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

David Scott wrote on 2/3/2021 4:24 PM:
On Wednesday, February 3, 2021 at 4:02:37 PM UTC-8, Eric Greenwell wrote:
David Scott wrote on 2/3/2021 2:24 PM:
On Tuesday, February 2, 2021 at 1:26:10 PM UTC-8, David Scott wrote:
I DON'T mean to stir up trouble on this forum with this question, especially being new, but have been wondering about this for some time. I am wondering how feasible it would be to do this with either a homebuilt or experimental glider here in the US?

I figure this has been asked but didn't find any threads on it.

Thanks to all for your responses. What I am hearing certainly doesn't scare me away from the idea, which is all it is at the moment but I have been "thinking" about this and possible solutions for years. My biggest take is to talk to those who would be signing it off to find out what they think of it.

I have been very involved in high-performance composites for many years, have been machining for 33 years now, and doing product development longer. I have my own CNC machine shop where I mostly make my own products so I am well equipped to do the design and manufacturing. I have done enough projects that took over 2000 hours to get into production that I do understand there is always way more work than expected, but this really isn't that big of a job, comparatively.

I really like the FES idea for modifying a stock glider for its simplicity. The only structural change to the glider would be to cut off the nose but the firewall would certainly reinforce it, depending on how the batteries are stored. The biggest downside is that the propeller has to be too small for efficiency.

Are you familiar with 4 kwh lithium battery packs and BMS units? How about 20-25 kw DC motors
and the electronic controllers for them? The mechanical part of an electric propulsion system
might be harder (perhaps much harder) than the electrical part.

I think you can buy a complete FES system (includes drawings for the installation) for many of
the popular gliders. That would save you an immense mount of design and testing time. Visit the
FES developer's site at

http://www.front-electric-sustainer.com/index.php

--
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

When I checked a year-ish ago you had to go through their distributor in the US and they had to install it. I never checked but figured it would be in the $40k neighborhood. At least their distributor is close by here in Washington. I'm just outside of Hood River.

You can see why some choose to install jet engines: simpler, lighter, more compact (no
propeller), and the fuel is pumped in, avoiding the need for a door in fuselage.

--
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 Wednesday, February 3, 2021 at 5:10:11 PM UTC-6, Mark Mocho wrote:
Not to hijack the thread, but in response to the reliability issue of two-stroke engines, the primary culprit seems to be the different altitudes at which the engine is supposed to start and operate. The fuel/oil/air mixture has to be within certain parameters for decent running and starting reliability. An increase in altitude (or high density altitude conditions) reduces the amount of available oxygen, which contributes to fouling the spark plugs. I used to ride the Yamaha RD-350 and TZ-250 motorcycles from Albuquerque (elevation ~5,500 ft. MSL) up to Sandia Crest (10,678 ft. MSL) and used to have to stop and adjust the needles in the carburetors four times on the way up and four times on the way down or risk plug fouling or overheating and possibly seizing the engine. About a 1,000 ft. change in altitude was all it took to affect the performance and reliability. Newer two-stroke engines with more sophisticated fuel injection systems seem to be much more reliable in motorgliders.

Oh, that brings back memories. I too rode an RD-350 (voted as the "Bike most likely to lose you your driver's license"). Even tried production class road racing on it a couple times (scary). Had the same experience as you with riding in the mountains. Used to stop on the way up to Deal's Gap and drop the carb needles a notch. Put 38,000 miles on the bike. Never failed to start and run. Stopped being scooter trash and became glider trash, but still have that bike (mothballed since 1981).

On 2/3/2021 10:50 AM, Hank Nixon wrote:
If you want an electric sailplane- buy one.

Take two aspirin, and call me in the morning.

Talk about hijacking...

I've had my Harley Davidson Wide Glide for almost 17 years and 137,000
miles and don't ride it too much any more though I did get it out a
couple of days ago when the temperature got up to 60 deg. Just
wondering what you did to mothball it. I've never done more than to put
on a battery charger now and then.

Dan
5J


On 2/3/21 9:36 PM, Wallace Berry wrote:
but still have that bike (mothballed since 1981).

On Thursday, February 4, 2021 at 10:51:36 AM UTC-6, Dan Marotta wrote:
Talk about hijacking...

I've had my Harley Davidson Wide Glide for almost 17 years and 137,000
miles and don't ride it too much any more though I did get it out a
couple of days ago when the temperature got up to 60 deg. Just
wondering what you did to mothball it. I've never done more than to put
on a battery charger now and then.

Dan
5J
On 2/3/21 9:36 PM, Wallace Berry wrote:
but still have that bike (mothballed since 1981).
Drained the transmission case and replaced with fresh oil. Drained the fuel tank, lines, carbs. Flushed everything with clean fuel and stabilizer, then drained again and let dry before reassembly. Drained the forks and replaced the fork fluid. Drained the front brake hydraulics. Fogged the cylinders with Marvel Mystery Oil and turned them over a few times. Threw the battery away. Heavily Armor All'ed the exterior rubber and vinyl. Probably should have used products expressly made to pickle engines, but I didn't know I was going to keep the bike stored for 40 years. Front fork wipers, brake lines, and tires have deteriorated. Everything else seems OK. RD 350's were still being made (in India) up into the late 1990's or early 2000's so parts are still available. Hoping to do a complete restoration as a retirement project, but I don't plan on taking up riding scooters again. Old bones and all...

Thanks!

Took mine to the store today and it was too cold for me. Temperature in
the 40s. Put her back to sleep...

Dan
5J


On 2/4/21 1:13 PM, Wallace Berry wrote:
On Thursday, February 4, 2021 at 10:51:36 AM UTC-6, Dan Marotta wrote:
Talk about hijacking...

