I originally thought this would have been an early VLS system, but the Iroquois carried an even more interesting design then I thought.
Basically the quad launcher is a tubular beam with four launch rails mounted side-by-side on it. The center of this beam is attached to an extending arm by a pivot joint. In action, the door on the side of the deckhouse slides down and the arm extends outward (the ship's side is sealed up again while the launcher is extended). The beam can then train and elevate the missiles toward the target.
The system was expensive and complicated, required a lot of maintenance.
Tha advantage over the octuple launcher was 360 degree coverage. If the octuple launcher was mounted forward or aft you had a 60 to 90 degree blind spot aft or forward. Early seasparrows had a very small turn capability, by launching from the sides, outboard, you got 360 degree coverage. Newer seasparrows have a much larger turn capability which made the system obsolete.
The hatches in the side are blow out hatches for an accidental ignition of a seasparrow. They were clampted securly in place and would not move if ignition occured in the magazine.
the early seasparrow was in fact the RIM-7E. when the NSSM came around, with an much better turning capabilty, this system had lost it's use. it is unknown if newer missiles were ever fired from it, but we all know that the system was removed in the TRUMP rebuild.
source:
http://warships1discussionboards.yuku.c ... t_LTlaa9aw
thanks TimothyC for helping me out with the research for this thing.
I hope some of the more serious AU designers find their way to this interesting system, IMO it is a shame only 4 ships ever sailed with it. (ok, it was complicated, heavy and expensive, but still, it was AWESOME!)