B-52s and KC-135s have that feature. Boeing must have liked it.
At my time at a couple of B-52 bases, I only saw folded fins a couple of times.
A USAF article on the B-52 feature:
https://www.barksdale.af.mil/News/Featu ... x-and-fly/I
And one on a KC-135:
https://www.afcent.af.mil/News/Photos/i ... 000876165/And from Google a copyright-free USAF photo for your piece.
The story of that various twin and triple tail types went with the feature to allow them to use existing hangars, but wouldn't a folding fin night make more sense considering the extra drag and weight of the multiple fins?
Good grief! that USAF article says the fin fold is done BY HAND?? Literally four airmen, one hand crank, manually cranking for 2-4 hours!
Tom P.