US3140685A - Propeller stabilized and controlled torpedoes - Google Patents

Description

T. G. LANG July 14, 1964 PROPELLER STABILIZED AND CONTROLLED TORPEDOES Filed NOV. 5, 1958 2 Sheets-Sheet 1 m MW m VG s A w m E m flm 0 T V. T B A mm 3 a 5 3 ll .11! Q9 F a m m. 8 Y 9 m mm mm a t mm 2 ll I F N N I 1 Q N July 14, 1964 1'. e. LANG 3,140,635

PROPEZLLER STABILIZED AND CONTROLLED TORPEDOES Filed Nov. 5. 1958 2 Sheets-Sheet 2 INVENTOR.

/ i9 5 THOMAS s. LANG 4! ATTofilYg.

United States Patent Ofifice 3,140,685 Patented July 14, 1964 tary of the Navy Filed Nov. 5, 1958, Ser. No. 772,146 4 Claims. (Cl. 114-43 (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to underwater vehicles and more particularly to improvements in propulsion, stabilizing and controlling apparatus for torpedoes.

It is well known that torpedo hulls of conventional shape, generally defined as circular in cross section with an ogival nose and tapered tail section, are inherently unstable in maintaining a desired course due to the lack of symmetry of the hydrodynamic forces acting on the hull. It has, accordingly, been conventional practice to provide such torpedoes with fixed fins at the tail, usually four in number, disposed in the vertical and horizontal planes. The hydrodynamic forces acting on such fins tend to stabilize, in pitch and yaw, the otherwise unstable hull and keep it on its desired course when it tends to deviate from same. It is also known that propellers. in addition to their propulsive function, tend to stabilize torpedoes similar to fins. The development of torpedoes of the type propelled by rotating propellers and stabilized by fixed fins to operate at greater speeds has created severe problems in attempting to produce torpedoes which operate quiet and cavitation-free. These are important factors to be considered with the advent of the homing torpedo and increased speeds required of same for it to adequately intercept faster moving targets. A few of these and other problems may be briefly noted. For example, very small misalignments of fixed fins which may result from manufacturing tolerances or handling of a torpedo introduce large spurious moments on the torpedo adversely affecting its performance. Shrouded propellers have been employed to suppress propeller cavitation but these are expensive and introduce stability and control problems. The heavy loading on conventional propeller blades operating in the wake of stabilizing fins is also conducive of cavitation. From those considerations it becomes apparent that the propeller-fixed fin combination is not necessarily the ideal arrangement for all torpedoes for all purposes. The desirability of eliminating the stabilizing fins normally employed on a torpedo hull ahead of the propeller has been recognized in a recent development as disclosed in the copending application of Barnes W. McCormick et al., Serial No. 668,267, filed June 26, 1957. In this development a single propeller is employed at the rear end of a finless tail cone, behind which is disposed a multi-bladed fixed fin, the blades of which are suitably shaped to produce equal and opposite torque of the propeller to thus effect a zero torque on the torpedo hull.

The present invention advances the development of the prior art, generally referred to, by a new concept, which, in its broadest aspects, provides a torpedo which is stabilized by contra-rotating propellers without the use of fixed stabilizing fins, this being the primary object of the invention.

Another object is to both propel and stabilize a torpedo against pitch and yaw with contra-rotating propellers without the use of fixed stabilizing fins.

Another object, in a preferred embodiment of the invention, is to propel, stabilize and directionally control a torpedo with contra-rotating propellers without the use of fixed stabilizing fins and movable control surfaces, such as conventional rudders and elevators.

Another object is to reduce propeller cavitation by employing relatively low speed, large diameter, lightly loaded, contra-rotating propellers.

Another object is to provide improvements in apparatus for opposing roll moments of torpedoes having substantially torque balanced contra-rotating propellers.

Another object is to provide a torpedo, the turning tendency of which is unaffected by damage to or misalignment of certain of its parts.

