As followers of Jon Favreau's on-set tweets will know, today is the half-way point in the Iron Man 2 shoot as the production starts to take shape. Favreau recently gave Empire a few pointers on Tony Stark's arc as he faces down new villains Whiplash (Mickey Rourke) and Justin Hammer (Sam Rockwell).

"Tony's expected to be a role model and I don't think he's ready to be one. He's under a great deal of pressure and when you're under pressure, I think you find outlets for that. That's one of the tensions of the film: it's one thing to say you're Iron Man, and another thing to actually become Iron Man."

And what of Stark's friend and confidant Jim Rhodes? Favreau hinted that Rhodes, now played by Don Cheadle, will be tooling up big-time when he dons his own armoured suit as War Machine. "Rhodesy is definitely stepping up in this film. Let me put it this way: Tony's not the only person with technology in the film."

Meanwhile, Mickey Rourke, who appears as new Iron Man nemesis Whiplash, was back on set last week after a stint with Sly, Li, Lundgren, Statham et al on The Expendables. "I'm having the time of my life!" he enthused about joining the Iron Man franchise. "It's been really brutal, because my Iron Man suit weighs 23lb. It's sort of a half-suit, with half my skin showing, with lots of Russian tattoos, because [Whiplash is just] out of a Russian-zone prison."

For more from the set, check out the July issue of Empire. Iron Man 2 hits cinemas on 7 May 2010.