my ignorance

[LCT Paintball]

I've been reading every post here for a few weeks. I am absolutely amazed by
the amount of knowledge that lives here!
With the butt kissing done, I hope you'll excuse my ignorance. ;)

I was interested in the discussion concerning the weight of different prop
materials. Has anybody tried to make a hollow aluminum prop? What about
titanium? Carbon fiber?

What kind of testing needs to be done on a home built prop?
Are there prop styles that can be copied without patent infringements?

Has anybody tried making a flexible prop? My thinking is that it might be
possible to create a prop with a low angle of attack for high power take
offs, then have it flex to a higher angle of attack as the load decreases.
Could something like that give the performance of a constant speed prop
without the complexity and added weight?

If I were to play around with different prop designs, is there somebody
around here with the knowledge and time that might be willing to test them
for me?
--
"Don't be misled, bad company corrupts good character."
www.LCTPaintball.com
www.LCTProducts.com

[Morgans]

"LCT Paintball" > wrote in message

> With the butt kissing done, I hope you'll excuse my ignorance. ;)

That is some first class "butt kissing." <g>

I don't have many answers, but I'll answer what I think I know, since no one
else has answered.

> I was interested in the discussion concerning the weight of different prop
> materials. Has anybody tried to make a hollow aluminum prop?

They are a standard in larger props.

>What about titanium?

Don't know. I think the answer here, is that it is too brittle to stand up
to the vibration, torque, and twisting.

> Carbon fiber?

Yes. Some have been made with carbon fiber or fiberglass over wood or foam
cores.

> What kind of testing needs to be done on a home built prop?

Much has been written, and there are even programs to predict performance.

> Are there prop styles that can be copied without patent infringements?

As long as you don't copy too closely. There are some special features of
some props that are copyrighted.

> Has anybody tried making a flexible prop?

Yes. Warp drive makes a flexible prop with a steel rod in the middle that
twists the tips with an electric motor, to change profiles for climb to
cruise. That is one feature that had better not be copied.

> My thinking is that it might be possible to create a prop with a low angle
of attack >for high power take offs, then have it flex to a higher angle of
attack as the load
>decreases.

This has been done with a extremely swept back shape, called "scimitar",
that as it unloads at high speed, the tips twist back to higher angles of
attack. I am unaware if this is currently being produced. The trick is to
select materials and thickness, to get the twist just right, to work as
desired.

> Could something like that give the performance of a constant speed prop
> without the complexity and added weight?

There will always be tradeoffs of complexity and weight for this.

> If I were to play around with different prop designs, is there somebody
> around here with the knowledge and time that might be willing to test them
> for me?

Hmm. My suggestion is learn, and do it yourself. <g>

I am sure there are more, here, that will correct some of what I have said,
and add more, given time.
--
Jim in NC

[Frank]

"LCT Paintball" > wrote in
news:wtn4e.12908$Vx1.12789@attbi_s01:

> I've been reading every post here for a few weeks. I am absolutely
> amazed by the amount of knowledge that lives here!
> With the butt kissing done, I hope you'll excuse my ignorance. ;)
>
> I was interested in the discussion concerning the weight of different
> prop materials. Has anybody tried to make a hollow aluminum prop? What
> about titanium? Carbon fiber?
>
Yes, to carbon fiber at least.

> What kind of testing needs to be done on a home built prop?
> Are there prop styles that can be copied without patent infringements?
>
Whatever you feel safe with, and a minimum of 40hrs (I think) on an
experimental, if it is a new combination or major change.

> Has anybody tried making a flexible prop? My thinking is that it might
> be possible to create a prop with a low angle of attack for high power
> take offs, then have it flex to a higher angle of attack as the load
> decreases. Could something like that give the performance of a
> constant speed prop without the complexity and added weight?

> Warnke almost constant speed among some.

> If I were to play around with different prop designs, is there
> somebody around here with the knowledge and time that might be willing
> to test them for me?

Can you also provide the proper vehichle for the test period?


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[Jim Carriere]

Morgans wrote:
> "LCT Paintball" > wrote in message
> >What about titanium?
>
> Don't know. I think the answer here, is that it is too brittle to stand up
> to the vibration, torque, and twisting.

