Cherokee 180 prop RPM

On 04/17/06 15:11, wrote:
On Mon, 17 Apr 2006 15:23:42 +0000 (UTC),
wrote:

snip
All I was trying to point out is that the (deserved) bad reputation of the
PA-28 gliding like a refrigerator with power-off can be partially mitigated by the VG
installation.
snip

Ever driven a 114 Commander? You'd think it was a refrigerator with
the door open...

so ... the interior light is on? ;-)


TC


--
Mark Hansen, PP-ASEL, Instrument Airplane
Cal Aggie Flying Farmers
Sacramento, CA

On Mon, 17 Apr 2006 15:22:47 -0700, Mark Hansen
wrote:

On 04/17/06 15:11, wrote:
On Mon, 17 Apr 2006 15:23:42 +0000 (UTC),
wrote:

snip
All I was trying to point out is that the (deserved) bad reputation of the
PA-28 gliding like a refrigerator with power-off can be partially mitigated by the VG
installation.
snip

Ever driven a 114 Commander? You'd think it was a refrigerator with
the door open...

so ... the interior light is on? ;-)

heh.

was lucky enuff years back to have the opportunity to take a newer 114
for a test-hop after work. at the time was also familiar
with/comfortable in constant-chord PA28's & 32's of just about every
variety.

less than 2 hours of fuel onboard plus a couple of guys from the prop
shop that wanted to go along.

wasn't particularly comfortable with the climbout, but the
base-to-final rate of descent was a real eye-opener
(rectum-clencher?). running out of rudder over the threshold irritated
me slightly also.

TC

wrote:
: less than 2 hours of fuel onboard plus a couple of guys from the prop
: shop that wanted to go along.

: wasn't particularly comfortable with the climbout, but the
: base-to-final rate of descent was a real eye-opener
: (rectum-clencher?). running out of rudder over the threshold irritated
: me slightly also.

Flew one once. Thet's why those guys land at Vno, I guess. Let the landing
gears soak up the arrival.
--
Aaron C.

On Mon, 17 Apr 2006 15:23:42 +0000 (UTC),
wrote:

Quite true, but then the concept of "floating" is relegated to any
approach speed above stall-speed. How much speed margin is included in the POH

I always heard it used as referencing the plane not touching down when
it should and all finals as opposed to approaches are normally flown
above stall speed. If the final is normally flown at 1.3 Vso and the
most of the speed bled off in the round out as the plane enters ground
effect the touch down should be gentle.

Think of it this way. As you go into the flare the plane should not
start climbing again. The speed should bleed off so as the plane
comes out of the round out pretty much level in ground effect. Then
just above the runway the nose is raised slightly to finish slowing to
the point where the wheels will settle onto the runway.

approach speed? Indeed, for a "slam-dunk" short-field approach, one hangs it on the
prop with a minimal speed margin that gust factor allows.

Even a short field can be done with out a "slam dunk". Cherokees are
very good at a nice touchdown, immediately lower the nose (after the
mains are on), raise those mechanical flaps, get on the brakes and
full up elevator and they will really stop short.


All I was trying to point out is that the (deserved) bad reputation of the
PA-28 gliding like a refrigerator with power-off can be partially mitigated by the VG
installation.


I've heard people joke about the steep glide, but this is the first I
ever heard it referred to as having a bad reputation.
Why would the PA-28 have a bad reputation for its glide ratio with
power off. I put a bit over 300 hours on one and was quite comfortable
with it. Many high performance singles have a faster rate of descent
with a steeper final than the Cherokee.

As a representative datapoint, I fly the approach in my PA-28-180 at 80mph IAS
with 2-notches. The book value says 85 mph (minus 2 x 3mph for the flaps) = 79mph.

That's faster than I land a Deb or Bonanza, but it is as I recall
about what I used to fly final in the 180. OTOH Vso with only me and
half fuel in the Deb is about 55 MPH. and that equates to a final at
71 MPH. Now that is *steep* and requires a fair amount of power.
Engine out is quite a bit faster as at 71 MPH you don't have enough
energy to flare.

With that speed, I've got just a second or two of "finesse" to do at the flare before
the energy is gone and it sinks on. At 75 mph it's a flare-drop-chunk one-motion.
Given the VG's and aftermarket wingtips on it, that's pretty much book corrected for
5mph or so.

Prior to the mods, coming in at 80mph with 2-notches had a pretty ugly sink
rate associated with it.

I never noticed that and I always used full flaps in both the Cherokee
and the Deb.. It's what I was taught, it's what I was used to and it
was just a matter of controlling the airspeed and initiating both the
round out and flare at the right time.

Actually the Deb with power off and full flaps at the proper speed is
very much like landing a Cherokee 180 in the same configuration. With
practice you can make a gentle touchdown and use very little runway.
They have almost identical wing loading. However with the larger
flaps on the Deb I can hit about 2200 FPM rate of descent if in a
hurry. That does require a bit of a slip though.:-))

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


-Cory

: I would think that still means the landing is too fast. With STOL
: mods that lower the stall speed the landing speed would be adjusted to
: meet the new stall speeds.

: Float normally means too fast. If the mods change the characteristics
: so that float is still there at the corrected speeds I'd have some
: concern.

: Typically it takes a while to get used to flying the proper speeds
: after adding mods that reduce the stall speed and increase lift at low
: speed.

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

Interesting. I noticed on a flight the other day (first major flight since
Annual) that I was at or above redline on climbout, and had a lot of trouble
keeping it below redline at cruise. We'd almost never seen redline before
except on fast descents at cruise power. (1974 Archer). The muffler was
replaced at annual, and this problem has suddenly appeared. The prop was
filed and painted at Annual, but nothing else changed. I joked with my
partners that perhaps the prop was repitched, or that the engine was making
20% more power. Perhaps it IS now making more power. Guess we need to look
at the prop after all.

--
Bob (Chief Pilot, White Knuckle Airways)


wrote in message
oups.com...

The Visitor wrote:
If your tach is correct within reason. It may not be the prop is under
pitched. But rather filed away too much and really under sized. Is it
really old?


I'll go with that answer! I always wondered why the prop on my
Cherokee 180 would turn redline speeds at 11K ft. when the book said it
shouldn't. When I put the new engine on last summer, I sent the prop
to the prop shop and found out why. 36 years of filing had left the
prop substantially thinner than standard (although it was still 76"
long). Prop shop said it was out of spec., so I had to shell out for a
brand new one. When I put the old and the new prop side by side, they
didn't even look like the same model.

With the new prop, the rpm now maxes out where the book says it
should.

John Galban=====N4BQ (PA28-180)