On Monday, December 28, 2015 at 5:38:01 AM UTC-8, wrote:
On Monday, December 28, 2015 at 7:53:48 AM UTC-5, wrote:
Two obvious reasons for not putting the batteries in the fuselage:

1 - that's where the motor assembly is.

2 - Even if the batteries and motor assembly could be fitted in the aft fuselage the C of G issues would be a big problem in such a light glider. A lot of lead in the nose would be required.

The bigger issue is the mass of non lifting items. With a low mass glider this becomes a big deal. Batteries in the fuselage increase this mass, leading to need for heavier structure, primarily the spar, this making the whole glider heavier. Move the mass to the wing, somewhat outboard is better, and this problem is avoided.
Bigger motor buys takeoff margin, then throttle back to lower consumption for balance of the climb. Larger battery not really needed.
UH


The glider will have 8 gallons of disposable fuselage ballast:

http://www.gpglidersusa.com/gp14/

Maybe that 30 kg of ballast is only for light pilots. If not, it appears the glider has space in the fuselage for the 20 kg of batteries, as well as no W & B or structural issues if fuselage batteries are installed in the area planned for the fuselage ballast.