The first look at the concept art for the SHIELD Helicarrier in Joss Whedon's The Avengers has gone online.  The Helicarrier was originally supposed to appear in Iron Man 2. According to Spidermedia.ru [via io9], Marvel Studios head Kevin Feige "wants to build one of these puppies atop the convention center for the 2011 San Diego Comic-Con."  Because Comic-Con isn't stressful enough without being worried that you'll be crushed to death by a giant marketing gimmick.

Hit the jump to check out the concept art and to learn more about the helicarrier  The Avengers stars Robert Downey Jr., Chris Hemsworth, Chris Evans, Scarlett Johansson, Jeremy Renner, Mark Ruffalo, and Samuel L. Jackson.  It's slated to open in 3D on May 4, 2012.

Concept art courtesy of Spidermedia.ru [via io9].

For those who who want to know more about the helicarrier beyond it's a flying aircraft carrier (although I'm pretty sure you figured that part out from the name), here's some info from Wikipedia:

The Helicarrier is a fictional flying aircraft carrier specifically designed to be itself capable of independent powered flight in addition to the conventional functions of aircraft carriers. It is the signature capital ship of the fictional intelligence/defense agency S.H.I.E.L.D., usually shown in Marvel Comics-published comic book magazines.

Originally designed by Jack Kirby for the Nick Fury, Agent of S.H.I.E.L.D. serial in Strange Tales # 135 (August, 1965), the Helicarrier concept has survived multiple redesigns whilst rarely straying from its originally depicted role as a mobile headquarters of S.H.I.E.L.D. until recent years.

There have been eight different helicarriers in the comics over the years and it's unknown which model Whedon will chose, if he'll blend the functions and designs of the various models, or if his model will be something entirely different.