US2111093A

US2111093A - Propeller

Info

Publication number: US2111093A
Application number: US44073A
Authority: US
Inventors: Droullard Edward
Original assignee: Individual
Current assignee: Individual
Priority date: 1935-10-07
Filing date: 1935-10-07
Publication date: 1938-03-15
Anticipated expiration: 1955-03-15

Description

March 15, 1938. E. DROULLARD 2,111,093

PROPELLER Filed 001;. 7, 1935 15 INVENTOR 5014/??? DROUZLHED ATTORNEY.

Patented Mar. 15, 1938 UNITED STATES PROPELLER Edward Droullard, Detroit, Mich. Application October 7, 1935, Serial No. 44,073

3 Claims.

The present invention pertains to a novel propeller used in connection with a boat, although the invention is not limited to any particular form of boat in combination with the propeller.

The object of the invention is to provide a propeller of higher than usual efliciency.

In connection with this object, I have observed that the leading edge of most propeller blades of the prior art lies perpendicular to the axis of the shaft, regardless of the slope of the body of the blade. In the present invention, the leading edge of the blade lies at the desired pitch angle to the axis of the shaft, the body of the blade being substantially in a plane with the leading edge, the blade being without the usual twist although scooped slightly at its rear face and concave slightly at its forward face for better action in the water.

Further the conventional propeller blade lies entirely within a quarter circle around the propeller shaft. In the present invention, the blade lies in two quadrants around the propeller shaft axis, presenting a leading edge prolonged across the axis of the shaft in a substantially straight 5 line at a pitch angle to the axis.

The invention is fully disclosed by way of example in the following description and in the accompanying drawing in which Figure l is a side elevation of a boat and pro- 30 pellers according to the invention;

Figure 2 is an end view;

Figure 3 is an elevation of the propeller blade, viewed perpendicularly to the face of the blade;

Figure 4 is a plan view of the blade, and

35 Figure 5 is a section on the line 5-5 of Figure 4.

Reference to these views will now be made by use of like characters which are employed to designate corresponding parts throughout.

In Figure 1 is shown a motor boat or speed boat 40 I of more or less conventional design except for certain particulars to be described below. From a point 2 approximately directly below the drivers station, the keel 3 is arched or concaved upwardly as indicated by the numeral 4, to the 45 stern. A hearing 5 is mounted in the keel at the point 2, and a combined bearing and gear casing 6 is supported in the arch near the stern. In these bearings is journaled a propeller shaft 1 with its forward end approximately two inches 50 higher than its rear end. An intermediate bearing 8 for the shaft is provided if necessary.

In the boat is provided an engine 9 with a drive shaft Ill geared at l l to the shaft 1 at a ratio of two to one. In the stem is mounted the usual rudder l2.

Since the propeller blades are mounted at intervals on the shaft 7, each is preferably formed as an integral part of a hub I3. The blade proper may best be described with relation to its leading edge 14 as seen in top plan in Figure 4. This edge 5 lies at one side of the axis of the hub for the propeller shaft, in a straight line at a fixed angle to this axis. Also, this edge is prolonged slightly at the other side of the axis as indicated by the numeral l5, so that the leading edge may be said 10 to be a substantially straight line prolonged across the propeller shaft axis at a fixed angle. From the outer end of the line 15, the trailing edge of the blade follows a downward curve on a gradually increasing radius, to a point directly below 15 the hub axis. This curve is indicated by the numeral It. From the last named point, the trailing edge of the blade slopes in a nearly straight line I! to the outer end of the line [4 but is rounded at its lower end to merge with the 20 line l6 and also at its upper end to avoid a sharp corner in meeting the line I4. I

The blade lies substantially in a plane with the line H! as distinguished from the twist in the usual propeller blade to provide the proper pitch angle beyond the shank or neck of different angle lying immediately adjacent to the hub. However, the blade is slightly dished to form a convex forward face and a concave rear face l8 for a scooping action in the water.

The distances from the axis to the bottom of curve I6 and to the outer end of line 14 are approximately equal. By reason of the leading edge being prolonged across the propeller shaft axis as previously set forth, there is provided a comparatively long cutting edge with relation to the extent of projection of the blade outwardly from the shaft, so that the length of cutting edge within a given turning radius is considerably increased. The prolongation of the leading edge across the shaft axis distributes the weight of the blade in two quadrants around the axis or on both sides of a plane passing through the axis and perpendicular to the edge I l, l5. Such construction is better balanced and more durable than in the usual case where the blade lies entirely in one quadrant around the propeller shaft axis. Although the edge I4 is longer than the edge 15, the weight of the blade is substantially equal on both sides of a normal to said edges, because of the tapering of the blade along line ll and the thinning of the metal towards the outer ends of lines l4, H.

In connection with the arched bottom, it is well known that at high speed a propeller has a tendency to sink into the water. A boat having a single propeller at the stern lifts its bow out of the water at high speed. The long propeller here disclosed would pull the boat into the water to an undesirable depth. This tendency is overcome in the present invention by the arched bottom which receives an increasing upward force from the Water at high speed. In other words, the arched bottom wedges the boat upwardly, thereby balancing to some extent the downward pull of the propeller at high speed. The water lines when standing and at high speed are indicated by the numerals l9 and 20 respectively, and the boat is always level due to the substantial length of the arch 4.

The shaft, preferably tapers from stern to bow so that the rearward force on the propellers tightens the hubs IS on the shaft. Each hub is keyedv to the shaft as indicated by the numeral 2! in.

Figure 5.

Although a specific embodiment of the invention hasbeen illustrated and described, it will be understood that various alterations in the details of construction may be made without departing from the scope of the invention, as indicated by the appended claims.

What I claim is:

1. A propeller comprising a hub, a blade mounted thereon presenting a straight leading edge at an oblique angle to said hub and prolonged across said hub, said blade having a convex rear edge extending from the outer end of said leading edge to the outer end of its prolongation, said leading edge'being substantially longer than its prolongation, the radius of curvature of said rear edge increasing from said prolongation to its intersection with a normal to the hub end of said leading edge, said rear edge sloping from said intersection to the free end of said leading edge, and the weight of said blade being substantially equal on both sides of said normal.

2. A propeller comprising a hub, a blade mounted thereon presenting a straight leading edge at an oblique angle to said hub and prolonged across said hub, said blade having a convex rear edge extending from the outer end of said leading edge to the outer end of its prolongation, said leading edge being substantially longer than its prolongation, the distance from said axis to said convex edge on the line perpendicular to said leading edge being substantially equal to the distance, from said axis to the forward end of said leading edge, the weight of .said blade being substantially equal on both sides of said line.

3. A propeller comprising a hub, a blade mounted thereon presenting a straight leading edge at an oblique angle to said hub and prolonged across said hub, said blade having a convex rear edge extending from the outer end of saidleading edge to the outer endof. its prolongation, said leading edge being substantially longer than its prolongation, said blade having its forward face dished, said leading edge being substantially longer than its prolongation, the radius of curvature of said rearedge increasing from said prolongation to its intersection with a.- normal to the hub end of. said leading edge, said rear edge sloping from said .in tersection to the free. end of said leading edge, and the weight of said blade being substantially equal onboth sides of said normal.

EDWARD DROULLARD.