First of all lock on to the critical parts with the rocket launcher, you do that by holding down the FIRE button NOT THE AIM BUTTON. But the trick is to fire 3 or 4 rockets at once while locked on multiple parts, if u dont shoot more than 2 missiles the buraq will launch flares and drive them away. Hope this helps, and remember, keep moving or it will tear you to shreds.
This fight is easy when you figure out the pattern.
You need to make sure that after your first rocket hit (one lock on) that on subsequent attacks that you launch three locked on rockets simultaneously. The flares are a big give away and take out 2/3 rockets, the third always hits its mark.
If you find that you've got 2 rounds left, then you need to waste em and wait for a full pick-up, or if you're lucky one will drop anyways. You can always use the leftover on the polycraft that appear.
I found that swinging back and forth from the top girders close to buraq was best.
C'mon how easy would the fight be if you only needed to fire three rockets and game over for the buraq?