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astrowikizhang
Guest
Hello, I have a question about SRB thrust.<br />Many technical info, e.g. http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/srb.html state that each booster has a sea level thrust of approximately 3,300,000 pounds at launch. Two SRBs contribute to 71% thrust at liftoff and during first-stage ascent.<br /><br />The confusion is three SSMEs have a total thrust of nearly 1.2 million lb. But:<br /><br />(3.3*2)/(3.3*2+1.2)=85%<br /><br />Some reports say each SRB has a liftoff thrust of 2.8 million lb, Then:<br /><br />(2.8*2)/(2.8*2+1.2)=82%<br /><br />Where the number of 71% comes from? I believe it has its reason to exist and NASA would not made such a mistake. Please help me out of this confusion.<br /><br />More questions about thrusts: what is the difference between sea-level thrust, vaccum thrust, and peak thrust? Is the 3.3 million lb the vaccum thrust of SRB or peak thrust?<br /><br />Thanks,<br /><br />zhang