Bamboo Propellers
Bob
the only response indicates a misunderstanding of how bamboo is used
for such things.
In the tropics -- with Vietnam being a fair example -- bamboo often
has a diameter of several inches. When split AND STEAMED you're left
with a PLANK having remarkable characteristics with regard to strength
& grain.
I assumed any propeller fabricated from bamboo would use such planks,
probably glued in a steam- or water-heated clamp that would impregnate
the grain of the planks with epoxy or something having similar
characteristics. A further assumption on my part was that the airfoil
shape would be routed -- or even MOLDED -- from the section of the
planks that were fully impregnated with the epoxy, which would then
receive a finishing coat.
Perhaps we would be lucky enough to make use of a FURNITURE
MANUFACTURER or some other manufacturer who is already equipped for
dealing with bamboo.
Finally, perhaps someone can point me toward a Group that is more
familiar with Bamboo.
-R.S.Hoover
-veed...@chuggers.net
Philippe
> In a related post I asked if anyone had heard of such a thing. So far
> the only response indicates a misunderstanding of how bamboo is used
> for such things.
Never hear obout that, but bamboo laminate for a slow, low power
prop... it seems possible
Regards
--
ￜ Si tous les poￜtes voulaient se donner la main, ils toucheraient enfin
des doigts d'auteur! ￜ
Philippe Vessaire Ò¿Ó¬
Morgans
"Bob" <veed...@chuggers.net> wrote
>
> Perhaps we would be lucky enough to make use of a FURNITURE
> MANUFACTURER or some other manufacturer who is already equipped for
> dealing with bamboo.
>
> Finally, perhaps someone can point me toward a Group that is more
> familiar with Bamboo.
Bamboo floor company
http://www.ambientbp.com/index.htm
Charlie
wondered about whether it was available in long enough pieces, but it
looks like it is.
http://floorus.com/Bamboo6FPro.aspx
Question is, whether it's stiff enough to make a good prop.
It is an interesting idea, though. The grain should be very straight &
consistent.
Charlie
Charlie
http://www.youtube.com/watch?v=_V912q4rZSg
I think that they say urea formaldehyde is used to glue the pieces. Is
that the same stuff used in OSB panels?
Ed
wrote:
>
>I think that they say urea formaldehyde is used to glue the pieces. Is
>that the same stuff used in OSB panels?
It is the same stuff used to stick Mosquito bombers together.
cavelamb himself
> You can buy flooring made from bamboo from lots of flooring dealers. I
> wondered about whether it was available in long enough pieces, but it
> looks like it is.
>
> http://floorus.com/Bamboo6FPro.aspx
>
> Question is, whether it's stiff enough to make a good prop.
>
> It is an interesting idea, though. The grain should be very straight &
> consistent.
>
> Charlie
The answer, of course, is another question.
What is the propeller being asked to do?
cl...@snyder.on.ca
Used to be able to buy Bamboo model aircraft props.
Veeduber
I believe we've made our point, albeit indirectly. Bamboo in the form
of planks is available. We still need more information with regard to
length and thickness. I will create a Bamboo Group to serve as an
archive for information as it is developed.
-R.S.Hoover
Veeduber
> I will create a Bamboo Group to serve as an
> archive for information as it is developed.
Or perhaps not.
The last step in creating a Group is for Yahoo to send a confirming
message to your email address. After a four hour wait, nothing has
appeared.
Perhaps they want only Yahoo email addresses.
If one of you uses Yahoo.com for email perhaps you would care to try
creating a Group specific to aviation & bamboo.
-R.S.Hoover
Le...@caspercityauto.com
It seems to me after a VERY quick session of internet research that
bamboo, due to its high density and variability, may not be very
usable for aircraft structures. Good selection, grading, and using
the fibers similar to Microlam's use of conventional wood fibers -
might - produce an aircraft grade material. This probably would not
be cheap nor something an impoverished home builder could fabricate.
Makes nice cutting boards and floors!
=========================
Leon McAtee
Still testing materials for an improved version of
TPG..................
Veeduber
> http://scholar.lib.vt.edu/theses/available/etd-08212000-10440027/unre...
