What is the "Z" designation?

[Cubs2jets]

What does the "Z" prefix on these manuals mean?

[mike furline]

What does the "Z" prefix on these manuals mean?

I can't "Z" the manuals.

[Cubs2jets]

OK, let's try again...

Dag nabbit! This is the message I get: Sorry, the board attachment quota has been reached.

I'm looking at both the Operating Manual and Erection and Maintenance Manual for the Piper L-4A, B and H. Originally published in 1943 and updated in 1949. The aircraft is listed as "ZL-4A, ZL-4B and L-4H". I have an idea what it means, but am looking for confirmation.

C2j

[quemerford]

Z used in this way used to mean 'obsolete', though a lot of obsolete types (or those deemed to be obsolete) remained in service in the '50s.

I'm not sure what criteria were used, but there are cases of 'Z' allocated aircraft operating concurrently with older types that were not given a Z. Most obvious is the C-47, which I can't recall ever seeing with a Z prefix.

[k5083]

Dag nabbit! This is the message I get: Sorry, the board attachment quota has been reached.

Yes, I think we overloaded the forum with Oshkosh photos. Too bad, I had a lot more to share. Can't post any more unless you have a separate host you can link to.

August

[Noha307]

What does the "Z" prefix on these manuals mean?

For what it's worth, this confused someone on the J3 forums as well.

As per page 7 of Modification, Classification, Designation of Heavier than Air Aircraft, T.O. 01-1-81, dated 11 June 1948:

e. "Z" Classification Symbol. Technical orders affecting safety of flight will be complied with on "Z" prefixed aircraft listed in Appendix "A." Technical orders affecting combat equipment or its installation will not be mandatory as "Z" (obsolete) aircraft will not be returned to combat operational status.

(Source: AirCorps Library)

So, in other words the "Z" prefix took the place of "R" to mean "restricted from combat". (e.g. an RB-24 became a ZB-24) Why the change? Presumably to free up the "R" prefix for "reconnaissance", as appendix B of the same technical order notes that, for example, the F-10 was redesignated the RB-25 on that same date.

It was also a nice fit, as "X" and "Y" already meant "experimental" and "service test", respectively. So, with the change, all three status prefixes (as contrasted with mission prefixes) were consecutive alphabetically.

Finally, and this is a bit of personal conjecture, Z is a "weird" letter like X and Q as it is not used much in the English language and given that obsolete aircraft are already unusual in a sense, it would have only seemed natural to designate them in this way. If it helps, think of "Q" from James Bond. (Yes, I know it supposedly stood for "quartermaster", but it also worked as a "weird" letter for someone with "weird" gadgets.)

I'm not sure what criteria were used, but there are cases of 'Z' allocated aircraft operating concurrently with older types that were not given a Z.

Appendix A of the above technical order provides a list of all redesignated aircraft:

 PRESENT        NEW
DESIGNATOR      DESIGNATOR          SERIES

OA-9           A-9         All Series
 A-20          B-20        All Series
 A-24          F-24        All Series
 C-45          C-45        "D" Series
 B-24          B-24        All Series Except "M"
 C-46          C-46        "A" and "E" Series
 C-54          C-54        "A" Series
 P-38          F-38        "All Series Except "R"
 P-51          F-51        "B," "J," and "K" Series
 P-59          F-59        "B" Series
 P-61          F-61        "A" Series
 L-4           L-4        "L-4," "A," "B," and "K" Series
AT-7           T-7         "A" and "B" Series

(Source: AirCorps Library)

As an aside, it's worth noting the awkwardness that the lack of a variant suffix on the first L-4s creates.

Can't post any more unless you have a separate host you can link to.

Aircraft Reports has an example of the pilot's handbook for the ZL-4 with a picture of the cover:

(Source: Aircraft Reports)

EDIT: Upon further consideration, in addition to "Z" being a weird letter, it is also of course the last letter of the alphabet. Or, to put it another way, it is at the end, just as the obsolete aircraft were at the end of their service lives.

Also, to point out another designation transition, note that in the upper-right corner the front cover of the L-4 manual the old number, AN 01-140DA-1, has been scratched out and replaced with a handwritten number, 1L-4A-1. As explained in an AirCorps Aviation blog post, this is the result of a change made in 1953 when the USAF and USN stopped using a combined system. For more on the technical order format, see another thread.

[Cubs2jets]

Thank you quemerford and Noha307. In the back of my mind I suspected "obsolete". Your information has confirmed and I appreciate it.

C2j