Not that I know (because I don't know), but it doesn't make sense
that titanium would be an unsuitable material. Gas turbines using
titanium alloy compressors have been around for, well, decades. Sort
of an apples and oranges comparison, but still... On the other hand
google doesn't seem to turn up anything, and it _always_ seems to
turn up something (!?).

[wright1902glider]

Morgans wrote:
> "LCT Paintball" > wrote in message
>
> > With the butt kissing done, I hope you'll excuse my ignorance. ;)
>
> That is some first class "butt kissing." <g>
>
> I don't have many answers, but I'll answer what I think I know, since
no one
> else has answered.
>
> > I was interested in the discussion concerning the weight of
different prop
> > materials. Has anybody tried to make a hollow aluminum prop?
>
> They are a standard in larger props.
>
> >What about titanium?
>
> Don't know. I think the answer here, is that it is too brittle to
stand up
> to the vibration, torque, and twisting.
>
> > Carbon fiber?
>
> Yes. Some have been made with carbon fiber or fiberglass over wood
or foam
> cores.
>
> > What kind of testing needs to be done on a home built prop?
>
> Much has been written, and there are even programs to predict
performance.
>
> > Are there prop styles that can be copied without patent
infringements?
>
> As long as you don't copy too closely. There are some special
features of
> some props that are copyrighted.
>
> > Has anybody tried making a flexible prop?
>
> Yes. Warp drive makes a flexible prop with a steel rod in the middle
that
> twists the tips with an electric motor, to change profiles for climb
to
> cruise. That is one feature that had better not be copied.
>
> > My thinking is that it might be possible to create a prop with a
low angle
> of attack >for high power take offs, then have it flex to a higher
angle of
> attack as the load
> >decreases.
>
> This has been done with a extremely swept back shape, called
"scimitar",
> that as it unloads at high speed, the tips twist back to higher
angles of
> attack. I am unaware if this is currently being produced. The trick
is to
> select materials and thickness, to get the twist just right, to work
as
> desired.
>
> > Could something like that give the performance of a constant speed
prop
> > without the complexity and added weight?
>
> There will always be tradeoffs of complexity and weight for this.
>
> > If I were to play around with different prop designs, is there
somebody
> > around here with the knowledge and time that might be willing to
test them
> > for me?
>
> Hmm. My suggestion is learn, and do it yourself. <g>
>
> I am sure there are more, here, that will correct some of what I have
said,
> and add more, given time.
> --
> Jim in NC

[Jean-Paul Roy]

"Yes. Warp drive makes a flexible prop with a steel rod in the middle that
twists the tips with an electric motor, to change profiles for climb to
cruise. That is one feature that had better not be copied."

Sorry Morgan, but it is Ivo that makes them prop. Warpdrive are rather
rigid.

J.P.
"Morgans" > wrote in message
...
>
> "LCT Paintball" > wrote in message
>
> > With the butt kissing done, I hope you'll excuse my ignorance. ;)
>
> That is some first class "butt kissing." <g>
>
> I don't have many answers, but I'll answer what I think I know, since no
one
> else has answered.
>
> > I was interested in the discussion concerning the weight of different
prop
> > materials. Has anybody tried to make a hollow aluminum prop?
>
> They are a standard in larger props.
>
> >What about titanium?
>
> Don't know. I think the answer here, is that it is too brittle to stand
up
> to the vibration, torque, and twisting.
>
> > Carbon fiber?
>
> Yes. Some have been made with carbon fiber or fiberglass over wood or
foam
> cores.
>
> > What kind of testing needs to be done on a home built prop?
>
> Much has been written, and there are even programs to predict performance.
>
> > Are there prop styles that can be copied without patent infringements?
>
> As long as you don't copy too closely. There are some special features of
> some props that are copyrighted.
>
> > Has anybody tried making a flexible prop?
>
> Yes. Warp drive makes a flexible prop with a steel rod in the middle that
> twists the tips with an electric motor, to change profiles for climb to
> cruise. That is one feature that had better not be copied.
>
> > My thinking is that it might be possible to create a prop with a low
angle
> of attack >for high power take offs, then have it flex to a higher angle
of
> attack as the load
> >decreases.
>
> This has been done with a extremely swept back shape, called "scimitar",
> that as it unloads at high speed, the tips twist back to higher angles of
> attack. I am unaware if this is currently being produced. The trick is
to
> select materials and thickness, to get the twist just right, to work as
> desired.
>
> > Could something like that give the performance of a constant speed prop
> > without the complexity and added weight?
>
> There will always be tradeoffs of complexity and weight for this.
>
> > If I were to play around with different prop designs, is there somebody
> > around here with the knowledge and time that might be willing to test
them
> > for me?
>
> Hmm. My suggestion is learn, and do it yourself. <g>
>
> I am sure there are more, here, that will correct some of what I have
said,
> and add more, given time.
> --
> Jim in NC
>

