Originally Posted by
dook
The glide angle will not change.
It depends what level of detail you want to go to. It*may* change because:
1. Form drag increases with the square of velocity whilst lift will remain the same, reducing (steepening) L/D, and;
2. At the higher airspeed the wing will be operating at a higher Reynolds Number, which will usually increase Cl for a given AoA and so keeping the lift constant would increase (flatten) L/D.
Which of these effects dominates (or indeed if they cancel out) is down to the individual aeroplane, but it's not at all uncommon to find an aeroplane whose best L/D is higher at higher weights even though the sink rate is higher. That's why cross-country sailplanes carry water ballast.
PDR