GrantR
Well-Known Member
I figured this up strictly for my entertainment with no intent on building something based on this. I am just trying to understand how wing loading and bending moments work together and how a spar is loaded from wing tip to root.
Please see the attached picture. I based this on an airplane with a weight of 600 pounds, a 5’ X 24’ wing 120 sq feet, wing loading of 5 pounds per square foot.
Based solely on this number, the bending moment or foot pounds of torque applied to the root of one 12 foot wing half is 1650 pounds.
The way I did this seems logical to me even though this is probably way off. What I did is determined the wing area in one foot increments. So 5’ X 1’= 5 square feet X the wing loading (5) X the moment (wing span) to the root. I did this by the foot and added the numbers together to come up with the total.
The reason I did it this way is because the wing supports the weight of the airplane across the entire wing. With it being known that each square foot supports 5 pounds, this seemed like the way to figure the loading.
I recalculated it the same except I did it in ¼ foot increments which worked out to 1.25 square feet per ¼ foot and 6.25lb per ¼ foot. The bending moment or foot pounds of torque applied to the root of one 12 foot wing half is 1763 pounds or 113 pounds more.
Please see the attached picture. I based this on an airplane with a weight of 600 pounds, a 5’ X 24’ wing 120 sq feet, wing loading of 5 pounds per square foot.
Based solely on this number, the bending moment or foot pounds of torque applied to the root of one 12 foot wing half is 1650 pounds.
The way I did this seems logical to me even though this is probably way off. What I did is determined the wing area in one foot increments. So 5’ X 1’= 5 square feet X the wing loading (5) X the moment (wing span) to the root. I did this by the foot and added the numbers together to come up with the total.
The reason I did it this way is because the wing supports the weight of the airplane across the entire wing. With it being known that each square foot supports 5 pounds, this seemed like the way to figure the loading.
I recalculated it the same except I did it in ¼ foot increments which worked out to 1.25 square feet per ¼ foot and 6.25lb per ¼ foot. The bending moment or foot pounds of torque applied to the root of one 12 foot wing half is 1763 pounds or 113 pounds more.