Fuzes Mk 162 and Mk 166 constitute the fuzes in the group known as Deceleration Discriminating Rocket Fuzes. These fuzes in their cycle of functioning depend on pressure arming from rocket motor gases, deceleration in air (creep), and deceleration after im-pact. The latter permits discrimination of targets until the deceleration reaches a certain amount in accordance with the fuze design.

The complex nature of the fuze requires that a considerable variety of tests be made to establish the complete details of performance. Most of these tests were performed. However, rocket fuzes design and development for the Bureau of Ordnance was accom-plished almost entirely by the California Institute of Technology. Inasmuch as these fuzes were amongst the latest fuzes designed by that activity, the end of the war and conse-quent termination of fuze activities prevented the completion of some additional tests that appeared desirable. For these reasons and because of fuze safety problems that were encountered in the desing by Bureau production contractors, the Fuzes Mk 162 Mod 0 and Mk 166 Mod 0 are not considered fully developed as of the date of this publi-cation. Bureau projects, now under way, have been instituted to develop a more reliable fuze under all conditions of use and testing.