On Wednesday, 7 December 2016 17:49:59 UTC+11, Per Carlin wrote:
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.


Not really a problem. Look at the old TOP installs on LS3s and 4s. An AD was issued that increased max weight of non-lifting parts. The tradeoff was a reducing in Vne and other airspeeds. So long as you stayed within CofG limits, then tradeoffs of weight for speed can always be done.