Pre-Preg

On Tuesday, December 6, 2016 at 6:15:46 PM UTC+1, wrote:
On Monday, December 5, 2016 at 7:59:28 PM UTC-5, Casey wrote:
On Monday, December 5, 2016 at 4:58:14 PM UTC-5, Casey wrote:
On Monday, December 5, 2016 at 2:23:59 PM UTC-5, Jonathan St. Cloud wrote:
For the guys with an engine weight does make a difference. Imagine if the 100 pounds of engine and fuel were offset by construction methods that lowered the empty weight of the glider by even 50-70 pounds. YOu would functionally have the same wing loading range as a pure glider.

Just saying.
On Thursday, December 1, 2016 at 4:09:14 PM UTC-8, wrote:
4 Pretty much nobody cares much about weight, except the little gliders. For all the rest we just want to know how much water can we get in it.

Different building methods in same factory brings several issues I could think of.
Cost of buying and storing different materials, cost of process, possible mistakes in manufacturing, return on investment, different flying characteristics. Just throwing this out there.

Maybe this is why GP decided to put the batteries in the wings. Removal for light days without changing CG. All other FES gliders have batteries behind cockpit and have to fly with batteries.

Putting the batteries in the wings reduces the weight of non lifting parts which means the wing spars and root area don't have to be made as heavy.
UH

And this is exactly why retrofitting an older glider to FES is impossible. With an max weight of non lifting part typically in the range of 230-250kg is it not enough marginal to put in an extra weight of 40-50kg for motor, electronics and battery in the fuselage unless you are a really light weight pilot.
I have asked the FES guys several times if it would be possible to get batteries suitable for wing installation and the answer is no.