Silent Super Efficient Propeller!

On Sep 5, 5:44*pm, Jim Logajan wrote:
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/Propell..._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. ;-)

Yeah, it'll take some magic to convert rotary power into throwing air
backwards hard enough to improve efficiency very much, at least for ga
airplanes. A big fluted duct to take advantage of ram air induction
might help, but any back of the envelope sketches doesn't show much
room for other things, like pilots, and hauling around ducts adds
weight too. I'm not expecting to see many breakthroughs, but if they
are coming we'll probably see it in a home built at Oshkosh one of
these years.

Now woludnt a shorter prop with a bigger chord(and q-tips) move more air and thus creating equal thrust as a longer propeller with thinner chord?

when I tried the patented fan it was pretty quiet however.

Originally Posted by a[_3_]

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, 10:42 am, Gezellig wrote:

So is the vertical winglet

1) To increase wing length while
2) Looking cute

?

3) Is sometimes used as a marketing tool, I think, like fins on
cars in the late '50s and '60s.

Winglets improve efficiency by controlling wingtip vortices. A
vortex represents lost energy or drag, whichever way you want to see
it, and if the airflow that forms the vortex can be directed in some
way that minimizes the loss, then winglets are worth it. Some winglets
are claimed to convert some of the reclaimed energy into thrust. Burt
Rutan could speak to that one.
Laying it down would have the effect of making the wingtip very
small, of short chord, and such tips make smaller vortices. Famously
fast and efficient airplanes have often used sharply tapered wings;
think Spitfire or DeHavilland DH88 Comet. Or Google those images.

On Sep 5, 6:46*pm, Leviterande Leviterande.
wrote:
Now woludnt a shorter prop with a bigger chord(and q-tips) move more air
and thus creating equal thrust as a longer propeller with thinner chord?

when I tried the patented fan it was pretty quiet *however.

How did you try the patented fan?

AS for longer chords? Probably not. Think of the most efficient wings
for airplanes -- the ones that provide the best lift/drag. They are
long and slender. The same principles hold for props. You can be sure
if wide chords were better they'd be showing up on experimental
aircraft, and they are not.

On Fri, 5 Sep 2008 15:50:09 -0700 (PDT),
wrote:

On Sep 5, 10:42 am, Gezellig wrote:

So is the vertical winglet

1) To increase wing length while
2) Looking cute

?

3) Is sometimes used as a marketing tool, I think, like fins on
cars in the late '50s and '60s.

Winglets improve efficiency by controlling wingtip vortices. A
vortex represents lost energy or drag, whichever way you want to see
it, and if the airflow that forms the vortex can be directed in some
way that minimizes the loss, then winglets are worth it. Some winglets
are claimed to convert some of the reclaimed energy into thrust. Burt
Rutan could speak to that one.
Laying it down would have the effect of making the wingtip very
small, of short chord, and such tips make smaller vortices. Famously
fast and efficient airplanes have often used sharply tapered wings;
think Spitfire or DeHavilland DH88 Comet. Or Google those images.

Thx Dan

On Fri, 5 Sep 2008 23:46:12 +0100, Leviterande
wrote:


Now woludnt a shorter prop with a bigger chord(and q-tips) move more air
and thus creating equal thrust as a longer propeller with thinner chord?


when I tried the patented fan it was pretty quiet however.

************************************************* *******************
How about thrust????

Big John

************************************************** ******************

'a[_3_ Wrote:
;659137']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.

does anybody have a good pic of a Q-tip propeller?

it seems hard to find any.. hartzell props are known but didnt find any pic..






the propelller efficiences have improved without doubt but what i am sayin is that particulary fan might be differnt.. we just have to try it out

here you go , old propellers were more efficent then peoble think , more then 65%
http://www.memagazine.org/flight03/propwr/propwr.html
propellers didnt advance much in 100 years

read in the links in the first post about the dihedral propeller for example

a wrote in news:e5fb9dcd-6bd8-42e3-9a50-f6370d188424
@x35g2000hsb.googlegroups.com:

On Sep 5, 6:46*pm, Leviterande Leviterande.
wrote:
Now woludnt a shorter prop with a bigger chord(and q-tips) move more air
and thus creating equal thrust as a longer propeller with thinner chord?

when I tried the patented fan it was pretty quiet *however.

How did you try the patented fan?

AS for longer chords? Probably not. Think of the most efficient wings
for airplanes -- the ones that provide the best lift/drag. They are
long and slender. The same principles hold for props. You can be sure
if wide chords were better they'd be showing up on experimental
aircraft, and they are not.



They do actually, and they can be very efficient indeed.


http://www.youtube.com/watch?v=Nxz1UF67EQI

There's also been the Dyke Delta, and the facetmobile, of course.



Bertie

On Sep 6, 3:51*am, Bertie the Bunyip wrote:
a wrote in news:e5fb9dcd-6bd8-42e3-9a50-f6370d188424
@x35g2000hsb.googlegroups.com:

On Sep 5, 6:46*pm, Leviterande Leviterande.
wrote:
Now woludnt a shorter prop with a bigger chord(and q-tips) move more air
and thus creating equal thrust as a longer propeller with thinner chord?

when I tried the patented fan it was pretty quiet *however.

How did you try the patented fan?

AS for longer chords? Probably not. Think of the *most efficient wings
for airplanes -- the ones that provide the best lift/drag. They are
long and slender. The same principles hold for props. You can be sure
if wide chords were better they'd be showing up on experimental
aircraft, and they are not.

They do actually, and they can be very efficient indeed.

http://www.youtube.com/watch?v=Nxz1UF67EQI

There's also been the Dyke Delta, and the facetmobile, of course.

Bertie

I don't think you'd find these as 'efficient' as conventionally shaped
aircraft, else we'd be seeing competition gliders shaped this way.
Those airplane shapes would have very light wing loading of course,
but huge wetted areas -- think drag.

.. As for using that concept for prop blade shape, , where efficiency
is defined in the conventional engineering sense as power out divided
by power in, long and thin blades seem to win over short and fat.