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

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.

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.

I assume that you are talking about a glider registered experimental. The major obstacle beyond design, implementation and testing, is to get an AI to sign off on a conditional inspection. I would consult with that AI before you start modifying the glider. You may also have to hire a DAR (designated airworthiness representative). Again, doing this before modifying the glider is highly advisable. Another resource is the EAA. Look up this webinar (https://www.eaa.org/videos):
Webinar- Building an Aircraft - What You Need to Know
You will need to be an EAA member to watch it. Charlie Becker is the presenter and he is presumably building an electric glider, so he could be a great resource.

Tom

On Tuesday, February 2, 2021 at 3:43:09 PM UTC-8, 2G 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.
I assume that you are talking about a glider registered experimental. The major obstacle beyond design, implementation and testing, is to get an AI to sign off on a conditional inspection. I would consult with that AI before you start modifying the glider. You may also have to hire a DAR (designated airworthiness representative). Again, doing this before modifying the glider is highly advisable. Another resource is the EAA. Look up this webinar (https://www.eaa.org/videos):
Webinar- Building an Aircraft - What You Need to Know
You will need to be an EAA member to watch it. Charlie Becker is the presenter and he is presumably building an electric glider, so he could be a great resource.

Tom
Probably best to start by reviewing the limitations letter that’s attached to your experimental airworthiness certificate.
Many contain a statement like, “ any major change to this aircraft invalidates this airworthiness certificate�. You will need to request a new airworthiness certificate and prove to the inspector that all is well with your new machine?
JJ

On Tuesday, February 2, 2021 at 6:43:09 PM UTC-5, 2G 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.
I assume that you are talking about a glider registered experimental. The major obstacle beyond design, implementation and testing, is to get an AI to sign off on a conditional inspection. I would consult with that AI before you start modifying the glider. You may also have to hire a DAR (designated airworthiness representative). Again, doing this before modifying the glider is highly advisable. Another resource is the EAA. Look up this webinar (https://www.eaa.org/videos):
Webinar- Building an Aircraft - What You Need to Know
You will need to be an EAA member to watch it. Charlie Becker is the presenter and he is presumably building an electric glider, so he could be a great resource.

Tom
I was not able to find the webinar. Can you give a better guiding link?
Thx
UH

Hank Nixon wrote on 2/8/2021 6:19 AM:
On Tuesday, February 2, 2021 at 6:43:09 PM UTC-5, 2G 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.
I assume that you are talking about a glider registered experimental. The major obstacle beyond design, implementation and testing, is to get an AI to sign off on a conditional inspection. I would consult with that AI before you start modifying the glider. You may also have to hire a DAR (designated airworthiness representative). Again, doing this before modifying the glider is highly advisable. Another resource is the EAA. Look up this webinar (https://www.eaa.org/videos):
Webinar- Building an Aircraft - What You Need to Know
You will need to be an EAA member to watch it. Charlie Becker is the presenter and he is presumably building an electric glider, so he could be a great resource.

Tom
I was not able to find the webinar. Can you give a better guiding link?
Thx
UH

This works:
https://www.eaa.org/videos/6226408033001

--
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 Monday, February 8, 2021 at 9:27:36 AM UTC-5, Eric Greenwell wrote:
Hank Nixon wrote on 2/8/2021 6:19 AM:
On Tuesday, February 2, 2021 at 6:43:09 PM UTC-5, 2G 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.
I assume that you are talking about a glider registered experimental. The major obstacle beyond design, implementation and testing, is to get an AI to sign off on a conditional inspection. I would consult with that AI before you start modifying the glider. You may also have to hire a DAR (designated airworthiness representative). Again, doing this before modifying the glider is highly advisable. Another resource is the EAA. Look up this webinar (https://www.eaa.org/videos):
Webinar- Building an Aircraft - What You Need to Know
You will need to be an EAA member to watch it. Charlie Becker is the presenter and he is presumably building an electric glider, so he could be a great resource.

Tom
I was not able to find the webinar. Can you give a better guiding link?
Thx
UH

This works:
https://www.eaa.org/videos/6226408033001
--
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

Title for the video?
Thx
UH

Hank Nixon wrote on 2/8/2021 7:29 AM:
On Monday, February 8, 2021 at 9:27:36 AM UTC-5, Eric Greenwell wrote:
Hank Nixon wrote on 2/8/2021 6:19 AM:
On Tuesday, February 2, 2021 at 6:43:09 PM UTC-5, 2G 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.
I assume that you are talking about a glider registered experimental. The major obstacle beyond design, implementation and testing, is to get an AI to sign off on a conditional inspection. I would consult with that AI before you start modifying the glider. You may also have to hire a DAR (designated airworthiness representative). Again, doing this before modifying the glider is highly advisable. Another resource is the EAA. Look up this webinar (https://www.eaa.org/videos):
Webinar- Building an Aircraft - What You Need to Know
You will need to be an EAA member to watch it. Charlie Becker is the presenter and he is presumably building an electric glider, so he could be a great resource.

Tom
I was not able to find the webinar. Can you give a better guiding link?
Thx
UH

This works:
https://www.eaa.org/videos/6226408033001
--
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

Title for the video?
Thx
UH

"Webinar- Building an Aircraft - What You Need to Know"

The link takes me right to it, but it does require logging in as an EAA member to view it.

--
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 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.

AHHH! The dreaded question, "How hard could it be?" See Dave Nadler's 2020 SSA Convention presentation on motorglider reliability.

https://www.youtube.com/watch?v=R--m0NDR0j8&t=8s

Electric or internal combustion (or jet or warp drive, or....) the problem is lots more complex than it seems. I have been involved with seven jet engine/glider conversions, and everything takes a lot of serious analysis. Hint: start with a glider that already has an engine bay for a fuselage mounted power plant. Or at least check with Emir Sherbi about his Grasshopper electric conversion.

https://www.facebook.com/charlysierragolf/

On Tuesday, February 2, 2021 at 5:10:00 PM UTC-8, 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.

This would be cost prohibitive to certify; possibly hundred$ of thousands and years of your life. However, there are several ways to accomplish this with experimentals. As you mentioned, you could modify a homebuilt sailplane with an Amateur Built experimental airworthiness certificate. Alternatively, you could put a factory-built sailplane into an experimental category for R&D or Racing and Exhibition.

As somebody mentioned, each experimental airworthiness certificate is issued with a list of operating limitations. Almost always, the operating limitations require you to notify the FAA of any major alterations. The FAA would most likely require an airworthiness inspection, just to make sure you didn't do anything silly. They would also require a flight test period. Usually, this is 40 hours for an amateur built experimental with an uncertified engine/prop.

I've brought numerous aircraft into experimental categories and modified the hell out of them. In every case, the FAA was super easy to work with. I'd recommend that you make an appointment to discuss this with your local FSDO.