What is involved regulation wise adding an electric motor to a glider?

John Sinclair wrote on 2/8/2021 12:02 PM:
Your reduced pilot weight (165+ 15 parachute) only reduces the fuselage load by 20 # below my LS-3a example, and that still leaves you something like 50# over the max allowable fuselage load. I’d nail down all these little problems before committing to the project..........you will find plenty of unforeseen issues that you haven’t even thought about.
I agree that a pylon motor mount is far superior to a FES, because there is no big CG issues to deal with. The FES nose motor weight must be counterbalanced with an aft battery which is located as far behind Your CG, as the nose motor is in front of the CG!
A big problem in selecting a ship to modify is the area you wish to install a pylon is the area where the wing controls are located on most ships.........ailerons, flaps and dive breaks......... need to come up with a plan on how to redesign the control linkage? BTW, installing a ballistic parachute shares this same problem........the chute and rocket need to go in the area where the wing controls are located.........?
I would think batteries located inside a wings D tube should be attached to the vertical shear web and strong enough to withstand a 5G load, none of which is taken by the wing skin? I’d place the batteries as far out in the wing as they will fit and you will need to design a way to get cooling air to all the battery cells. Make sure to properly repair any holes you cut in the D tube as that section takes some of the bending load and all of the twisting load seen by the wing!
What have I missed? Oh, how about a fire extinguisher......Inside the wing would be nice?
Have fun,
JJ

It's not quite so bad, JJ. A 20kw motor might weigh only 7 kg; a 4.7kWh battery would weigh
about 22kg, so the battery can usually be mounted behind the wing. That also puts it clear of
the wing control mechanisms. The total added weight will easily be below 45kg/100lb. If that
still exceeds the non-lifting weight limit, the Vne, etc, can be reduced to keep the structure
safe.

There are many advantages to the fuselage mounted batteries. A major one is easy removal for
charging elsewhere. A BRS is desirable, but the only there aren't many that offer it. The GP15
and the Silent Electro are the only two I know of. A fire extinguishing system is also
desirable, but I only know of one glider that plans to offer one (GP15).

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

On 2/7/21 12:46 PM, David Scott wrote:

The biggest problem to an electric propulsion system is the batteries, and those are going to get vast improvements in the near future.

That's a big red flag. I hope you're not doing this project assuming
the batteries are going to be a lot better. Lithium batteries have been
commercially available for about 20 years, and the annual compounded
rate of improvement in energy density is not that impressive. It's been
claimed that batteries are somehow subject to Moore's Law, which is an
extremely incorrect assumption.

Still think you're underestimating the scope of the project. For
example, the Glasflugel folks are working on a self-launch retrofit for
Libelle's. Been at it for five years, been flying for three years, and
they're still not ready to announce pricing or availability. See story
at 7:50 he

https://www.youtube.com/watch?v=DZNr2BIOXBw

Someone converted a Cessna Caravan to electric and put on a big demo
flight for the press. It suffered a partial inverter failure during
that flight, now has been converted back to turbo jet and is up for
sale. The good folks at GP Gliders are five years late in delivering
product, when they finally got one out the door last year, the motor
lasted 10 minutes before something burned out. You'd think electric
systems would be so reliable, but there's tons of things that can go wrong.

The Antares was one of the first on the market, never really lived up to
its promised performance. On a hot day, the motor can overheat after a
thousand foot climb, batteries didn't deliver the capacity or lifetime
they were supposed to. Mr. Nadler may someday enlighten us with a few
more of its weak points.

Dave

Pipistrel is working on a hydrogen fuel cell powered aircraft. This might be an interesting idea to consider.
I have heard of another company working on a larger 6 person aircraft that recently took flight.

https://www.compositesworld.com/news...t-takes-flight

Darren

That's really great! I wonder, however... Are they also setting up the
infrastructure? How many airports have hydrogen? If I chose to carry
my own, where would I get it?

Seriously, I think fuel cells are a better way to go for electrics, but
where does the fuel come from? In a reasonable amount of time.

Dan
5J

On 2/8/21 8:37 PM, Darren Braun wrote:
Pipistrel is working on a hydrogen fuel cell powered aircraft. This might be an interesting idea to consider.
I have heard of another company working on a larger 6 person aircraft that recently took flight.

https://www.compositesworld.com/news...t-takes-flight

Darren

On Tuesday, February 9, 2021 at 7:21:05 AM UTC-8, Dan Marotta wrote:
That's really great! I wonder, however... Are they also setting up the
infrastructure? How many airports have hydrogen? If I chose to carry
my own, where would I get it?

Seriously, I think fuel cells are a better way to go for electrics, but
where does the fuel come from? In a reasonable amount of time.