>---------------------------------------------------------------------------
Dear Leon,
After reading the report you've cited (Thank you) I am more wiling
than ever to carve a prop from bamboo.
Since I can't seem to open a Group dedicated to Bamboo, I can at least
open a file dedicated to that subject. It will be in the Chuggers-alt
Group.
-R.S.Hoover
Stealth Pilot
wot I'd like to know is not how strong the bamboo is but how strong
the bamboo nodes are. you know, the cell ends that occur about every
so many inches along the length.
Stealth Pilot
Peter Dohm
news:aa6efe12-2e75-46b7...@w40g2000yqd.googlegroups.com...
First, thanks for the link to a very interesting research result.
The report looked interesting enough to print out Chapter4 and the
conclusion for review later today--when I have committed to a real estate
open house even though it *really* looks like rain!
However, even without having read more than a few lines, a couple of things
did catch my eye:
1) Carefull hand selection of materials is an unbearable burden for a
volume manufacturer; but not necessarily for a hobbyist--and people who live
where doing so is common practice tend to become very good at it. And I
might add that doing so might simply be convenient for someone who lives
some distance from suppliers, or someone who is simply in proximity to a
large selection of cheap material from which to conveniently select. I
might add that Bob has been advocating something of the sort for those
willing to select small quantities of straight grained soft woods from the
local Borg. That can often be quicker, more convenient and more
entertaining than ordering from one of the "aircraft grade" suppliers--so
poverty is far from the only motivation, but bamboo could easily be a very
low cost solution for someone who lives where it is locally grown.
2) The small sizes of clear grained material available may not be that
severe of a problem for a rimary glider or a very small and basic single
seat airplane. Actually, that "problem" could even be a blessing in
disguise by forcing, or at least strongly encouraging, the builder to put
redundancy into the structure--which might provide a greater real world
margin of safety than simply "overbuilding" with more typical materials.
3) It is just as possible to make too much of the weight issue as it is
to make too little of it. Here in the US, we tend to think of strict weight
limits in terms of FAR Part 103--and recently in terms of Light Sport--but
those specific weight and performance limitations are far from universal.
If you think of utility in terms of simply flying and safely landing your
aircraft, then it also gets a lot easier!
I am amoung those who tend to think of airplanes in terms of fast and
convenient travel over long distances, so I must admit that I bamboo is not
for me. But for any who might be interested in the entire treatise, here is
the link:
http://scholar.lib.vt.edu/theses/available/etd-08212000-10440027/
Thanks to Leon for providing the reference, which I would never hae found on
my own.
Peter
Peter Dohm
news:de07fc1f-826b-4e29...@t21g2000yqi.googlegroups.com...
uses of bamboo.
Peter
Veeduber
> That might actually be a better choice, as you should get fewer unrelated
> uses of bamboo.
Dear Peter,
It might also be more realistic.
In the portion of the report showing preparation of test samples, they
appear to have been taken from bamboo that was about 2" in diameter.
Then Stealth mentions the nodes occurring every few inches. What I am
thinking of is bamboo having a diameter of 6" and up, with a couple of
FEET between nodes.
I believe their are government entities in India and the Philippines
similar to our own Forest Products Laboratory, in that they are
dedicated to providing quantified data about their nation's forest
products. These are the people who should be able to provide the
information we need... once we track them down.
In India there is the 'Indian Academy of Wood Science,' which may be
of some use.
I should also point out that I am not locked in to the idea of bamboo
propellers. But I have seen some bamboo of remarkable size growing
like weeds. The stuff is probably too heavy to be used for longerons
and the like but it may be useful as propeller-carving material.
-R.S.Hoover
Charles Vincent
> In India there is the 'Indian Academy of Wood Science,' which may be
> of some use.
>
> I should also point out that I am not locked in to the idea of bamboo
> propellers. But I have seen some bamboo of remarkable size growing
> like weeds. The stuff is probably too heavy to be used for longerons
> and the like but it may be useful as propeller-carving material.
>
> -R.S.Hoover
>
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
Veeduber
> ...The buildings being built are
> incredibly tall and surrounded with hand tied bamboo scaffolding.
Dear Charles (and the Group),
In shipyards and aboard ships, too.
