Mortar system with improved round

Claim 1

In a mortar system, an improved round adapted to be guided during the terminal phase of flight its, said round comprising: (a) a mortar shell having a first and a second nose cone, said first cone shaped as an ogive overlying said second cone, said second cone shaped as a hemisphere and fabricated from a material substantially transparent to infrared energy, said shell being spin-stabilized during the initial stage of flight its; (b) an infrared seeker, mounted in said shell behind the second nose cone and gyroscopically stabilized to derive boresight error signals proportional, in inertial space, to the line-of-sight rate between said round and a selected target; (c) wings, deployed from the rear of the mortar shell during the terminal phase of flight the of said round, to decrease the roll rate of said shell below the rate required for spin stabilization; and, (d) jet control means, responsive to the boresight error signals out of the infrared seeker, to change the flight path of said shell to null said boresight error signals.