[Morgans]

"Jim Carriere" > wrote

> Not that I know (because I don't know), but it doesn't make sense
> that titanium would be an unsuitable material. Gas turbines using
> titanium alloy compressors have been around for, well, decades. Sort
> of an apples and oranges comparison, but still...

Two big differences, as I see it. One, props on piston engines receive
massive power pulses, which are almost like stop and go, every 1/3rd to 1/2
rotation. A gas turbine blade has no pulses going to it; constant power and
constant rotation. Two, the turbine blade is very short and wide, compared
to the long slender prop.
--
Jim in NC

[Morgans]

"Jean-Paul Roy" > wrote

> Sorry Morgan, but it is Ivo that makes them prop. Warpdrive are rather
> rigid.

Ivo that makes them prop, Huh? <g>

See, I told you I wuld git somethang wong. ;-)
--
Jim in NC

[abripl]

> Warp drive makes a flexible prop with a steel rod in the middle that
> twists the tips with an electric motor, to change profiles for climb
> to cruise. That is one feature that had better not be copied.

That has been done by Ivo Prop for a long time - www.ivoprop.com

[Corky Scott]

On Tue, 05 Apr 2005 03:19:57 GMT, "LCT Paintball"
> wrote:

>I was interested in the discussion concerning the weight of different prop
>materials. Has anybody tried to make a hollow aluminum prop? What about
>titanium? Carbon fiber?

I am not a prop expert and don't play one on TV either, but like you
I've been hanging around here for a while (quite a long while
actually) and have learned a thing or two. I also spoke with a
Hamilton Standard engineer about a prop they built for the Lexus V-8
engine conversion. Hollow aluminum props are not uncommon. Don't
know about titanium. Carbon fiber props are made all the time by a
number of manufacturers, many are certified. Googling "carbon fiber
propeller" brings many hits including Warp Drive, Ivo and Sensenich,
to name a few.
>
>What kind of testing needs to be done on a home built prop?
>Are there prop styles that can be copied without patent infringements?

Be aware, props live in an EXTREMELY harsh environment. They are
subject to twisting loads, bending loads, centrifical forces and
engine power pulses. In addition they suffer abrasion from sand, dust
and gravel to rain and hail.

The one material I'm pretty sure you can use without much worry about
having one half of it disappear in flight is wood. Wood props dampen
vibration, metal and some composites can accelerate vibration if
encountered at the right frequency. The engineer I mentioned warned
me that in his opinion, many of the non certified prop makers were
making props that scared the absolute bejeesus out of him. Very few
did the kind of comprehensive vibration testing that they (the makers
of certified props) had to do, nor did they do long term systematic
test runs. He thought that people should be extremely careful about
what they use for a prop.
>
>Has anybody tried making a flexible prop? My thinking is that it might be
>possible to create a prop with a low angle of attack for high power take
>offs, then have it flex to a higher angle of attack as the load decreases.
>Could something like that give the performance of a constant speed prop
>without the complexity and added weight?

Yes, a company did attempt to create a fixed pitch prop that varied
it's pitch by being flexible fairly recently. They called it the
Quasi Constant Speed Prop. It was computer designed using very
special composite materials oriented in specific patterns and thread
direction. They were scimitar shaped. They also incorporated
different airfoils for different parts of the prop because the prop
itself sees different airspeeds at different locations from the hub to
the tip. Many props use a Clark Y airfoil, which seems counter
intuitive when you realise that out at the tip, most props are going
some 400 to 500 mph.

