ZPG-3W_blimp_US_Navy_1960Fifty years ago: 19 June 1959 – the first ZPG-3W airship designed to supplement the AEW barrier patrol was delivered to the Navy.  To see other uses of LTA’s, head over to the USNI blog for today’s Flightdeck Friday…

The ZPG-3W was the follow-on and larger AEW blimp to the ZPG-2N and was the largest non-rigid airship ever built. It was used to fill radar gaps in the North American early warning network during the Cold War between the Contiguous Barrier and the Inshore Barrier. The popular name for the ZPG-3W was Vigilance. The ZPG-3W was unique in that the huge antenna for the early warning radar was enclosed inside the helium filled envelope. Four airships were delivered to the U.S. Navy.  The AN/APS-70 radar used by the ZPG-3W was a UHF radar (and distant cousin to the E-2’s).  The huge antenna (measuring some 42 ft spanwise) was suspended in the helium envelope and carried a height-finding radar on the top of the envelope.  There actually was some very interesting and elegant engineering performed on the radar processing side in terms of clutter rejection – but we’re saving that for another time.

The ZPG-3Ws didn’t remain in service very long, being deactivated with the rest of the Navy’s LTA fleet in November 1962.