sentences:  In June 1942, assisted by Mills and Miller, he focused his attention on developing an effective method of restricted burning when using solid rocket fuel, as the military demanded JATOs that could provide over 100 pounds of thrust without any risk of exploding.Although solid fuels such as GALCIT-27 were more storable than their liquid counterparts, they were disfavored for military JATO use as they provided less immediate thrust and did not have the versatility of being turned on and off mid-flight.Parsons tried to resolve GALCIT-27's stability issue with GALCIT-46, which replaced the former's ammonium nitrate with guanidine nitrate.