I recently did some testing where I shot arrows from under 400 grains to 2220 grains from longbows and recurves of 40 something to 64 pounds - KE and momentum ALWAYS increased as arrow weight increased, and speed decreased. Across all the bows, the differeing arrow weights only lost about 100 feet per second total - interesting. Now, the 2220 grain arrow would be difficult to shoot much past 25 yards, but, suprisingly, it wasn't that hard to shoot under 20 yards - and really rocked the target. It would seem a bow would launch an arrow up to the weight of the draw weight of the bow less the friction against the rest - a 45 pound arrow may not fly very far out of a 50 pound bow, but it seems, in my mind, that it should "launch" it.