hi!
in my opinion studying ballistics to solve the grenade throwing bug is a
somewhat "academic" approach..
As this isn't about reinventing the wheel I' d rather propose a more practical attempt: Check out how the others are doing...
Joebot
does throw grenades quite frequent and well aimed and at some point in the code there's a hint like "substrakt 15 to avoid the grenade hitting the ceiling" or so.
So why not get "inspiration" by someone who solved the problem? (And probably follows this thread leaning back in his comfortable chair with this biiig grin

in his face?)