By using the sphere model

the influences of outline of missile tail upon the thrust peak

pressure distribution on the tail and the oscillation character of the thrust for solid motor launching under water are numerically studied.Results indicate that the half-cone-angle of convergent segment has great effect upon thrust peak.The thrust peak decreases slowly as the half-cone-angle is above 45 degree

and decreases quickly as the half-cone-angle is less than45 degree.But the half-cone-angle has very little effect upon the time for thrust reaching the peak.It is also shown that the pressure distribution varies a lot on the convergent segment of the missile tail as thrust reaches the peak value.The half-cone-angle has little effect on the oscillation frequency of thrust.