How was the continuous looping of tape in an old-school mechanical cockpit voice recorder physically implemented? 30 minutes seems like a lot of tape to loop continuously, did it move more slowly than a normal audio tape?

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    $\begingroup$ you do understand that the tape is an actual loop because on the tape spool, the inside end of the tape has been pulled out of the spool and spliced together with its outer end? $\endgroup$ Commented Jun 2, 2020 at 7:13
  • $\begingroup$ I think it's clear that the OP didn't know that, which is the reason for the question. The question is based on the obvious meaning of "loop" in the sense that a belt or a rubber band is a kind of loop. I think this is a good question. $\endgroup$ Commented Jun 2, 2020 at 13:53

1 Answer 1


Most looped tape mechanisms are a variation of this:

enter image description here

(this is an 8-track audio cassette)

The tape is pulled from the center of the spool, and fed back to the outside of the spool.

Some CVRs use two spools and autoreverse instead.

On the right, an example of a flight data recorder. (on the left, the digital storage of a modern FDR). enter image description here

  • $\begingroup$ I thought that most flight recorders used wire instead of tape. $\endgroup$
    – GdD
    Commented Jun 2, 2020 at 7:40
  • $\begingroup$ Early ones used wire, but tape was also used (airandspace.si.edu/collection-objects/…) $\endgroup$
    – Hobbes
    Commented Jun 2, 2020 at 7:45

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