"John Szalay" wrote in message
42...
"Morgans" wrote in
n
I might then be able to imply that the later models were the ones that
need this feature.

Is that on the right track?


Photos of the Blackbird as early as 1979 & 1980 show the ECM dents

I guess for a plane as old as the SR-71, that qualifies as relatively
recent.
--
Jim in NC