Prop performance in clouds question

On Mar 2, 7:08 pm, " wrote:
Only flying after today for the next month will be as a passenger as
November 1943 lima has been delivered to Batesville for the extreme
interior makeover. I asked the interior guy if he could email me some
progress pics and he said he would.

Another pilot followed me up in his piper seen here athttp://picasaweb.google.com/allenlieberman/AirplanePics/photo#5173324...

I **thought** air is less dense in a cloud, but when you watch the
prop strobing athttp://www.youtube.com/watch?v=QniPjy0gkBIyou can
see the regression of the prop strobing, and in my experiences when
the prop starts turning counter clockwise, the prop RPM is slowing
down.

We were in level flight, 6000 feet. Engine is 180 hp. I don't
remember what settings he had for the prop or engine.

Would the moisture in the cloud cause a change in the prop speed even
though we couldn't detect it via gauge or sound? Or is air inside a
cloud more dense?

What I found most fascinating is that we both left the same time, and
he only got there 2.5 minutes faster. I was 45 to a downwind when his
wheels touched down. He planned 130 knots, I planned 110 knots and
the trip was 116 NM.

This for sure verfied I don't need a high performance plane for my
kind of flying as even on my trips to Bessemer, who would really
notice 7 to 10 minutes longer flight time difference **in the full
scheme of things**.

Allen

The prop strobing clockwise does not necessarily mean the prop is
slowing down. If you've ever seen a turboprop shut down under the
artificial 60hz strobing lights of an airport apron, you'll see the
prob strobe back and forth as it gradually slows down.

On Mar 3, 11:02*am, buttman wrote:

The prop strobing clockwise does not necessarily mean the prop is
slowing down. If you've ever seen a turboprop shut down under the
artificial 60hz strobing lights of an airport apron, you'll see the
prob strobe back and forth as it gradually slows down.- Hide quoted text -

- Show quoted text -

Yeah, I figured the clockwise motion wasn't indication of it slowing
down, it was when I was IMC, that it "stopped" or started going
counter clockwise, and then when I popped out, it resumed it's
clockwise motion.

It was "hands off flying" before entering the cloud, smooth inside and
same outside and NO changes in airplane configuration insofar as prop,
mixture or throttle.

Something I can try to experiment in my Sundowner a month down the
road when it gets back in service since I only have a fixed pitch
prop.

Allen

"John T" wrote in message
m...
wrote in message


It may be an optical illusion, but engine RPM for a fixed
throttle/mixture setting will most definitely change because of the
air, otherwise there would be no reason to have a mixture control.

Would the use of a constant speed prop change your equation?

--
John T
http://sage1solutions.com/blogs/TknoFlyer
http://sage1solutions.com/products
NEW! FlyteBalance v2.0 (W&B); FlyteLog v2.0 (Logbook)
____________________



No, since there is a concept of a "dead zone" where there needs to be a more
than a minimum change for a the servo to react. Otherwise a concept of
"hunting" kicks in and the RPM constantly change and "hunts" for a center of
the constant RPM speed.

--
BobF.

"Bob F." wrote in message


No, since there is a concept of a "dead zone" where there needs to be
a more than a minimum change for a the servo to react. Otherwise a
concept of "hunting" kicks in and the RPM constantly change and
"hunts" for a center of the constant RPM speed.

True, but as you allude, only to a limited extent. It wasn't clear to me
from Jim's post that he was accounting for CS props.

--
John T
http://sage1solutions.com/blogs/TknoFlyer
http://sage1solutions.com/products
NEW! FlyteBalance v2.0 (W&B); FlyteLog v2.0 (Logbook)
____________________

wrote in message


I am using a Kodak Easy Share camera. Does that adjust based on what
it "sees"?

Cameras typically use a combination of shutter speed, aperture and exposure
to maintain the "best" picture (as defined by the software). I haven't
researched your camera, though I suspect it manipulates all three based on
the video I've seen on your channel. I know for certain your shutter speeds
are way different from mine based on the prop filtering.

Unless of course if the frame rate can change based on what the camera
sees being "so automatic"?

Possible, though I doubt actual frame rate is changing (different from
shutter speed).

I sure don't know myself, but pretty coincidental seeing the strobe
change in VMC vs IMC.

I don't doubt a small change in prop speed as I've seen similar changes in
my own prop "strobe," but I'd put it more to general atmospheric (or, more
likely, attitude changes) rather than specific to clouds as I've seen
similar changes well outside clouds on "severe clear" days.

Try this: Take video during a flight on a clear VMC day. Maintain level
flight as absolutely as you can, then enter climbs and descents. See what
that does to your prop strobe. I suspect even slight attitude changes will
show different strobe patterns without touching engine or prop controls.

--
John T
http://sage1solutions.com/blogs/TknoFlyer
http://sage1solutions.com/products
NEW! FlyteBalance v2.0 (W&B); FlyteLog v2.0 (Logbook)
____________________

On Mar 2, 9:08 pm, " wrote:
Only flying after today for the next month will be as a passenger as
November 1943 lima has been delivered to Batesville for the extreme
interior makeover. I asked the interior guy if he could email me some
progress pics and he said he would.

Another pilot followed me up in his piper seen here athttp://picasaweb.google.com/allenlieberman/AirplanePics/photo#5173324...

I **thought** air is less dense in a cloud, but when you watch the
prop strobing athttp://www.youtube.com/watch?v=QniPjy0gkBIyou can
see the regression of the prop strobing, and in my experiences when
the prop starts turning counter clockwise, the prop RPM is slowing
down.

We were in level flight, 6000 feet. Engine is 180 hp. I don't
remember what settings he had for the prop or engine.