Unfortunately, during vibration testing they discovered that the prop
had some problems and the last time I checked they'd given up
attempting to make an actual fixed yet variable pitch prop.
>
>If I were to play around with different prop designs, is there somebody
>around here with the knowledge and time that might be willing to test them
>for me?
>--
There are several on-line programs that allow you to design a prop.
The problem is prop design is inherently complicated due to the many
factors that go into their design. You have to factor in airplane
weight, wingspan, how fast the airplane is supposed to go, altitude it
will fly, air density, drag of the airframe, engine speed, prop
diameter, pitch, material to be used, air foil design, planform. I
mean it's almost hopelessly endless.

The formulas used to determine various aspects of prop design look
like nighmarish versions of greek. And that's if you're a
mathematician. :-)

There are also proprietary software designs that allow you to design
your own prop. These aren't cheap but they will allow you to create
your own prop and design virtually all aspects of it including the
planform. All the formulas are built into the program. You have to
plug in the particulars of your airplane.

To me, prop making is such a black art that I gave up attempting to
design my own and bought an Ivo.

Corky Scott

[Darrel Toepfer]

Morgans wrote:

> This has been done with a extremely swept back shape, called "scimitar",
> that as it unloads at high speed, the tips twist back to higher angles of
> attack. I am unaware if this is currently being produced. The trick is to
> select materials and thickness, to get the twist just right, to work as
> desired.

Hartzell, very popular with the racing and nonracing Lancairs...

Nice photo of one here:
http://www.ramaircraft.com/Whats-New-Ticker/Hartzell-Scrimitar-Plus-Propeller/Hartzell-ScimitarPlus-Propeller.htm

Thrust comparison here:
http://www.beryldshannon.com/Hartzell/chart.htm

[LCT Paintball]

> Can you also provide the proper vehichle for the test period?

Nope, I can't even fly, unless of course I talk one of you guys into taking
me up. ;)

I find the prospect of building an airplane very interesting. I've studied
the skills required, and have decided that I can handle it. I've also
studied the time required and found I'm not even close! ;(

I thought it might be interesting to play around with building a prop. I own
a machine shop complete with design tools, CAM software, and CNC equipment.
I have a better than average grasp of high school math, but obviously can't
handle the kind of design work it would take to pull of a project like this.

I enjoy wrapping my brain around a problem, and coming up with a low tech
solution. I don't have the time, or budget to get involved with a large
project, but thought a prop might be within reach. After reading the group's
responses, I'm still confident I can build one, but I don't think I can
design it. ;(

[Dave S]

>
>
>>Has anybody tried making a flexible prop?
>
>
> Yes. Warp drive makes a flexible prop with a steel rod in the middle that
> twists the tips with an electric motor, to change profiles for climb to
> cruise. That is one feature that had better not be copied.
>

I want to say that the IVO prop has this mode of operation. I have not
looked at the Warp Drive closely enough to validate what you are saying.

The IVO has some drawbacks, however. I don't believe it's compatible
with 4 cylinder lycomings (torque pulses are damaging...) and i know of
a few who have tried to use the IVO in flight adjustable prop for high
speed flight, and found it less than satisfactory. Since the inboard
portion doesnt rotate as much, it must produce some "flat plate" drag..
anecdotal reports of a 10 mph penalty on a 200 mph aircraft are what I
recall.

For the slower planes, this may not be an issue..

Dave

[Doc Font]

In article <wtn4e.12908$Vx1.12789@attbi_s01>,
"LCT Paintball" > wrote:

>
> Are there prop styles that can be copied without patent infringements?
>
Try at the Prop Carving website; http://www.wood-carver.com/store.html

[[email protected]]

> >What about titanium?
>
I think that the lack of titanium bladed props is purely economic. It is a
very tough material, so I don't think strength or brittleness would be a
problem. Compared to wood, aluminum, and composite construction, it is very
expensive.

tom

[abripl]

> i know of
> a few who have tried to use the IVO in flight adjustable prop for
> high speed flight, and found it less than satisfactory. Since the
> inboard portion doesnt rotate as much, it must produce some "flat
> plate" drag.. anecdotal reports of a 10 mph penalty on a 200 mph
> aircraft are what I recall.

