Bamboo Propellers

On Mon, 25 May 2009 12:32:15 -0500, Charles Vincent
wrote:

Stealth Pilot wrote:
On Sun, 24 May 2009 21:48:27 -0500, Charles Vincent
wrote:

Bamboo is put to some pretty incredible uses. A trip to Hong Kong or
even Beijing will leave you astounded. The buildings being built are
incredibly tall and surrounded with hand tied bamboo scaffolding. I
have walked under and on a lot of it at this point and I have taken many
pictures of it. I have also seen a lot of lifting engines put together
with it hoisting heavy electrical equipment.

Charles

dont be bamboozled by this. asian scafolding uses the strength of the
building for stability and support. western scafolding is usually self
supporting and free standing.
the underlying approach to the scaffolding is quite different
structurally.

btw why would anyone bother with bamboo when the same locales have
mahogany propeller woods as native forestry?

I assumed as much, as the bamboo is not graduated from top to bottom.
Still, and impressive structure nonetheless.

http://www.travelpod.com/travel-photo/wells2008/1/1223530200/bamboo-scaffolding-on-high-rise-buildingsx.jpg/tpod.html

I know the British preferred mahogany for their propellers, but as I
recall, mahogany had some serious knocks as prop material. I can't
bring them to mind at the moment though.

Charles

mahogany was used by the brits, to quote lattimer-needhams engineering
text,
"mahogany is largely employed in the manufacture of airscrews, and the
variety that grows in honduras is favoured for that class of work. The
suitability of honduras timber is due chiefly to the fact that its
liability to shrink (after efficient seasoning) is only very slight
and that it possesses particularly satisfactory glue retaining
qualities. it is a strong, hard, straight grained wood and is not
difficult to work."

To All,

As a point of interest, in the 1970's I was able to buy all the
STRAIGHT-GRAINED maple I wanted at bargain prices because (here it
comes) the straight-grained varieties ( sometimes called 'sugar
maple' ) was LESS desirable for furniture than the 'curly' varieties.
The same was true for mahogany; with straight, hard-grained mahogany
did not have as much 'figure' and was therefore used only for the
hidden portions of the furniture. Which lead to.... Bob, the Garbage
Thief.

Back in the Day, whenever that was, people used to get rid of unwanted
furniture by simply sitting it out by the road-side on Garbage Day
(whenever THAT was). I found that couches and chairs USUALLY had
frames made of straight-grained maple or oak, often in pieces long
enough for making a prop-blank. After dismantling the piece I would
return the residue to the road-side (something we are not allowed to
do today). And WOOD residue went into the stove.

Unless you were seriously poor you would never consider such sources
for hardwood, partly because of the difficulty in removing the
zillions of pneumatically-installed staples and nails. But when you
can't allow your hobby to financially intrude on your family's
welfare, you treat your time as having zero-value when involved in the
recovery of wood from old furniture, tables and what-have-you.

-R.S.Hoover

On Tue, 26 May 2009 10:03:08 -0700 (PDT), Veeduber
wrote:

To All,

As a point of interest, in the 1970's I was able to buy all the
STRAIGHT-GRAINED maple I wanted at bargain prices because (here it
comes) the straight-grained varieties ( sometimes called 'sugar
maple' ) was LESS desirable for furniture than the 'curly' varieties.
The same was true for mahogany; with straight, hard-grained mahogany
did not have as much 'figure' and was therefore used only for the
hidden portions of the furniture. Which lead to.... Bob, the Garbage
Thief.

Back in the Day, whenever that was, people used to get rid of unwanted
furniture by simply sitting it out by the road-side on Garbage Day
(whenever THAT was). I found that couches and chairs USUALLY had
frames made of straight-grained maple or oak, often in pieces long
enough for making a prop-blank. After dismantling the piece I would
return the residue to the road-side (something we are not allowed to
do today). And WOOD residue went into the stove.

Unless you were seriously poor you would never consider such sources
for hardwood, partly because of the difficulty in removing the
zillions of pneumatically-installed staples and nails. But when you
can't allow your hobby to financially intrude on your family's
welfare, you treat your time as having zero-value when involved in the
recovery of wood from old furniture, tables and what-have-you.

