Originally Posted by
yellowtriumph
I believe also, according to something I read a long time ago, that when the Saturn V engines actually ignited the total overall weight of the complete assembly is too heavy for them to lift it. During the first few seconds when the engines were getting up to full power sufficient fuel is burned off in that start up process that the overall weight of the complete craft is reduced such that the engines do then have the power to lift it. Sounds right somehow to this totally non expert.
I'm not aware that was ever the case.
At lift off the five first stage engines generated a total of (nominal) of 7.5 million pounds of thrust ( 5 X F-1s at 1.5 million pounds each)
The nominal lift off weight was usually 6 million pounds, so there was about 1.5 million pounds of excess thrust at lift off.
The fuel burn was about 15 tonnes a second, so yes the weight was reducing rapidly..but OTOH they would still have been in serious ***** if an engine had failed on or just after liftoff.......