Thats at least partially true of all inflight adjustable props. For a
particular speed and power there is an ideal shape that can be achieved
by fixed pitch props. The adjustable (CS) props design their shape for
an average effect over the speed range. But the adjustable prop still
gives a decent high speed efficiency while giving that extra safety
factor at takeoff and landing - takeoff like a slingshot and you can
really slow down the plane on landing with low pitch setting. So you
have to take your choices - can't have everything.
----------------------------------------
SQ2000 canard http://www.abri.com/sq2000

[abripl]

A number of aftermarket manufacturers make coil springs for racing
cars. Titanium has good retention for a short period but eventually
loses shape under high stress - see description at
http://www.coilspring.com/performance/auto_racing/ particularly the
comment: "Titanium springs are not 'forever'..."

[Ernest Christley]

LCT Paintball wrote:
>>Can you also provide the proper vehichle for the test period?
>
>
> Nope, I can't even fly, unless of course I talk one of you guys into taking
> me up. ;)
>
> I find the prospect of building an airplane very interesting. I've studied
> the skills required, and have decided that I can handle it. I've also
> studied the time required and found I'm not even close! ;(
>
> I thought it might be interesting to play around with building a prop. I own
> a machine shop complete with design tools, CAM software, and CNC equipment.
> I have a better than average grasp of high school math, but obviously can't
> handle the kind of design work it would take to pull of a project like this.
>
> I enjoy wrapping my brain around a problem, and coming up with a low tech
> solution. I don't have the time, or budget to get involved with a large
> project, but thought a prop might be within reach. After reading the group's
> responses, I'm still confident I can build one, but I don't think I can
> design it. ;(
>
>
>

http://ernest.isa-geek.org/Delta/Library/HowIMakeProp.pdf

--
This is by far the hardest lesson about freedom. It goes against
instinct, and morality, to just sit back and watch people make
mistakes. We want to help them, which means control them and their
decisions, but in doing so we actually hurt them (and ourselves)."

[Jim Carriere]

abripl wrote:
>>i know of
>>a few who have tried to use the IVO in flight adjustable prop for
>>high speed flight, and found it less than satisfactory. Since the
>>inboard portion doesnt rotate as much, it must produce some "flat
>>plate" drag.. anecdotal reports of a 10 mph penalty on a 200 mph
>>aircraft are what I recall.
>
>
> Thats at least partially true of all inflight adjustable props. For a
> particular speed and power there is an ideal shape that can be achieved
> by fixed pitch props. The adjustable (CS) props design their shape for
> an average effect over the speed range. But the adjustable prop still
> gives a decent high speed efficiency while giving that extra safety
> factor at takeoff and landing - takeoff like a slingshot and you can
> really slow down the plane on landing with low pitch setting. So you
> have to take your choices - can't have everything.

Variable pitch isn't only useful over an aircraft with a wide speed
range, it is practically necessary for a turbocharged engine.

If the engine maintains power up at a high altitude, coarser prop
pitch is required to take a bigger bite out of the thinner air.

I should be more specific and state a turbo-normalized engine (or
supercharged-normalized, if such things exist in great numbers).
Point being a powerplant that produces it's rated sea level power at
high altitude.

[Jan Carlsson]

I know of two company that sell propeller design software, and there are
some other online, but them seems all to be incomplete, I am not saying this
to sell more, just fact, but some don't calculate the Diameter ! one of the
most important design criteria, other lack strength and safety
calculations...

I made my program for my own use, then I have changed it many times to be
more user friendly and complete, Rome wasn't built in one day, so I have but
in many hours making the program work as I wanted it and by requests from
customers, and not least making it work with both US system and metric
system, and on computers all around the globe.

My program is made for the home builder in mind, it is not that difficult to
make a wood prop, if you can make a airplane you can make a propeller,
calculate it can be time consuming, isn't that the reason we have computers?
all the time we save with the computer... or is it spend with the computer?
anyway, Now it is possible to calculate a prop in a minute, make it in a CAD
program in 10 minutes, make drawings and templates or even let a CNC router
make the prop. (but we have to glue the laminates together) Making it by
hand is still an option, and very satisfying when finished, not all have a
home made prop in the nose or rear, at the fly-ins!

Real Propeller design software cost some, but that is saved in on the first
propeller made. then you can make props for your friends too.