-R.S.Hoover

bob you are amazing.
(in a very positive way)

Stealth Pilot

Stealth Pilot wrote:
On Mon, 25 May 2009 12:32:15 -0500, Charles Vincent
wrote:

Stealth Pilot wrote:
On Sun, 24 May 2009 21:48:27 -0500, Charles Vincent
wrote:

Bamboo is put to some pretty incredible uses. A trip to Hong Kong or
even Beijing will leave you astounded. The buildings being built are
incredibly tall and surrounded with hand tied bamboo scaffolding. I
have walked under and on a lot of it at this point and I have taken many
pictures of it. I have also seen a lot of lifting engines put together
with it hoisting heavy electrical equipment.

Charles
dont be bamboozled by this. asian scafolding uses the strength of the
building for stability and support. western scafolding is usually self
supporting and free standing.
the underlying approach to the scaffolding is quite different
structurally.

btw why would anyone bother with bamboo when the same locales have
mahogany propeller woods as native forestry?
I assumed as much, as the bamboo is not graduated from top to bottom.
Still, and impressive structure nonetheless.

http://www.travelpod.com/travel-photo/wells2008/1/1223530200/bamboo-scaffolding-on-high-rise-buildingsx.jpg/tpod.html

I know the British preferred mahogany for their propellers, but as I
recall, mahogany had some serious knocks as prop material. I can't
bring them to mind at the moment though.

Charles

mahogany was used by the brits, to quote lattimer-needhams engineering
text,
"mahogany is largely employed in the manufacture of airscrews, and the
variety that grows in honduras is favoured for that class of work. The
suitability of honduras timber is due chiefly to the fact that its
liability to shrink (after efficient seasoning) is only very slight
and that it possesses particularly satisfactory glue retaining
qualities. it is a strong, hard, straight grained wood and is not
difficult to work."

OOps,didn't quite get to your post before I posted mine. Jerry

Stealth Pilot wrote:
On Mon, 25 May 2009 12:32:15 -0500, Charles Vincent
wrote:
I know the British preferred mahogany for their propellers, but as I
recall, mahogany had some serious knocks as prop material. I can't
bring them to mind at the moment though.

Charles

mahogany was used by the brits, to quote lattimer-needhams engineering
text,
"mahogany is largely employed in the manufacture of airscrews, and the
variety that grows in honduras is favoured for that class of work. The
suitability of honduras timber is due chiefly to the fact that its
liability to shrink (after efficient seasoning) is only very slight
and that it possesses particularly satisfactory glue retaining
qualities. it is a strong, hard, straight grained wood and is not
difficult to work."

I found the reference. It was in Martin Hollman's Modern Propellor and
Duct Design book. It just notes that mahogany tends to splinter easily
and is therefore not a good choice. In any event, mahogany doesn't
grow here in Texas, at least anywhere near me. Bois dArc does though
and has ridiculous strength in compression - double mahogany (I have a
house built on Bois D Arc stumps, the tree is so ugly, termites won't
touch it) I have the compressive strength numbers since it is a common
foundation material, but do not have the normal engineering values for
the rest. I need to find them.

Charles

Charles Vincent wrote:
Stealth Pilot wrote:
On Mon, 25 May 2009 12:32:15 -0500, Charles Vincent
wrote:
I know the British preferred mahogany for their propellers, but as I
recall, mahogany had some serious knocks as prop material. I can't
bring them to mind at the moment though.

Charles

mahogany was used by the brits, to quote lattimer-needhams engineering
text,
"mahogany is largely employed in the manufacture of airscrews, and the
variety that grows in honduras is favoured for that class of work. The
suitability of honduras timber is due chiefly to the fact that its
liability to shrink (after efficient seasoning) is only very slight
and that it possesses particularly satisfactory glue retaining
qualities. it is a strong, hard, straight grained wood and is not
difficult to work."

I found the reference. It was in Martin Hollman's Modern Propellor and
Duct Design book. It just notes that mahogany tends to splinter easily
and is therefore not a good choice. In any event, mahogany doesn't
grow here in Texas, at least anywhere near me. Bois dArc does though
and has ridiculous strength in compression - double mahogany (I have a
house built on Bois D Arc stumps, the tree is so ugly, termites won't
touch it) I have the compressive strength numbers since it is a common
foundation material, but do not have the normal engineering values for
the rest. I need to find them.

Charles

I seem to recall that just about any straight grain wood - hardwood or
softwood or both laminated together will do the job. Some protection
against leading edge erosion is desired - used to be brass, now could be
fiberglass. The slender trailing edge would be a good candidate for a
hardwood lamina in my view. Wooden pros are MUCH kinder to cranks than
glass or metal.

