Guys,

The thing you have to realise is that while talk about "Wind Penetration" etc is from your point of view on the ground, and aircraft in flight has no idea as to whether there is any wind blowing or not. All it reacts to is the air passing ove it, usually termed relative wind or relative airflow.

The aircraft that will fly fastest into the wind is the same one that flys fastest in nil-wind or down-wind. Thus a light model that can fly fast will fly upwind just as well as a heavy model that can fly fast.

In powered models there is the advantage that a heavier model will be less effected by gusts.

In Gliders there IS an advantage in using ballast. The distance a glider will travel relatve to the air (and thus, in nil wind, relative to the ground) for a given loss of altitude at a particular angle of attack is it's glide ratio and is also equal to it's lift/drag (l/d) ratio. This is independent of wieght. Two gliders identical except for weight will glide the same distance if flown at the same AofA, but the hgeavier one will do so faster both vertically and horizontally. Thus if you ballast a glider it WILL have a higher maximum griound distance (assuming no assistence by external lift) into the wind, as it will experience the headwind for a shorter time. It will also have LESS potential distance down-wind.

Cross-country gliders carry ballast if there is going to be good lift available, as the slower climb in thermals is made up for by the higher speeds available in between them. In light conditions they will fly without ballast, and dump it on route if the lift weakens or isn't as good as predicted.

A slope-racer will achieve it's best speed when ballated such that it's sink rate at its best l/d speed is equal to the available slope lift- any heavier or lighter and it will hve to fly at a different, and thus less efficient, angle of attack to fly level.