not wrong to say that estimated drag is for example 30% lower and that info is based on wind tunel testing ;)

Here we are not investors - mostly we discuss about our dream projects and ideas.
As mentioned before - if something has been not in flight tested is not shame to say it.

During flight test you can find out many not expected things - sometimes positive, sometimes negative. But it always gives you valuable experience about differences between calculations and "real life" performance ;)
 

John.Roo

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Sinus, Phoenix, Lambada.... all these LSA TMG equipped with engine Rotax 912 and 80-100 lit. fuel tanks are able to fly 8-10 hours (of course not in fast cruise at 100-110 kts but with "eco" settings) ;)
And some versions of above mentionned airplanes had 140-200 lit fuel tanks....

It is not secret or something new that energy in fuel is much higher than any actually available battery. 1 lit. of fuel has approx 8,9 kWh of energy,
100 lit. of fuel = 890 kWh of energy.
890 kWh battery would have weight of 4 500 kg :cool:

And from other point of view....
Would you make a trainig with student in airplane with 2,5 liters of fuel in fuel tanks? 🤔
Well that is exactly Pipistrel Velis - 21 kWh / 8,9 kWh (energy in one lit of fuel) = 2,359 lit.
 

henryk

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explanation

=rear tube is working as a thruster ="negative" drag(look tha angle of thin linen),
thanks vortex flow !

-for comparation=sigle tube, V=7.5 m/s ...

BTW=in vortices it is accumulated big energy (from sorrounding atmosphere !)
"
With angular vibrations of the wing (in the form of a plate), an averaged force will arise, directed
along the average position of the wing. "
"
We experimentally investigated the mechanical, kinematic, dynamic and energy
characteristics of an oscillating plate as a propellant. And we found modes in which the specific
thrust was more than 200 kG / hp!!! On a real vehicle, the efficiency of the engine and
transmission elements will reduce the total specific thrust for an umbrella to 80 kG / hp, for a
wing aircraft 120 kG / hp. " <dr Sorokodum>
 

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John.Roo

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I know we are pilots and our dream machines are flying, but lets stay "on the ground" with used technology.
"Oscilating plates", "flaping wings".... it can be interesting project for students.

I would personally really prefer conservative way.... simple small glider like Axel or eBirdie.
Material - glass fibre with carbon reinforcements (maybe carbon main spare).
Control lines - automatic or very simple connections to make dismantling easy and fast.
Standard control system - no combination of trike and airplane. Controlled should be elevator, rudder, ailerons and airbrakes. Flaps are nice option, but if plane stall speedfits into UL category than lets keep it simple without flaps.
Simple propulsion system - no contra-rotation, no multimotor config (ok ok, lets say that two motors should be maximum) ;) Ideally only folding prop(s). Of course feathering / in flight adjustable prop could be interesting option for flight testing.
No special cells used in main battery - lets take standard Li-Ion 18650 or 21700.
No need of super high Vne and cruise speed.

Main requirements:
- MTOM +-300 kg
- Vne 180-200 kmph
- as low as possible airframe and propulsion price
- nice handling
- safe flight characteristics
- L/D 30:1 or better
- comfortable cocpit with simple instrument panel layup
- perfectly vissible upper hemisphere
- min. safety factor for airframe 1,875
 

John.Roo

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+BRS (GRS) or SECONDCHANTZ...!

PS=some peaple have problems with hand/futh coordination.
For him and futh disfunctiones=hand only controll system.
BRS - good idea 👍

Only hand control system.... well this could be a interesting option for disabled pilots, however for young pilots or retired (older) pilots is this not good option.

Reasons are simple....
Young pilot needs to practice "standard" control system to be able to "grow" and fly with bigger planes.
Retired (older) pilots have their experience and they don´t want to learn new things ;)
 

John.Roo

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No but a Heron sports 52 x better endurance with more weight than a Velis.
Well in my opinion is necessary to compare "comparable" configurations.
Heron is using Rotax 914 so should be compared with Velis with Rotax 912 or 914.
Also would be interesting to know fuel tanks volume of Heron and Empty Weight.
Heron has 1 150 kg MTOM and Velis only 600 kg.
If EW is the same and fuel consumption will be similar (same type of engine) that is also efficiency similar and only difference are huge fuel tanks of Heron ;)

By the way....
15 lit / hour = 780 lit of fuel per 52 hours = approx. 600 kg of weight.
MTOM difference is 550 kg....
In my opinion is efficiency (if measured by fuel consuption at comparable airspeed) very similar.
 

henryk

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"standard" control system

=iff compare AEROPRAKT A-22 /A-32 systems=my Fellow prefer to fly A-22 yoke mode
(A-32 have better parameters!)...=probably long cardriver practice ?

-I personally like motorcykle like system=



(at the end=two halves of "bike" controllbar )

-or simpler, "SILENTGLIDER" (one rotating bar).

 
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peter hudson

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...
I would personally really prefer conservative way.... simple small glider like Axel or eBirdie.
Material - glass fibre with carbon reinforcements (maybe carbon main spare).
Control lines - automatic or very simple connections to make dismantling easy and fast.
Standard control system - no combination of trike and airplane. Controlled should be elevator, rudder, ailerons and airbrakes. Flaps are nice option, but if plane stall speedfits into UL category than lets keep it simple without flaps.
Simple propulsion system - no contra-rotation, no multimotor config (ok ok, lets say that two motors should be maximum) ;) Ideally only folding prop(s). Of course feathering / in flight adjustable prop could be interesting option for flight testing.
No special cells used in main battery - lets take standard Li-Ion 18650 or 21700.
No need of super high Vne and cruise speed.

Main requirements:
- MTOM +-300 kg
- Vne 180-200 kmph
- as low as possible airframe and propulsion price
- nice handling
- safe flight characteristics
- L/D 30:1 or better
- comfortable cocpit with simple instrument panel layup
- perfectly vissible upper hemisphere
- min. safety factor for airframe 1,875

That's pretty close to my project goals for Echo:

MTOW = 220 kg
Vne = 185 kph
Price? Well it's a home-built structure
(no price estimate yet, but really its just materials, molds and fixtures, (contract out canopy?) plus smaller electric pod maybe $30K-$35K?)
Conventional, auto hook up controls, stores in trailer.
L/D (current estimate with fixed wheel and pod is 32:1 )
Pilot view is just in front of and above LE
aft folding prop (passive)
+6/-3 g plus factor of safety of 2 on all composites (1.5 on metal components)

I think where we deviate is that I don't plan to carry more than 20 to 30 minutes of battery. And I need to use more carbon to meet my weight and stiffness goals.

But as you can see I think we have pretty similar ideas on taking the current state of the art and applying it to electric flight in a realistic manner.
As opposed drawing up a vertical take off super-cruiser and planning for next gen batteries.
 
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