 | CHAPTER VIII.
THE REAL FLYING MACHINE. Flying Machines: Construction and Operation: A Practical Book Which Shows, in Illustrations, Working Plans and Text, How to Build and Navigate the Modern Airship. |  |
Why Wood Is Favored.
A frequently asked question is: "Why is not aluminum, or some similar metal, substituted for wood." Wood, particularly spruce, is preferred because, weight considered, it is much stronger than aluminum, and this is the lightest of all metals. In this connection the following table will be of interest:
| Material | Weight per cubic foot in lbs. | Tensile Strength per sq. inch in lbs. | Compressive Strength per sq. inch in lbs. |
| Spruce | 25 | 8,000 | 5,000 |
| Aluminum | 162 | 16,000 | ...... |
| Brass (sheet) | 510 | 23,000 | 12,000 |
| Steel (tool) | 490 | 100,000 | 40,000 |
| Copper (sheet) | 548 | 30,000 | 40,000 |
As extreme lightness, combined with strength, especially tensile strength, is the great essential in flying-machine construction, it can be readily seen that the use of metal, even aluminum, for the framework, is prohibited by its weight. While aluminum has double the strength of spruce wood it is vastly heavier, and thus the advantage it has in strength is overbalanced many times by its weight. The specific gravity of aluminum is 2.50; that of spruce is only 0.403.
| CHAPTER VIII.
THE REAL FLYING MACHINE. Flying Machines: Construction and Operation: A Practical Book Which Shows, in Illustrations, Working Plans and Text, How to Build and Navigate the Modern Airship. | |