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

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#### Sraight'nlevel

##### Well-Known Member
Glide ratio?

Or is it just a box you check off on a form?

page 2 for "box";

Some information about pilot training for motorgliders;

Is 20:1 ok ?

For a soarer ?

#### blane.c

##### Well-Known Member
Some certified motorgliders have 18:1

#### blane.c

##### Well-Known Member
200ft per minute descent rate 60mph = loss of 200 ft ----- each mile = 26.4:1 glide ratio
200ft per minute descent rate 120mph = loss of 200 ft each two miles = 52.8:1 glide ratio

#### blane.c

##### Well-Known Member
Much instrument approach work is based off the "five mile fix", as the name implies it is approximately five miles from the runway (not always exact but always close) and about 1,500 feet above the threshold (not always exact but always close) so universally you know when you get to the "five mile fix" you need to descend at about 300ft per mile.

#### John.Roo

##### Well-Known Member
When do we talk about soaring....and when just a motorplane ?

Is it the span ?

Is 12,2 meters still a soarer and what about under 10 meter spanning plane?
SGS 1-26 is beautifull "oldtimer" glider
Performance is OK for electric propulsion installation.
Glide ratio 23:1 is acceptable. Sink rate 0,88 m/s is also good.
The only problem is (as usually) EW vs MTOM....
Above written performance is for MTOM 700 lb (318 kg).
EW is 445 lb (202 kg).
In some old posts before we calculated +- min. weight of propulsion system (5 kWh / 30 kg battery, motor, controller, wiring....).
If you add min. 50 kg (propulsion) to EW + pilot weight (min. 200 lb) than is necessary to increase MTOM to +-770 lb (350 kg), probably a bit more.
Would be possible to increase MTOM legally?

I remember similar problem with ASK 14.

#### John.Roo

##### Well-Known Member
When do we talk about soaring....and when just a motorplane ?
Is it the span ?
Is 12,2 meters still a soarer and what about under 10 meter spanning plane?
It is not only about the wing span, however wing span and wing aspect ratio shows a lot.
I would personally look for combination of L/D, min, sink ratio and weight (EW and MTOM)

#### henryk

##### Well-Known Member
combination of L/D, min, sink ratio and weight

+AR (Aspect Ratio, span)=

-iff compare SGS 1-26

with BKB1-A...AR=10, L/D=29 , EW=? (NO tail, NO problem with back folding propeller !)

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#### Sraight'nlevel

##### Well-Known Member
It is not only about the wing span, however wing span and wing aspect ratio shows a lot.
I would personally look for combination of L/D, min, sink ratio and weight (EW and MTOM)

Do you think a 9,4 m spanning 2 seat plane could still be a motor glider ?

#### John.Roo

##### Well-Known Member
Do you think a 9,4 m spanning 2 seat plane could still be a motor glider ?
Honestly.... no. At least not for me - I don´t know exact FAA (CAA) TMG definition.
Of course you can achieve interesting parameters even with low aspect ratio wing.
With large wing area you get low wing load etc.

I have been flying many times with 10-11 m wing span airplanes with engine off.
But even with "reasonable" L/D (a bit over 20:1) I could not reach "glider feeling".
12-13 m wing span starts to be interesting.
13-15 m is my favorite wing span.
Wing span over 15 m is of course even better, but than are starting problems with storage, strength testing etc.

#### blane.c

##### Well-Known Member
Do you think a 9,4 m spanning 2 seat plane could still be a motor glider ?

I don't know what country you are in. In the USA for experimental amateur built it is the box you check off on the application forms with the caveat that you will need a glider DAR to sign off on it. It would be wise to discuss with DAR what they find acceptable as a glider before building such a large lawn ornament. However for example this is a glider to at least one DAR;

#### PiperCruisin

##### Well-Known Member
Do you think a 9,4 m spanning 2 seat plane could still be a motor glider ?
In the US, I think Advisory Circular (AC) 21.17-2a covers this. Less than 0.62 lbs/ft2 span loading (Gross Weight / Span^2) and 850kg (1874 lbs) maximum weight.

I'm guessing that a 2 place, 9.4 m span would have a gross weight of about 500 kg. 9.4 m span would meet the requirement for a GW of 268 kg.

#### Sraight'nlevel

##### Well-Known Member
In the US, I think Advisory Circular (AC) 21.17-2a covers this. Less than 0.62 lbs/ft2 span loading (Gross Weight / Span^2) and 850kg (1874 lbs) maximum weight.

I'm guessing that a 2 place, 9.4 m span would have a gross weight of about 500 kg. 9.4 m span would meet the requirement for a GW of 268 kg.

#### PiperCruisin

##### Well-Known Member
Correct, according to the AC, but they might accept something else if you "check the box".

#### blane.c

##### Well-Known Member
In the US, I think Advisory Circular (AC) 21.17-2a covers this. Less than 0.62 lbs/ft2 span loading (Gross Weight / Span^2) and 850kg (1874 lbs) maximum weight.

I'm guessing that a 2 place, 9.4 m span would have a gross weight of about 500 kg. 9.4 m span would meet the requirement for a GW of 268 kg.

Wrong. (AC) 21.17 pertains to Type Certificated Gliders and is not pertinent to Experimental Amateur Built.

https://www.faa.gov/regulations_pol....cfm/go/document.information/documentID/22059

#### blane.c

##### Well-Known Member
Basically E.A.B. is whatever a DAR will sign off. So good idea I think to talk to one about what you plan to do first.

#### Sraight'nlevel

##### Well-Known Member
What is the smallest aircraft ever considered a glider ? ( manned )

I know BD-5 was supposed to have a motor glider version of it.