Propeller Efficiency

On Tue, 15 Apr 2008 16:56:39 -0700 (PDT),
wrote:


Mx in disguise, for sure. The more you post, the more we realize
you don'y fly.

Dan


Not a flyer of aircraft, but I don't think it's MX.

The posting IP shows as used by Road Runner in Tampa, FL and Austin,
TX.

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Just another wannabe or frustrated simmer taking advantage of the fact
that most actual pilots (or students) who come here take flying pretty
seriously. Since you can only whack it to web porn for so long before
things get sore, it gives them something to do until the abrasions on
the private parts heal.

On Apr 15, 4:02 am, WingFlaps wrote:
On Apr 15, 3:11 pm, wrote:
The
Wright Brother's propeller on their Flyer had an efficiency of 83%
because they understood that it was a rotating airfoil rather than
some sort of paddlewheel.

83%? BS. Even if it had reached optimal speed it would have struggled
to get 70% (note the CFD calcs do not include surface roughness
losses):

http://www.fluent.com/about/news/new...i2_fall/a2.htm

It was lucky that Orville knew from tests a bit about about props (he
estimated 66% efficiency) or it might not have flown at all. That of
course was not such great insight on his part as the theory of
propellor design was well known from naval architecture.

Better see this: http://www.memagazine.org/flight03/propwr/propwr.html

Wright estimated an efficiency of 66%. Later, more
sophisticated tests on the Flyer's prop design gave an efficiency of
82%.

A quote from the article:

"These data show that the 1903 Wright propeller had a maximum
efficiency of 82 percent.
"Based on Wilbur Wright's notes on the fourth flight of Dec. 17,
1903, the Flyer had an estimated forward speed of 31 mph during the
steady flight portion of its path and the propellers were turning at
379 rpm, which yields an advance ratio of 0.85. Hence, the 1903 Wright
propellers were operating at a mechanical efficiency of slightly over
75 percent during steady flight.
"This was a remarkable feat, considering the state of propeller
knowledge prior to World War I.
"Since Wilbur estimated their propeller performance to be 66
percent in March of 1903, we found the results of our experimental
tests to be quite surprising. Using Wright bent-end propeller
reproductions as our reference test case (there are several well-
preserved sets in existence), we have subjected these propellers to
multiple wind tunnel tests. We recalibrated the instrumentation used
in the propeller tests and we subjected the bent-end geometry
propellers to a full Navier-Stokes equation computational fluid
dynamics analysis in order to affirm our test results. The bent-end
propellers had peak efficiencies of nearly 87 percent. The overall
comparisons between the numerical predictions and the test results
agreed. To our surprise, we learned that the Wrights' bent-end
propeller twist distribution (a variation of pitch angle with radius)
was in nearly exact agreement with modern computer-based designs over
the outer two-thirds of the propeller blade."

How's that?

Dan

In article Le Chaud Lapin writes:

I would design first for mechanism, leaving policy 100% in the
software domain. For example, I imagine that there are many "hard-
coded" feedback systems in basic GA aircraft,

You "imagine" -- you don't KNOW?

You might want to learn a bit more about aircraft before you proceed.

Alan

Le Chaud Lapin wrote:

That's the part I am working on. Note that I don't necessary mean a
new type of egine. I mean the ICE/prop combination. If we could get
rid of this somehow, it would solve several problems at once.

And create several new ones.



Why? Most light aircraft do not fly high enough to require
pressurization -- just an added expense/weight/complexity.

The computer system. It would allow the owner to be able to use
inexpensive COTS components (generic, $100, 1TB hard disks).



What the hell does that have to do with altitude and the need for
pressurization?


9. Computer assisted take-off, computer assisted approach, computer-
assisted stabilization, computer-assisted tracking.
Again -- why? Anybody competent rnough to fly has to be competent enough
to navigate. Added expense/complexity.



Why? On trek to Bahamas from Florida, certainly it would be more
pleasant to have a bit of entertainment. I would also use USB ports
for headsets, like the high-quality $30 USB model from Logitech I
bought not long ago.


There are plenty of entertainment systems for aircraft already. The
Garmin 396 & 496 GPS have XM radio built in.

That nice $30 Logitech headset you bought is indeed nice. I have one too
but it has no noise attenuation properties which is the main reasons you
have a headset in a small plane. Back when I got my initial flight
training wearing headsets was the exception not the rule. You talked on
the radio through a hand mic and listened on a crappy speaker. It is one
of the reasons my hearing sucks today.