Jan Carlsson
www.jcpropellerdesign.com



"LCT Paintball" > skrev i meddelandet
news:wtn4e.12908$Vx1.12789@attbi_s01...
> I've been reading every post here for a few weeks. I am absolutely amazed
by
> the amount of knowledge that lives here!
> With the butt kissing done, I hope you'll excuse my ignorance. ;)
>
> I was interested in the discussion concerning the weight of different prop
> materials. Has anybody tried to make a hollow aluminum prop? What about
> titanium? Carbon fiber?
>
> What kind of testing needs to be done on a home built prop?
> Are there prop styles that can be copied without patent infringements?
>
> Has anybody tried making a flexible prop? My thinking is that it might be
> possible to create a prop with a low angle of attack for high power take
> offs, then have it flex to a higher angle of attack as the load decreases.
> Could something like that give the performance of a constant speed prop
> without the complexity and added weight?
>
> If I were to play around with different prop designs, is there somebody
> around here with the knowledge and time that might be willing to test them
> for me?
> --
> "Don't be misled, bad company corrupts good character."
> www.LCTPaintball.com
> www.LCTProducts.com
>
>
>

[LCT Paintball]

Your website said that your software supports Solid Works. Does it actually
create a solidworks geometry file?

--
"Don't be misled, bad company corrupts good character."
www.LCTPaintball.com
www.LCTProducts.com

[Jan Carlsson]

Hi,

My program create text .txt files that is used in SolidWorks and Rhino3D
It is 7 files, one for each blade station, that have X, Y and Z
co-ordinates, with the proper angle and placed correctly in relation to the
plan form that is chosen (6 of them)

In SolidWorks it is just to insert "curve through free points" one by one
txt file, then loft from station 1 to 7 and the blade is don. It is don
faster then it take to write this, it's just a matter of clicking with the
mouse. no writing of co-ordinates.

Jan Carlsson
www.jcpropellerdesign.com

"LCT Paintball" > skrev i meddelandet
news:k1j5e.12776$g65.6998@attbi_s52...
> Your website said that your software supports Solid Works. Does it
actually
> create a solidworks geometry file?
>
> --
> "Don't be misled, bad company corrupts good character."
> www.LCTPaintball.com
> www.LCTProducts.com
>
>
>

[LCT Paintball]

> My program create text .txt files that is used in SolidWorks and Rhino3D
> It is 7 files, one for each blade station, that have X, Y and Z
> co-ordinates, with the proper angle and placed correctly in relation to
> the
> plan form that is chosen (6 of them)
>
> In SolidWorks it is just to insert "curve through free points" one by one
> txt file, then loft from station 1 to 7 and the blade is don. It is don
> faster then it take to write this, it's just a matter of clicking with the
> mouse. no writing of co-ordinates.

So the .txt files are a text based set of points that can be imported like
an .igs file? Then add some "skin" to them and you're ready to go?

[Jan Carlsson]

Almost,

The txt files is inserted, then a SW or Rhino file is made, and a iges or
other files can be exported.

Jan

"LCT Paintball" > skrev i meddelandet
news:DMD5e.1641$GJ.1526@attbi_s71...
> > My program create text .txt files that is used in SolidWorks and Rhino3D
> > It is 7 files, one for each blade station, that have X, Y and Z
> > co-ordinates, with the proper angle and placed correctly in relation to
> > the
> > plan form that is chosen (6 of them)
> >
> > In SolidWorks it is just to insert "curve through free points" one by
one
> > txt file, then loft from station 1 to 7 and the blade is don. It is don
> > faster then it take to write this, it's just a matter of clicking with
the
> > mouse. no writing of co-ordinates.
>
> So the .txt files are a text based set of points that can be imported like
> an .igs file? Then add some "skin" to them and you're ready to go?
>
>
>

[LCT Paintball]

> Almost,
>
> The txt files is inserted, then a SW or Rhino file is made, and a iges or
> other files can be exported.
>


Can you send me a sample of the .txt file?

[Jan Carlsson]

Please send me your name and address.

Jan

www.jcpropellerdesign.com

"LCT Paintball" > skrev i meddelandet
news:tzT5e.14764$g65.7579@attbi_s52...
> > Almost,
> >
> > The txt files is inserted, then a SW or Rhino file is made, and a iges
or
> > other files can be exported.
> >
>
>
> Can you send me a sample of the .txt file?
>
>