727 tail skid?
I recall an early magazine article about the brand-new 727-100 about the time of first deliveries (EAL?). One photo was of the aft fuselage, including the (pre-D.B. Cooper) airstair and an extended tailskid.
The text described the skid as having a crushable cushion of aluminum honeycomb. I'm fairly sure the skid was retractable.
Is my memory correct? Did this feature remain on 727 production ships? Have other types copied this idea?