Like so many things, it all depends. Modern beers have increased in strength. It's not unusual to get beers approaching 6% alcohol by volume, so unless you're a giant, 2 of those will have you well above 80mG alcohol per 100mL of blood if you drink them within an hour. And that seems to be the magic number in most countries outside Scandiwegia.

It's implicitly assumed here that we're talking IC engined "normal" R/C aircraft. i agree that flying such a model with alcohol in your system would be unadvisable, but at the BMFA Nationals, there was a lot of flying of foamies in the hangar of an evening, by people who were very, very drunk; and it was very very funny. And all supervised by the Marshals.