Dan
5J
On 2/8/21 8:37 PM, Darren Braun wrote:
Pipistrel is working on a hydrogen fuel cell powered aircraft. This might be an interesting idea to consider.
I have heard of another company working on a larger 6 person aircraft that recently took flight.

https://www.compositesworld.com/news...t-takes-flight

Darren




Eric,
Installing an electric propulsion system involves a good deal more weight than just the motor and battery weight. There must be battery cables large enough to carry hundreds of amps + controller+ motor mount+ propeller + spinner and a fire resistant battery box? Hank Nixon has made such an instillation and he said it weighed an additional 100#...........I’ll take Hanks figure!
As for “backing off of the red-line�, if you exceed the maximum weight of non lifting surfaces............your Experimental Airworthiness Certificate, contains the following.........This aircraft will be operated in accordance with the Flight Manual and maintained in accordance with the Maintenance Manual!
I’d hate to hear that read to me by an insurance lawyer in court, some day!
JJ

John Sinclair wrote on 2/9/2021 11:48 AM:

Eric,
Installing an electric propulsion system involves a good deal more weight than just the motor and battery weight. There must be battery cables large enough to carry hundreds of amps + controller+ motor mount+ propeller + spinner and a fire resistant battery box? Hank Nixon has made such an instillation and he said it weighed an additional 100#...........I’ll take Hanks figure!
As for “backing off of the red-line”, if you exceed the maximum weight of non lifting surfaces............your Experimental Airworthiness Certificate, contains the following.........This aircraft will be operated in accordance with the Flight Manual and maintained in accordance with the Maintenance Manual!
I’d hate to hear that read to me by an insurance lawyer in court, some day!
JJ

Was it 100 lbs for the total system, including the mast? Or just the stuff he added to the ASW24E?

Ken is using a Russia 5, which already has a motor & mast in it, so he's removing the gas
engine, and adding an electric motor - that's probably the same net weight, or less. The
batteries will add a lot of weight (maybe 30 lbs, given the Kwh Kenn wants); the controllers,
and cables with add some more, but it seems unlikely it will exceed 60 lbs.

If it's experimental, surely the owner/modifier gets to acquire a new Airworthiness
certificate, and change the flight manual to match the changes he's made in the aircraft? It
wouldn't make sense to require Hank to adhere to the flight manual for an ASW24E (gas sustainer
engine) after he's made it into an electric self-launcher, for example.


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

On Tuesday, February 9, 2021 at 3:58:12 PM UTC-5, Eric Greenwell wrote:
John Sinclair wrote on 2/9/2021 11:48 AM:

Eric,
Installing an electric propulsion system involves a good deal more weight than just the motor and battery weight. There must be battery cables large enough to carry hundreds of amps + controller+ motor mount+ propeller + spinner and a fire resistant battery box? Hank Nixon has made such an instillation and he said it weighed an additional 100#...........I’ll take Hanks figure!
As for “backing off of the red-line�, if you exceed the maximum weight of non lifting surfaces............your Experimental Airworthiness Certificate, contains the following.........This aircraft will be operated in accordance with the Flight Manual and maintained in accordance with the Maintenance Manual!
I’d hate to hear that read to me by an insurance lawyer in court, some day!
JJ
Was it 100 lbs for the total system, including the mast? Or just the stuff he added to the ASW24E?

Ken is using a Russia 5, which already has a motor & mast in it, so he's removing the gas
engine, and adding an electric motor - that's probably the same net weight, or less. The
batteries will add a lot of weight (maybe 30 lbs, given the Kwh Kenn wants); the controllers,
and cables with add some more, but it seems unlikely it will exceed 60 lbs.

If it's experimental, surely the owner/modifier gets to acquire a new Airworthiness
certificate, and change the flight manual to match the changes he's made in the aircraft? It
wouldn't make sense to require Hank to adhere to the flight manual for an ASW24E (gas sustainer
engine) after he's made it into an electric self-launcher, for example.
--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

The net change for my '24E was 2 lb increase compared to condition before change, weighed without fuel.
Battery weighs 60 lb, 120V 5.75kwh.
Motor weighs 18 lb
Controller weighs 4-1/2
2 batteries in the nose. 12 lb
The 100 lb comparison I made is my 24E compared to a pure glider. This reflects the above plus structural changes between 24 and 24E as well as the lift mechanism.
UH

Hank Nixon wrote on 2/9/2021 1:29 PM:
On Tuesday, February 9, 2021 at 3:58:12 PM UTC-5, Eric Greenwell wrote:
John Sinclair wrote on 2/9/2021 11:48 AM:

Eric,
Installing an electric propulsion system involves a good deal more weight than just the motor and battery weight. There must be battery cables large enough to carry hundreds of amps + controller+ motor mount+ propeller + spinner and a fire resistant battery box? Hank Nixon has made such an instillation and he said it weighed an additional 100#...........I’ll take Hanks figure!
As for “backing off of the red-line”, if you exceed the maximum weight of non lifting surfaces............your Experimental Airworthiness Certificate, contains the following.........This aircraft will be operated in accordance with the Flight Manual and maintained in accordance with the Maintenance Manual!
I’d hate to hear that read to me by an insurance lawyer in court, some day!
JJ
Was it 100 lbs for the total system, including the mast? Or just the stuff he added to the ASW24E?

