On Sun, 05 Sep 2004 00:59:49 GMT,
Brian Whatcott wrote:
On Sat, 04 Sep 2004 23:30:33 GMT, Jim Richardson
wrote:
the autoprop turns it's blades, to be parallel to the axis of the
shaft, resulting in less drag than in the fwd or reverse direction,.
How is that not feathering?

I an unfamiliar with the autoprop.If it turns its blades' angle of
attack to the near zero angle (actually slightly negative angle) that
minimizes drag, then this is said to be a feathering prop.
[one realises that a blade's angle varies with distance from the hub,
so that the idea of a fixed angle of attack is a slight abstraction]

If a prop system allows the blades to fold at the hub in order to
minimize drag this is usually described as a folding prop.

If a prop system allows the prop blades' angle of attack to vary so as
to maximize power transfer at the present water speed, this is said to
be a variable pitch prop system.

Let me ask Jim specifically (in order to avoid interjections from the
lunatic fringe) which of these three types of prop system he would
call the Autoprop?

Regards


I'd say it's either a variable pitch, or simple feathering, since I am
unsure from a casual perusal of their website whether the blades are
fixed in pitch when set to forward or reverse, or are variable based on
rpm.



--
Jim Richardson http://www.eskimo.com/~warlock
Rule 1: You can't cure stupid

Jim Richardson wrote:

I'd say it's either a variable pitch, or simple feathering, since I am
unsure from a casual perusal of their website whether the blades are
fixed in pitch when set to forward or reverse, or are variable based on
rpm.


From the sites, I get the feeling the pitch is adjustable at
installation but fixed from that point on, which would mean it is
"feathering", not "variable" (?)

otn

So are you claiming that the MIT study that said that a 3-blade prop could
slow
a boat up to 0.8 knots was bad science?

MIT didn't say that. the editor (singular) or Pop Mechanixs did. MIT just
reported the data from a prop test.

take a look at the damned prop for the kristes sake before you claim you know
what it looks like.

geesh. what a clewless turd.

From: Jim Richardson
Date: 9/6/2004 4:00 PM Eastern Daylight Time
Message-id:

On Sun, 05 Sep 2004 00:59:49 GMT,
Brian Whatcott wrote:
On Sat, 04 Sep 2004 23:30:33 GMT, Jim Richardson
wrote:
the autoprop turns it's blades, to be parallel to the axis of the
shaft, resulting in less drag than in the fwd or reverse direction,.
How is that not feathering?

I an unfamiliar with the autoprop.If it turns its blades' angle of
attack to the near zero angle (actually slightly negative angle) that
minimizes drag, then this is said to be a feathering prop.
[one realises that a blade's angle varies with distance from the hub,
so that the idea of a fixed angle of attack is a slight abstraction]

If a prop system allows the blades to fold at the hub in order to
minimize drag this is usually described as a folding prop.

If a prop system allows the prop blades' angle of attack to vary so as
to maximize power transfer at the present water speed, this is said to
be a variable pitch prop system.

Let me ask Jim specifically (in order to avoid interjections from the
lunatic fringe) which of these three types of prop system he would
call the Autoprop?

Regards


I'd say it's either a variable pitch, or simple feathering, since I am
unsure from a casual perusal of their website whether the blades are
fixed in pitch when set to forward or reverse, or are variable based on
rpm.



--
Jim Richardson http://www.eskimo.com/~warlock
Rule 1: You can't cure stupid

HOOOOONK!! Wrong answer. Try again.

From: otnmbrd
Date: 9/6/2004 5:02 PM Eastern Daylight Time
Message-id: . net



Jim Richardson wrote:

I'd say it's either a variable pitch, or simple feathering, since I am
unsure from a casual perusal of their website whether the blades are
fixed in pitch when set to forward or reverse, or are variable based on
rpm.


From the sites, I get the feeling the pitch is adjustable at
installation but fixed from that point on, which would mean it is
"feathering", not "variable" (?)

otn

Wrong again jaxie. The Practical Sailor article quoted a different MIT study
which predicted the speed loss that would be created by that much drag.
Remember, this is the department of MIT that created and refined the VPP
(Velocity Prediction Program) used by USSailing for their Polar Speed charts.
They know a little bit about this sort of thing.



"JAXAshby" wrote in message
...
So are you claiming that the MIT study that said that a 3-blade prop could
slow
a boat up to 0.8 knots was bad science?

MIT didn't say that. the editor (singular) or Pop Mechanixs did. MIT just
reported the data from a prop test.

jeffies, you can't read. the drag over every boat type is different. Maybe --
if you were a tad more alert -- you would have noticed that a J-30 moves faster
than a Westsail 32.

now, jeffies, go light incense to the gods that made you smart enough to
"invest" in feathering props for your training wheels.

Wrong again jaxie. The Practical Sailor article quoted a different MIT study
which predicted the speed loss that would be created by that much drag.
Remember, this is the department of MIT that created and refined the VPP
(Velocity Prediction Program) used by USSailing for their Polar Speed charts.
They know a little bit about this sort of thing.



"JAXAshby" wrote in message
...
So are you claiming that the MIT study that said that a 3-blade prop
could
slow
a boat up to 0.8 knots was bad science?

MIT didn't say that. the editor (singular) or Pop Mechanixs did. MIT just
reported the data from a prop test.

Subject: What are the pros and cons of a folding prop?
From: (JAXAshby)
Date: 09/07/2004 04:51 Pacific Standard Time
Message-id:

jeffies, you can't read. the drag over every boat type is different. Maybe
--
if you were a tad more alert -- you would have noticed that a J-30 moves
faster
than a Westsail 32.

now, jeffies, go light incense to the gods that made you smart enough to
"invest" in feathering props for your training wheels.


G Poor ole Doodles can't seem to remember who said what, who "invested" in
what, can't spell past a third grade level, punctuates worse than I do,
misquotes most sources, understands fewer, can't navigate, doesn't know the
"Rules", wouldn't know a Sulzer RND from an 8-71, a feathering prop from a
fixed pitch prop, etc., etc., .....
Ah well, look at the bright side, Doodles, you have a certain entertainment
value for the majority.

Shen

shen wrote this of interest

Subject: What are the pros and cons of a folding prop?
From: (JAXAshby)
Date: 09/07/2004 20:57 Pacific Standard Time
Message-id:

shen wrote this of interest


G