Vanguard SLV-3

  1958-U01

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The first Vanguard Cloud Cover payload was lost in the launch failure of SLV3 on 1958 Sep 26. The second stage underperformed because of clogging in the UDMH injector; the third stage fired, but the vehicle did not reach orbit, being 76 m/s short of orbital velocity. The satellite separated and its despin device worked. Mass was 10.6 kg. Stage 1 used X-405 S/N 15. Stage 2 used tank 429376 and engine C-20.

Vanguard Cloud Cover
Date	Time	Event	Orbit
1958 Sep 16		Launch	CC LC18A
		T+0.1s shutdown
		T+0.2s back on stand	Apo 1 cm
1958 Sep 26	1538	Launch by Vanguard SLV-3	CC LC18A
	1540	T+2:20 Stage 1 sep, 65 km
	1540	T+2:52 Fairing sep
		Stage 2 underburn
	1542	T+4:08 Stage 2 burnout, 222 km
	1545	T+7:02 Stage 2 sep
	1545	T+7:16 Stage 3 burn, 413 km
	1545	T+7:49 Stage 3 burnout, 420 km, 7.54 km/s
	1546	T+8:04 Stage 2 apogee, 422 km
		T+8:15 despin jets fire
	1550	T+12:18 Stage 3 sep	89.50 65 x 425 x 32.8
		Apogee 426 km
		Stage 2 impact range 1815 km
		Reentry 15000 km downrange