Prop to High RPM on downwind

"Brenor Brophy" wrote in message
news
Jim talked about speed not power. The point is that the power is already
reduced to the point where the Prop control does nothing (the prop is at
its stops) so pushing the prop control to fine pitch does nothing - the
prop is already at its finest pitch because the governor set it there
trying to maintain whatever RPM setting (say 2200) you had set for cruise

I'm talking about power though, which is the point here. In my airplane, if
I push the prop control to full fine pitch while in the pattern, I will
require a significantly high RPM to have enough power to maintain level
flight at my pattern speed (which is, coincidently, the same speed I fly my
approach). Many airplanes have this characteristic.

Similarly, even in an airplane where the required power setting is
relatively quiet, you can still be even quieter if you pull the prop back
further. Who cares if your cruise setting was 2200 RPM? If you're trying
to fly friendly, then fly a power setting that slows the prop down even
more. 2000, 1800 RPM, whatever it takes to get that prop back off the stops
at your current power setting.

Bottom line: from level flight in the pattern, it requires a power reduction
to descend to the runway. If the prop is at fine pitch during that level
flight segment, it doesn't need to be, and you could reduce prop RPM (and
noise) even further. By doing so, you'll fly quieter and more efficiently
(not that efficiency really matters so late in the flight).

I recognize that many people call it "good enough" and don't bother to try
to get their airplane any quieter. But IMHO, it's pretty hypocritical to
claim to be in favor of not pushing the prop control to max RPM until the
power is set low enough, but to not be willing to minimize one's noise
footprint by reducing RPM in the pattern as well.

Pete

Brenor Brophy wrote:

I fly downwind at 90 KIAS, 15" MP nice and level. Its a bit faster than
Jim, but a nice easy number to remember and consistent with everything
else in the pattern for the most part.

In a 182 with the gear down? I can fly level at 15" with the gear up, but
with the gear down it'll need more power in my experience (and
recollection).

- Andrew

"Peter Duniho" wrote in message
...
"Chris" wrote in message
...
[...]
With the 182, it is 80 knots turning from the 45 to downwind, 75 on
base, and 70
on final. I don't understand why pushing the prop to full flat has any
noise
effect whatsoever.

Exactly

Exactly, except for those airplanes that cannot maintain level flight at
pattern speed with gear and flaps out at final descent power settings.

Which is, by the way, all airplanes with a constant speed prop. The power
setting for final descent is necessarily lower than that required for
level flight within the pattern, even if you slowed ALL the way to your
final approach speed. RPM will thus be higher, assuming the pitch is set
to full fine pitch (high RPM). Higher RPM means more noise.

If Jim's 182 flies along level in the pattern at the same airspeed and
prop RPM that he uses for final descent, I have no idea how he
accomplishes a final descent at all. A plane like that would be stuck up
in the pattern indefinitely.

Pete

Why would anyone want to fly around the pattern at a constant altitude with
gear and flaps out except on a circling approach? I was leave the gear and
flaps up until I want to descend. I was under the impression that virtually
everyone did it this way.

Mike
MU-2

"Mike Rapoport" wrote in message
nk.net...
Why would anyone want to fly around the pattern at a constant altitude
with gear and flaps out except on a circling approach? I was leave the
gear and flaps up until I want to descend. I was under the impression
that virtually everyone did it this way.

Your impression is mistaken. In fact, I've never had a single instructor
comment on my habit of lowering the gear as I enter the downwind, and I see
plenty of retractable gear airplanes flying in the pattern with their gear
lowered.

Just as a "for example", in my airplane having the flaps and gear out do a
couple of things: they help stablize the aircraft, making flying in the
pattern easier, and the flaps ensure that even though I'm slowing to 80
knots in the pattern, I'm still comfortably above stall speed. Aircraft
handling is significantly better with the flaps and gear out.

When I was flying 182RGs, I found similar benefits, though the stabilizing
factor was the primary issue (stall speed wasn't as big of a problem, being
lower than in the airplane I fly now).

But, even if you prefer to fly with gear and flaps up until beginning your
descent, you still need less power during the descent than you needed during
level flight in the pattern. It doesn't change the fundamentals of what I
wrote.

Pete

On Mon, 22 Nov 2004 13:59:04 -0800, "Peter Duniho"
wrote:

"Chris" wrote in message
...
[...]
With the 182, it is 80 knots turning from the 45 to downwind, 75 on base,
and 70
on final. I don't understand why pushing the prop to full flat has any
noise
effect whatsoever.

Exactly

Exactly, except for those airplanes that cannot maintain level flight at
pattern speed with gear and flaps out at final descent power settings.


You should hear me on a circle to land. Gear out, bout 20-25 deg of
flaps and go to cruise power until within about 30 degrees of the
landing runway heading. Then back to about 12" and full flaps. Turning
with everything hanging out while maintaining altitude takes about
22-23" of MP at 2400 RPM. At that power setting and low altitude
~500' AGL I try to keep it over the airport for the full circle to
land.

Which is, by the way, all airplanes with a constant speed prop. The power
setting for final descent is necessarily lower than that required for level
flight within the pattern, even if you slowed ALL the way to your final
approach speed. RPM will thus be higher, assuming the pitch is set to full
fine pitch (high RPM). Higher RPM means more noise.

For a VFR pattern: On my old Debonair they taught; slow to 110-100 on
down wind, 90 on base and 80 minus 1 MPH for each 100# under gross on
final. This produces quite a steep final, but with the consequences
of a relatively short roll out.

I generally start the descent after gear down at the end of the runway
on down wind. Prior to that with the old 2-blade prop would have been
noisy.

Some airports want you to keep pattern altitude much longer. Some till
you start final.

