Re: re : "The helicopter was under direct threat of being shot down by people with an RPG launcher"
"A number of Apaches have been lost to ground fire, and it appears that one Apache has been lost to specifically an RPG (http://www.defenceaviation.com/2011/09/attack-helicopters-losing-their-touch.html). Once again, you’re wrong."
The original design specification of the apache required it to be able to take 23mm anti aircraft fire, as found on warsaw pact mobile AA systems (remember this is a deep cold war warrior aircraft), and surprisingly a helo pilot doesn't stay around when being shot at, regardless of what the DoD or MoD have told him about his armour protection.
The article you site is highly biased to pushing fixed wing CAS, by talking down the effectivenes of attack helo's.
If you are really lucky, you can down an apache (or anyother turbine based aircraft) with pigons by putting them through the turbine intakes, but nobody would suggest that is an effective or repeatable tactic, and the laws of probability apply to anything, if you lob enough rounds against anything you will eventualy get one that goes somewhere damaging, and as what we are discussing is 1st round kill probability, rather academic.
The average transport helo "armour" is litle more than spalling protection and confidence sop for the crews. They're primary protection is to not get hit in the first place, hence some of the really "creative" flying done by RAF Chinook crews trying to get troops out under fire, leading to DFC's etc.
Fast jets have no armour, and very little inside that reacts well to forgien objects (hence why airfields are hot on FOD), so yes, laws of probability say if you shoot at enough aircraft over enough years with enough small arms ammuntion you're eventually going to get something. If you want to look at an armoured aircraft, look at the specs on an A-10 (fixed wind) or Hind (helo)
I would observe that the military frequently overstated the effectiveness of SA ground fire against combat aircraft to infantry, primarily as the truth is bad for morale, most SA ground fire is little more effective than distracting to the inbound pilot, if the pilot has planned his mission properly. If anybody is interested in some colourful first hand accounts of this, I would recomend "RAF Harrier Ground Attack, Falklands" by Jerry Pook.
By the way, I have never played shooter video games, but I can explain how to calculate structural airspeed.