On May 5, 7:58 am, Stealth Pilot
wrote:
The alternate wood I'm using has been australian queensland hoop pine.
I found the batch I had a bit brash (a timber term meaning brittle
short grained wood) so I was on the lookout for something a little
safer for use in my Turbulent. well for the structural bits anyway.

Australia's equivalent of Home Depot is Bunnings hardware. The stores
are layed out as an exact clone of the american stores, but that is
bye the bye. What I discovered in Bunnings one day was some extremely
knotted planks of some yellowish wood. between the bazillion (a huge
number) of knots was some amazingly fine grained timber. about 0ne
ring per millimeter. the wood felt quite reasonable for weight so I
bought a plank to experiment with. At this stage I had no idea what
the wood species was.

the stuff had a weedy smell when cut. it steamed easily and seemed to
glue with epoxy really well. I used the straight grained pieces for
the turtledeck bows of my first Turbulent fuselage.

I experiemented some more with the remaining wood and couldnt fault it
as a construction timber.

I had a brainwave one day and hunted out the receipt off the floor of
the car. alaskan yellow cedar was what the receipt called it.
I had visions of weedy little trees in wind swept tundra being raped
over by alaskan timber harvesters :-)

I discussed the need to test the wood to determin its strength with an
aero engineer friend. the next night he sent me the full design
strength specs for the wood.
having never heard of it before, this stunned me.

I did some google searching and discovered some truely interesting
facts regarding alaskan yellow cedar.

the weedy smell only occurs when the wood has a high moisture content.
when the wood is down at moisture contents suitable for aircraft use
the wood is odourless. what a useful property an indicator of useful
moisture content is.
Trees have been discovered in forests that have no insect or
microrganism attack even after standing as dead trunks for 150 years.
It turns out that alaskan yellow cedar is rated as the softwood most
inherently resistant to attack by bugs. another really useful
property.

I discovered an early aeroengineering text that gave comparitive
rundowns of alternative woods to the ubiquitous Spruce.
Alaskan yellow Cedar is rated as a highly shock absorbent/resistant
wood sutiable for the most arduous structural use, which is the very
opposite of brash timber.
the thing that floored me though was the reason why spruce was
selected as the wood of choice, it wasnt spruce's properties, it was
just that there appeared to me more millable timber available.

Alaskan yellow cedar, far from being a lower grade alternative wood to
spruce, is actually a better timber in a number of it's properties.

I was amazed. an alternative timber selected on a hunch turned out to
be a winner.
My second attempt D3 Turbulent is shaping up to be a pearler of an
aircraft in Alaskan Yellow Cedar and Qld Hoop Pine marine ply.

Dont knock some of those alternative timbers. Some mean that the
drying up of spruce is an artifact of history, not the end of timber
aircraft.
...which is good 'cause timber aircraft are wonderful building
experiences.

Stealth (not a single nail used in construction) Pilot

btw my rape picture turned out to be a vivid imagination. there are
huge stands of majestic alaskan yellow cedar all down the southern
coast. there are a lot of aircraft in those trees.

I grew up in the Canadian province of British Columbia, right
next to Alaska. We used yellow cedar sometimes. Stuff stinks when you
cut it. There are other BC woods that are useable in aircraft, too,
like Engelmann Spruce (similar to Sitka Spruce but found in the drier
areas), Ponderosa Pine (though BC's pines have been decimated in the
recent Pine Beetle infestation) and Douglas Fir, which, while
technically a softwood, is considerably harder and stronger and
dimensions can be reduced 10% or so when using it in airplanes.
Reducing any dimension can upset hundreds of other dimensions, so most
people don't bother with it. It would still be heavier than Sitka
anyhow, even at 10% smaller. And it splits/splinters easily. Western
Red Cedar has been used in airplanes, too, but it's not so strong.
When I was in South Africa last fall the local homebuilders there were
using Eucalyptus, which they call Saligna once it's turned into
lumber. South Africa has huge plantations of this stuff. In the US a
few years ago I flew over big pine plantations in North Carolina.
Trouble with those is the rapid growth and therefore low ring count
per inch. The Americans also have Basswood and some different Cedars.

Dan