But the 'hand-tied' may be misleading. The ties are pre-bent hair-
pins of iron wire, about 3/16" thick. When being pre-bent they leave
a loop about an inch in diameter, while the throat of the hair-pin may
be as wide as 10" The hair-pins are slipped onto the joint and a
standard rigger's bar is inserted into the eyelet and the rigger's-bar
is turned, tightening the connection to whatever spec was required.
You're correct with regard to strength and their swiftness of erection
but of even more interest is their method of transporting the poles
used to build the structure, which is done by HAND, catching each pole
and passing it overhead to the next team.
-R.S.Hoover
Stealth Pilot
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?
Veeduber
wrote:
>
> btw why would anyone bother with bamboo when the same locales have
> mahogany propeller woods as native forestry?
Dear Stealth,
If valid, that's a good point. Does mahogany grow in proximity to
bamboo?
I've sent a number of queries to offices and individuals supposedly
involved in promoting forest products of India and other SE Asian
countries without receiving a single reply.
When I worked along-shore I was surprised to see that ships carrying
cargos from that part of the world used MAHOGANY for dunnage. Indeed,
some years later when stationed at Naval Air Station Alameda I build a
14 foot cat-boat. All of the solid lumber parts were made from
mahogany dunnage I salvaged from piles of the stuff down near the
carrier piers. (The mast was a section of Fir banister-rail; the boom
scarfed from pieces of pine.
-R.S.Hoover
Charles Vincent
I assumed as much, as the bamboo is not graduated from top to bottom.
Still, and impressive structure nonetheless.
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
Charles Vincent
> When I worked along-shore I was surprised to see that ships carrying
> cargos from that part of the world used MAHOGANY for dunnage. Indeed,
> some years later when stationed at Naval Air Station Alameda I build a
> 14 foot cat-boat. All of the solid lumber parts were made from
> mahogany dunnage I salvaged from piles of the stuff down near the
> carrier piers. (The mast was a section of Fir banister-rail; the boom
> scarfed from pieces of pine.
>
> -R.S.Hoover
A friend imports a lot of stuff from India and China. He was amazed
that the crates and pallets were often mahogany. He is a woodworker and
salvaged a lot of it for his projects. He said the quality was not
great, but you could get more than enough really nice material to make
smaller projects.
Charles
Peter Dohm
> On May 25, 4:04 am, Stealth Pilot <notranspon...@aeroplanes.com.au>
> wrote:
>>
>> btw why would anyone bother with bamboo when the same locales have
>> mahogany propeller woods as native forestry?
>> ---------------------------------------------------------------------------------------
>
> Dear Stealth,
>
> If valid, that's a good point. Does mahogany grow in proximity to
> bamboo?
I don't know it they would normally grow adjacent to one another, but both
can be grown successfully in southern Florida and mahonany does grow wild in
the Florida everglades and bamboo does easily reach its full height, with
approximately six inch diameter stalks, when grown in Florida as an
ornamental.
Therefore, I can only surmise that they could at least be grown within a
very few miles of one another in those climates that overlap both of their
needs.
Peter
cl...@snyder.on.ca
African Mahogany and bamboo grow side by side.
Phillipine as well.
cl...@snyder.on.ca
Also, remember bamboo is NOT wood, or even technically a "forest"
product. Bamboo is a reed, or a GRASS.
Stealth Pilot
<xlc...@swbell.net> wrote:
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."
Veeduber
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
Jerry Wass
Also there is HONDURAS mahogany----& then there is the other stuff that
looks like it. Jerry
Jerry Wass
OOps,didn't quite get to your post before I posted mine. Jerry
Ron Webb
there was that if you went down to the lumber yard, the 2x4's you got would
be straight grained Phillipine mahogany. And it was cheap!
I've sometimes wondered if it would be profitable to travel to Guam, or the
Phillipines, or wherever, and put together a big platform consisting of
nothing but the most valuable wood at hand, then mount a GPS, a satellite
phone, and a set of sails controlled by computer. Tell the thing to sail
itself to L.A. or wherever, and call me when you're close...then sell all
that beautiful wood...
"Veeduber" <veed...@chuggers.net> wrote in message
news:88a4b29d-1fe7-4956...@j18g2000yql.googlegroups.com...
