Aerowerx
Well-Known Member
Question for the aerogurus on the group.
Lets say that you have a design for a plane that has an empty weight of 400 pounds. The plans call for using Spruce.
You substitute Douglas Fir. The wood will, of course, weigh 26% more but it will also be 23% stronger.
Does this increase the useful load? Increase the allowed G forces with the same useful load? Subtract from the useful load?
Same question but this time you reduce the cross sectional area of each piece by 23%.
When answering these questions, keep in mind that the solid wood parts are only a part of the total weight. So even if you increase the weight of these parts by 26%, the empty weight will have less of an increase (percentage wise).
Lets say that you have a design for a plane that has an empty weight of 400 pounds. The plans call for using Spruce.
You substitute Douglas Fir. The wood will, of course, weigh 26% more but it will also be 23% stronger.
Does this increase the useful load? Increase the allowed G forces with the same useful load? Subtract from the useful load?
Same question but this time you reduce the cross sectional area of each piece by 23%.
When answering these questions, keep in mind that the solid wood parts are only a part of the total weight. So even if you increase the weight of these parts by 26%, the empty weight will have less of an increase (percentage wise).
