> Failing to restart an engine in a retrograde trajectory
That's not a failure, that's the effect of some upstream failure.
What failure are they repeating? Pumps sized too small? Improper torquing? You talk like you know the details, so share them.
Re:SpaceX SN9 Explodes on Landing
by sudosysgen on Thursday February 04, 2021 @02:56AM
(#26023539)
There are a lot of reasons for which an engine would fail to start in such a scenario. They all boil down to the turbulent airflow and high pressure in the nozzle inhibiting the ignition process.
How exactly you decide to fix it depends on many things. It's impossible to tell. But they are all downstream of the same failure, which is overcoming the high pressure and turbulent flow.
It's very difficult because of the turbulent airflow in an engine bell pointed against the airspeed vector. Despite this, many rocket engines can do it reliably.