"The signal on the Zibby is dead" - what is the meaning of "Zibby"?

Question

I am line editing a book about World War II and the Battle of the Coral Sea. The action is taking place in the front and rear cockpits of a Devastator torpedo-bomber aircraft. The pilot and gunner dropped a torpedo and have lost contact with the rest of the squadron.

There are two lines:

"The signal on the Zibby is dead." "The radio's dead, too."

So ... the Zibby is not the radio. Is it the torpedo's signal? Or is it some other communication device?

The author doesn't know, having created the manuscript from a now-deceased relative's journals.

My online searches for Navy aircraft torpedo pilot (etc.) slang has been unsuccessful.

== Additional information ==

The are trying to return to the aircraft carrier. No Zibby and no radio, so they are using the plotting board with its mechanical nautical(?) compass as a last resort.

Answer 1

The US Navy used a classified (at the time) homing system during WWII called the YE/ZB series. It was a homing system designed to guide aircraft safely back to their carriers. Although I have no source to back this up, I suspect 'zibby' is referencing the aircraft's ZB system (the YE system was the beacon on the carrier).

The ZB homing system

The ZB system was a rather ingenious method, classified until 1947, of homing in to an aircraft carrier. The carrier sent out a Morse code letter for every of 30 degrees of the carrier's compass direction points synchronized with the position of a rotating antenna. The coded letters for each of the twelve compass points were changed each day and sent as Modulated CW (Morse code tones). The code was modulated in the lower part of the broadcast band (for example at 800 KHz). That broadcast band RF signal was then used to further modulate the 234 to 258 Megahertz VHF signal (called UHF in the era). The VHF signal was mostly line-of-sight. If the pilot could hear one or two of the Morse code letters, he would know his relative position to the carrier. The double modulation would make it difficult for an enemy to easily detect the MCW content of the signal. The VHF signal was reportedly reliable to about 40 to 70 miles out for an aircraft at 10,000 feet and further at higher altitudes. The accessory ZB adapter was a relatively simple VHF receiver that would demodulate the received signal back to the lower portion of the broadcast band and the MCW signals were then detected by the ARB.

(info taken from this page on the Ohio University amateur radio pages.)

You can also find some pictures of the adapter here.