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The story of wood verses timber

How February 2004 became wood month

Wood has no fatigue life, although metal attaching parts have fatigue lives. Wood is a non-strategic renewable resource. It’s the wood I reject that adds integrity of my Jodel.

During and following World War 2 the Australian aircraft industry was producing British Beaufort and Beaufighter aircraft at the Government Aircraft Factory and Mosquito aircraft at de Havilland’s. They were continually beset by material shortages. Aluminium alloys were in short supply and timber was investigated as an alternative for some structural components. The CSIRO Division of Aeronautics and of Forest Products found that Victorian mountain-ash and Queensland hoop-pine were acceptable for primary structures, whilst coachwood was a suitable substitute for imported birch plywood. A number of native Australian timbers as spruce substitutes were identified and details published as emergency wartime specifications (e)2D-811 for hoop pine, bunya pine, Queensland maple, bollywood, silver quandong and silver silkwood. (The Australian Standard for Aircraft Materials (1944))

The only timbers on Frank Rogers plan for the Jodel D150 (dated October 1976) are Sitkas spruce and Ash but these plans were drawn up prior to the emergence of “EXPERIMENTAL” in September 1998. Plywood specified is both Gaboon (Okoume) and Birch. Plywood these present no problem as both are available from Mister Ply and Wood at sensible prices. On the other hand although it is still possible to source Sitka Spruce it’s imported, expensive and excellent pieces of timber are not readily available. It’s likely that the very best Sitka spruce comes from old growth forests in Canada.

For my aircraft I have decided to use Australian hoop pine both timber and ply and Victorian mountain ash. This is my choice and all that remains is for me to select timber and ply of aircraft quality.

About hoop pine

(Araucaria cunninghamii)
A large tree can attain 50 metres in height, hoop pine occurs naturally in drier rain forests from the Hastings River in NSW to Far North Queensland and in Papua New Guinea. It is grown in plantations, predominantly in South Queensland and this is where I sourced my timber.
Grain: Very fine and even textured. Growth rings usually detectable but indistinct.
Density: 575 Kg/cubic metre at 12 % moisture content. This compares with Sitka spruce which is reported to be 449 Kg per cubic metre. The average Jodel will contain 5 to 6 cubic feet of timber. Using hoop pine in the place of Sitka spruce will add about 12Kg in weight. It is generally considered that hoop pine is 10% stronger than Sitka spruce.

These are my requirements when selecting hoop pine:
? Plantation grown timber, kiln dried to 12% moisture content.
? Perfect grain direction (not less than 6 growth rings per inch)
? Absence of knots, grain waviness and excessive grain slope (not more slope than 1:12)
? Quarter cut.

References for selecting hoop pine for aircraft construction:

Commonwealth of Australia Department of Aviation Air Navigation Orders Part 108 Section 108.29of 21 May 1982.
An introduction to Timber Aircraft Building SAAA National Convention 2003

Feb 2004 visit from Bob Furness

Bob delivered some aircraft parts and inspected the Hoop Pine used for the tailplane. He expressed an opinion on the use of Hoop Pine verses Sitka Spruce
In his opinion Sitka Spruce is the timber of choice.
He recommended I speak to Frank Rogers.

Frank Rogers

Hoop Pine is accepable if quality issues are address and if weight penalty is aceptable
Notes from Frank Rogers Sky Prince Building Instructions.
When selecting timber, look for grain direction and quality
Max grain slope is 1 in 15 (SAAA say 1 in 16)
Cut edge grain not more than 45 degrees to horizontal
not less than 6 rings per inch but 8 to 12 is to be prefered

I called the SAAA

spoke to Gary Spicer who is in NZ his wife put me onto Peter Bennett

Peter Bennett

Try Frank Rogers and Randell Krebbs

Randell Krebbs (Marine engineer)

Originally planned on Hoop Pine but has been using Sitka Spruce from Trend Timbers but he selected 1 piece out of the 90 they showed him. This is a ten year project
I plan to see Randell in Dural this week

John Mills Director State Forrests

See his email re testing facilities

Thomas Philippa (ex teacher)

See notes on Thomas phone call Essentially he says use Hoop Pine it is 20% heavier and 10% stronger all up weight of the Jodel D150 will go up 24lb

Arthur at Rosshaven Marine
Townesville

They supply Sitka Spruce old growth imported from Cananda. Cost is $25.00 per super foot. Density of Sitka spruce is 430Kg per cubic meter Hoop Pine is 560Kg cube m

Bob Faddy

Used his thicknesser to finish some hoop[ pine which I rejected due wavey grain

Timber Town Doors

Purchase 4.8m 40x200 Hoop Pine clear at $12 per metre. I rejected all of this timber due knots, wavey grain and excess grain slope

Other contacts
Rudi Pleschutschnig

Rudi has constructed a number of timber and fabric aircraft he has the wing to SIJ

Alan Bradtke

Alan has finished off construction of a KR2 says weight kills performance

Terry Ryan

 

Bob Furness

Delivered Info on testing requirements for timber

Customline Joinery Wauchope

Ian Chedwigen will source aircraft quality timber and cut and finish as required 6585 3065. Discussed differences between Resorcinol and West System epoxy. West System is a good gap filler but requires plenty of thin glue to fill end grain

Campbell and Jones Taree

 

Barry Graham Timber Coffs Harbour

Spoke to Nathan they can supply Clears #1 with knots? Furniture grade?

Barry Bishton Building ?

In wood using Bollywood from flitches

Randell Krebbs (Marine engineer)

Collect wing jig and discuss Jodels 12.02.04

Harry Bellott

Started building DRJ (D11) in early 1980"s spruce from flitches Then built Luten Minor. Harry is very keen on the Subaru engine because it is cheap. Recommends Peter Knowles as ex Dept Aviation LAME

Wauchope Wood and Turning supplies

David Hayes has supplied clear no knots kiln dried hoop pine for aircraft construction

Teak and Fancy Timbers

Rupert Goodall www.woodworld.com.au they supply clear Hoop Pine to aircraft builders

See notes on wood under Project Jodel
 
25th Feb 2004

Purchased 22.5 metres clear hoop pine from David Hayes

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Stick and Rudder
PO Box 284 Laurieton NSW Australia 2443
Ph: 02 6559 9953 Fax: 02 6559 7797 E: bill@stickandrudder.com.au

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