Best option for electric self starting glider

To quote Dave Nadler, "How hard could it be?"

Love the quote. I'm thinking this might actually be pretty easy to do as a modification to an existing glider with a FES configuration. Most of them already have two batteries and it would be simple to add a second motor controller. The hard part would be mounting the second sustainer motor in a clean manner. I'd have to do some structural analysis, but it might be possible to add a motor to the vertical stabilizer. Alternatively, one could glass motor mounts onto the wings for a pair of 5kW motors.

On 4/9/20 12:05 AM, wrote:

To quote Dave Nadler, "How hard could it be?"

Love the quote. Actually, this would be right up my alley. I've developed a few aircraft from scratch and people pay me a lot of money to modify special mission airplanes. A multi-motor self-launcher would be pretty easy to do as a modification to an existing self-launcher; probably a 3 month project. Perhaps I'll get around to this eventually, but first I have some more pressing items on my wish list!


Wow. The GP folks are about four years late in delivering product and
you can do all this in three months!! Go for it!!!

Actually the Alice electric plane has much of the redundancy that you're
asking for. Three motors with dual inverters on each of them, a highly
segmented battery configuration that can be reconfigured almost
infinitely. At least on paper it has those things, they burned up their
prototype before getting to taxi tests.

On Thursday, April 9, 2020 at 7:57:10 AM UTC+1, kinsell wrote:
On 4/9/20 12:05 AM, wrote:

To quote Dave Nadler, "How hard could it be?"

Love the quote. Actually, this would be right up my alley. I've developed a few aircraft from scratch and people pay me a lot of money to modify special mission airplanes. A multi-motor self-launcher would be pretty easy to do as a modification to an existing self-launcher; probably a 3 month project. Perhaps I'll get around to this eventually, but first I have some more pressing items on my wish list!


Wow. The GP folks are about four years late in delivering product and
you can do all this in three months!! Go for it!!!

Actually the Alice electric plane has much of the redundancy that you're
asking for. Three motors with dual inverters on each of them, a highly
segmented battery configuration that can be reconfigured almost
infinitely. At least on paper it has those things, they burned up their
prototype before getting to taxi tests.

If we're diving into pipedreams seeking maximum redundancy, what if there's a shared software bug between the parallel systems, like the firmware bug triggered by date that affected many GPS's simultaneously.
It'd be safer to combine two completely different systems for maximum redundancy, like Igor's MiniLAK FES-Jet (https://imgur.com/a/Y6uK4fP)
Plus you get the benefit of both propeller for climb and jet for cruise.

On Thursday, April 9, 2020 at 2:57:10 AM UTC-4, kinsell wrote:
On 4/9/20 12:05 AM, wrote:

To quote Dave Nadler, "How hard could it be?"

Love the quote. Actually, this would be right up my alley. I've developed a few aircraft from scratch and people pay me a lot of money to modify special mission airplanes. A multi-motor self-launcher would be pretty easy to do as a modification to an existing self-launcher; probably a 3 month project. Perhaps I'll get around to this eventually, but first I have some more pressing items on my wish list!


Wow. The GP folks are about four years late in delivering product and
you can do all this in three months!! Go for it!!!

Actually the Alice electric plane has much of the redundancy that you're
asking for. Three motors with dual inverters on each of them, a highly
segmented battery configuration that can be reconfigured almost
infinitely. At least on paper it has those things, they burned up their
prototype before getting to taxi tests.

Clearly you are a brilliant developer.
I'll describe my experience with this task.
Start with existing self launch sailplane having a fuel to noise converter. ASW-24E
Procure a group of components from existing supplier that was/is being used by a developer of self launch sailplanes. 10 week delivery.
Engineer and implement modifications to incorporate "proven" components. 10 weeks part time.
Test
Component failure (drive).
Return for warranty repair 4 weeks.
Test
Component failure (drive).
Return for warranty repair 4 weeks.
Test
Component failure (drive).
Return for warranty repair. Manufacturer say they can't repair due to my modifications. There were none. 3 weeks.
Source alternative controller used in another proven glider. 3 weeks.
Integrate, develop control and instrumentation to replace items obsoleted by controller change and get running. 6 weeks.
Test fly. Multiple sessions.
Now flying but more work to do to get full power and functionality.
So far this has taken a bit over 2 years, admittedly not full time.
If there was am identified and proven set of compatible components it might be possible for a very skilled person or group to do fast track. Given that I have seen no such group, I seriously doubt the projection is even close to realistic.
Given time this will be made to work well, but it won't be fast, or cheap.
Been there- Doing that
UH

