'HaveQuick2' on page 85 of this thread enquired about roll posts ("...does the efflux impinge..."):
http://www.pprune.org/military-aircr...ml#post7777988
The closest view of the outlet of one that some will get to see one day:
http://www.codeonemagazine.com/image...28237_9911.jpg
The MLG door provides protection for MLG, whilst the roll post door provides protection, to some unknown degree, for any weaponry on any pylons on the other side of it.
