|Quoting DocLightning (Reply 2):|
However, AFAIK, climb power is not a constant setting all the way from climbout to initial cruise altitude. I think it's a gradual decrease.
It's something of a stepwise decrease in terms of fan speed. You're initially at takeoff power, then climb power from about 1500' to your initial clearance altitude (typically not your initial cruise altitude). ATC often has to make a few "steps" to get you up to initial cruise. At each level-off you're controlling on speed rather than thrust.
On top of all that, the actual engine thrust (amount of power being dumped into the air) is dropping with altitude due to the falling air density.
|Quoting ZSOFN (Reply 3):|
I've noticed the leading edge slats create a huge amount of wind noise as airflow gets disturbed and becomes non-laminar around the fuselage by wing's the leading edge.
It's almost always non-laminar around the fuselage unless you're in the flight deck. The slat noise is caused by separated flow, not turbulent (non-laminar) flow.
|Quoting PHX787 (Thread starter):|
I know the pilots probably don't use full power all the time, but they sure don't use anything lower than normal, in my opinion, so what causes the change in noise that is heard in the cabin?
Pilots will use as little power as necessary to get the job done. This applies to all flight phases, so the actual engine speed at any portion of the flight may differ considerably from flight to flight, even on the same aircraft. You will get a huge shift in engine noise when the fan tips drop below sonic speed. The only time you can be pretty confident that the engine is always at the same speed is on descent, when the engine is usually at flight idle. That speed may shift with whether anti-ice is on or not though.