US750036A - Ernst alfred nilsen - Google Patents

Description

No. 750,036. PATENTED JAN. 19, 1904.

E. A. NILSEN.

SCREW PROPELLER. APPLICATION FILED JUNE 27. :1903.

N0 MODEL.

Witnesses: A 'IIlVBIltDI"? V BAlfnNilsan Attorneys f Patented January 19, 1904.

PATENT OFFICE.

ERNST ALFRED NTLSEN, OF CHRISTIANIA, NORWAY- SCREW-PROPELLER.

SPECIFICATION forming part of Letters Patent No. 750,036, dated January 19, 1904.

Application filed June 27, 1903.

represent so large a part of the screw-surface.

that complete channels are produced, which very efliciently control the direction of the water. Propellers of this kind, so-called channel-propellers, I have employed very satisfactorily. On these propellers the blades,however, were exactly bent after a screw-surface, so that the pitch allover had a constant value.

The improvement in the present propeller constructionconsists therein that the blades of the channel-propeller near their front and rear edges are given a somewhat greater bending than that corresponding to the exact screw-surface. Hereby the water is more efiiciently caught and is in a certain manner pressed through the channels with a velocity which on account of the said bending of the blades always is increased and greatest at the rear edge where the water escapes. I

My invention is illustrated in the accompanying drawings, in which Figure 1 is a rear perspective View of the propeller. Fig. 2 is the propeller in side elevation, and Fig. 3 is a section along the curved line a b in Fig. 1.

In Fig. 2 the dotted line 1 2 indicates the exact screw-line. It is seen that the outer edge of one of the blades at its middle part follows this screw-line exactly; but at certain points 3 and 4 the edge begins to diverge from the screw-line, being given a sharper bending, which increases toward both ends. ()n the part 3 4 thus the pitch of this edge line is held constant, whereas the pitch is continuously increased from 3 to 5 and from 4 to 6, the pitch being greatest at both ends near 5 and 6, but in such a manner that in each separate radial line from any point in the line 5 3 4 6 to the axis of rotation for the propeller the pitch is the same on all points of this cises on the water.

Serial No. 163,415. (No model.)

radial line. If, consequently, a section is taken along a line a 6 having all its points located in the same distance from the axis, then the line 7 8 9, Fig. 3, which hereby is obtained will be exactly the same as the line 10 3 5, only'decreased in the same proportion as the distances between the axis and the lines a Z) and 5 1O 2, respectively. The point 3 in Fig. 2 therefore lies on the same radial line as the point 8 in Fig. 3. By this particular bending the blades at their end edges 11 obtain the shape like a spoon.

The propeller is assumed to rotate in direction of the arrows 12, Figs. 1 and 2. Then the water will be caught by the front edges 13 of the blades and forced through the channels until the water at the middle part 4 1O 3 of the blades has obtained a velocity corresponding to the pitch on this middle part. As soon as the water, however, has passed the point3 the pitch is beginning to increase and the water therefore from said point will run with always increasing velocity until it at the rear edge 11, where the pitch is greatest, slips the propeller with the greatest velocity and correspondingly greater propelling action on the ship. It also, by considering the perspective view, Fig. 1, is easy to imagine the energic action which the rear part of the blades exer- The action of the propeller upon thewater consequently consists therein that the Water is uniformly accelerated through the channels and "is successively brought up to the full velocity.

That a considerably better result is obtained by such a propeller than by propellers with quite constant pitch on all points of the bladesurfaces is clearly stated by the extensive practical experiments which I have done. The experiments state'that a channel-propeller acts considerably better than a usual screw-propeller, while a propeller constructed according to my present invention further gives a better result than a usual channel-propeller with exactly the same main dimensions.

It is also understood withoutfurther explaining that quite the same action is obtained.

Either the present propeller runs forward orbackward.

Having now described my lnvention, what I claim as new, and desire to secure by Letters Patent, is

A screw-propeller having blades, the middle portion of which is bent With constant pitch as a screw, and the leading and rear portion of Which are bent inversely With a variable pitch, which increases continuously from the middle to the edges, Where the pitch is greatest and in such a manner that the blades are inversely symmetrical to middle 1 axis.

In testimony whereof I have hereunto affiXed my signature, this 11th day of June, 1903, in the presence of two Witnesses.

ERNST ALFRED NILSEN.

Vitnesses:

AXEL LAHN, RICHARD TROKKE.

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