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Alternative woods.

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Autodidact

Well-Known Member
Joined
Oct 21, 2009
Messages
4,511
Location
Oklahoma
I think it is interesting to try and see what ways wood can be used to make
an airplane. I looked through wood-database.com and picked out the ones that
had at least the strength-to-weight of Douglas Fir and an elastic modulus of
not less than 1,400,000 lbf/in2. Some have very high Modulus of Rupture and
are usually very heavy as well and some of the heavy ones have very high
strength-to-weight ratios and I included them because I thought there might
be some way to use them such as spar caps or even glued up longerons and
struts with a softer lighter wood filler or even foam filler (an extreme case
I admit). Some of them have the weight and Rupture Modulus of Spruce but the
Elastic Modulus is lower so I didn't include them as direct substitutes for
Sitka. Same goes for Douglas Fir substitutes. I am only going by the data
available on the above website and there may be other reasons a certain type
of wood is not suitable for aircraft structures. All of the types below were said
to work easily and glue up well.

So, what if you lived in some exotic location where spruce was unobtanium and
you wanted to build a Pietenpol or some thing? Or maybe build a seaplane and
live out your own Tales of the Gold Monkey?



Note: s/w=(Modulus of Rupture)/(weight/ft3)



Sitka Spruce

s/w=362.5
Common Name(s): Sitka Spruce
Scientific Name: Picea sitchensis
Distribution: Northwestern North America
Tree Size: 160 ft (50 m) tall, 5 ft (1.5 m) trunk diameter
Average Dried Weight: 28 lbs/ft3 (455 kg/m3)
Specific Gravity (Basic, 12% MC): .36, .46
Janka Hardness: 510 lbf (2,270 N)
Modulus of Rupture: 10,150 lbf/in2 (70.0 MPa)
Elastic Modulus: 1,600,000 lbf/in2 (11.03 GPa)
Crushing Strength: 5,610 lbf/in2 (38.7 MPa)
Shrinkage: Radial: 4.3%, Tangential: 7.5%, Volumetric: 11.5%, T/R Ratio: 1.7




Douglas Fir

s/w=347.2

Common Name(s): Douglas-Fir
Scientific Name: Pseudotsuga menziesii
Distribution: Western North America
Tree Size: 200-250 ft (60-75 m) tall, 5-6 ft (1.5-2 m) trunk diameter
Average Dried Weight: 36 lbs/ft3 (570 kg/m3)
Specific Gravity (Basic, 12% MC): .45, .57
Janka Hardness: 620 lbf (2,760 N)
Modulus of Rupture: 12,500 lbf/in2 (86.2 MPa)
Elastic Modulus: 1,765,000 lbf/in2 (12.17 GPa)
Crushing Strength: 6,950 lbf/in2 (47.9 MPa)
Shrinkage: Radial: 4.5%, Tangential: 7.3%, Volumetric: 11.6%, T/R Ratio: 1.6




Alskan Yellow Cedar

s/w=358
Average Dried Weight: 31 lbs/ft3 (495 kg/m3)
Modulus of Rupture: 11,100 lbf/in2 (76.6 MPa)
Elastic Modulus: 1,420,000 lbf/in2 (9.79 GPa)
Crushing Strength: 6,310 lbf/in2 (43.5 MPa)


Cedar of Lebanon

s/w=371.5
Average Dried Weight: 32 lbs/ft3 (510 kg/m3)
Modulus of Rupture: 11,890 lbf/in2 (82.0 MPa)
Elastic Modulus: 1,465,000 lbf/in2 (10.10 GPa)
Crushing Strength: 6,090 lbf/in2 (42.0 MPa)



Port Orford Cedar

s/w=423.8
Average Dried Weight: 29 lbs/ft3 (465 kg/m3)
Modulus of Rupture: 12,290 lbf/in2 (84.8 MPa)
Elastic Modulus: 1,646,000 lbf/in2 (11.35 GPa)
Crushing Strength: 6,080 lbf/in2 (41.9 MPa)



