This question would actually go under physics
Assuming that the model rocket goes straight up into the air and not at an angle, you can calculate for the maximum height by finding how long it takes for the velocity of the rocket to reach 0.
This can be calculated using the equation
t = (v sinx) /g
where t=time, v=velocity at zero seconds, x=angle of launch, g=gravity
Since we are assuming that the rocket flies straight up, the angle would be 90º, so sinx would be equal to 1.
That reduces are equation to
t = v / g
g=9.81 m/s^-2
So we need to convert gravity to feet/second^-2 and divide 160 by g, 160 being the initial velocity.
g=9.81 m/s^-2 = 32.2 ft/s^-2
160/32.2 ≈ 4.97 seconds
