This is an aluminum nose cone shell from an Aerobee sounding rocket. This nose cone is part of a collection of high-energy detectors from the Naval Research Laboratory and covered an instrument rack also in the collection (see Catalogue numbers 19880001000-19880017000). It was transferred to NASM in 1987.
This object is on display in Rockets & Missiles at the Steven F. Udvar-Hazy Center in Chantilly, VA.