Actually, I have written about this more than three times. Some unnumbered ones were:
Mk 4 Atomic Bomb: https://tailspintopics.blogspot.com/2011/07/getting-it-right.html
J79 Exhaust Nozzles: https://tailspintopics.blogspot.com/2012/12/j79-exhaust-nozzles.html
Grumman F9F-8T Nose Strut Extension: https://tailspintopics.blogspot.com/2014/06/grumman-f9f-8ttf-9j.html
Part Three (AD Skyraider Vertical Fin: note that in this case, the fin shape of readily available examples has almost always been ignored): https://tailspintopics.blogspot.com/2017/08/relying-on-museum-pieces-for-accuracy.html
on their requests and questions, I can vouch for their desire for
accuracy, at least in this instance. The latest one was about this
feature under the forward fuselage between the forward speed brake and
the NACA air inlets.
I'd never noticed it before but quickly tracked this example down to BuNo 141735, now at the Yanks Air Museum at Chino, California. At first, I assumed it was for the attachment of an antenna that wasn't present, probably specific to this particular Tiger since it wasn't evident in pictures of any operational or Blue Angels F11Fs. I finally found one that wasn't BuNo 141735 with a shape there that seemed familiar:
More searching and I found a few more examples of Navy Training Command F-11s with the shape, in particular this one:
That's when the light dawned (no pun intended). At some point after the collision between two airliners over the Grand Canyon in June 1956, the CAA/FAA decreed a requirement for anti-collision lights on U.S. civil aircraft. The military was not required to comply but did so voluntarily. As a result, anti-collision lights were eventually added to the Navy Training Command's surviving F11Fs, including the early ones.