24. Electronic megaphone for voice communication to those in immediate
vicinity of aircraft.
KISS!

Not too hard to do.


But of very little to no use.


27. Significant reduction in sound pollution.
KISS!

Sound reduction would be natural side-effect of propulsion system I
have in mind.


You going to get rid of the prop? That is where most of the noise comes
from.

28. Rear-mounted fuel-tank.

Ahem..I should not have mentioned this. It turns out that, for my
propulsion system, this is optimal location of fuel tank, and it is
not because of balance.


You had better start thinking of balance. Not that it really matters.
Moller's aircraft will be in every garage before you get your idea on
paper.


-Le Chaud Lapin-

On Apr 16, 8:35*am, Gig 601Xl Builder
wrote:
Le Chaud Lapin wrote:
That's the part I am working on. Note that I don't necessary mean a
new type of egine. I mean the ICE/prop combination. *If we could get
rid of this somehow, it would solve several problems at once.

And create several new ones.

The new ones would likely be less painful than the old ones.

Why? Most light aircraft do not fly high enough to require
pressurization -- just an added expense/weight/complexity.

The computer system. It would allow the owner to be able to use
inexpensive COTS components (generic, $100, 1TB hard disks).

What the hell does that have to do with altitude and the need for
pressurization?

Pressurizing aircraft would allow use of COTS components that have
maximum altitude specifications.

Why? On trek to Bahamas from Florida, certainly it would be more
pleasant to have a bit of entertainment. I would also use USB ports
for headsets, like the high-quality $30 USB model from Logitech I
bought not long ago.

There are plenty of entertainment systems for aircraft already. The
Garmin 396 & 496 GPS have XM radio built in.

Probably expensive. That is a theme here. Pratically everything I
named, with exception of new type of propulsion system and
computerized actuation, could be had today. But the prices are
outrageous. For example, I know that it is possible to build cock-pit
to cock-pit communication system using WiMaxed PDA's. If I were to do
it for myself, it would cost $1000 for all equipment including
software. But if an aircraft company does it, that price would
increase dramatically.

That nice $30 Logitech headset you bought is indeed nice. I have one too
but it has no noise attenuation properties which is the main reasons you
have a headset in a small plane. Back when I got my initial flight
training wearing headsets was the exception not the rule. You talked on
the radio through a hand mic and listened on a crappy speaker. It is one
of the reasons my hearing sucks today.

24. Electronic megaphone for voice communication to those in immediate
vicinity of aircraft.
KISS!

Not too hard to do.

But of very little to no use.

27. Significant reduction in sound pollution.
KISS!

Sound reduction would be natural side-effect of propulsion system I
have in mind.

You going to get rid of the prop? That is where most of the noise comes
from.

I have thought about it, yes, which is what lead me to the original
topic.

28. Rear-mounted fuel-tank.

Ahem..I should not have mentioned this. It turns out that, for my
propulsion system, this is optimal location of fuel tank, and it is
not because of balance.

You had better start thinking of balance. Not that it really matters.
Moller's aircraft will be in every garage before you get your idea on
paper.

I have and will. The conventional aircraft design requires thinking a
lot about balance. The very structure of the aircraft is a direct
result of distribution of weighty components. But if there were a
different distribution, then that would change how one approaches the
problem of balance. The problem might be significantly abated with a
more even distribution.

Do you actually believe this? Apparently there are posters who believe
it won't.

-Le Chaud Lapin-

On Apr 16, 12:58*am, (Alan) wrote:
In article Le Chaud Lapin writes:

I would design first for mechanism, leaving policy 100% in the
software domain. For example, I imagine that there are many "hard-
coded" feedback systems in basic GA aircraft,

* You "imagine" -- you don't KNOW?

* You might want to learn a bit more about aircraft before you proceed.

Of course.

But deliberately remaining in a state of ignorance about particular
aspects of the status quo is often the clearest path to finding a new
solutions to old problems.

I would distinguish between aspects of the old that are relevant, and
those are not.

Trying to figure out how to counteract the weight of a massive ICE and
prop at the front of plane, for example, would not be relevant in the
model that I have in mind, although the notion that balance is
necessary, would be relevant. Similary, trying to determine the proper
grade of lubricant to lubricate a series of mechanical interlocks
would irrelevant, although the notion that actuators will have to be
controlled from a central location would be relevant.

