sorry, i say mass will usefull by impulse and momentum calculation.
ref. link
http://www.grc.nasa.gov/WWW/K-12/airplane/specimp.htmlref. example 4-1 from book "Rocket Propulsion Elements", Seventh Edition, GEORGE P. SUTTON
and OSCAR BIBLARZ.
The trajectory angle should under 80 deg to bee calculed also 79,3 deg. , the impact angle 79,7 deg.