Originally Posted by
remi
ASR-11 test requirement is detection of 1m2 RCS with a single pulse at a range of 55 nmi with a probability of 0.8. That is to say, even though it's smaller than an aircraft, an object the size of a door is precisely within the design of the radar to detect. What the RCS of a falling metal door plug is, who knows, but it's not stealthy.
Except that I would think something that shape could possibly lose forward momentum quite quickly if tumbling, so that its trajectory quickly becomes more vertical and therefore the radial speed falls below the threshold of Moving Target Indicator (MTI) suppression speed (used to eliminate clutter). If it did paint initially, I suspect it would fade pretty quickly.