Would the moisture in the cloud cause a change in the prop speed even
though we couldn't detect it via gauge or sound? Or is air inside a
cloud more dense?

What I found most fascinating is that we both left the same time, and
he only got there 2.5 minutes faster. I was 45 to a downwind when his
wheels touched down. He planned 130 knots, I planned 110 knots and
the trip was 116 NM.

This for sure verfied I don't need a high performance plane for my
kind of flying as even on my trips to Bessemer, who would really
notice 7 to 10 minutes longer flight time difference **in the full
scheme of things**.

Allen

I am not sure how you came to the conclusion that air is less dense in
the cloud than the surrounding air. Density decreases with increasing
moisture for unsaturated air, but once the air is saturated (clouds),
any excess moisture is suspended as tiny droplets, and the average
density will start to increase. Darker the cloud, the higher the
density. This is why you need an updraft to hold these clouds up. When
the density gets too large to overcome the updrafts, you get rain, and
the density returns to normal.

On Mar 4, 8:27*am, Andrew Sarangan wrote:
On Mar 2, 9:08 pm, " wrote:





Only flying after today for the next month will be as a passenger as
November 1943 lima has been delivered to Batesville for the extreme
interior makeover. *I asked the interior guy if he could email me some
progress pics and he said he would.

Another pilot followed me up in his piper seen here athttp://picasaweb.google.com/allenlieberman/AirplanePics/photo#5173324...

I **thought** air is less dense in a cloud, but when you watch the
prop strobing athttp://www.youtube.com/watch?v=QniPjy0gkBIyoucan
see the regression of the prop strobing, and in my experiences when
the prop starts turning counter clockwise, the prop RPM is slowing
down.

We were in level flight, 6000 feet. *Engine is 180 hp. *I don't
remember what settings he had for the prop or engine.

Would the moisture in the cloud cause a change in the prop speed even
though we couldn't detect it via gauge or sound? *Or is air inside a
cloud more dense?

What I found most fascinating is that we both left the same time, and
he only got there 2.5 minutes faster. *I was 45 to a downwind when his
wheels touched down. *He planned 130 knots, I planned 110 knots and
the trip was 116 NM.

This for sure verfied I don't need a high performance plane for my
kind of flying * as even on my trips to Bessemer, who would really
notice 7 to 10 minutes longer flight time difference **in the full
scheme of things**.

Allen

I am not sure how you came to the conclusion that air is less dense in
the cloud than the surrounding air. Density decreases with increasing
moisture for unsaturated air, but once the air is saturated (clouds),
any excess moisture is suspended as tiny droplets, and the average
density will start to increase. Darker the cloud, the higher the
density. This is why you need an updraft to hold these clouds up. When
the density gets too large to overcome the updrafts, you get rain, and
the density returns to normal.- Hide quoted text -

- Show quoted text -

BINGO!

Cheers

On Mar 3, 1:27*pm, Andrew Sarangan wrote:

I am not sure how you came to the conclusion that air is less dense in
the cloud than the surrounding air. Density decreases with increasing
moisture for unsaturated air, but once the air is saturated (clouds),
any excess moisture is suspended as tiny droplets, and the average
density will start to increase. Darker the cloud, the higher the
density. This is why you need an updraft to hold these clouds up. When
the density gets too large to overcome the updrafts, you get rain, and
the density returns to normal.- Hide quoted text -

While I plan to ask on a meteorological forum when I get home, play
with me a sec...

I am not talking about small clouds vs big rain making clouds. What I
am talking about is the density of the air comparing VMC to IMC at an
established level of flight.

If that cloud was "denser" then the surrounding air (as you can see in
the video, it was a sparse cloud cover), then why doesn't the cloud
sink if that parcel of air is heavier (denser) then the surrounding
air?

Winds aloft were 35 knots so surely, the updraft time was extremely
minimal and I would say none, since I didn't get any lifting feeling
in the seat of my pants in penetrating that volkswagon size puffy.

When I googled the topic, it talked mainly of stratiform clouds, and
that layer being less dense below the cloud deck, which I already
understand the higher you go, the less dense the air. This is
probably where I got my initial impressions that the air in clouds is
less dense.

Allen

On Mar 3, 1:19*pm, "John T" wrote:

Try this: Take video during a flight on a clear VMC day. Maintain level
flight as absolutely as you can, then enter climbs and descents. See what
that does to your prop strobe. I suspect even slight attitude changes will
show different strobe patterns without touching engine or prop controls.

Actually, with my Sundowner, prop controls will be one less variable
in the equation. (one month down time will feel like eternity!)

The trick will be to maintain the "exact" flight "attitude" throughout
the cloud as YOU ARE RIGHT, any pitch up or pitch down will affect the
RPM as I noticed this on my ILS approaches in my Sundowner. (Video
was in a Piper).

I like to listen to the engine noise as well as watch the strobing to
associate the quality of the approach, I.E the less power changes I
hear, the more stable the approach, and strobing remains "constant"
whether it be clockwise, or counter clockwise or even standing still.

It may be that there was a pitch change in the plane that I couldn't
feel in the video that just may have existed even though I didn't feel
it in the seat of my pants (I was passenger holding the camera). Of
course in IMC, we will really never know but gauges were steady as
they can be.

Allen

On Mar 3, 2:20*pm, " wrote:

When I googled the topic, it talked mainly of stratiform clouds, and
that layer being less dense below the cloud deck, which I already
understand the higher you go, the less dense the air. *This is
probably where I got my initial impressions that the air in clouds is
less dense.

Allen

To clarify, the above should say MORE dense below the stratiform cloud
deck!

Allen