during phase i, a group of yawsonde-instrumented projectiles was fired at wallops island, va., to test a non-toxic simulant for liquid white phosphorous (wp) and to examine the flight stability of two diagnostic wick-type configurations. tests were conducted at charge 4w with yaw induction. yaw levels of up to 15 deg were achieved. the simulant and the diagnostic payloads reproduced wick-type instabilities with unstable coupled spin-yaw behavior for fill ratios of 90 and 100. it was concluded that the presence of a liquid free surface is not required for poor flight behavior and that the wp simulant should be used in future testing. during phase ii, eight projectiles were tested at dugway proving ground, utah, to examine the flight stability of three diagnostic payloads. standard wick payloads, impregnated with water and launched with yaw levels of 8.5 and 11.5 deg, produced stable and unstable flights, respectively during phase iii, clean cylinders without wicks were loaded with liquids whose viscosities were one thousand to ten million times above that of water. unstable, wick-like instabilities occurred for a viscosity of approximately one million times above water, with all other flights exhibiting stable behavior. it is possible that the wp/wick payload can be represented by an artificial viscosity, and such a viscosity would probably be very large. it can not be established that the unstable high viscosity rounds model the wick-type instability