While Northrop Grumman will have extensively tested the nozzle and design following the issue on the Cert-2 flight this probably points to either a condition only seen with one or more of the following:
* vertical
* with lower atmospheric pressure
* due to a harmonic induced by being attached to the rest of the vehicle
all of which are not practical for them to replicate with the current test stands.
The nozzle split location was different which maybe incidental or a result of the changes made after Cert-2. It also could mean it's unpredictable which might mean they were just lucky a couple of times.
philipwhiuk•1h ago
* vertical
* with lower atmospheric pressure
* due to a harmonic induced by being attached to the rest of the vehicle
all of which are not practical for them to replicate with the current test stands.
The nozzle split location was different which maybe incidental or a result of the changes made after Cert-2. It also could mean it's unpredictable which might mean they were just lucky a couple of times.