Originally Posted by
XB70_Valkyrie
... small auxiliary hardened FDR memory units.... They wouldn't have to be as large (they don't need any of the input processing etc.) ... as the main FDR....
This is not a comment on your idea as such.
But most present-day FDRs don't do any input processing.
Their input processing is done by a separate FDAU (flight data acquisition unit) which then sends the data in digital format (ARINC 717, usually) to the hardened FDR.
CJ