Reduce RPM to "coast" in long descent?

I don't recall a VFR flight being REQUIRED to descend at a minimum
speed/rate. See and avoid applies regardsless of the hemispheric rule.
If he wants to come down at 200/min instead of 500 or 1000/min, thats
his call. My personal pref is around 500/min but again, its not
mandated. When under IFR I believe there is a requirement to notify ATC
if you cant meet a minimum rate.

Dave


Yes I am sure you are correct. I know its proper/expected IFR piloting
to descend at a minimum 500 fpm but there are issues of rapid cooling
the engine, and 200-300 fpm allows me to make more gradual changes in
engine power and airspeed. A fringe benefit of VFR flight I enjoy is a
more gradual descent.

This descent will be mostly on an airway and I hope with Flight
Following. I guess that it is safer to be in a constant descent for 12
minutes rather than 25 even if it is out over the Atlantic Ocean.

I think I DID find the answer in my pilot handbook. The range curves
show significant increase in range with the same MP and lower RPM.
Manifold pressure 22" and 1800 RPM for example. In descent the reduced
power would be made up for by gravity for a more constant airspeed. I
think I will try this.

Still like to hear what other people do.

I think I DID find the answer in my pilot handbook. The range curves
show significant increase in range with the same MP and lower RPM.
Manifold pressure 22" and 1800 RPM for example. In descent the reduced
power would be made up for by gravity for a more constant airspeed. I
think I will try this.

Still like to hear what other people do.

I fly 24 square. when decending I push the stick forward. I watch my airspeed
so not to get to far into the yellow arc. Watch my
MP so that it does not go much above 24.
HANK

"Stuart Grant" wrote in message
om...
[...]
I think I DID find the answer in my pilot handbook. The range curves
show significant increase in range with the same MP and lower RPM.
Manifold pressure 22" and 1800 RPM for example.

Your handbook is telling you something different. That is, that the engine
is generally more efficient for a given percentage horsepower when the lower
RPM is selected.

That will always be true, but it doesn't mean there's a reduction in
airframe drag, which is what you asked about. As Dale said, if the engine
is driving the prop rather than the other way around, reducing prop pitch
isn't going to change the drag of the prop.

Now, if you have an engine failure, or are gliding with the power completely
reduced, that's a different story and reducing prop RPM will increase your
glide range. But that's not what you asked.

In descent the reduced
power would be made up for by gravity for a more constant airspeed. I
think I will try this.

I don't understand "more constant airspeed". In a stabilized descent, the
airspeed should always be constant. You are certainly right that in a
descent, gravity adds thrust (equivalent to adding power), so you can reduce
power and maintain the same airspeed.

This is, in fact, a technique that is usually taught to every pilot during
their initial training: to descend while maintaining your current airspeed,
simply reduce power. The airplane will remain at (or near) its trimmed
airspeed, and will descend at that airspeed.

Pete