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