According to FPL Report # 354, Aircraft Woods, Their Properties, Selection and Characteristics it seems that Yellow Poplar (Liriodenden Tulipifera) is a viable substitute for Spruce in, to quote the report, "highly stressed parts such as wing beams". According to the same report Yellow Poplar compares to Sitka Spruce as follows:
Sitka Spruce, modulus of rupture - 9400 psi, Yellow Poplar, modulus of rupture - 9100 psi
Balsam Poplar(Populus Balsamifera), a.k.a cottonwood is NOT suitable as an aircraft wood. So my question is what exactly is the Poplar that is commonly available, Yellow or Balsam?
Here is the final paragraph from the report:
Sitka Spruce, modulus of rupture - 9400 psi, Yellow Poplar, modulus of rupture - 9100 psi
Balsam Poplar(Populus Balsamifera), a.k.a cottonwood is NOT suitable as an aircraft wood. So my question is what exactly is the Poplar that is commonly available, Yellow or Balsam?
Here is the final paragraph from the report:
