Glide

[black gun]

Quick question- does glide increase or decrease with weight?

[chris keeping]

In nil wind conditions (rare I know) distance covered over the ground remains the same, but time aloft decreases.

[biscuit74]

And generally you'd expect best glide speed to increase with increased weight. The lift drag curve moves to the right, so best L/D is at higher speed.

Which follows from what Chris Keeping said, I think.

[Nubboy]

This is well known to glider pilots.

On days with strong lift, or windy conditions, they use ballast (normally water in special tanks) to make the glider heavier. They achieve the same glide angle, through the air, but at higher airspeeds (both TAS and IAS).

Glider pilots tend to use the lift drag curve upside down and call it a polar curve and are able to find optimum weights, or more precisely wing loading, for the days conditions. Lots of work has been done on this and being on old crusty I grew up with Reichman's Croos Country Soaring (Streckensegulflug if I've got it right) explains this and other stuff brilliantly.