Brian W

On May 26, 6:21*pm, Brian Whatcott wrote:

I seem to recall that just about any straight grain wood - hardwood or
softwood or both laminated together will do the job.
---------------------------------------------------------------------------------------------

Dear Brian,

Sorta-hard softwoods such as fir, do just fine with the VW. Trailing
edge can be relatively blunt and still get the job done. Leading edge
-- the outboard foot or thereabouts -- needs to be glassed then fitted
with a slippery tape. But rpm is definitely a factor. Use the proper
cam on a seriously over-square engine and a tip-speed of no more than
880fps, you can even use spruce... but ONLY if you are running a
flywheel. Maple remains the best choice, not so much for its
durability but because of its MASS. Turns the veedub into a real
chugger.

Wait until you see what Bruce King & Steve Bennett have come up with
for the BK1.3. One of the engine options is a surprisingly light-
weight package that's all wrong... according to the instant
experts :-)

-R.S.Hoover

Charles Vincent wrote:

I found the reference. It was in Martin Hollman's Modern Propellor and
Duct Design book. It just notes that mahogany tends to splinter easily
and is therefore not a good choice. In any event, mahogany doesn't
grow here in Texas, at least anywhere near me. Bois dArc does though
and has ridiculous strength in compression - double mahogany (I have a
house built on Bois D Arc stumps, the tree is so ugly, termites won't
touch it) I have the compressive strength numbers since it is a common
foundation material, but do not have the normal engineering values for
the rest. I need to find them.

Charles

Are you making propellers from mesquite?

cavelamb wrote:
Charles Vincent wrote:

I found the reference. It was in Martin Hollman's Modern Propellor
and Duct Design book. It just notes that mahogany tends to splinter
easily and is therefore not a good choice. In any event, mahogany
doesn't grow here in Texas, at least anywhere near me. Bois dArc does
though and has ridiculous strength in compression - double mahogany (I
have a house built on Bois D Arc stumps, the tree is so ugly, termites
won't touch it) I have the compressive strength numbers since it is a
common foundation material, but do not have the normal engineering
values for the rest. I need to find them.

Charles

Are you making propellers from mesquite?

Nope. Hard to find a section of mesquite with straight grain around
here. I have heard of a furniture maker around Austin using mesquite,
but he is using mesquite growing on river banks, as it grows taller and
straighter. I was musing on the applicability of Bois DArc, or Bodark
colloquially. Used by the native for making bows, and by the early
settler for fence posts ( there was once a thriving market in Texas for
bodark seeds and plenty of the material was sent north for fences there
as well. This was just in line with Bob Hoover's "use what is found
locally and cheap" approach.

Charles

On Wed, 27 May 2009 11:42:23 -0500, Charles Vincent
wrote:

cavelamb wrote:
Charles Vincent wrote:

I found the reference. It was in Martin Hollman's Modern Propellor
and Duct Design book. It just notes that mahogany tends to splinter
easily and is therefore not a good choice. In any event, mahogany
doesn't grow here in Texas, at least anywhere near me. Bois dArc does
though and has ridiculous strength in compression - double mahogany (I
have a house built on Bois D Arc stumps, the tree is so ugly, termites
won't touch it) I have the compressive strength numbers since it is a
common foundation material, but do not have the normal engineering
values for the rest. I need to find them.

Charles

Are you making propellers from mesquite?

Nope. Hard to find a section of mesquite with straight grain around
here. I have heard of a furniture maker around Austin using mesquite,
but he is using mesquite growing on river banks, as it grows taller and
straighter. I was musing on the applicability of Bois DArc, or Bodark
colloquially. Used by the native for making bows, and by the early
settler for fence posts ( there was once a thriving market in Texas for
bodark seeds and plenty of the material was sent north for fences there
as well. This was just in line with Bob Hoover's "use what is found
locally and cheap" approach.

Charles

It always pays to pick up the dregs from a pranged propeller and look
at what has actually let go as opposed to what you'd think would let
go.

I did a quiet post mortem on a prop made with curly wood in part of
the blades. wood in the hub was straight but it was quite curly in
sections of the blades. all for the reject bin you'd think.

well when that prop was shattered in a wheels up landing of the
sidlinger hurricane it was on, not one part of the curly grain had let
go. no glue breaks in the curly grain. no breaks of any type in the
curly grain area. all the breaks were in the adjoining straight
grained sections at radiuses either side of the wrong grained wood.

it showed me again that doing it often shows you that the conventional
wisdom in aviation is either wrong or was formed when the
constructional conditions were quite different from what we are doing
today. as veedubber says dont be afraid to do and learn from *current*
experience.

more wood is usable than you'd think.
Stealth Pilot