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

### Help Support Homebuilt Aircraft & Kit Plane Forum:

#### BBerson

##### Light Plane Philosopher
Supporting Member
AC 21.17-2A is guidance for type certification as it says in the title. Any criteria can be used by the type certificate applicant including FAA Basic Glider Criteria. EAA should not be asking for criteria more restrictive than Europe. Or asking for any performance criteria at all for EA-B.

1. PURPOSE• This advisory circular (AC) provides information and guidance concerning acceptable means, but not the only means, of showing compliance with § 21.17(b) of part 21 of the Federal Aviation Regulations (FAR) for type certification of gliders and powered gliders. Accordingly, this material is neither mandatory nor regulatory in nature and does not constitute a regulation. General guidance relative to glider type certification is also provided.

Last edited:

#### PiperCruisin

##### Well-Known Member
Supporting Member
Now that I have had a minute to think about it, what a load of horse manure!!
I want a physical confrontation with whoever is behind this poop. To the death.

Ha ha! He said "poop".

You'll have to ask EAA about that one. I suppose it does not matter much for EAB. For that matter, I could take my Cherokee, shut off the engine and call it a motorglider. Wouldn't perform very well. I'd rather have something that roughly meets their criteria.

#### blane.c

##### Well-Known Member
Supporting Member
Ha ha! He said "poop".

You'll have to ask EAA about that one. I suppose it does not matter much for EAB. For that matter, I could take my Cherokee, shut off the engine and call it a motorglider. Wouldn't perform very well. I'd rather have something that roughly meets their criteria.

Lets meet and have a cup of coffee?

#### Sraight'nlevel

##### Well-Known Member
Now that I have had a minute to think about it, what a load of horse manure!!
I want a physical confrontation with whoever is behind this poop. To the death.
That makes it very challenging to make a small motorized glider , but not impossible. Even 8 metre spanning is doable if not a 250 lbs or heavier pilot on it. Also a 12 metre two seater can weigh 432 kilos.

a) The number of occupants does not exceed two
b) Maximum weight does not exceed 850 kg (1874 pounds), and
c) The maximum weight to wing span squared (w/b2) does not exceed 3.0 kg/m2 (0.62 lb./ft.2)

Last edited:

#### John.Roo

##### Well-Known Member
That makes it very challenging to make a small motorized glider , but not impossible. Even 8 metre spanning is doable if not a 250 lbs or heavier pilot on it. Also a 12 metre two seater can weigh 432 kilos.

a) The number of occupants does not exceed two
b) Maximum weight does not exceed 850 kg (1874 pounds), and
c) The maximum weight to wing span squared (w/b2) does not exceed 3.0 kg/m2 (0.62 lb./ft.2)
FAA TMG requirements are OK
Is interesting that there are no requirements for stall speed, wing loading etc.
With wing span from 14-15 meters (two seater) you are perfectly in with MTOM 600 kg (Phoenix, Sinus, Lambada...).
And with wing span 10 meters you can have nice one seater with reasonable MTOM of 300 kg (Axel, Sagitta etc...).

Last edited:

#### Sraight'nlevel

##### Well-Known Member
Axel is cool, but is it self launching ?

As it needs a man in the wing tip on take off ?

#### henryk

##### Well-Known Member
is it self launching ?

=semi-selflaunching...

(I was seeing selflaunching AXEL drived by RAKET120, ,piloted by constructor,Zenon Pietruszka)

#### blane.c

##### Well-Known Member
Supporting Member
That makes it very challenging to make a small motorized glider , but not impossible. Even 8 metre spanning is doable if not a 250 lbs or heavier pilot on it. Also a 12 metre two seater can weigh 432 kilos.

a) The number of occupants does not exceed two
b) Maximum weight does not exceed 850 kg (1874 pounds), and
c) The maximum weight to wing span squared (w/b2) does not exceed 3.0 kg/m2 (0.62 lb./ft.2)

It is fine for my purposes, but I see no need to put these additional restrictions on EAB glider, it is just unnecessary.

