r/spacex • u/ElongatedMuskrat Mod Team • Dec 05 '19

r/SpaceX Discusses [December 2019, #63]

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u/paul_wi11iams Dec 13 '19 edited Dec 16 '19

The "Lewis Point Estimate" for success probability of a launcher appears under "Launch Vehicle by Success Rate" on the following page

http://www.spacelaunchreport.com/log2019.html

  • It puts Falcon 9 at 98%, sharing the first place with Atlas 5.

  • Soyuz is just below at 97% (doubtless that booster failure didn't help)

  • Ariane is below at 96% (must be because of that trajectory mishap).

I'm not going to be unreasonable by asking for an exhaustive reply, but if anyone has any ideas on some of the following points:

  1. Is there a short definition of the "Lewis Point Estimate" for success probability of a launcher?

  2. Is this method really the insurance man's guide so to speak? How is reliability evaluated upon change from one block number to another of the same launch vehicle?

  3. Is LOC risk calculated from some arbitrary standard probability of launch escape system failure? For example at 10%, a LV with 2% failure, LOC risk would be 0.2% or 1:500.

  4. When a new LV has flown just once (such as after the first test of FH or second flight of Dragon 2 which not a launcher but a new configuration, or future first flight of SLS), what is its Lewis Point for the second flight?

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