What do you think about "e-soaring"?

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Speedboat100

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=thanks Goldschmied aerodynamic (rear part of fuselage compensate nase drag)

and extended laminar flow =


CELERA 500L have extra high fuel (energy) efficiency !


=IFF hybrid drive ???

Poor mans area ruling worx too.
 

John.Roo

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To keep it cheap it has to have an empty weight less than 70 kg ( without batteries ). Using just 2-3 kw to stay airborne..Rochelt managed with under 1 kw.

Keeping pace is important nobody wants a 40 mph vehicle...60-100 mph is preferable.

You could also glide...with speed.....ascending to 4 km at 100 mph....and gliding rest 100 km at 120 mph.

View attachment 107085

View attachment 107086

HPAs weigh only 25-40 kg empty...with stupendous span.

What an inspiration !!!

View attachment 107087
OK, so 2-3 kW was theoretical aerodynamic power, not incl. efficiency of propulsion system.
Lets assume 3 kW.
Prop efficiency 80%
Motor efficiency 85%
Controler 95%
We can "play" with efficiency of propulsion system components but seems that you will take from battery approx. 4,6 kW of power. If will be your plane light and efficient that you may stay arround 4 kW.
Still not bad.
And if you expect to use theoretical power of 12 kW for TakeOff that is also OK.

"HPA" airplane is not airplane designed to glide at 190 km/h or climb to 4 km. It is beautifull sample of extremelly light construction designed for special purpose. Very low speed will not cause any aeroelastic isues on this extremelly flexible and high aspect ratio wing.
 

John.Roo

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=thanks Goldschmied aerodynamic (rear part of fuselage compensate nase drag)

and extended laminar flow =


CELERA 500L have extra high fuel (energy) efficiency !


=IFF hybrid drive ???

Thanks for interesting documents - I will go thru both PDF files :)
 

henryk

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OK, so 2-3 kW was theoretical aerodynamic power, not incl. efficiency of propulsion system.
Lets assume 3 kW.
Prop efficiency 80%
Motor efficiency 85%
Controler 95%
=EFFICENCY of propulsion system=can be simple gained by 30-50 %
via CR (Differential) drive...

=EFFICIENCY of airplane (L/D) =can be gained simple too=
via TAIL cutting... (tail less).

f.e BKB1-A =AR=10, L/D=30 (very low surface of rudders/winglets...

-not so buaty as classic,but lighter,smaller, cheaper !
 

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John.Roo

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=EFFICENCY of propulsion system=can be simple gained by 30-50 %
via CR (Differential) drive...

=EFFICIENCY of airplane (L/D) =can be gained simple too=
via TAIL cutting... (tail less).

f.e BKB1-A =AR=10, L/D=30 (very low surface of rudders/winglets...

-not so buaty as classic,but lighter,smaller, cheaper !
I normally suppose that:
- efficiency of prop = max. 80% (typically between realistic 70% and very optimistic 85-90%)
- efficiency of electric motor = 85% (yes, producers are saying that is over 90% but....)
- efficiency of controller = 95% (again - declared is 99% but if you need cooling than is usually lower)
- not calculating losses on wiring etc.

All together means that ratio between theoretical power and "real power you need" is +-0,65. In other words - 10 kW from batteries will give you approx. 6,5 kW power on propeller.

Now... if I use CR system and I see 10 kW going out from batteries (place where is easy to measure Amps and Volts) how much power I have on propeller?

Cutting tail.... can be better but in my point of view they are in flight situatios not easy to be recovered by tail less airplanes. So I prefer to keep tail surfaces where they are. And again - that is my personal opinion. I have nothing against flying wings etc. ;)
 

henryk

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if I use CR system and I see 10 kW going out from batteries (place where is easy to measure Amps and Volts) how much power I have on propeller?
-essential parameter=propeller surface loading (Thrust Force/ Surface,

[kG/ m^2]...

and Specific Thrust (Thrust Force/ Mechanical Power ,
[ kG/ kW].

in auer CR case (GREEN KASPERWING) 80 kG / 15 kW= 5.3 kG/kW...

at 80 kG/ 1.3 m^2 =62 kG/m^2.

in modell (0.7/1.3 m ) from 0.96 kW accu power (24 V x 40 A)
we get 15 kG Thrust Force... (circa 16 kG/kW !)
(upper right corner)

BTW=probably SWIFT AERIANE is TUCK REZIST !

