 In fact, the Demon that emerged from development was a missile-armed all-weather fighter over heavier than the XF3H-1 had been, and even the high-powered J71 could not restore its performance.The F3H-1N Demon single-engine jet fighter was initially a severe disappointment, due to the unreliability of the J40 and the difficulties of flying the much heavier airframe with the lower-powered J40-WE-22A engines.The airframe design had assumed the higher-powered J40-WE-10 would be the power plant.