PLANE MONSTROSITIES.—Growing out of the idea that the wing in nature must be faithfully copied, it is believed by many that a plane with a pronounced thickness at its forward margin is one of the secrets of bird flight.
Accordingly certain inventors have designed types of wings which are shown in Figs. 28 and 29.
Fig. 28 Changing centers of Pressures.
Fig 29. Bird-wing structures.
Both of these types have pronounced bulges, designed to "split" the air, forgetting, apparently, that in other parts of the machine every effort is made to prevent head resistance.
THE BIRD WING STRUCTURE.—The advocates of such construction maintain that the forward edge of the plane must forcibly drive the air column apart, because the bird wing is so made, and that while it may not appear exactly logical, still there is something about it which seems to do the work, and for that reason it is largely adopted.
WHY THE BIRD'S WING HAS A PRONOUNCED BULGE.—Let us examine this claim. The bone which supports the entire wing surface, called the (pectoral), has a heavy duty to perform. It is so constructed that it must withstand an extraordinary torsional strain, being located at the forward portion of the wing surface. Torsion has reference to a twisting motion.
In some cases, as in the bat, this primary bone has an attachment to the rear of the main joint, where the rear margin of the wing is attached to the leg of the animal, thus giving it a support and the main bone is, therefore, relieved of this torsional stress.
THE BAT'S WING.—An examination of the bat's wing shows that the pectoral bone is very small and thin, thus proving that when the entire wing support is thrown upon the primary bone it must be large enough to enable it to carry out its functions. It is certainly not so made because it is a necessary shape which best adapts it for flying.
If such were the case then nature erred in the case of the bat, and it made a mistake in the housefly's wing which has no such anterior enlargement to assist (?) it in flying.