Mxsmanic wrote:
When I change the prop setting on my (simulated) Baron 58, lowering
the prop RPM, my airspeed drops. I thought that for a given throttle
setting, the actual thrust produced by the powerplant was supposed to
remain the same for a wide range of prop settings, because of
automatic pitch changes made when I change the prop RPM. However,
that doesn't seem to be the case. A lowering of the prop RPM also
lowers airspeed, which implies a change in thrust. The fuel flow also
diminishes, which implies a change in power (?).

So, exactly what do I gain or lose by adjusting prop RPM when I'm
cruising along? Why would I want to change it? Some sources I've
read say that the prop makes less noise, which is surely true, but it
seems that I can't lower the RPM without losing airspeed (and thus I
must be losing power, right?).

As a pilot who has never flown a a/c with a CSU I might have this all
wrong, but this is AFAIK...

With a fixed pitch prop you can fit a climb prop which gives good climb
but poor cruise, or a cruise prop which is the other way around. A
variable pitch prop allows us to vary the pitch to suit the conditions.
Are you perhaps pulling the RPM back too much and seeing a decrease in
airspeed?
The only firm example I have here is for the Cherokee 6, which has
climb settings of 25" and 2500rpm, and cruise setting of 23" and
2400RPM, so not a huge difference.

Takeoff and landing of course are with the prop set to full fine

Hope I didn't stuff that up and hope that helps