A question only a newbie would ask

On 13 Aug 2004 14:10:13 -0500, Todd Pattist
wrote:

It's that and the fact that you can't keep on increasing the
prop diameter - you run out of ground clearance, exceed
material limits or hit the inefficiencies of supersonic
tips.

As I mentioned, that's why the prop designer came up with such a
strange looking planform. The prop is wide where it's most efficient
(aproximately halfway out from the hub where the prop speed is way
below sonic speed) and can produce the greatest thrust, then narrows
down rapidly from that point from both leading and trailing edges,
then the leading and trailing edges get to running roughly parallel
before they stop abruptly at the tip which is squared off.

As I mentioned, since the tip is moving the fastest, it's smart to
present very little for the air to get draggy about at that point.

Some props have rather wide tips, which get hugely draggy at high
rpms, and also produce a lot of noise.

This things is very odd looking but produces good thrust while being
quieter than most props.

Corky Scott

On Thu, 12 Aug 2004 at 11:01:06 in message
, Corky Scott
wrote:
The designer of the prop I mentioned wrote in the article about the
fallacy of single bladed prop. Regardless the dubius advantage of
biting into clean air, the problems associated with the unbalanced
thrust produced by the single blade spinning around, despite it being
counter balanced weightwise, are for all practical purposes
insurmountable.

This is successfully been done at model scale, where the effective
diameter is more important and High Mach numbers are not used. This is
especially true of rubber powered models where the high torque needs a
large diameter slow turning airscrew. The mass balance is angled
backwards so the offset thrust can be, to some extent, be balanced.
--
David CL Francis

David CL Francis wrote in message ...
On Thu, 12 Aug 2004 at 11:01:06 in message
, Corky Scott
wrote:
The designer of the prop I mentioned wrote in the article about the
fallacy of single bladed prop. Regardless the dubius advantage of
biting into clean air, the problems associated with the unbalanced
thrust produced by the single blade spinning around, despite it being
counter balanced weightwise, are for all practical purposes
insurmountable.

This is successfully been done at model scale, where the effective
diameter is more important and High Mach numbers are not used. This is
especially true of rubber powered models where the high torque needs a
large diameter slow turning airscrew. The mass balance is angled
backwards so the offset thrust can be, to some extent, be balanced.

I have seen a motorglider at a couple of airshows that has a single-
blade counterweighted propeller. In this case the purpose is to make
the engine and prop stowable in the gliding mode. The propulsion as-
sembly is mounted on a mast above and behind the pilot, and pivots
backwards into a well in the fuselage. The drill is to rotate the
prop till the blade is pointing straight down, then lower the mast
assembly into the well and close the bay doors. It obviously works -
I watched the owner take off and fly away. Whether or not it is
satisfactory would be for those who fly it to decide. I haven't
heard any comments either way

David Johnson

In my own experience with American Greens, they oppose anything that
THEY don't do, while demanding outrageous privileges from government.
Example: $4 million to have a bicycle lane across the Dumbarton Bridge
in San Francisco Bay. Maybe three people a week use it.

Iowa City spent a hundred thousand dollars (or more) installing "bicycle
lifts" on the front of all city buses. These contraptions allow the bus
driver to stop, get out, and "easily" load a bicycle onto a rack mounted on
the front of the bus.

The Greens insisted that this would encourage the use of public
transportation (which has been a financial catastrophe here -- we could
literally buy each rider a car for less tax money), and rammed the issue
through our sheepish city council.

As most of us knew all along, they (like the buses) are rarely used --
thankfully. Each time they ARE used, the bus -- which, of course, must stop
at curbside, blocking the traffic lane -- sits for up to 5 minutes while the
poor driver wrestles the bike onto the rack.

I often wonder how much gas those 25 cars idling behind the bus are "saving"
thanks to the Greens.

But, of course, we're the idiots for letting them control the agenda...
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

In my own experience with American Greens, they oppose anything that
THEY don't do, while demanding outrageous privileges from government.
Example: $4 million to have a bicycle lane across the Dumbarton Bridge
in San Francisco Bay. Maybe three people a week use it.

Iowa City spent a hundred thousand dollars (or more) installing "bicycle
lifts" on the front of all city buses. These contraptions allow the bus
driver to stop, get out, and "easily" load a bicycle onto a rack mounted on
the front of the bus.

The Greens insisted that this would encourage the use of public
transportation (which has been a financial catastrophe here -- we could
literally buy each rider a car for less tax money), and rammed the issue
through our sheepish city council.