One can argue that, since an aircraft is mostly mechanical anyway,
there is some educational benefit from studying what has already been
done, for example, the cabling system to control airfoils. To that I
would agree, but because the system is already so big to start with,
there will not be a lack of opportunity to learn from analyzing those
aspects of the old which are relevant.

-Le Chaud Lapin-

On Apr 16, 11:17 am, Le Chaud Lapin wrote:
On Apr 16, 12:58 am, (Alan) wrote:

In article Le Chaud Lapin writes:

I would design first for mechanism, leaving policy 100% in the
software domain. For example, I imagine that there are many "hard-
coded" feedback systems in basic GA aircraft,

You "imagine" -- you don't KNOW?

You might want to learn a bit more about aircraft before you proceed.

Of course.

But deliberately remaining in a state of ignorance about particular
aspects of the status quo is often the clearest path to finding a new
solutions to old problems.

Ah. So the old saying about knowing history lest you make
the same mistakes doesn't apply here, huh?

I would distinguish between aspects of the old that are relevant, and
those are not.

With no frame of reference, none of the old will make sense to
you. You need to learn to fly first. And then take some mechanical
training. Then you'll have a vague idea that you know next to nothing.
There are many intelligent and educated people trying to design new
airplanes, and finding that it's not nearly as easy as they thought.

He's doing nothing but trolling, guys. He enjoys pulling our
tails just to get a reaction. Can't take him seriously at all.

Dan

On Apr 16, 10:17 am, Le Chaud Lapin wrote:
On Apr 16, 12:58 am, (Alan) wrote:

In article Le Chaud Lapin writes:

I would design first for mechanism, leaving policy 100% in the
software domain. For example, I imagine that there are many "hard-
coded" feedback systems in basic GA aircraft,

You "imagine" -- you don't KNOW?

You might want to learn a bit more about aircraft before you proceed.

Of course.

But deliberately remaining in a state of ignorance about particular
aspects of the status quo is often the clearest path to finding a new
solutions to old problems.

Remote Controlled flying would be a cheap
and easy way to start to put a new design
in the air. Join the EAA.
You should sharpen your mission objective.
Good Luck
Ken

On Apr 16, 12:26*pm, wrote:
On Apr 16, 11:17 am, Le Chaud Lapin wrote:
But deliberately remaining in a state of ignorance about particular
aspects of the status quo is often the clearest path to finding a new
solutions to old problems.

* * * * * *Ah. So the old saying about knowing history lest you make
the same mistakes doesn't apply here, huh?

It applies, but if someone asked you to build a fort, in 2008, you
most like would not start with brick and mortar. You probably would
not use wood. You probably would not insist on having a moat around
it. This is an extreme analogy, but you get the point.

A designer should use principles and materials that are appropriate
for the times. I would imagine this same conversation occurred during
the 20th century between two electrical engineers, one who cut his
teeth on vacuum tubes, the other who is abot to forsake vaccum tubes
in favor of transistors. The Old Guard would say, "You really ought
to rethink your decision to not study vacuum tubes. You could learn
quite a bit."

Well, I am an electrical engineer, and though I know the basics of
vacuum tubes, I never studied them, and no reputable engineering
school consider them to be a requisite part of its curriculum.

The Dean of Engineering at my university expended extraordinary effort
to create "cross-displine projects" among the engineering and science
discplines. He was fanatical about it. It was as if he was promoting
interdepartmental marrying. I failed to see his motivation, why there
was a sense of urgency and conviction. Later in life, I realized that
there are entire industrial groups who isolate themselves from other
industrial groups from whom they might greatly benefit. It *seems*
like this is not happening, because in design meetings, there will be
representatives of various discplines present. But sometime happens
in those meetings, and the result is what you get is not as good as
what could be, certainly not as cheap, at least in case of software.
The Dean saw this and probably trying to induce his departments to
break this pattern, first in the context of academia, then later, in
industry.

Each time I get into a Tomahawk or C172, or DA-20, I am excited, but I
can't help thinking, "This stuff looks 40 years old." Then I realize,
in the case of the Tomahawk, it really is 40 years old. It should come
as no surprise that a software engineer or electrical engineer might
see signifcant room for improvement. In fact, this might be one
reason why Garmin does so well. They fill a gap that the aircraft
manufacturers have refused to fill, cheaply. The auto industry is not
much better. There are commercials on TV today about Microsoft
Sync. http://www.syncmyride.com This might be a big deal to auto
industry, but to a software engineer experienced in these types of
technologies, it is shockingly unimpressive relative to the cost.

