Silent Super Efficient Propeller!

Hi all!
Volf propeller he
http://www.rexresearch.com/volfprop/volfprop.htm


I have been thinking alot about how this propeller would do, I wish I had a workshop, CNC, and tools to build one.. this amazing prop is claimed to be super quiet and efficient.. so any more info from the article on it or any word of experience in propellers are very appreciated





what about this propeller
( hit CTRl-F and type "An Air Screw That Ridicules Propeller" )
http://www.rexresearch.com/aero/1aero.htm

regards
kalle

On Sep 5, 1:10*am, Leviterande Leviterande.
wrote:
Hi all!
Volf propeller hehttp://www.rexresearch.com/volfprop/volfprop.htm

I have been thinking alot about how this propeller would do, I wish I
had a workshop, CNC, and tools to build one.. this amazing prop is
claimed to be *super quiet and efficient.. so any more info from the
article on it or any *word of experience in propellers are very
appreciated


Looks like a ducted fan to me. Judging from the pictures, it's
doubtful CFD existed when the patent was approved and modern rotor
design would probably be more efficient. Technology progresses, ya
know?

On Sep 5, 1:10*am, Leviterande Leviterande.
wrote:
Hi all!
Volf propeller hehttp://www.rexresearch.com/volfprop/volfprop.htm

I have been thinking alot about how this propeller would do, I wish I
had a workshop, CNC, and tools to build one.. this amazing prop is
claimed to be *super quiet and efficient.. so any more info from the
article on it or any *word of experience in propellers are very
appreciated

what about this propeller
( hit CTRl-F *and type "An Air Screw That Ridicules Propeller" )http://www.rexresearch.com/aero/1aero.htm

regards
kalle

--
Leviterande

That's a very old patent! If you think about a propeller for low speed
flight, think about it as a rotating wing. You'll notice high
perfornance gliders have long slender wings, and the best props look a
lot like that, with an additional twist. Ducting helps, as do Q tips
on propeller edges, but I did read somewhere you gain as much
efficiency by increasing the propeller diameter as the q tip length.
Makes me wonder if the vortex decreasing terminations on wings might
be as well used just by increasing the wingspan by that amount.

On Sep 5, 7:26*am, a wrote:
That's a very old patent! If you think about a propeller for low speed
flight, think about it as a rotating wing. You'll notice high
perfornance gliders have long slender wings, and the best props look a
lot like that, with an additional twist. Ducting helps, as do Q tips
on propeller edges, but I did read somewhere you gain as much
efficiency by increasing the propeller diameter as the q tip length.
Makes me wonder if the vortex decreasing terminations on wings might
be as well used just by increasing the wingspan by that amount.

That's exactly what Steve Wittman found 25(?) years ago on his Buick-
powered tailwind. He stuck some winglets on it, got some improvement,
then laid them down horizontally and found that they worked just as
well that way.

Dan

Originally Posted by a[_3_]

On Sep 5, 1:10 am, Leviterande Leviterande.
wrote:
Hi all!
Volf propeller hehttp://www.rexresearch.com/volfprop/volfprop.htm

I have been thinking alot about how this propeller would do, I wish I
had a workshop, CNC, and tools to build one.. this amazing prop is
claimed to be super quiet and efficient.. so any more info from the
article on it or any word of experience in propellers are very
appreciated

what about this propeller
( hit CTRl-F and type "An Air Screw That Ridicules Propeller" )http://www.rexresearch.com/aero/1aero.htm

regards
kalle

--
Leviterande

That's a very old patent! If you think about a propeller for low speed
flight, think about it as a rotating wing. You'll notice high
perfornance gliders have long slender wings, and the best props look a
lot like that, with an additional twist. Ducting helps, as do Q tips
on propeller edges, but I did read somewhere you gain as much
efficiency by increasing the propeller diameter as the q tip length.
Makes me wonder if the vortex decreasing terminations on wings might
be as well used just by increasing the wingspan by that amount.

so your guess is that none of the props are more efficient then todays propellers? the todays propellers didnt differ from the ones used 100 years ago btw...

Kalle

On Fri, 5 Sep 2008 07:55:15 -0700 (PDT),
wrote:

On Sep 5, 7:26*am, a wrote:
That's a very old patent! If you think about a propeller for low speed
flight, think about it as a rotating wing. You'll notice high
perfornance gliders have long slender wings, and the best props look a
lot like that, with an additional twist. Ducting helps, as do Q tips
on propeller edges, but I did read somewhere you gain as much
efficiency by increasing the propeller diameter as the q tip length.
Makes me wonder if the vortex decreasing terminations on wings might
be as well used just by increasing the wingspan by that amount.