Charles Vincent
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
Brian Whatcott
> I lived on the island of Guam from 1985 thru 1988. One of the things I noted
> there was that if you went down to the lumber yard, the 2x4's you got would
> be straight grained Phillipine mahogany. And it was cheap!
>
> I've sometimes wondered if it would be profitable to travel to Guam, or the
> Phillipines, or wherever, and put together a big platform consisting of
> nothing but the most valuable wood at hand, then mount a GPS, a satellite
> phone, and a set of sails controlled by computer. Tell the thing to sail
> itself to L.A. or wherever, and call me when you're close...then sell all
> that beautiful wood...
>
>
What an imaginative idea. I know there is a certain class of folks who
already make surface submersibles (only the snorkels show...)
but they keep them crewed, and run a diesel to get them to the US with
their valuable aromatic or sensory modification goods.
Brian W
Brian Whatcott
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
cavelamb
>
> 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?
Jerry Wass
Surely you've seen some native Indian bows (old ones) the wood is split
from a tree so that the heart (dark wood) and the lighter (outside,sap
wood ) both appear in the bow..The dark is placed on the inside of the
curve because it is much higher in compressive strength..The back side
is the sap wood which is much higher in tensile strength.
Pore old uneducated indians--didn't know much did they <G> --also
Bois= wood d'Arc= of the arc or bow. Jerry--(used to live on
Bois d'Arc in ElPaso.)
Veeduber
>
> What an imaginative idea. I know there is a certain class of folks who
> already make surface submersibles (only the snorkels show...)
> but they keep them crewed, and run a diesel to get them to the US with
> their valuable aromatic or sensory modification goods.
Dear Brian (and the Group),
If you are familiar with trans-Atlantic flights of model airplanes...
or of the campus-to-campus flights of model airplanes buzzing along a
carefully pre-planed flight-path between Miami and Boston, the
following will not come as a surprise.
The original Varieze was meant to be powered by a VW... and would have
been far more successful, in my opinion, had they used my engine
instead of Ted's. Water under the bridge and so forth. However, some
diligent gentlemen from south of the border have apparently been
making flights north of it in un--manned Variezes using VW engines
with the prop on the proper end of the crank. One of their flight
paths is said to be from the strip at the LA Bay junction to one of
the WWII air strips out in the Mohave, where control is transferred to
a local transmitter for landing. Once on the ground the cargo is
removed, the bird refueled and sent back south. Another flight path,
said to be the original, was from a strip in Sinaloa to a stretch of
highway in Arizona, the move to Baja and the Mojave the result of
inter-tribal warfare.
All just Hobby Shop rumor, of course. Or rather the product of
several hundred rumors about home-built RPV's heard but not seen as
they putter their merri way back & forth at zero altitude, delivering
Ami-Rica's most popular yarb at a hundred keys per trip. And if they
lose one now & then it's no big deal. VW engines are cheap and so are
N7EZ's if you don't have to worry about a canopy nor any human flight
controls.
-R.S.Hoover
Veeduber
> 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
Dana M. Hague
<veed...@chuggers.net> wrote:
> ...However, some
>diligent gentlemen from south of the border have apparently been
Hmmm, "back in the day" I recall discussing the possibility of such
flights in a VariEze, which would naturally have a very low radar
signature. The idea was to paint it black, except for weird
phosphorescent shapes on the underside, and a small black light
mounted under the aircraft to light them up. The idea was that even
if anyboby _did_ report such a strange apparition crossing the border,
he wouldn't be believed...
-Dana
--
When you get it right
mighty beasts float up into the sky
When you get it wrong
people die
-Roger Bacon (c1384)
Charles Vincent
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
Brian Whatcott
Trans-Pacific endeavors too,) but the inter campus express had passed me by.
But in that connection, I can tell you about a hardware equivalent to
the hugely successful Open Software movement, GNU, copyleft, and all
that good stuff.
It focusses on a little microcontroller card called the Arduino,
of which the current implementation is called the Duemilanuove
(Italian for "2009") It is about 2 X 2 inches.
This has attracted a large active following from
people who make things. It has a USB socket for power and downloading.