#### EzyBuildWing

##### Well-Known Member
Lighter and higher-tech eMotors on the way:

Infinitum Electric has raised an
$80M Series D led by Riverstone Holdings to expand production and complete EV motor development. Infinitum's motors are also being targeted for use in heating, cooling, ventilation, and portable power generators, among other applications. • Infinitum uses a printed circuit board stator, which enables the copper winding core of the motor to be integrated into a thin, disc-shaped PCB, which reduces the size and weight of the motor. The PCB stator uses two-thirds less copper compared to a conventional iron-core stator. • The company claims its electric motors provide up to 65% savings in energy versus regular motors. • Infinitum expects to scale production to 50,000 motos per year starting in 2023, 5x from this year. #### John.Roo ##### Well-Known Member Axel is cool, but is it self launching ? As it needs a man in the wing tip on take off ? Axel, Sagitta, GP gliders, Apis, Silent, Atlas... all this small e-gliders are existing in self launch version and typicaly you don´t need somebody to hold your wing #### John.Roo ##### Well-Known Member Lighter and higher-tech eMotors on the way: Infinitum Electric has raised an$80M Series D led by Riverstone Holdings to expand production and complete EV motor development.
Infinitum's motors are also being targeted for use in heating, cooling, ventilation, and portable power generators, among other applications.
• Infinitum uses a printed circuit board stator, which enables the copper winding core of the motor to be integrated into a thin, disc-shaped PCB, which reduces the size and weight of the motor. The PCB stator uses two-thirds less copper compared to a conventional iron-core stator.
• The company claims its electric motors provide up to 65% savings in energy versus regular motors.
• Infinitum expects to scale production to 50,000 motos per year starting in 2023, 5x from this year.
This is interesting.
I would like to see some direct comparizon with "regular" motor because info "65% savings in energy" needs a bit better explanation.
If typical (as they say - "regular") electric motor has actually efficiency of 85-90% than how they calculate 65% energy saving?
In exact numbers.... if I need 5 kW cont. power (power required for horizontal flight) than what power is "flowing" from batteries if I use their motor?
Would be better to show some exact measurements instead of playing with great looking but meaningless percentages

#### henryk

##### Well-Known Member
electric motor has actually efficiency of 85-90% than how they calculate 65% energy saving?

=today >95 % (BLDC) and SRMotors, Asynchronous (magnetless!) too...

#### Sraight'nlevel

##### Well-Known Member
Axel, Sagitta, GP gliders, Apis, Silent, Atlas... all this small e-gliders are existing in self launch version and typicaly you don´t need somebody to hold your wing

I disagree...you cannot fly those to places without a decent concrete or asphalt runway....or very short cut grass field. Or you can, but it would be tricky to get out ( take off ). I mean you need some sorta 3 wheel system for it to be stable...preferably a tail dagger.

#### John.Roo

##### Well-Known Member
I disagree...you cannot fly those to places without a decent concrete or asphalt runway....or very short cut grass field. Or you can, but it would be tricky to get out ( take off ). I mean you need some sorta 3 wheel system for it to be stable...preferably a tail dagger.
I was taking off on grass RWY with Sagitta without external help - not a problem.
Of course if on RWY is 1 m grass it would be difficult, but typical maintained grass RWY is not complication at all

Taildragger type undercarriage could be helpfull - I agree. It depends on owner’s preferences.

Last edited:

#### EzyBuildWing

##### Well-Known Member
More motors and battery-combinations on the way:

#### John.Roo

##### Well-Known Member
Taildragger undercarriage on small UL glider....
It was used on Straton - old Czech construction.
Aiframe has been made from wood - simple nice design

Original version had one wheel "glider like" undercarriage...

#### raytol

##### Well-Known Member
Supporting Member
A lot of "overestimating" the performance and "underestimating" the time to market in the market of batteries and electric motors at the moment!

#### Sraight'nlevel

##### Well-Known Member
A lot of "overestimating" the performance and "underestimating" the time to market in the market of batteries and electric motors at the moment!
In general or here at the HBA ?

#### John.Roo

##### Well-Known Member
A lot of "overestimating" the performance and "underestimating" the time to market in the market of batteries and electric motors at the moment!
I agree. Therefore I don´t like claims like "60% better efficiency" etc.
Never forget that informations about "great efficiency", "better capacity" etc. are aimed to investors.

Physical laws are still valid
If you like to design or buy electric propulsion (or whole electric airplane) you can simply check real performance numbers.
1 kWh capacity = approx. 5 kg weight.
There is no "magic" inside batteries - normal cells are used.
It means is good to ask what exact type of cells are inside battery you are interested to buy.
Motor + controler efficiency is max. 85-90% (95% is usually "laboratory" efficiency).
In case of whole airplane check always real EW personally (on advertising paper are every numbers looking better)
During test flight watch motor / controller / battery temperature.
Two seat "motorglider like" LSA airplane needs 12-15 kW of power to stay in the air.
Two seat "normal" LSA airplane will need 20-25 kW of power to stay in the air.

No need to be disappointed - just use real numbers

Last edited:

#### henryk

##### Well-Known Member
real numbers

Total Efficiency=Motor Eff. * Controller Eff. * Battery Eff.

ech Eff <1 ,
Total Eff. << 1!

=0.9*0.9*0.9=0.73 ! (allmost 30 % energy into heat )