Loblolly Pine

s/w=365.7
Average Dried Weight: 35 lbs/ft3 (570 kg/m3)
Modulus of Rupture: 12,800 lbf/in2 (88.3 MPa)
Elastic Modulus: 1,790,000 lbf/in2 (12.30 GPa)
Crushing Strength: 7,130 lbf/in2 (49.2 MPa)



Radiata Pine

s/w=358.8
Average Dried Weight: 32 lbs/ft3 (515 kg/m3)
Modulus of Rupture: 11,480 lbf/in2 (79.2 MPa)
Elastic Modulus: 1,458,000 lbf/in2 (10.06 GPa)
Crushing Strength: 6,030 lbf/in2 (41.6 MPa)



Scots Pine

s/w=355.3
Average Dried Weight: 34 lbs/ft3 (550 kg/m3)
Modulus of Rupture: 12,080 lbf/in2 (83.3 MPa)
Elastic Modulus: 1,461,000 lbf/in2 (10.08 GPa)
Crushing Strength: 6,020 lbf/in2 (41.5 MPa)



Shortleaf Pine

s/w=374.3
Average Dried Weight: 35 lbs/ft3 (570 kg/m3)
Modulus of Rupture: 13,100 lbf/in2 (90.3 MPa)
Elastic Modulus: 1,750,000 lbf/in2 (12.10 GPa)
Crushing Strength: 7,270 lbf/in2 (50.1 MPa)



Slash Pine

s/w=397.6
Average Dried Weight: 41 lbs/ft3 (650 kg/m3)
Modulus of Rupture: 16,300 lbf/in2 (112.4 MPa)
Elastic Modulus: 1,980,000 lbf/in2 (13.70 GPa)
Crushing Strength: 8,140 lbf/in2 (56.1 MPa)



California Red Fir

s/w=384
Average Dried Weight: 27 lbs/ft3 (435 kg/m3)
Modulus of Rupture: 10,370 lbf/in2 (71.5 MPa)
Elastic Modulus: 1,483,000 lbf/in2 (10.23 GPa)
Crushing Strength: 5,410 lbf/in2 (37.3 MPa)



Noble Fir

s/w=415
Average Dried Weight: 26 lbs/ft3 (415 kg/m3)
Modulus of Rupture: 10,790 lbf/in2 (74.4 MPa)
Elastic Modulus: 1,619,000 lbf/in2 (11.17 GPa)
Crushing Strength: 5,730 lbf/in2 (39.5 MPa)



Pacific Silver Fir

s/w=379.3
Average Dried Weight: 27 lbs/ft3 (435 kg/m3)
Modulus of Rupture: 10,240 lbf/in2 (70.6 MPa)
Elastic Modulus: 1,681,000 lbf/in2 (11.59 GPa)
Crushing Strength: 6,060 lbf/in2 (41.8 MPa)



White Fir

s/w=373
Average Dried Weight: 26 lbs/ft3 (415 kg/m3)
Modulus of Rupture: 9,700 lbf/in2 (66.9 MPa)
Elastic Modulus: 1,485,000 lbf/in2 (10.24 GPa)
Crushing Strength: 5,740 lbf/in2 (39.6 MPa)



Poplar

s/w=348.3
Average Dried Weight: 29 lbs/ft3 (455 kg/m3)
Modulus of Rupture: 10,100 lbf/in2 (69.7 MPa)
Elastic Modulus: 1,580,000 lbf/in2 (10.90 GPa)
Crushing Strength: 5,540 lbf/in2 (38.2 MPa)



Western Hemlock

s/w=389.7
Average Dried Weight: 29 lbs/ft3 (465 kg/m3)
Modulus of Rupture: 11,300 lbf/in2 (77.9 MPa)
Elastic Modulus: 1,630,000 lbf/in2 (11.24 GPa)
Crushing Strength: 7,200 lbf/in2 (37.3 MPa)



Sapele

s/w=379.3
Average Dried Weight: 42 lbs/ft3 (670 kg/m3)
Modulus of Rupture: 15,930 lbf/in2 (109.9 MPa)
Elastic Modulus: 1,746,000 lbf/in2 (12.04 GPa)
Crushing Strength: 8,750 lbf/in2 (60.4 MPa)



