Best option for electric self starting glider

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

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 4/8/20 5:41 PM, wrote:
I'm hoping that someone creates an electric self-launch glider with complete propulsion redundancy: two 20kW motors, two propellors, two batterey packs, two speed controls. Any single failure would leave you with at least sustainer performance.

A traditional motorglider must be flown like an unpowered sailplane; you must keep safe landing options within glide. With sufficient redundancy, it would not be unreasonable to enjoy soaring in some entirely new and inhospitable places.




Just start with a King Air and drop in a couple electric motors. Makes
more sense than a lot of electric conversions I read about.

wrote on 4/8/2020 4:41 PM:
I'm hoping that someone creates an electric self-launch glider with complete propulsion redundancy: two 20kW motors, two propellors, two batterey packs, two speed controls. Any single failure would leave you with at least sustainer performance.

A traditional motorglider must be flown like an unpowered sailplane; you must keep safe landing options within glide. With sufficient redundancy, it would not be unreasonable to enjoy soaring in some entirely new and inhospitable places.

Here is the simplest system I have thought of: Start with an FES self-launcher,
then add a fixed mast with a similar motor and a pusher folding propeller. One
battery for each motor, giving you two independent systems. You still have the
same available climb or distance ability.

--
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 Thursday, April 9, 2020 at 1:41:58 AM UTC+2, wrote:
I'm hoping that someone creates an electric self-launch glider with complete propulsion redundancy: two 20kW motors, two propellors, two batterey packs, two speed controls. Any single failure would leave you with at least sustainer performance.

A traditional motorglider must be flown like an unpowered sailplane; you must keep safe landing options within glide. With sufficient redundancy, it would not be unreasonable to enjoy soaring in some entirely new and inhospitable places.


There is a the Euroglider under design and testing in France with 2 electric motors with folding propellers on the wings - see Soaring International February 2020 issue.

Magnus, with a LAK17C you won't be able to take off safely from Montricher, especially not to the northeast. I wouldn't go for less than 50 hp, and that leaves you with Ventus 2CM, DG800, Antares 20E or ASH26E with the Schleicher prop.

Bert
Ventus cM "TW"
working in Lausanne, flying in Bex

I'm not familiar with that airport, but my Stemme has 115 turbocharged
horsepower and a reliable Rotax 4-stroke engine.Â* It climbs at 800 fpm
at high density altitudes and, with a full gas tank of 30 US gallons,
can cruise for 8 hours at over 100 kts at 18,000' (more if you want to
be cold).

Or are we just talking about single seaters with delightfully light
controls? :-D

On 4/8/2020 10:23 PM, Tango Whisky wrote:
Magnus, with a LAK17C you won't be able to take off safely from Montricher, especially not to the northeast. I wouldn't go for less than 50 hp, and that leaves you with Ventus 2CM, DG800, Antares 20E or ASH26E with the Schleicher prop.

Bert
Ventus cM "TW"
working in Lausanne, flying in Bex

--
Dan, 5J

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?

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!