Tallboy Terminal Velocity
The rule of thumb formula we used at NASA for quick calculations of terminal velocity was:
Vt = sqrt((2.m.g)/Cd.p.a))
Cd is drag coefficient, p is air density, a is cross sectional area.
If you plug in some “best guestimate” figures for the tallboy you get terminal velocity figures close to the quoted 3,700 ft/sec.
Bob C