Black Spruce

s/w=360.7
Average Dried Weight: 28 lbs/ft3 (450 kg/m3)
Modulus of Rupture: 10,100 lbf/in2 (69.7 MPa)
Elastic Modulus: 1,523,000 lbf/in2 (10.50 GPa)
Crushing Strength: 5,410 lbf/in2 (37.3 MPa)



Red Spruce

s/w=354.8
Average Dried Weight: 27 lbs/ft3 (435 kg/m3)
Modulus of Rupture: 9,580 lbf/in2 (66.0 MPa)
Elastic Modulus: 1,560,000 lbf/in2 (10.76 GPa)
Crushing Strength: 4,870 lbf/in2 (33.6 MPa)



Lati

s/w=376.7
Average Dried Weight: 49 lbs/ft3 (785 kg/m3)
Modulus of Rupture: 18,460 lbf/in2 (127.3 MPa)
Elastic Modulus: 2,147,000 lbf/in2 (14.81 GPa)
Crushing Strength: 9,070 lbf/in2 (62.5 MPa)



Black Walnut

s/w=356.1
Average Dried Weight: 41 lbs/ft3 (655 kg/m3)
Modulus of Rupture: 14,600 lbf/in2 (100.7 MPa)
Elastic Modulus: 1,680,000 lbf/in2 (11.59 GPa)
Crushing Strength: 7,580 lbf/in2 (52.3 MPa)



English walnut

s/w=394.1
Average Dried Weight: 41 lbs/ft3 (655 kg/m3)
Modulus of Rupture: 16,160 lbf/in2 (111.5 MPa)
Elastic Modulus: 1,568,000 lbf/in2 (10.81 GPa)
Crushing Strength: 7,280 lbf/in2 (50.2 MPa)



Cucumber tree (Cucumber Magnolia)

s/w=372.7
Average Dried Weight: 33 lbs/ft3 (530 kg/m3)
Modulus of Rupture: 12,300 lbf/in2 (84.8 MPa)
Elastic Modulus: 1,820,000 lbf/in2 (12.55 GPa)
Crushing Strength: 6,310 lbf/in2 (43.5 MPa)



Camphor

s/w=353.6
Average Dried Weight: 33 lbs/ft3 (520 kg/m3)
Modulus of Rupture: 11,670 lbf/in2 (80.5 MPa)
Elastic Modulus: 1,676,000 lbf/in2 (11.56 GPa)
Crushing Strength: 5,820 lbf/in2 (40.1 MPa)



Canarywood

s/w=358
Average Dried Weight: 50 lbs/ft3 (795 kg/m3)
Modulus of Rupture: 17,900 lbf/in2 (123.5 MPa)
Elastic Modulus: 2,285,000 lbf/in2 (15.76 GPa)
Crushing Strength: 9,550 lbf/in2 (65.9 MPa)



Turkey Oak

s/w=368.2
Average Dried Weight: 45 lbs/ft3 (720 kg/m3)
Modulus of Rupture: 16,570 lbf/in2 (114.3 MPa)
Elastic Modulus: 1,568,000 lbf/in2 (10.81 GPa)
Crushing Strength: 8,170 lbf/in2 (56.4 MPa)



Wild Cherry

s/w=384.1
Average Dried Weight: 39 lbs/ft3 (620 kg/m3)
Modulus of Rupture: 14,980 lbf/in2 (103.3 MPa)
Elastic Modulus: 1,529,000 lbf/in2 (10.55 GPa)
Crushing Strength: 7,250 lbf/in2 (50.0 MPa)



Direct substitues for Spruce:

Port Orford Cedar s/w=423.8

Noble Fir s/w=415

Pacific Silver Fir s/w=379.3

Western Hemlock s/w=389.7




Almost direct substitutes for Sitka Spruce:

Poplar (comes very close, oddly enough) s/w=348.3

Black Spruce (almost, just slightly inferior) s/w=360.7



Direct substitues for Douglas Fir:


Loblolly Pine s/w=365.7

Shortleaf Pine s/w=374.3
 
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