Page 268 - Numerical Methods for Chemical Engineering

Problems 257

The viscosity of air is µ air and the projectile radius is R p . Drag coefficient data may be
found in Table 5-22 of Perry & Green (1984) or the empirical correlations in (2.163) and
the data of Table 2.2 may be used instead. We assume that the atmospheric conditions take
◦
their standard sea-level values (25 C, 1 atm). For simplicity we neglect any variation of
wind speed with altitude.
Write a program that computes the optimal angles for a specified compass bearing
and distance D to the target, the gun elevation h gun and that of the target h tar , the density ρ s
and mass m p of the projectile, the wind speed W and the compass bearing of the wind W
(e.g. 360 if the wind is from the north), and the speed v gun at which the projectile leaves
◦
the gun.
Using this program, compute the optimal angles for the case where the gun and target
are both at the same elevation, the projectile is made of steel and weighs 10 Kg, and the
gun barrel velocity is 100 m/s (chosen to be quite low so that compressibility effects are
negligible, for a more realistic case the gun velocity would be higher). The target is at a
distance of 500 m to the east, and the wind is at 15 mph from the north.
How much of a lateral distance error would you have made if you had neglected wind
and drag?
5.C.3. Modify your program from Problem 5.C.2 to account for a moving target.