Back in ?81 when I started my KR2 I thought $3.50 per lineal foot of aircraft grade Sitka Spruce was a little high so I went to the one and only lumber yard here in John Day and bought a clear edge grain board of Douglas-fir to see if I could make aircraft material. Sawed out 5/8? width stringers that looked darn good, and at $1.10 a lineal foot for six inch wide boards the price was right.
Of course a planed one inch board is actually 11/16? thick, so it added a little extra. And per the FPL book Douglas-fir is 10% heavier and 10% stronger than Sitka Spruce. And is an acceptable substitute for spruce if it meets the grading specs. Also clear edge grain western hemlock meeting grading specs can be used as a direct spruce substitute. When I went back to the lumber yard to buy more wood and the owner found out that I was building an airplane he helped me sort out the best wood. Turned out that he and his wife pursued their private pilot training in the past and given up. My building and working towards my pilot license inspired them to continue and eventually buy a plane. I laminated up my spar caps using the same Douglas-fir wood and after 30 years of flying with 1501.1 logged hours in the air, and plenty of high-g maneuvers and some real hard landings the airframe has held up well. About to start the engine rebuild so come spring I hope to be back in the air again. Not bad for a seventy nine year old codger. Dave F
