Hi RainingLogic. I agree reduced thrust TO (flex thrust, etc.) will certainly reduce noise. From a non-certification or operational level, however, sideline noise is (I believe) almost never measured because that measurement must be at THE point of highest noise, laterally 450 meters away. So, for an airport authority, it would be impractical to decide where along the takeoff path to actually put the microphone(s) for different aircraft.
I am more concerned about the takeoff or flyover measurement taken at 6500 meters from brake release and the effect reduced weight has upon it. Naturally, the higher the altitude (read: further away because of better climb) the airplane is at that point, the lower the noise. (Even though it has at least been inferred in this thread that a higher deck angle may increase noise somewhat. I'm not sure there's evidence of this).
So, let me summarize in statement form some of what those responding to this thread have indicated. Please anyone, copy and correct any of these if you can confirm, if you disagree or have something to add:
A. Given all engine climb (AEO) at V2+10, both the deck angle and climb angle will increase as will climb rate compared with a same configuration climb at V2.
B. Given all engine climb (AEO) at V2+20, both the deck angle and climb angle will increase as will climb rate compared with a same configuration climb at V2+10.
C. AEO deck angles at V2+10 or V2+20 will be excessive, or at least may be uncomfortable for PAX.
D. V2 varies with weight, but A thru C above are still valid.
Remember we're talking about a twin engined biz-jet in the Gulfstream class. Thoughts welcomed.
Cheers,
Tom