I've had my Harley Davidson Wide Glide for almost 17 years and 137,000
miles and don't ride it too much any more though I did get it out a
couple of days ago when the temperature got up to 60 deg. Just
wondering what you did to mothball it. I've never done more than to put
on a battery charger now and then.

Dan
5J
On 2/3/21 9:36 PM, Wallace Berry wrote:
but still have that bike (mothballed since 1981).
Drained the transmission case and replaced with fresh oil. Drained the fuel tank, lines, carbs. Flushed everything with clean fuel and stabilizer, then drained again and let dry before reassembly. Drained the forks and replaced the fork fluid. Drained the front brake hydraulics. Fogged the cylinders with Marvel Mystery Oil and turned them over a few times. Threw the battery away. Heavily Armor All'ed the exterior rubber and vinyl. Probably should have used products expressly made to pickle engines, but I didn't know I was going to keep the bike stored for 40 years. Front fork wipers, brake lines, and tires have deteriorated. Everything else seems OK. RD 350's were still being made (in India) up into the late 1990's or early 2000's so parts are still available. Hoping to do a complete restoration as a retirement project, but I don't plan on taking up riding scooters again. Old bones and all...

On Tuesday, February 2, 2021 at 4:26:10 PM UTC-5, David Scott wrote:
I DON'T mean to stir up trouble on this forum with this question, especially being new, but have been wondering about this for some time. I am wondering how feasible it would be to do this with either a homebuilt or experimental glider here in the US?

I figure this has been asked but didn't find any threads on it.

It's "easy" for a qualified definition of "easy" meaning "straightforward". Several of us are already well down this route, if you're interested reach out to me and I'll send you an invite to our Slack group.

The FAA's regulations are no big deal. Others have pointed out the steps that you have to go through, and Bob Kuykendall pretty much nails it. Don't do bad work, don't do work which will manifestly endanger you or-- worse-- the public, don't just wing it. Aside from that, if the system works and you are happy to be the test pilot, the FAA is more than willing to give you the rope you need to hang yourself with.

Practically, it's not easy to find the right combination of propeller and motor and battery and layout which works. Every glider has its own peculiarities, and those need to be negotiated at some cost of time and money.

I would caution you against considering anything but the lightest of gliders. There's nothing wrong or unsafe about larger self-launching gliders, but when you're pulling this together in your shop it's a world of different if you're working with a 15kW motor, a 3kW-hr battery, and a 1.3m prop vs. a 40kW motor a 6kW-hr pack, and a 2m prop. Good candidates are the AC-5M and the Carbon Dragon. The former because all you have to do is swap out the existing engine, and the latter because it's so very, very light.

Kenn Sebesta wrote on 2/5/2021 7:02 AM:
On Tuesday, February 2, 2021 at 4:26:10 PM UTC-5, David Scott wrote:
..
..
..
Practically, it's not easy to find the right combination of propeller and motor and battery and layout which works. Every glider has its own peculiarities, and those need to be negotiated at some cost of time and money.

I would caution you against considering anything but the lightest of gliders. There's nothing wrong or unsafe about larger self-launching gliders, but when you're pulling this together in your shop it's a world of different if you're working with a 15kW motor, a 3kW-hr battery, and a 1.3m prop vs. a 40kW motor a 6kW-hr pack, and a 2m prop. Good candidates are the AC-5M and the Carbon Dragon. The former because all you have to do is swap out the existing engine, and the latter because it's so very, very light.

I've been comparing electric self-launching gliders, including the JS3 RES (15M), GP15,
miniLak, and Silent Electro. It became obvious the dramatic difference low weight can make in
powered performance. For example, when both have the "big batteries": the JS3 RES 15M is 250
pounds heavier than the GP15, and for that reason it's max altitude gain is about 9000',
compared to 13,000' for the 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 2/2/21 6:09 PM, David Scott wrote:
On Tuesday, February 2, 2021 at 1:26:10 PM UTC-8, David Scott wrote:
I DON'T mean to stir up trouble on this forum with this question, especially being new, but have been wondering about this for some time. I am wondering how feasible it would be to do this with either a homebuilt or experimental glider here in the US?

I figure this has been asked but didn't find any threads on it.

Thank you for your responses. To be clear I don't have a sailplane but would like to get into the sport and the answers to this question would possibly affect what glider I would get. I am smart enough to get all my ducks in a row before doing anything, and this is the first I have talked about it. From an engineering standpoint, it doesn't look too difficult, navigating the regulations is where I expect the most trouble.


Putting together a motorglider is a strange path towards getting
involved with the sport. Might be better to take lessons, get the
rating, and have some time under your belt before taking on a project
like this.

In my local club, I see people going solo and maybe getting their
rating, and immediately thinking about buying a glider. This is with a
reasonable selection of under utilized club ships sitting around. I
encourage them to wait a couple years first.

If you're all set on owning an electric motorglider, there's a
reasonable selection of Silent 2 Electro's on W&W. Do yourself and the
owners a big favor and pick up one of those.

-Dave

On Wednesday, February 3, 2021 at 3:10:11 PM UTC-8, Mark Mocho wrote:
...I used to ride the Yamaha RD-350 and TZ-250 motorcycles...

I raced RD-250 in 250 Modified Production and TA-125 in GP classes during my mis-spent youth. Fun stuff, but there is no way I'd trust my life to the continued operation of a tightly-wound two-stroke motor. I didn't think I'd mess around with motorgliders at all until brushless motors and Lithium batteries came along. Now I think that electric motorgliders are poised to become the core of our sport, with pure sailplanes becoming more of a fringe activity.