Warhead
The warhead of the Atlas D was originally the G.E. Mk 2 "heat sink" re-entry vehicle with a W-49 bomb, combined weight 3700 lb and yield 1.44MT. The W-49 was later placed in a Mk 3 ablative RV, combined weight 2420 lb. The Atlas E and F had an AVCO Mk 4 re-entry vehicle containing a W-38 thermonuclear bomb with a yield of 3.75 MT megatons which was fuzed for either air burst or contact burst. The Mk 4 RV also deployed penetration aids in the form of mylar balloons which replicated the radar signature of the Mk 4 RV. The Mk 4 plus W-38 had a combined weight of 4050 lb.
Read more about this topic: SM-65 Atlas