Ok just so I have it right, the dorsal fin on the P-51D is the added area at the lower leading edge of the tail, correct? The smaller upright blade in the center between tail and canopy is an antenna, right?
Well now you got me confused, and I'm now I'm doubting myself. From what I read I was almost certain it was the antennae looking thing between the bubble and the tail. I read that it helped stabilize the air before it reached the tail. However, I do see what you mean about the shape of the tail on some models.
Dorsal fin speaks something separate of the tail on the top of the aircraft to me, I suppose it could be interpreted many ways. I don't think they'd call an elongated leading edge of the vertical stabilizer a dorsal fin, would they...?
EDIT:
Ah ha! I was wrong, here's a little exerpt:
"The cut-down back for the new bubble canopy lead to a loss of surface area. This caused the P-51D to have directional problems (especially with full fuel in the fuselage tank creating an aft CG) for all but the most proficient pilots. The solution was to add a fillet (often called the "dorsal fin") to the vertical stabilizer that extended down and towards the front. The fillet was also added to other P-51 models already in the field."
(Source:
http://www.mustangsmustangs.com/p-51/p51variants/P-51D.shtml)
