On Wed, 30 Aug 2017 14:15:24 -0400, J Three
wrote:

I've never know you to be wrong but this doesn't look like a fighter.
Isn't the XF indicative of a fighter under testing while bombers get
XB?

During WWII, the USAAF used 'F' to denote reconnaissance (F for Foto,
since P was already used for Phighter [okay, Pursuit]), i.e. Lockheed
F-4, F-5 variants of the P-38; F-6 variant of the P-51; and even the
F-13 variant of the B-29.

After the war, 'R' was used for a bit as the primary designator, but
quickly became a prefix to the primary aircraft mission, such as
RB-26, RB-36, etc.

More at:

https://en.wikipedia.org/wiki/List_o...nce_air craft