Using imagery taken by classified sources during the 12 April launch of North Korea’s Unha-3 launch vehicle from Tongchang-ri, Western intelligence analysts have now ruled out first stage failure as the cause of failed orbital launch the Kwangmyongsong 3 satellite. Instead they cite that the liquid fuel first stage fired correctly but that it was an aerodynamic pressure/resonant vibration-induced collapse of the third stage rocket structure and nose cone that caused the controversial flight to fail.
North Koean Unha-3 launch vehicle before its launch which caused international protests. ©Rex Features
A structural failure of the third stage, dubbed a “catastrophic disassembly” by space intelligence analyst Charles Vick of Globalsecurity.org in an article in EE Times, was noted as probably occuring during the Max Q portion of the flight, where the combination of air speed and atmospheric pressure yields a peak aerodynamic load. The existence of Max Q is the reason why many western rockets throttle back to limit aerodynamic forces as they go through this flight phase.
A flash of flame escaping from the forward part of the launch vehicle was reportedly seen at 81 seconds after lift-off and subsequent tracking of the assembly led analysts to believe that the ...