BK23

Two stage. Launched 27 July 1965 at 03:30. Apogee 306.1 miles. Re-entry head: GW 20 coated with PTFE.

Shut down of the first stage occurred about 3% seconds early, and as a result it under-performed by about 700 ft/second. The head appeared to disintegrate on re-entry at a height of about 28,600 ft.

BK24

Two stage. Launched 29 September 1965 at 00:05. Apogee 376 miles. Re-entry head: GW 20 made of silica.

There was a misalignment of the radar beam (about 0.8°) tracking the vehicle which sent the vehicle further downrange than expected, but the second stage velocity increment was fortunately at 10° to the vertical, and uprange, which helped compensate for the error.

The head survived re-entry down to 100,000 ft, when flakes of silica were observed flaking off for several seconds before the break up at 45,000 ft. Only the transponder and the stainless steel base plate were recovered.