I'm looking to build an ultralight (Beaujon's Viewmaster if you're familiar with it). The fuselage is composed primarily of spruce with 6061 as the engine and wing support material. Since the engine mounts and supports are designed to be made of 6061, I can't see as vibration would be an issue. The struts are also designed to be 6061, so I don't think that it has anything to do with compression and tension. The only thing that the spruce has going for it as far as I can see on matweb is the weight, which should be easy to fix using thinner aluminum.
I'm new at this, so my assumptions could be very wrong. Does anyone have any ideas, suggestions, and/or dissuasions for me?
Thanks for the help.