A FREE soft development capability on your PC. Hundreds or thousands
of applications in software - available cards for expanders and whatever.
And the good news is - the entry price for the whole shebang is under
$50 - and you will be testing an on board flasher you programmed and
compiled, on the first day you get it. It has AtoDs DtoAs, DOs DIs
a k or two of memory for code, etc, etc....
The reason I gushed on about this is that I stumbled on it when reading
about a drone (RPV) autopilot, wing leveler, GPS waypoint follower -
with smooth switchover to radio control. This is the Ardupilot.
Around $100 basic.
Less than $500 gets the controller, the servoes the GPS the
application, the custom PCB, an IR horizon wing leveler and pitch
controller. Oh, and the model electric plane and RC gear to try it out with.
First batch sold out....
http://blog.makezine.com/archive/2009/01/ardupilot_arduino_compatible_uav_co.html
or in tiny format:
http://tinyurl.com/pqz2ev
Ardupilot home page
http://diydrones.com/profiles/blog/show?id=705844%3ABlogPost%3A44814
or in tiny format:
http://tinyurl.com/5g5gho
Amazing!
Brian W
Veeduber
Brian said...
> Ha!
...and later on...
> Amazing!
> --------------------------------------------------------------------------------
Well... Ha! right back atchew :-)
(and tanks for the URL's)
I first mentioned the 'Roll Yer Own RPV' 'way back when sometime...
back before the Big C came to call. The typical response was from
Good Ol' Boyz telling me all the reasons why it couldn't be true,
which generally boiled down to the fact they'd never heard of it
before.
Among the reasons why it wouldn't work was the 'fact' that every one
of those 'mystery' aircraft penetrating American air space was being
tracked by FLIR-equipped helicopters, so that by the mystery airplane
touched down, there was a reception committee there to meet it.
Not so. Because APPARENTLY each of those mystery airplanes was NOT
carrying anything besides extra fuel. So let's say ten drones cross
the border. Their flight path takes them through a populated area
where they are VISUALLY checked to see if they are being followed. If
they are, the flight path is re-programmed and eventually returns home
without ever touching down. Or it may be carrying external tanks,
dropped near downtown Sage, California. (Lookitup :-)
The guy on the ground with the sound-tracking FLIR is the 'cleaner.'
His job is to look for anything-anyone following the Mystery
Airplane. If the answer is 'yes' it simply turns around and goes
home. But the truth is, we don't have enough aerial assets to track
each Mystery Airplane 100% of the time.
But the very BEST of the Good Ol' Boy reasons is that Messicans just
aren't smart enough to run 'something like that.' Meaning the Good
Ol' Boys aren't bright enough to appreciate the problem.
Personally, I think it's funny as hell :-) Because as soon as someone
underestimates the problem, they've lost the war by default.
-R.S.Hoover
Stealth Pilot
bob you are amazing.
(in a very positive way)
Stealth Pilot
Stealth Pilot
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
Stealth Pilot
wrote:
>
>Surely you've seen some native Indian bows (old ones) the wood is split
>from a tree so that the heart (dark wood) and the lighter (outside,sap
>wood ) both appear in the bow..The dark is placed on the inside of the
>curve because it is much higher in compressive strength..The back side
>is the sap wood which is much higher in tensile strength.
>
>Pore old uneducated indians--didn't know much did they <G> --also
>Bois= wood d'Arc= of the arc or bow. Jerry--(used to live on
>Bois d'Arc in ElPaso.)
the actual examples of english longbows that remain were recovered
from the holds of the Mary Rose. no other *actual* medieval english
longbows existed. the making of them was pretty well lost to hearsay.
they are made from Yew wood exactly as you describe for the american
indians.
most are apparently roughly shaped but I think that that was so that
the wood behaved as needed.
Stealth Pilot
Morgans
"Stealth Pilot" <notran...@aeroplanes.com.au> wrote
> 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.
>
If the curly wood is in the middle of the prop blank, or carved section of the
blade, it is only taking up the centripetal forces (I know, they don't exist)
and not any bending load. It is only serving to hold the outer sections away
from each other, like the web in an I beam.
--
Jim in NC
Stealth Pilot
centripetal forces exist.
it is centrifugal forces that dont.
Stealth Pilot