Arthur D. HILL, Jr.
Fishtail Propeller
Popular Science (Oct, 1939), p. 103
Fishtail Drive Propels Boats and Model Planes

FOR ten years, Arthur D. Hill, Jr., a California commercial fisherman, has been observing and studying how the vibrating tails of fish enable them to dart through the water at great speeds. He also noted that birds, with their flapping wings, were still more efficient in flight than the most modern of airplanes with fixed wings. Puzzling out the principles involved, Hill determined to combine the methods of bird and fish, and he has finally developed an odd fishtail drive for Propelling model airplanes, and boats ranging from toy craft up to vessels thirty-five feet in length. On tiny boats having a single rudder, Hillís fishtail mechanism is vibrated back and forth by means of an ordinary door-bell buzzer, powered by two dry-cell batteries. By reversing the rudder, the flutterings cause the craft to move backward. Dry-cell batteries also power the vibrating wings of Hillís model airplane, shown in the photograph above. When suspended from the ceiling on a string, the little ship whirls around a circular course, its wings whirring so rapidly that they become invisible. For rowboat and canoe use, the inventor connects his fishtail propellers to handles, which the operator pumps up and down. This is said to drive the boat forward three feet for every foot the power device moves. On small toy boats and planes, such as shown in the accompanying illustrations, the fishtail drives are made of wood and silk, while for the larger craft airplane linen covered with creosote is used.

Arthur D. Hill, Jr., driving a canoe through the water at high speed with his strange device copied from a fish.

Hill's fishtail-drive model plane, powered by two flashlight dry cells.

Propelling Mechanism

USP # 2,173,415

Publication date:     1939-09-19
Applicant(s):  ROLAND C HILL
Classification:  - international:     A63H23/04; A63H23/00 - European:     A63H23/04

This invention relates to improvements in  propelling mechanism and has particular reference to a propelling mechanism for a toy boat.

The principal object of this mechanism is to provide means for propelling a toy boat through the water with a minimum amount of power with a simple mechanism, and at the same time having the boat present the appearance common to boats.

Other objects and advantages will be apparent during the course of the following description.

In the accompanying drawing forming a part of this specification and in which like numerals are employed to designate like parts throughout the same,

Fig. 1 is a side elevation of my boat;

Fig. 2 is a top plan view thereof;

Fig. 3 is a modified form of my boat;

Fig. 4 is a side elevation of the propeller per se;

Fig. 5, 6, and 7 are similar views showing modified forms; and

Fig. 8 is a cross sectional view taken on  the line 8-8 of Fig. 5.

The ordinary toy boat is propelled by a clock work propeller which is very inefficient and requires a large spring, which is hard to wind, if the boat is to run for any length of time.

I have, therefore, devised a simple mechanism whereby a small battery will operate an ordinary electromagnet buzzer mechanism for a considerable period of time, the clapper of which buzzer is extended so as to vibrate a propeller within the water.

In the accompanying drawing wherein for the purpose of illustration is shown a preferred embodiment of my invention, the numeral 5 designates  the hull of the boat having cabin spaces, as shown at A and  B. Within the cabin spaces I prefer to mount my mechanism which consists of a battery 6 and an electromagnet vibrator 7. This vibrator is connected to the battery in the customary manner, and a switch is shown at  8. The armature or clapper 9 is extended outside of the cabin B and bent downwardly to form a curved section 11 beneath the water line. A member 12 serves to hold the upper end of a flexible flap 13.

In the modified form shown in Fig. 3, I have shown the same construction, with the exception that I provide two clappers so that I have two propellers 15.

The result of this construction is that when the clapper vibrates back and forth, as indicate by arrows, the flexible portion  13 will belly first to one side and then to the other, as illustrated in Fig. 8, thus producing a vibrating or propulsive force. The pendulum spring action of the clapper makes possible the use of a comparatively small amount of power and saves energy.

[ N.B. -- Or : The Milkovic Two-Stage Oscillator... Ed. ]

The construction of the propellers is shown in Figs, 5, 6, and 7 is substantially the same in that they consist of a supporting rod and flexible members secured thereto. The rods will have a substantially sharp leading edge and the flexible members will have a thin tapering following edge.

The modified forms shown in Figs 6 and 7 provide means for increasing or decreasing the amount of sag in the flexible member 13 so that the pendulum action may be governed at will. The amount of sagginess of the flexible member 13 is regulated by adjusting the length of the turnbuckle arm positioned above the support member pivoted to the clapper arm 9, as shown in Figs. 6 and 7. In Fig. 7 extra pivoted support arms are provided to be used with larger propellers so as to provide a more sensitive action without undue strain upon the flexible portion of said propellers.

It is to be understood that the form of my invention herewith shown and described is to be taken as a preferred example of the same and that various changes relative to the material, size, shape and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the subjoined claims. for instance, my invention can be used with large boats as well as small and can be adapted for use with airplanes and gliders, using a substantially similar type of propeller, although obviously designed to meet aerodynamic requirements...

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