[Milsurplus] Last flight of the LBG

[Mike Morrow]

Mac wrote:

>I can't swear it was Fair, but somewhere around
>'54-'55 I bought an AN/APS-13 (I think it was)
>from some outfit for $4.95.

Yes, I remember the "tail-end charley" phrase in the adds for these sets in the back of my Dad's 1950s "CQ" magazines.  I recall that they came without tubes, for about $2.  If they were going for $5, then they'd have been quite expensive...that would be about $40 in today's dollars.

>It was described as some sort of IFF, ("tail end charley"?) from B-29.

It was a pulsed 420 mc radar designed to detect aircraft approaching from the rear.  It was installed on USAAF night fighters like the P-61 Black Widow, and I've heard, on other aircraft like some models of P-51.  I don't think it had bomber application.  When an object was detected. a bell and light energized in the cockpit.  The big problem was that as an active radar, its signal could be used to detect and track the aircraft carrying it.  I think all were ultimately withdrawn from service for this reason.

Four of these RT-34/APS-13 units were modified (for wider frequency range) and installed on each of the atomic bombs dropped on Japan.  They were part of the fusing system used to determine proximity to ground for an air-burst detonation.  Fusing was complete when at least two out of the four APS-13s signaled 1800 feet above ground.

Practically, it's useless, but historically and technically, it's a very interesting set.

73,
Mike / KK5F