From: nospam@127.0.0.1   
      
   On 2/4/2021 4:59 PM, Sylvia Else wrote:   
   > On 04-Feb-21 2:37 am, JF Mezei wrote:   
   >   
   >> If this is ever to be man-rated, SpaceX will need to demonstrate ability   
   >> to have backup engine light up in time to save the day shoudl one fail   
   >> to ignite. And this is likely major because it would require the final   
   >> engine ignition happen a number of seconds before so there is time to   
   >> detect failure and relight another engine with enough time to slow down   
   >> and land gracefully.   
   >>   
   >> Or lights all 3 engines and then turn one off if you have 2 working.   
   >>   
      
   Elon has already tweeted that going forward this will be the approach.   
   So expect to see such on SN10.   
      
   >   
   > I'd expect that man-rating required the ability to handle an engine   
   > failure at any point during the landing, including during the last   
   > couple of seconds. This could be difficult.   
   >   
      
   You mean to compare this to rocket science? :-) As Rand Simberg points   
   out in his excellent book "Safe is not an Option", how 'man-ratings' are   
   determined is largely contemporaneous. Doubly so when it's a brand new   
   technology. It will be up to SpaceX to determine what the 'man-rating'   
   criteria are, with the FAA passing judgement largely on the   
   'reasonableness' of SpaceX's approach. It isn't like there is a CRC   
   reference manual on Methalox rockets that the FAA can consult. We're   
   very much back in the era of aviation as it was in the 1930's here.   
      
   Dave   
      
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