Bows vs. Crossbow (for discussion)

[Swadius]

If you ever watched movies with medival battles you might have seen the archer scenes.  They always show the high long shots they used with multiple shots.  It was not accurate, but the long trip down gained the arrow "terminal velocity".  It is not that the arrow gains more, but it regains the potential kinetic energy it expended on the trip up as it travel back down.  If you fire from a point higher then your target the arrow does gain more potential kinetic energy as it passes the archer height to the targets lower position.  A crossbow bolt would have this happen, but usually less effective due to the lighter weight/less curved flight path.

While an arrow coming back down the the earth will gain some momentum on the up shot, I do not think it that it would retain as much of their velocity when it parted from the bow. The first few instances that the arrow leaves the bow will be it's fastest, in effect, this is faster than it's terminal velocity due to it not just being pulled by gravity, but shot out of a bow. If it has reached terminal velocity on the down arc of the shot, this is tremendously slower than when it was shot out of the bow.

In context to the other things that he wrote, he seems to be saying that arrows do indeed speed up the longer they are in flight as he was talking about piercing plate (which I don't think it's possible to do given actual plate made for armor purposes). That he was talking about plate I think determines this quite well. All that time the arrow spends in the air is time that the arrow is meeting air resistance, having been shot faster than terminal velocity, this means that the arrow will continually slow down to that point, and never go above this again. Hitting plate at the instance the arrow flies off the bow is the best chance the arrow has of penetrating it.