Prop angle of attack vs age

On older planes, does the angle of attack change ? Does the prop angle
relax like a motorboat prop does after 1 or 2 decades of constant
use ? (fixed pitch of course)

There are some older warriors on the field (20 - 25) years, and it
seems that there props don't have the bite that the new warrior (10
years old) does.

Thanks

sid wrote in news:702f8b8d-b77e-452c-904c-
:

On older planes, does the angle of attack change ? Does the prop angle
relax like a motorboat prop does after 1 or 2 decades of constant
use ? (fixed pitch of course)

There are some older warriors on the field (20 - 25) years, and it
seems that there props don't have the bite that the new warrior (10
years old) does.


No, but years of wear and dressing the prop because of nicks and what not
doesn't do them any good at all.


Bertie

On Fri, 11 Jul 2008 08:57:13 +0000 (UTC), Bertie the Bunyip
wrote:

sid wrote in news:702f8b8d-b77e-452c-904c-
:

On older planes, does the angle of attack change ? Does the prop angle
relax like a motorboat prop does after 1 or 2 decades of constant
use ? (fixed pitch of course)

There are some older warriors on the field (20 - 25) years, and it
seems that there props don't have the bite that the new warrior (10
years old) does.


No, but years of wear and dressing the prop because of nicks and what not
doesn't do them any good at all.


Bertie


I have a fibreglass covered wooden prop which makes it reasonably
resilient in light rain. I paint it.
when the aforesaid light rain has eroded the paint near the leading
edge I lose 5 knots in cruise speed.

also If I alter the shape with a poor paint coat I lose cruise speed.

the other factor with some commercial aircraft is that there are often
3 props approved for them. a climb, a utility and a cruise prop.
on little cessnas they are each 2 inches of pitch apart.
memories of cruise with a cruise prop would make cruise on a climb
prop seem quite anaemic.

.....and what bertie wrote.

Stealth Pilot

On Jul 11, 7:09*am, Stealth Pilot
wrote:
On Fri, 11 Jul 2008 08:57:13 +0000 (UTC), Bertie the Bunyip
wrote:



sid wrote in news:702f8b8d-b77e-452c-904c-
:

On older planes, does the angle of attack change ? Does the prop angle
relax like a motorboat prop does after 1 or 2 decades of constant
use ? (fixed pitch of course)

There are some older warriors on the field (20 - 25) years, and it
seems that there props don't have the bite that the new warrior (10
years old) does.

No, but years of wear and dressing the prop because of nicks and what not
doesn't do them any good at all.

Bertie

I have a fibreglass covered wooden prop which makes it reasonably
resilient in light rain. I paint it.
when the aforesaid light rain has eroded the paint *near the leading
edge I lose 5 knots in cruise speed.

also If I alter the shape with a poor paint coat I lose cruise speed.

the other factor with some commercial aircraft is that there are often
3 props approved for them. a climb, a utility and a cruise prop.
on little cessnas they are each 2 inches of pitch apart.
memories of cruise with a cruise prop would make cruise on a climb
prop seem quite anaemic.

....and what bertie wrote.

Stealth Pilot

I can understand why a poor -- as in not smooth -- paint job would
alter the prop's efficiency, but never would have guessed having a
fractional mm of paint ablated from the leading edge of the prop would
affect it that much. Tongue in cheek question -- did the natural color
of the prop clash with that color and scare the air, or something?

On a serious note, have you any thoughts as to why such a minor change
in shape would have such a remarkable change in efficiency? A 5 knot
change in airspeed is like reducing the manifold an inch or so, isn't
it? That's huge! It also suggests there may be very minor changes in
prop that could improve performance too.

l

wrote in message
...

I can understand why a poor -- as in not smooth -- paint job would
alter the prop's efficiency, but never would have guessed having a
fractional mm of paint ablated from the leading edge of the prop would
affect it that much. Tongue in cheek question -- did the natural color
of the prop clash with that color and scare the air, or something?

On a serious note, have you any thoughts as to why such a minor change
in shape would have such a remarkable change in efficiency? A 5 knot
change in airspeed is like reducing the manifold an inch or so, isn't
it? That's huge! It also suggests there may be very minor changes in
prop that could improve performance too.

---------------------------------------------------

You are absolutely right, and his is just exaggerating again as usual.

