05-22-2012, 10:42 AM
About thw A5 retro-cocket for FS seperation. The 16 tonne force gives an idea on how depressed first stage trajectory it can handle.
The prime cause of in atmosphere seperation is that the when old stage expends, it carries its momentum but does not suffer any appriciable drag, while the stages upstream see a retarding force due to supersonic drag, thus if expended stage is separated, the rear stage will stay into the shockwave shadow and bump into upstream stages with very high certainity.
FYI for Agni-V stage at 18 km altiude sees pressure drag of 9 tonne force, hence 16 tonne retro rocket is right sized to provide those crucitial seconds to allow upper stage to fire and ramp up thrust above 9 tonnes, while the expended stage is assured to be retarding and trailing behind.
Lower sepration altidue and the drag can be many times more.
The prime cause of in atmosphere seperation is that the when old stage expends, it carries its momentum but does not suffer any appriciable drag, while the stages upstream see a retarding force due to supersonic drag, thus if expended stage is separated, the rear stage will stay into the shockwave shadow and bump into upstream stages with very high certainity.
FYI for Agni-V stage at 18 km altiude sees pressure drag of 9 tonne force, hence 16 tonne retro rocket is right sized to provide those crucitial seconds to allow upper stage to fire and ramp up thrust above 9 tonnes, while the expended stage is assured to be retarding and trailing behind.
Lower sepration altidue and the drag can be many times more.