That's exactly what Steve Wittman found 25(?) years ago on his Buick-
powered tailwind. He stuck some winglets on it, got some improvement,
then laid them down horizontally and found that they worked just as
well that way.

Dan

So is the vertical winglet

1) To increase wing length while
2) Looking cute

?

On Fri, 5 Sep 2008 12:42:38 -0400, Gezellig wrote in :

So is the vertical winglet

1) To increase wing length while
2) Looking cute

.... and to make it easier to clear obstacles when taxiing
in crowded airports?

Marty
--
Big-8 newsgroups: humanities.*, misc.*, news.*, rec.*, sci.*, soc.*, talk.*
See http://www.big-8.org for info on how to add or remove newsgroups.

On Sep 5, 1:21*pm, "Martin X. Moleski, SJ"
wrote:
On Fri, 5 Sep 2008 12:42:38 -0400, Gezellig wrote in :

So is the vertical winglet
1) To increase wing length while
2) Looking cute

... and to make it easier to clear obstacles when taxiing
in crowded airports?

* * * * * * * * * * * * * * * * * * * * Marty * * * * * * * * * * * * *
--
Big-8 newsgroups: humanities.*, misc.*, news.*, rec.*, sci.*, soc.*, talk..*
Seehttp://www.big-8.orgfor info on how to add or remove newsgroups.

Don't forget it makes it easier to parallel park too.

On Sep 5, 12:02*pm, Leviterande Leviterande.
wrote:
'a[_3_ Wrote:



;659074']On Sep 5, 1:10 am, Leviterande Leviterande.
wrote:-
Hi all!
Volf propeller hehttp://www.rexresearch.com/volfprop/volfprop.htm

I have been thinking alot about how this propeller would do, I wish I
had a workshop, CNC, and tools to build one.. this amazing prop is
claimed to be *super quiet and efficient.. so any more info from the
article on it or any *word of experience in propellers are very
appreciated

what about this propeller
( hit CTRl-F *and type "An Air Screw That Ridicules Propeller"
)http://www.rexresearch.com/aero/1aero.htm

regards
kalle

--
Leviterande-

That's a very old patent! If you think about a propeller for low speed
flight, think about it as a rotating wing. You'll notice high
perfornance gliders have long slender wings, and the best props look a
lot like that, with an additional twist. Ducting helps, as do Q tips
on propeller edges, but I did read somewhere you gain as much
efficiency by increasing the propeller diameter as the q tip length.
Makes me wonder if the vortex decreasing terminations on wings might
be as well used just by increasing the wingspan by that amount.

so *your guess is that none of the props are more efficient then todays
propellers? the todays propellers didnt differ *from the ones used 100
years ago btw...

Kalle

--
Leviterande

Oh? Constant speed props are that old? On a more serious note, today's
props are part of an aerodynamic systems and better engineered. Would
you care to cite a reference supporting your claim tha efficiencies
have not improved? Other than one you write yourself, of course.

a wrote:
On Sep 5, 12:02*pm, Leviterande Leviterande.
wrote:
the todays propellers didnt differ *from the ones used 100
years ago btw...

[...]
Would you care to cite a reference supporting your claim tha efficiencies
have not improved?

Barging in...

I don't know about 100 years ago, but many airship propeller efficiencies
were measured at over 65% efficient in 1920s. The reference I have is Table
13 from "Airship Design" by Charles P. Burgess (1927) [Still in print,
btw.] While there are some low "outliers" under 50% efficient, the bulk of
the 26 table entries show propeller efficiences between 55% and 65%. These
were prop efficiences at maximum speed and horsepower.

The airships LZ-120, LZ-121, Bodensee, and Nordstern appear to have had the
highest efficient props at 66%.

For more recent props, according to these sources:

http://en.wikipedia.org/wiki/Propeller
http://www.epi-eng.com/propeller_tec..._propeller.htm

current props peak around 87% efficient under optimum conditions.

If the average efficiency in the 1920s was ~60% and now is ~85% then that
is a an improvement of ~45%. On the other hand, no one will ever be able to
double on the efficiencies they were already getting over 80 years ago. ;-)