I have just watched a MythBusters episode investigating whether a concrete glider could fly. They conclude that it was plausible on the basis of a model concrete glider 'flying' 34 feet while dropping 9 feet, giving a glide ratio of nearly 4:1. Now if I recall correctly, the launch speed of the glider was 22 mph. Would I be right in thinking that a brick launched horizontally at 22 mph would achieve the same sort of results, making the conclusion inconclusive? (I am ignoring the fact that the presenter appeared to continue towing the glider on a line after the so called launch.) Also, someone in another forum said the lift/drag ratio of a glider is independent of the weight of the glider, (all else being equal). Is that true? If it is, does equal lift/drag ratio translate to equal glide ratio?