wb9omc@ea.ecn.purdue.edu (Duane P Mantick) (02/23/90)
From: wb9omc@ea.ecn.purdue.edu (Duane P Mantick) Someone stated that the difference between the SR71 and the YF12 airframes was in the engines (as far as he knew). It isn't *quite* that simple. The single difference that sticks out the most is the folding ventral fin on the YF12. Way back between the engines on the lower side of the fuselage was a folding ventral fin that, in flight, was used to counteract a change in aerodynamic forces that was caused by the different chines on the front end (and some other factors that I can't recall). The fin would normally be stored in the UP position on the ground and after takoff/rotation would fold down. Vice-versa for the landing. I *think* one of these birds was once landed with the fin down which was, of course, removed promptly upon contact with the runway (ouch!). If you go and dig into what stuff is publically available, there aren't *too many* AIRFRAME differences, so the original poster wasn't too far off. As far as I have been able to tell, differences were fairly slight until you look at more superficial add-ons (missles, for example...). Duane