Prop to High RPM on downwind

On Sun, 21 Nov 2004 23:51:25 GMT, Mitty wrote:

I've been taught to set the prop to high RPM on final, but I don't like this
very much because then, when I run my checklist for the first time on downwind,
I have to leave one item "open."

So what's wrong with doing it on downwind? (This in a Cherokee 6 or and Arrow)
It seems to work fine, does not disarrange the engine, etc. I suppose there
is some small noise increase, but hardly much.

So (1) is everyone taught to do it on final? (2) Why? (3) What's wrong with
doing it on downwind?

It depends on the airplane and prop, but it increases noise and drag.
Drag isn't bad if you wish to slow up and it's not at all uncommon to
wish to do so on down wind. OTOH that is not a problem with either
the Arrow or Cherokee family.

If you go full RPM in a Bonanza or Cessna 210 with a 2 blade prop,
the neighbors will not like you. With those there is a big increase
in noise until the MP is back to the point where it's controlling the
RPM.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

TIA

Mitty,

So (1) is everyone taught to do it on final? (2) Why? (3) What's wrong with
doing it on downwind?


Yes, noise, noise. Just listen to a Bonanza turning on the chain saw on
downwind once, and you'll never again say it's only a "small noise increase".
The effect, while differing from type to type, is huge. If you want airports
to stay open, don't do it on downwind.

Also, in case of a go-around, it is probably anyway a good idea to think in
terms of "all levers go full forward" rather than just "throttle full
forward".

--
Thomas Borchert (EDDH)

So (1) is everyone taught to do it on final? (2) Why? (3) What's wrong
with
doing it on downwind?

1. Yes.
2. Rote procedure.
3. Noise.

I had this brought home to me during Mary's biennial. I was working in the
hangar while she was coming into (and going out of) the pattern, and, boy,
could you tell when she pushed the prop control forward on a fast downwind.
That Lycoming O-540 just growled.

Now, personally, I LIKE that sound -- but I understand there are those in
the flight path who don't. Since we have to live with those folks, it's a
good idea not to give them the ammo with which to shoot us down. Noise
abatement is serious stuff when your community is not 100% for having an
airport in the first place.

We now don't push the prop full forward until we're on final, when the
airspeed and MP is already so low that it makes no audible difference.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

In article , Mitty wrote:
I've been taught to set the prop to high RPM on final, but I don't like this
very much because then, when I run my checklist for the first time...

Simple - change your checklist. They aren't set in stone.

In any case, forgetting the prop (especially on a plane like an Arrow or
Cherokee 6) is hardly critical - in the case of a go-around it's easy
enough to grab all the controls and push them forward when they are
arranged like this.

--
Dylan Smith, Castletown, Isle of Man
Flying: http://www.dylansmith.net
Frontier Elite Universe: http://www.alioth.net
"Maintain thine airspeed, lest the ground come up and smite thee"

Why even worry about it unless you're going to go around?


"Mitty" wrote in message
...
I've been taught to set the prop to high RPM on final, but I don't like
this very much because then, when I run my checklist for the first time on
downwind, I have to leave one item "open."

So what's wrong with doing it on downwind? (This in a Cherokee 6 or and
Arrow) It seems to work fine, does not disarrange the engine, etc. I
suppose there is some small noise increase, but hardly much.

So (1) is everyone taught to do it on final? (2) Why? (3) What's wrong
with doing it on downwind?

TIA

In article ,
Mitty wrote:
So (1) is everyone taught to do it on final? (2) Why?

1) Yes

2) To have something to break up the monotony of "gear. gear?? gear!!
better check the gear... gear? ok, gear down. gear is down. still down.
not gonna land gear up."

--
Ben Jackson

http://www.ben.com/

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.

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.

Jim



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

"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. If you do
that,
your power is already back for level flight to where the prop is in the
stops
anyway.

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.

Jim

Exactly

"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

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

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.


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.

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 - as you
reduce power it tried to keep the RPM up, until it couldn't make the pitch
any finer after which the RPM started to decline along with engine power.


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.

No, he like everyone else reduces the power - sets the pitch to get the
airspeed he wants and the plane comes down - flaps help even more. The RPM
reduces along with the power (irrespective) of the position of the prop
control.

-Brenor