Hi all,
I did some hangar talking in the glider pilots community and I had confirmation that one possible practical solution could be a FES ( Front Electric Selfsustaining) type of installation with the electric engine placed in the nose of CD and the battery pack behind the pilot so making CG original position unchanged.

For the sake of knowledge how far the electric power reality is coming in the soaring field see

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


The way that a FES is used on the Silent, or on other glider application accomplished as retrofit kit, is to keep the tail down during the take off and landing operation, you never level off with the landing gear wheel touching the ground. As soon as you lifted off you can reduce the angle and climb or fly leveled clear of the ground .Visibility in take off is normally affected on some gliders because of the nose high attitude ,which will be not the case on the CD because you have large windshield down to the front cone.
I did some sketches on the CD and to me, by increasing the wheel diameter to 400 mm, you can get acceptable prop clearance to adopt a 1.3 meter prop. This will allow the use of HPD 13.5 engine with one only battery pack of 40Ah weighing 16 kg.

I need to do some more investigation on HPD engine installation and on take off distances, but unless I made an error,this installation is feasible.

Weight breakdown could be

Empty basic 65 kg
Balistic 5
Engine kit 30

Total 100

Dream is getting closer.

Regards

Cesare

A really interesting site - I'm going to have to look at that in a lot more detail later!

As you suggest, it shouldn't be a problem keeping the CofG in the same place by careful positioning of the battery packs to offset the weight of the nose-mounted motor. I imagine it would be necessary to redesign the pilot pod to take the loads involved (weight and tension under thrust) as the existing pod and nose are pretty flimsy! Not a game stopper though. I'm planning on redesigning the pod using a tubular framework with clip-on farings along the lines of the Swift Lite or Archaeopteryx... after I get the original wooden pod flying! Adding hard-points for mounting the motor and batteries should be relatively straight forward.

Increasing the diameter of the main wheel is one way to raise the nose height for prop-ground clearance. Another possibility I am toying with is a fully retractable landing gear... and if it's retractable then there's no reason you couldn't extend it down as far as you like. Take a look at the drawing at the top of this page to see what I'm thinking about: ul-segelflug.de/f-a-e.html

Phil.

Just thought I would put some thoughts in on this subject. Firstly does anyone here know anything of the FES system out of Slovenia that I see on sailplane sites? I have some questions for the people who make the products and sent Luka some details about how I am thinking I could implement in my new two place REALM design....but have not yet heard back from them.

Following the eLazair here in the states and interesting the use of the JOBY motors and what eLazair is doing with them to develop better heat dissipation, control systems and battery/charging hardware.
Only thing I can see that is in question for me is they seem to like to sell with the statement that the cost up front will be somewhat more than recip. systems but you are in essense paying up front for the energy to fly 1000 or more charge cycles. They state in the one video that the costs I believe they said per bat pack to full is about $1.00 USD and since the eLazair will fly on as little a 2 packs for about he said 40 min. on average that is $2.00 plus the price of the whole system for a 40 min. flight. With up to 6 packs for nearly 2 hrs. $6.00. OK but how much will you fly in a year...say 400 hrs. (that would be quite a lot of air) and = 200 recharges of 6 packs. = $1200.00 USD plus the cost of the whole system. What will it cost to fly 400 hrs. with two recips for power? Fuel and Oil...mogas and two stroke oil lets figure it out. Say fuel stays at $2.00 p/gal. US and oil can be had for under $3.00 USD per 32 fl/oz.(US Quart) say mix 40:1 fuel to oil that would provide 10 US Gal. fuel with oil at 40:1. Say you burn on average 5 gal. fuel every 2 hrs in the air. = $10.00 fuel + $1.50 oil.= $11.50 USD. or X 200 flights (@ 2hr. each) = 400 hrs air time annual forj$2300.00 USD fuel/oil only and not considering maintenance of a recip. But, remember your costs are somewhat less in up front for the engines and accessories so looks to me like the costs might be similar overall at this time assuming say $14,000.00 USD for the electric systems up front as opposed to maybe $8,000 or $9,000.00 USD for the recip systems up front. Also, will the batteries get even 3 or four years of charges with only 400 per year and rest of the time sitting on float? I have questions about their overall charge performance acceptance life. How much flying for how long before additional costs in purchase of new packs required?

Just some thoughts...but I do think the idea that you are paying up front for power (as they state) is kinda strange way to look at it! Maybe I am missing something here...so please take a looksee at eLazair vids and tell me what you are thinking.

Sure would be nice to have the clean, smart, reliability electric should provide but wonder if the technology is here yet to really deliver bang for the buck?

Look forward to a smart discussion with anyone out there interested in some.

Thank you All,

Gus Malm 'Alnair' 601CE and builder building the 'Realm'.

One embodiment of the placement of the propeller. Yes, it is a model, but the solution to many good and beautiful that could work on a large glider, I think.

Val.

Hi to all...Phil, Cesare, Roger, Gus, et al...

I am still in the beginning stages of building the CD but am interested in the electric self launch concepts that I have read about here.  Are there any recent developments or discussions?  

We exhibited a mock up of our twin jet amphibian, the Sea Panther, at this years International Seaplane Fly In in Greenville, Maine.  It was good to get back to meeting people after covid is hopefully slowing down a little.

thanks.

John Pepin