As most of us knew all along, they (like the buses) are rarely used --
thankfully. Each time they ARE used, the bus -- which, of course, must stop
at curbside, blocking the traffic lane -- sits for up to 5 minutes while the
poor driver wrestles the bike onto the rack.

I often wonder how much gas those 25 cars idling behind the bus are "saving"
thanks to the Greens.

But, of course, we're the idiots for letting them control the agenda...
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"


Jay, you'd enjoy the HOV lanes on the Long Island Expressway (LIE), Long Island
NY.

Tthe LIE, like many other urban roads, is called by locals the world's longest
parking lot. Here's the fun thing. It's 4 lanes plus an HOV lane along much of
its length. The HOV lane, however, takes two lanes of width, the lane itself,
then transition and buffer areas. HOV traffic is MUCH less than 1/5 of the
traffic, I'd guess 1/20th is a better guess, but it owns 1/3 of the real
estate. It gets even better. The HOV lanes are only enforced during times of
high traffic flow! The times when the extra pavement could really be used by
the people going and coming from work, it's denied them. Of course, at times
when traffic is sparce, anyone may use the HOV lanes.

Now don't get me started on those damned walls along radways to control noise!

"Jay Honeck" wrote

Iowa City spent a hundred thousand dollars (or more) installing
"bicycle lifts" on the front of all city buses. These contraptions
allow the bus driver to stop, get out, and "easily" load a bicycle
onto a rack mounted on the front of the bus.

We have bike racks on all of our buses here in the Tampa Bay Area.
I use them frequently, and despite the Mercedes Diesel parked in my
carport, I consider my bicycle my main means of transportation
within Tarpon Springs and Pinellas County. We also pulled-up the
old railroad tracks and paved a bike-jog path for the entire 34 mile
length of the county. On my 68th birthday, I biked both directions
(68 miles)in 6 hours. Our bus drivers never touch the bikes, one
must view a 10-15 minute training video, pay for a photo ID card, and
display it to the bus driver each time that the bike rack is used.

As most of us knew all along, they (like the buses) are rarely used --
thankfully. Each time they ARE used, the bus -- which, of course,
must stop at curbside, blocking the traffic lane -- sits for up to 5
minutes while the poor driver wrestles the bike onto the rack.

Our bikes racks are so heavily used that the county is in the process
of upgrading the 2-bike racks to 3-bike racks. It takes this old man
only about 15 seconds to load and unload my bike from the rack while
the other passengers are boarding.

What comments do you have about the mandatory wheelchair lifts that we
also have on all of our busses? Using them does require driver
assistance and probably about 5 minutes per use. I don't think that
any one of those wheelchair users ever thought that one day they would
be in that position. I think that it is admiralable that the citizens
of Pinellas County have chosen to help these citizens remain independant
in their transportation needs.

But, of course, we're the idiots for letting them control the
agenda...

And I thank you very much! :-) I have found that as I age, I become
much more considerate and understanding of the needs of others.

Bob Moore

"Bob Moore" wrote in message
. 8...

I think that it is admiralable that the citizens of Pinellas County have
chosen to help these citizens remain independant in their
transportation needs.


If I needed help to remain independent I wouldn't consider myself
independent.

"Bob Moore" wrote in message . 8...
"Jay Honeck" wrote

Iowa City spent a hundred thousand dollars (or more) installing
"bicycle lifts" on the front of all city buses. These contraptions
allow the bus driver to stop, get out, and "easily" load a bicycle
onto a rack mounted on the front of the bus.

We have bike racks on all of our buses here in the Tampa Bay Area.

I've never seen a hydraulic one however. I've never seen a driver put
a bike in one either. If you're the type to be able to ride a bike, you're
usually able to lift it up into the rack yourself.

"Steven P. McNicoll" wrote in message thlink.net...
"Bob Moore" wrote in message


If I needed help to remain independent I wouldn't consider myself
independent.

Unless you are living hundreds of miles from other people and
surviving by using tools that you made with your own bare hands, you
are not independent. Everyone depends on other people to one degree or
another. At some point in your life, unless you enjoy sudden death,
you will be depending on other people more and more as your body and
mind decline. Then maybe you will appreciate the point that Bob Moore
made.

"lowflyer" wrote in message
om...

Unless you are living hundreds of miles from other people and
surviving by using tools that you made with your own bare hands, you
are not independent. Everyone depends on other people to one degree or
another. At some point in your life, unless you enjoy sudden death,
you will be depending on other people more and more as your body and
mind decline. Then maybe you will appreciate the point that Bob Moore
made.


Do you think you'll ever appreciate the point I made?