[The Only Real Estel]

I merely meant that even if a bow would usually go 400 yards, it doesn't mean it would fly 400 yards directly upwards, as it moves against gravity. The arrow would eventually slow to a crawl, stop, then come back down before reaching Orthanc

Given that it's all just good fantasy fun n' games I'm sure the bow would have no problem.
On a more Tolkienish note, I'm sure that a bow given to Legolas by Galadriel herself would be somewhat magical & would probably have very few limitations (realisticly).