(BKB1-A is more stabil, thanks wingtips extensiones...)


=very small control surfaces (winglets/rudders) !!!
 

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John.Roo

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-essential parameter=propeller surface loading (Thrust Force/ Surface,

[kG/ m^2]...

and Specific Thrust (Thrust Force/ Mechanical Power ,
[ kG/ kW].

in auer CR case (GREEN KASPERWING) 80 kG / 15 kW= 5.3 kG/kW...

at 80 kG/ 1.3 m^2 =62 kG/m^2.

in modell (0.7/1.3 m ) from 0.96 kW accu power (24 V x 40 A)
we get 15 kG Thrust Force... (circa 16 kG/kW !)
(upper right corner)

BTW=probably SWIFT AERIANE is TUCK REZIST !

(BKB1-A is more stabil, thanks wingtips extensiones...)


=very small control surfaces (winglets/rudders) !!!
OK - so CR will give you better thrust per weight ratio.

As I wrote - I have nothing against flying wings.
It's just not my "cup of tea".
I prefer to have tail of proper place :cool:
 

John.Roo

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-for clearity=we with Bogdan are not aviaspwecialists,
only hobbyst...

-than auer experiments are only for auer fan, not for following by others!

You do nice work Henryk - the airplane you are building is interesting. And according to photos is also "classic" configuration with "V" tail.
Trying to decrease drag is always a real challenge.

My experience is that sometimes is high efficiency in conflict with safety.
For example - some high performance profiles are more sensitive for angle of attack. So you can decide - airplane will be more safe or you gain some performance. In this case you have to think for what pilots you design the airplane.
It is for experienced competition pilot?
Than you can allow more "sharp" characteristics.
However most of time you have to think about "normal" pilot.
Pilot flying few hours every weekend. Even if you write perfect flight manual explaining how to recover stalls, spins or other non-standard situation his reaction will be "conservative". So finally you have to make safe airplane ideally spin and stall resistent.

We all have a very limited calculating and testing possibilities. So spin resistance and stall characteristics you have to test during flight testing and you have to do that for all CG positions (even behind).

Therefore I am a bit "conservative" with airplane configuration.
However I am not against new ideas. Some of flying wing projects are really beautifull...
1tb101kah4h51.jpg
 

henryk

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Some of flying wing projects are really beautifull...
=SB-13 ? looks really fine...but many problems in fly (flatter ...)

=SWIFT AERIANE (I was whitness in 1994 =Poznan=,SWIFT doing 3 loops
cascade, the same by Manfred Rumer =Kielce=

-NO danger of tuck or autorotation !)

=the same day,for comparation, ARCHEOPTERIX=
=and happy end !=


=KASPERWING possibility of extremally low speed ,circa 5 m/s !!! (take off,landing) and VERTICAL approche before landing =GRAND PRIX at
Oshkosh ,circa 1990...=
 

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John.Roo

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=SB-13 ? looks really fine...but many problems in fly (flatter ...)

=SWIFT AERIANE (I was whitness in 1994 =Poznan=,SWIFT doing 3 loops
cascade, the same by Manfred Rumer =Kielce=

-NO danger of tuck or autorotation !)

=the same day,for comparation, ARCHEOPTERIX=
=and happy end !=


=KASPERWING possibility of extremally low speed ,circa 5 m/s !!! (take off,landing) and VERTICAL approche before landing =GRAND PRIX at
Oshkosh ,circa 1990...=
SB-13 was just example that flying wing can be interesting solution.
And Swift is nice example of popular flying wing.
Archaeopteryx is also nice, but a bit fragile looking.
Kasperwing I don’t know...
 

John.Roo

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=how much shorter,as sommer flyng ?
This was photo from test flight of Phoenix with Rotax :)
However when we have been flyng with electric Phoenix in winter conditions in Sweden and Norway I didn´t noticed any difference. Battery warms up and keep his own temperature. However is important to keep plane in hangar - not outside. I suppose that "frozen" battery will have really lower performance.
 
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