i wouldnt say the last onto the bridge barrel roll is all luck..i can do it 1 in 5 times in the tspeed lap..i would neer use it in a race though..
to do it i pitch up high fly as right as possible to the wall on the approach and aim the nose of the craft exactly at the right side edge on the bridge..
the ship may seem like it will miss the bridge but it wont.
oh...btw i do the Br LRL not RLR..im not sure but i think doing it that way makes the ship br the otherway round making the bridge bit easier..but you need to check it out..