So for example, for a 5 inch high spar only ~3 3/8" of vertical grain is required to be acceptable as a solid spar in a certfied aircraft. Based on what you have said, I would imagine your wood is acceptable for solid spar material and should be acceptable for a box spar/laminated spar cap as well unless otherwise specified by the designer.

The cross section size of the spar member is defined by the maximum allowable stress (for wood compression strength is the dimensioning case). When properly manufactured it doesn't matter if the member is composed of more than one piece. The plywood side walls of the box spar carry shear loads, hence a fiber/grain orientation of +/- 45° is ideal.

Now a box spar is designed to try to load the spar caps in pure tension or compression. So the stress and strain is intended to be along the length of the spar caps. So vertical or flat, the internal stresses of the spar caps should be lower than what is …

May 18, 2013 · My question involves the selection of lumber for the built-up (three layers) spar caps at the top and bottom of the outer spars. The spar is a boxed I-beam (with three laminations of spruce for top caps and three for bottom caps) for the first two feet, and then transitions to no "I" web (but still boxed) for the remainder, with the center cap ...

Mar 5, 2017 · Example, Minimax uses a 1/16 plywood face web on the 3/4 x 1 upper and lower caps. I am looking for aircraft that gross at 1320 or better, and use the I Beam and Plywood with upper and lower caps, or the box play and upper and lower caps. i have the dimensions for the LMA 5, aircraft spar dimensions, that wing uses 8 and 5 inch tall spars.

Grain orientation in box spars is, and has been, a hot-button topic since Orville and Wilbur. Many years ago, the plans vendor for Piel aircraft designs in North America, Gene Littner (an aircraft engineer and designer specializing in wood airframes) maintained that spar caps need to be built from flat grain rather than vertical grain laminations.

The cross section size of the spar member is defined by the maximum allowable stress (for wood compression strength is the dimensioning case). When properly manufactured it doesn't matter if the member is composed of more than one piece. The plywood side walls of the box spar carry shear loads, hence a fiber/grain orientation of +/- 45° is ideal.

Jan 16, 2013 · I am building a 1930's design that was originally built with no drain holes in the wing box spars, or the box spars for the tail or elevator. A number of builders are closing the spars without any drain holes. A Canadian builder was told …

The wing incorporates a strengthened main spar enabling the main undercarriage track to be increased to 8' 6" for even better ground handling. Provision is made for two optional 5.5 Imperial gallon (25 litre) wing tanks,. The cabin doors are hinged on the windscreen bow, but a sliding canopy can be fitted if desired.

The wing incorporates a strengthened main spar enabling the main undercarriage track to be increased to 8' 6" for even better ground handling. Provision is made for two optional 5.5 Imperial gallon (25 litre) wing tanks,. The cabin doors are hinged on the windscreen bow, but a sliding canopy can be fitted if desired.