Just keep an eye on his posts, you will come to expect it in time.

"Maxwell" luv2^fly99@cox.^net wrote in news:ZhKdk.20173$%q.11589
@newsfe24.lga:


wrote in message
...

I can understand why a poor -- as in not smooth -- paint job would
alter the prop's efficiency, but never would have guessed having a
fractional mm of paint ablated from the leading edge of the prop would
affect it that much. Tongue in cheek question -- did the natural color
of the prop clash with that color and scare the air, or something?

On a serious note, have you any thoughts as to why such a minor change
in shape would have such a remarkable change in efficiency? A 5 knot
change in airspeed is like reducing the manifold an inch or so, isn't
it? That's huge! It also suggests there may be very minor changes in
prop that could improve performance too.

---------------------------------------------------

You are absolutely right, and his is just exaggerating again as usual.

Like you'd know, fjukktard.

Just keep an eye on his posts, you will come to expect it in time.



Snort!


Bertie

On Jul 11, 12:14*pm, Bertie the Bunyip wrote:
"Maxwell" luv2^fly99@cox.^net wrote in news:ZhKdk.20173$%q.11589
@newsfe24.lga:







wrote in message
....

I can understand why a poor -- as in not smooth -- paint job would
alter the prop's efficiency, but never would have guessed having a
fractional mm of paint ablated from the leading edge of the prop would
affect it that much. Tongue in cheek question -- did the natural color
of the prop clash with that color and scare the air, or something?

On a serious note, have you any thoughts as to why such a minor change
in shape would have such a remarkable change in efficiency? A 5 knot
change in airspeed is like reducing the manifold an inch or so, isn't
it? That's huge! It also suggests there may be very minor changes in
prop that could improve performance too.

---------------------------------------------------

You are absolutely right, and his is just exaggerating again as usual.

Like you'd know, fjukktard.



Just keep an eye on his posts, you will come to expect it in time.

Snort!

Bertie- Hide quoted text -

- Show quoted text -

Not knowing much about props, what do you mean by "... they are each
2 inches of pitch apart." ?
I thought props were measured in dia. and angle ?

Thanks

"sid" wrote in message
...

Not knowing much about props, what do you mean by "... they are each
2 inches of pitch apart." ?
I thought props were measured in dia. and angle ?

Thanks

--------------------------------------------------------------------

A propellers angle or pitch is expressed in inches. Theoretically, a 24"
pitch prop has an angle that would travel 24" forward with each revolution,
at zero angle of attack. The smaller the number, the flatter the prop.

If that seems confusing, consider a right trangle. If the circumference of
the propeller arc at any given station is the base, the pitch is the height,
and the resulting angle is the pitch angle for that station. That's why
props have less angle at the tip, than at the root. Theoretically, it keeps
the entire lenght of the blade working at the same angle of attack.

Thus climb props are flatter or less pitch, and cruise props have more.

On Jul 11, 3:13*pm, "Maxwell" luv2^fly99@cox.^net wrote:
"sid" wrote in message

...

Not knowing much about props, what do you mean by *"... they are each
2 inches of pitch apart." ?
I thought props were measured in dia. and angle ?

Thanks

--------------------------------------------------------------------

A propellers angle or pitch is expressed in inches. Theoretically, a 24"
pitch prop has an angle that would travel 24" forward with each revolution,
at zero angle of attack. The smaller the number, the flatter the prop.

If that seems confusing, consider a right trangle. If the circumference of
the propeller arc at any given station is the base, the pitch is the height,
and the resulting angle is the pitch angle for that station. That's why
props have less angle at the tip, than at the root. Theoretically, it keeps
the entire lenght of the blade working at the same angle of attack.

Thus climb props are flatter or less pitch, and cruise props have more.

That’s a good explanation.

Looking in my Warrior II Information manual, the prop is listed as a:
Sensenich 74DM6-0-60 or 74DM6-0-58.
Is the "inches of pitch" encoded in that number ?

In article ,
sid wrote:

Looking in my Warrior II Information manual, the prop is listed as a:
Sensenich 74DM6-0-60 or 74DM6-0-58.
Is the "inches of pitch" encoded in that number ?

Yes. 60 and 58

--
Bob Noel
(goodness, please trim replies!!!)