Rumors of a 15-inch MacBook Air have popped up for a while now. We told you last November that Apple actually had a 15-inch variant of the MacBook Air scheduled for release in late 2010 alongside 13-inch and 11-inch models. Apple ultimately put the launch of the 15-inch model on hold due to the larger MacBook requiring a redesigned hinge. Two new reports now claim that Apple is working on a new 15-inch MacBook Air again that could be launched as early as next month.

The first report comes from Electricpig, which claimed a “key player in MacBook docking solutions” informed it that the device, like the current Airs, will have ports on either side, but no Ethernet connection or optical drive. The source also pointed to an April launch, noting the new MacBook could effectively kill the 15-inch MacBook Pro offering. This would support reports about Apple having plans to revamp its MacBook Pros with an Air-like design. We heard in February that Apple plans to phase out the current MacBook Pro designs throughout 2012.

Backing the rumors is a report from HowToArena today that said its own sources in the “Far East Asian supply chain” confirmed a new “thinner 15 inch MacBook Pro” for release by the end of April. According to the source, the new notebooks will be “thicker than currently available MacBook Airs but thinner than MacBook Pros.” Not surprisingly, sources claim the new device will pack in Ivy Bridge Core i5 and Core i7 processors, which were recently delayed until as late as June.

This is not the first time we heard sources’ claiming a 15-inch MacBook Air-like notebook is the works. Digitimes reported twice since October (here and here) that parts for a 15-inch ultra-thin laptop were floating around suppliers. It is clear Apple is at least still testing a new 15-inch design of some sort, and some have mentioned a new 17-inch model as a possibility as well. However, most seem to agree at this point that Apple could keep a 17-inch MacBook Pro model around for professionals, while merging the Air and Pro models into one 15-inch offering for everyone else.