Item 1129
DESIGN: Dragonfly ~ Rotor -
Blade - 0012 - Wood - 4.75" - Core
Drawing:
xxx
Note:
Use Compufoil Professional to establish Template, Lofted and Coordinate files ??
Weight:
Density of spruce = 21.87 lb/ft3. From Wood Handbook: Wood as an Engineering Material (1987).
Density of spruce (seasoned and dry) = 450 kg/m3 = 28 lb/ft3.
Why the difference between the two?Volume of spruce for one blade plank (not considering root and tip modifications.); 4.75" x (12% of 4.75") x 78" = 211 in3 = 0.122 ft3.
Weight of spruce for one blade plank; 0.122 x 28 lb/ft3. = 3.42 pounds.
Area of cross-section of plank is 4.75" x (12% of 4.75") = 2.7075sq-in. = 43.32 sq- 1/4". Area of cross-section of airfoil is 29.1 sq- 1/4" (from;
DESIGN: Dragonfly ~ Rotor - Blade - 0012 - Leading Edge Weight Calculation). The ratio of airfoil area to rectangular area is 65%, giving 2.22 lbs. Will the humidity of the air increase the weight of the wood?Note that the composite blade is currently estimated at 4.67 lbs; and this includes a 0.66 lb tip weight.
I do not think it includes the leading edge weight.
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Last Revised: December 5, 2003