In article ,
"Rob Montgomery" wrote:

2100 is for when you're level (i.e. before you're abeam the numbers) and
trimming the airplane. Once you're abeam the numbers, you bring the power
back to something that gives you the rate of descent you'd like (and where
the previous posters point holds true... do get too fussy, look out thte
window at the airplane entering the pattern on an extended base or a long
final), put in your flaps, and slow to approach speed. Also keep in mind
that the actual power setting may vary from airplane to airplane.

The way I look at the pattern, what's really important is airspeeds, not
power settings. Power settings are just a way to get the airspeed you
want.

The most critical airspeed in the pattern is your final approach speed.
Everything else is just executing a controlled transition from cruise
speed to final approach speed. For most light planes, if you fly base
10 kts faster than final, and downwind 10 kts faster than base, you
should be doing OK. This should give you a good target speed for
downwind.

The problem is, you can't set airspeed directly, you can only set power.
So, it's a good idea to have a target power setting for downwind. For
most typical trainers, somewhere in the 1900-2100 RPM range is about
right, but ask your instructor for a good number to use for whatever
you're flying. You set that when entering the pattern (along with
whatever other configuration changes you're going to make, like gear and
flaps), and give the plane a little time to settle into a stable
airspeed. Then you can adjust the power if needed if you didn't get the
airspeed you wanted.

Keep in mind that you need to fit in with the existing traffic flow.
You may normally fly downwind at 90 kts, but if you're following
somebody going slower, you need to do something to avoid crawling up his
exhaust pipe. This can get really interesting as the mix of types gets
extreme (Bonanza following a Cub, for example).