Ken is using a Russia 5, which already has a motor & mast in it, so he's removing the gas
engine, and adding an electric motor - that's probably the same net weight, or less. The
batteries will add a lot of weight (maybe 30 lbs, given the Kwh Kenn wants); the controllers,
and cables with add some more, but it seems unlikely it will exceed 60 lbs.

If it's experimental, surely the owner/modifier gets to acquire a new Airworthiness
certificate, and change the flight manual to match the changes he's made in the aircraft? It
wouldn't make sense to require Hank to adhere to the flight manual for an ASW24E (gas sustainer
engine) after he's made it into an electric self-launcher, for example.
--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

The net change for my '24E was 2 lb increase compared to condition before change, weighed without fuel.
Battery weighs 60 lb, 120V 5.75kwh.
Motor weighs 18 lb
Controller weighs 4-1/2
2 batteries in the nose. 12 lb
The 100 lb comparison I made is my 24E compared to a pure glider. This reflects the above plus structural changes between 24 and 24E as well as the lift mechanism.
UH
So, motor battery weighs 60 lbs, but what are the 12 lbs of battery in the nose? Do you
remember the motor power wire size and weight?

How was your airworthiness certificate, Flight manual, and Maintenance manual affected by the
new power source?


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

The net change for my '24E was 2 lb increase compared to condition before change, weighed without fuel.
Battery weighs 60 lb, 120V 5.75kwh.
Motor weighs 18 lb
Controller weighs 4-1/2
2 batteries in the nose. 12 lb
The 100 lb comparison I made is my 24E compared to a pure glider. This reflects the above plus structural changes between 24 and 24E as well as the lift mechanism.
UH

Thanks for those figures. I've calculated similarly tiny net changes in weight for an electric conversion-- on paper, I should wind up all of 500g lighter. Of course, the reality won't perfectly track the numbers, but it's heartening to see my hunch played out in your case.

On Tuesday, February 9, 2021 at 5:06:42 PM UTC-5, Eric Greenwell wrote:
Hank Nixon wrote on 2/9/2021 1:29 PM:
On Tuesday, February 9, 2021 at 3:58:12 PM UTC-5, Eric Greenwell wrote:
John Sinclair wrote on 2/9/2021 11:48 AM:

Eric,
Installing an electric propulsion system involves a good deal more weight than just the motor and battery weight. There must be battery cables large enough to carry hundreds of amps + controller+ motor mount+ propeller + spinner and a fire resistant battery box? Hank Nixon has made such an instillation and he said it weighed an additional 100#...........I’ll take Hanks figure!
As for “backing off of the red-line�, if you exceed the maximum weight of non lifting surfaces............your Experimental Airworthiness Certificate, contains the following.........This aircraft will be operated in accordance with the Flight Manual and maintained in accordance with the Maintenance Manual!
I’d hate to hear that read to me by an insurance lawyer in court, some day!
JJ
Was it 100 lbs for the total system, including the mast? Or just the stuff he added to the ASW24E?

Ken is using a Russia 5, which already has a motor & mast in it, so he's removing the gas
engine, and adding an electric motor - that's probably the same net weight, or less. The
batteries will add a lot of weight (maybe 30 lbs, given the Kwh Kenn wants); the controllers,
and cables with add some more, but it seems unlikely it will exceed 60 lbs.

If it's experimental, surely the owner/modifier gets to acquire a new Airworthiness
certificate, and change the flight manual to match the changes he's made in the aircraft? It
wouldn't make sense to require Hank to adhere to the flight manual for an ASW24E (gas sustainer
engine) after he's made it into an electric self-launcher, for example..
--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

The net change for my '24E was 2 lb increase compared to condition before change, weighed without fuel.
Battery weighs 60 lb, 120V 5.75kwh.
Motor weighs 18 lb
Controller weighs 4-1/2
2 batteries in the nose. 12 lb
The 100 lb comparison I made is my 24E compared to a pure glider. This reflects the above plus structural changes between 24 and 24E as well as the lift mechanism.
UH
So, motor battery weighs 60 lbs, but what are the 12 lbs of battery in the nose? Do you
remember the motor power wire size and weight?

How was your airworthiness certificate, Flight manual, and Maintenance manual affected by the
new power source?
--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

Nose batteries power left as in original powering the lift and instruments and help with CG.
Motor wires are double 10 ga high conductive wire on each phase. There is a lot of wire but I don't think it is a major weight contributor.
I got a new AW certificate. I rewrote manual pages and operating limitations where they were affected. Feds spent about 2 minutes looking at all that..
UH