US921423A - Screw-propeller. - Google Patents

Description

G. MAUKANESS.

SGREW PROPELLER.

APPLICATION FILED xunzz. 1907.

Patented May 11, 1909.

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r: NORRIS Pink: 60-. WAIHINGTDN, n. c.

G'. MAGKANESS. SCREW PROPELLER.

APPLIOATION FILED JAN. 22. 1907.

Patented May 11, 1909.

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G. MACKANES'S. SCREW PBQPELLEB. APPLIOATION FILED 14.11.22. 1:197.

Patented May 11, 1909.

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hurrah snares l arner enrich GEORGE MAOKANESS, or nnuinvroYNE, sYnNEY, NEW souru WALES, AUSTRALIA, ASSIGNOR or ONE-HALF ro JOHN BARNES, or MOSMAN, SYDNEY, AUSTRALIA.

SCREW-PROPE LLER.

Specification of Letters Patent.

Patented May 11, 1909.

Application filed January 22, 1907. Serial No. 353,%95.

ist, have invented certain new and useful a Improvements in and Relating to Screw- Propellers; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to screw propellers with manifold blades, and comprises the general arrangement and disposition of such blades in groups or clusters, either upon a single hub or boss, or upon a number of bosses.

In the arra igement of the blades, it is de sirable to have certain correlative positions apportioned to them so as to produce an overlapping in the line of sight in the ease of each group or cluster. As a result of this grouping of the blades, convoluted spaces or channels are created between the clusters and running aslant of the axis of the boss. The largest blade in the group, which may be duly proportioned as in practice, or it may be of some special design, would serve as a standard for the construction of the other diminished blades comprised in each group or cluster, the method of diminishing depending wholly upon the pre-determined diameters of the largest and smallest blades. For instance, in the case of a cluster comprising three blades, the area of the smallest diameter would preferably be one half of the area of the diameter of the largest blade, and the area of the diameter of the middle blade would be a mean between the maximum and minimum areas. By using the largest blade as the standard for creating the diminished blades, it would only be necessary to excise the portion extending beyond each of the smaller diameters, thus each blade would be similarly proportioned up to the limit of its diameter.

In arranging the blades in their correlative positions, the convolute so formed would be oppositely dis osed to the natural or ordinary pitch of t e screw, such an arrangement being exceptionally serviceable for utilizing the rotary currents set in motion by the smaller advance blades. It has been ascertained that, as a propeller revolves, it causes an appreciable circular current to be set in motion just beyond the tips of the screw blades. Now, by having the blades ar ranged in clusters proportioned and placed as in this invention, the rotary currents, as they travel from cluster to cluster, are disturbed or ruptured, thereby producing an aggregation of fluid pressure which extends to the principal screw blades. Such pressure increases in intensity within the convoluted channels formed between the clusters, and, flowing thence to the blades having the maximum area, an increase of speed is obtained thereby. Another distinct advantage produced by the aggregation of the fluid pressure upon the standard blades, lies in the prevention of cavitation, which hitherto has been of common occurrence, and is caused by the presence of air and watery vapor in the vicinity of the blades. It is known that where cavitation exists, the propeller is rendered less effective.

It has been found by experiment that the propellers constructed in the manner hereinafter more fully described, are productive of additional speed without necessitating the increase of the driving power or the enlargement of the fuel consumption by which the driving power is maintained.

Referring to the accompanying drawings which form part of this specification and in which similar letters are used throughout the different views to indicate similar parts: Figure 1 is an elevation, as seen loolL'ng aft, of a two bladed propeller converted according to this invention into a manifold bladed propeller. Fig. 2 is an elevation similar to Fig. 1, as seen from astern, looking forward. Fig. 3 is an elevation of a triple bladed propeller, converted according to this invention into a manifold bladed propeller, as seen looking aft. Fig. l is a similar elevation to Fig. 3, as seen from astern, looking forward. Fig. 5 is a plan, showing the manifold blades in position upon one hub or boss, as they would appear projected from Figs. 3 and 4 within the arc X to X.

In the various'figures the same method of constructing the blade has been observed, and the same proportionate diameters have been maintained, which may be ascertained by reference to the accompanying scale associated with each figure, diameter A being approximately nine feet nine inches, diameter B eight feet five inches, and diameter C six feet ten inches, the areas of which would approximately represent the predetermined proportions as previously stated. This proportion establishes the existing relationship where the number of manifold blades are" as shown in each of the figures, but such 'pro portion would necessarily vary where the number of blades is diminished or increased.

The propeller shaft D carries the elongated hub or boss E, shown in Fig. 5 parallel and as one boss, and having the conical end F. A number of bosses may be substituted if it is desired to vary the direction of the convolutes hereinafter referred to. The propeller blade G is the standard blade, suitably proportioned as may be pre-determined according to the purpose to which it is to be applied, as is customary in engineering practice. It is shown similarly proportioned in each figure to the diameter A. The blades G are likewise proportioned as far as diameter B, similarly to blade G, but having the dotted portion H, (shown cross-hatched in Figs. 1 and 2, and lying between the concentric circles A and B) excised. Blades G are similarly proportioned to blade G, as far as diameter C, the cross-hatched portion H lying between the concentric circles A and C, being excised.

In Figs. 3 and 4 the blades G, G, and G are shown in their finished form, with the tips touching the diameters A, B, and C respectively. The radial center lines G G and G are so placed that the blades will each partially overlap the other when viewed either from ahead or astern, this mode of construction being essential to obtain the curved lines G, G, (as seen in Fig. 5), and likewise the convoluted spaces or channels G one only of which is shown in Fig. 5. The essen tial direction of the said curved lines and convoluted channels is aslant of the axis of the hub or boss, and in a direction oppositely disposed to the natural or ordinary pitch of the screw. By this means the desired correlative position of each set or cluster of blades is determined with a view to insuring the flow of the fluid in the manner shown by the series of arrows on Fig. 5, thus the blades Gr are made to act upon the blades G and blades G in like manner divert the aggregated fiow on to the standard blades G, while at the same time there is a tendency to maintain a constant flow through the channels G and a commingling of the various currents (rotary and otherwise in the desired location where the most efiective results may be obtained.

It is obvious that if a series of propellers with the blades proportioned and disposed as in Fig. 5 was used instead of in combination with a boss common to all of the blades, the correlative position of each set of blades might be varied to suit the class of vessel to which the screw was to be adapted, then the curved lines, as G and G and the convoluted channels G would be subject to modification or readjustment, but the primary feature of this invention would nevertheless be maintained.

Having thus described my inveniton, what I claim as new, and desire to secure by Letters Patent is: r

1. A propeller comprising an elongated hub, a plurality of series of blades, each series having its blades increasing in length and similarly proportioned up to the limit of their respective length, and said blades in each of said series arranged aslant the hub in a direction opposite the pitch of the blades and overlapping when viewed in a direction parallel to the axis of the hub.

2. A propeller comprising an elongated GEORGE MACKANESS.

Witnesses:

JOHN J. STONE, MABEL E. DE LANE.

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