I think the problem is one of turf - the aircraft manufacturers do
have their own electrical engineers and software engineers. But when
they do something that involves avant garde technology, the cost is
10x more than what it would be if a "normal" engineer did it. I think
what the Dean of Engineering was trying to say was, "Let each group of
people do what s/he is competent at, and get out of the way while they
are doing it." I don't see this happening in GA. Instead I see
companies like Garmin making a fortune in the void.

I would distinguish between aspects of the old that are relevant, and
those are not.

* * * With no frame of reference, none of the old will make sense to
you. You need to learn to fly first. And then take some *mechanical
training. Then you'll have a vague idea that you know next to nothing.
There are many intelligent and educated people trying to design new
airplanes, and finding that it's not nearly as easy as they thought.

Well, I do understand physics. I have flown. And I have built several
moderately complex machines, one more than 20 years ago.

As far as many intelligent and educated people trying to design new
airplanes, some of these people have been trying for quite a while.
Look at the results. In many cases, it actually looks like a car with
a propeller on it, and it is obvious from sight that it contains
severe design flaws.

Are you talking about these?

If you are talking about other ideas of flying cars, I would like to
see them. I have already seen enough contraptions that look like cars
with wings attached.

* * * He's doing nothing but trolling, guys. He enjoys pulling our
tails just to get a reaction. Can't take him seriously at all.

-Le Chaud Lapin-

Le Chaud Lapin wrote:
On Apr 16, 8:35 am, Gig 601Xl Builder
wrote:
Le Chaud Lapin wrote:
That's the part I am working on. Note that I don't necessary mean a
new type of egine. I mean the ICE/prop combination. If we could get
rid of this somehow, it would solve several problems at once.
And create several new ones.

The new ones would likely be less painful than the old ones.



You are basing that assumption on nothing other than your uninformed gut
feeling.

Why? Most light aircraft do not fly high enough to require
pressurization -- just an added expense/weight/complexity.
The computer system. It would allow the owner to be able to use
inexpensive COTS components (generic, $100, 1TB hard disks).
What the hell does that have to do with altitude and the need for
pressurization?

Pressurizing aircraft would allow use of COTS components that have
maximum altitude specifications.

So to use cheap off the shelf components you are going to add a system
that is not cheap and not off the shelf. Great idea.





Why? On trek to Bahamas from Florida, certainly it would be more
pleasant to have a bit of entertainment. I would also use USB ports
for headsets, like the high-quality $30 USB model from Logitech I
bought not long ago.
There are plenty of entertainment systems for aircraft already. The
Garmin 396 & 496 GPS have XM radio built in.

Probably expensive. That is a theme here. Pratically everything I
named, with exception of new type of propulsion system and
computerized actuation, could be had today. But the prices are
outrageous. For example, I know that it is possible to build cock-pit
to cock-pit communication system using WiMaxed PDA's. If I were to do
it for myself, it would cost $1000 for all equipment including
software. But if an aircraft company does it, that price would
increase dramatically.


Do you mean intercom. There are plenty of perfectly good intercom
systems on the market for $1000 already.


That nice $30 Logitech headset you bought is indeed nice. I have one too
but it has no noise attenuation properties which is the main reasons you
have a headset in a small plane. Back when I got my initial flight
training wearing headsets was the exception not the rule. You talked on
the radio through a hand mic and listened on a crappy speaker. It is one
of the reasons my hearing sucks today.



Skipped that one didn't you.


24. Electronic megaphone for voice communication to those in immediate
vicinity of aircraft.
KISS!
Not too hard to do.
But of very little to no use.

27. Significant reduction in sound pollution.
KISS!
Sound reduction would be natural side-effect of propulsion system I
have in mind.
You going to get rid of the prop? That is where most of the noise comes
from.

I have thought about it, yes, which is what lead me to the original
topic.

28. Rear-mounted fuel-tank.
Ahem..I should not have mentioned this. It turns out that, for my
propulsion system, this is optimal location of fuel tank, and it is
not because of balance.
You had better start thinking of balance. Not that it really matters.
Moller's aircraft will be in every garage before you get your idea on
paper.

I have and will. The conventional aircraft design requires thinking a
lot about balance. The very structure of the aircraft is a direct
result of distribution of weighty components. But if there were a
different distribution, then that would change how one approaches the
problem of balance. The problem might be significantly abated with a
more even distribution.

Do you actually believe this? Apparently there are posters who believe
it won't.

-Le Chaud Lapin-