Ha, ha; so nice to see so many optimists still exist in gliding.
The idea of a duplicate electric engine/battery system must
bring a smile to those existing realists who already own an
electric glider.
I suppose the thought that twin systems just doubles the
chance of failures has been noted? In the power world there
seems to be no obvious safety advantages in having two
engines. What do they say: "In a twin the remaining working
engine gate you safely to the accident site"....
Dave Walsh

On Thursday, April 9, 2020 at 10:04:25 AM UTC-4, wrote:
Been there- Doing that
UH

Aw Hank, don't be such a downer.
For your viewing pleasu
https://www.facebook.com/eNewsAZ/vid...2278014963205/
https://evtol.com/news/lilium-evtol-catches-fire/

Getting back to the original question, which to choose, it you are a
sport pilot rather than a competition pilot if you choose a 15 M
span you are going to be starting the motor sooner than a 17 or
18M. I would be choosing the one with the lower wing loading, you
can still fly 15M on a strong day

At 14:29 09 April 2020, Dave Nadler wrote:
On Thursday, April 9, 2020 at 10:04:25 AM UTC-4,

wrote:
Been there- Doing that
UH

Aw Hank, don't be such a downer.
For your viewing pleasu
https://www.facebook.com/eNewsAZ/videos/video-of-the-
airport-fire-eviation-prototype-plane/722278014963205/
https://evtol.com/news/lilium-evtol-catches-fire/

Getting back to the original question, which to choose, it you are a
sport pilot rather than a competition pilot if you choose a 15 M
span you are going to be starting the motor sooner than a 17 or
18M. I would be choosing the one with the lower wing loading, you
can still fly 15M on a strong day

At 14:29 09 April 2020, Dave Nadler wrote:
On Thursday, April 9, 2020 at 10:04:25 AM UTC-4,

wrote:
Been there- Doing that
UH

Aw Hank, don't be such a downer.
For your viewing pleasu
https://www.facebook.com/eNewsAZ/videos/video-of-the-
airport-fire-eviation-prototype-plane/722278014963205/
https://evtol.com/news/lilium-evtol-catches-fire/

On Thursday, April 9, 2020 at 2:12:46 AM UTC-4, wrote:
Out of curiousity, does anyone know how electric motorgliders handle prop strikes? I know that it can be very expensive to rebuild a conventional aircraft engine after a prop strike, but what are electric manufacturers recommending?

I am buying the Jeta because I have seen a Silent Electro prop strike on a grass field. The prop is just too close to the ground for reliable self-launching in an FES (my opinion). In the situation I saw the prop exploded but running the motor afterward showed no evidence of a bent shaft or other damage to the system. However they still recommend you send it back to the factory for inspection!

On Thursday, April 9, 2020 at 9:00:24 AM UTC-8, Soartech wrote:
On Thursday, April 9, 2020 at 2:12:46 AM UTC-4, wrote:
Out of curiousity, does anyone know how electric motorgliders handle prop strikes? I know that it can be very expensive to rebuild a conventional aircraft engine after a prop strike, but what are electric manufacturers recommending?

I am buying the Jeta because I have seen a Silent Electro prop strike on a grass field. The prop is just too close to the ground for reliable self-launching in an FES (my opinion). In the situation I saw the prop exploded but running the motor afterward showed no evidence of a bent shaft or other damage to the system. However they still recommend you send it back to the factory for inspection!

I have lifted the tail of a Silent 2 Electro three feet before the prop contacts a level surface. It has flaps and does a nice two point lift off. I think a mini Lax might be similar. The prop strike might of been to much foward stick.