I would add that I'm usually coming down hill just prior to the 45
entry (pattern alt one to two miles out) and the Deb takes its time
slowing down. I probably have the MP back to the point where the prop
is already turning slower prior to pattern entry.

Sooo... power is back (but a long way from idle) prior to pattern
entry, down wind is basically low power (16"-17")with the Deb slowing
down. Gear down at the end of the runway and a bit of flaps down to
about 100 MPH, MP about 12". Turn base, add flaps, retrim for the
slower speed of 90, Turn final, full flaps, speed ~75-80, prop full
in. Adjust MP to maintain aiming point.

Actually if I enter a bit on the fast side while slowing down I use
less power in the pattern than I would if I entered the pattern at 110
as I'd have to apply power on down wind while I'm normally reducing
power.

If I didn't put the gear down until I had the runway made it'd be one
mighty big pattern power off. Almost as big as some of the local
Cessnas and Cherokees fly. (sorry, I couldn't help it) :-))

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com
If Jim's 182 flies along level in the pattern at the same airspeed and prop
RPM that he uses for final descent, I have no idea how he accomplishes a
final descent at all. A plane like that would be stuck up in the pattern
indefinitely.

Pete

In article ,
Roger wrote:

On Mon, 22 Nov 2004 13:59:04 -0800, "Peter Duniho"
wrote:

"Chris" wrote in message
...
[...]
With the 182, it is 80 knots turning from the 45 to downwind, 75 on base,
and 70
on final. I don't understand why pushing the prop to full flat has any
noise
effect whatsoever.

Exactly

Exactly, except for those airplanes that cannot maintain level flight at
pattern speed with gear and flaps out at final descent power settings.


You should hear me on a circle to land. Gear out, bout 20-25 deg of
flaps and go to cruise power until within about 30 degrees of the
landing runway heading. Then back to about 12" and full flaps. Turning
with everything hanging out while maintaining altitude takes about
22-23" of MP at 2400 RPM. At that power setting and low altitude
~500' AGL I try to keep it over the airport for the full circle to
land.

I much prefer the 360 overhead pattern:

1) flying at cruise down the runway at pattern altitude from about 2
miles out (Initial) to just past the threshold,

2) break to downwind (traffic permitting), pulling power as you break,

3) Keeping at least 45 deg bank, drop gear and flaps when appropriate
speed is reached (usually at the 180 deg point),

4) slow to approach speed, while turning and keeping TD point in sight,

5) touch down on full 3-point attitude on the numbers.

Properly done, you don't add power any time after the break -- it is a
continuous circle to touchdown. It is the easiest way to recover a
formation -- each plane breaks at 2 - 4 second intervals. I do this all
the time in my Johnson Rocket; I have done it in a Zlin 242 and a
friend's big-engined T-34. The whole "pattern is within a 1/4 to 1/2
mile of the runway.

Prop goes in when you reach approach speed.

"Jim Weir" wrote in message
...
I must be stupid or missing something. Does everybody in this ng come into
the
pattern at cruise airspeed? I was taught, and teach, that you come into
the
pattern about 10 knots above your desired airspeed on final.

Do not high-volume airports prefer "local procedures" that encourage cruise
or near-cruise for the small types until just about base turn, just to keep
the traffic from backing up???

Icebound wrote:

Do not high-volume airports prefer "local procedures" that encourage
cruise or near-cruise for the small types until just about base turn, just
to keep the traffic from backing up???

I don't know about it being as well-defined as a "local procedure", but I've
been told to keep the speed up on final at some airports in the past
(Teterboro comes to mind). That's not always the best choice, though, and
I'm sure ATC knows it. On approach into Albany last week, I was able to
turn off quite early. If I'd been told to keep my speed up, I'd have
floated much farther.

Keeping the speed up is actually fun at the airports where it happens, as
there's plenty of runway for a slow-motion flair.

- Andrew

I must be stupid or missing something. Does everybody in this ng come into
the
pattern at cruise airspeed? I was taught, and teach, that you come into
the
pattern about 10 knots above your desired airspeed on final. If you do
that,
your power is already back for level flight to where the prop is in the
stops
anyway.

This is the standard procedure for entering a pattern.

Over the years, though, I've found that my pattern entry procedure varies
with conditions. If I'm alone in the pattern (as we often are, on a
Wednesday afternoon -- a day we typically fly), I'll zip around the pattern
at whatever speed works to get me down soonest.

This usually means a pattern entry speed of around 100 knots (or more), with
a gradual diminishing of speed down to 80 when we turn base, and another
gradual diminishing to 70 on final.

Earlier in my flying "career" I would not have been able to manage such a
thing, and religiously stuck to the 100% stabilized approach (which, at the
time, meant 80 mph from downwind all the way down). I had this drummed out
of me when I started flying into controlled airspace more often, where an 80
mph downwind leg would result in an exasperated controller having to
re-sequence the pattern.

Thus, long story short, yeah, we sometimes come into the pattern at such a
speed that pushing the prop full forward is going to result in a lot more
noise.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Then I hope you won't take my offer of a free biennial next July. I expect a
person to fly the same pattern from Anchorage to Dallas, no matter whether they
are the only person in the pattern or #25 to land.

Certainly we can make allowances for situations, but if you are saying that you
make different patterns when you are alone in the pattern, I'd suggest another
instructor. I certainly won't sign you off.

Jim




"Jay Honeck"
shared these priceless pearls of wisdom:

-
-This is the standard procedure for entering a pattern.
-
-Over the years, though, I've found that my pattern entry procedure varies
-with conditions. If I'm alone in the pattern (as we often are, on a
-Wednesday afternoon -- a day we typically fly), I'll zip around the pattern
-at whatever speed works to get me down soonest.



Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com