Further objects, advantages and salient features will become more apparent from a consideration of the description to follow. the appended claims, and the accompanying drawing, in which FIGS. 1 to 3 are exemplary of the preferred embodiment of the invention above referred to, and wherein:

FIG. 1 is a longitudinal central section of the rearmost portion of the tail cone of a torpedo;

FIG. 2 is an enlarged section taken on line 22, FIG. 1;

FIG. 3 is a side elevation of a portion of the tail cone and a portion of the torpedo at its largest diameter showing, also, one form of roll control; and

FIGS. 4A, 4B and 4C illustrate various forms of directional controls which may be employed in lieu of the preferred embodiment, above referred to.

Referring in detail to the drawing (FIG. 3), the torpedo 10 comprises any conventional casing or hull having an intermediate section 11 and a tail cone section 12, the former having the maximum diameter of the torpedo. As shown in this figure propellers 13, 14 are the same diameter as the maximum diameter of the torpedo.

Referring now to FIG. 1, the tail cone is provided with a pair of coaxial shafts 15, 16, mounted for rotation in bearing 17 and rotated at their forward ends by any suitable contra-rotating power supply, illustrated as the armature 18 and field 19 of an electric motor, connected to the shafts for rotating same in opposite directions and distributing equal torque thereto. Motors of this type are well known both in general applications of power transmission and in the torpedo art hence specific details have been omitted in the interests of clarity. Shaft 16 is connected to its rearward extension 16a by a conventional universal joint 20 while shaft 15 is connected to its rearward extension 15:: by a conventional universal joint, this being in the form of a splined sleeve 21, the splines of which engage curved mating splines 22, 22a disposed on shafts 15, 15a, respectively. A spherical type conventional anti-friction bearing 23, the inner and outer races of which may oscillate relatively about point 24 forms a support for shaft 15a on shaft 15. The rear inside face of the tail cone is provided with a concave spherical surface 25, the radius of which is the distance to point 24. A slideable swivel plate 26 having a mating convex spherical face slideably engages surface 25 so that the axis of shafts a, 16a may be oriented to various points on surfaces of cones having their apex at point 24. Shaft 15a, journaled in a bearing 27 and supported by swivel plate 26 extends through the rear end of the tail cone and is secured in any desired manner to forward propeller 13. Shaft 16a, journaled in shaft 15a and in bearing 28, extends to the rear of propeller 13 and is similarly secured to rear propeller l4. Suitable seals for preventing undesired fluid leakage into the torpedo hull or into or out of the various parts of the mechanisms may be employed as desired.

To effect angular orientation of shafts 15a, 16a relative to torpedo axis 29 there is provided a roller bearing 30 contained in an orientable block 31, the lateral movement of which is controlled by four hydraulic actuators 32 having pistons 33 the inner ends of which engage the bearing block in any suitable manner such as by abutments 34 having ball contacts engaging block 31. The actuators may be hydraulically connected to any conventional type hydraulic source which will move opposite pistons in opposite directions thereby disposing the axis of shafts 15a, 16a at any desired angular position relative to axis 29. Since hydraulic control actuators of this general type are employed for actuating the azimuthal (yaw) and elevational (pitch) rudders of torpedoes, further details are omitted in the interests of clarity. It is to be understood, however, that the actuators are under the control of the torpedo guidance system and function to guide the torpedo, by orientation of its propellers, in a manner similar to conventional guidance by rudders.

While shafts 15, 1.6 will preferably be torque balanced with respect to each other, bearing friction loss will apply a minor torque to the torpedo hull tending to cause roll. This may be compensated for in various ways. For example, the weight of the torpedo may be distributer' so that it is pendulous by choosing a center of gravity below axis 29. As illustrated in FIG. 3, an upper fin 45 and lower fin 46 are employed with a torpedo having the weight so distributed, the area of the lower fin being greater than that of the upper fin whereby the differen tial area serves the purpose of opposing the pendulou: centrifugal forces during turns while the sum of the fin areas reduces transient roll during turns. Shown in FIG. 1 is the preferable device for this purpose comprising a friction brake 40 which may be pivoted about pivot 41 to selectively engage brake shoes 42, 43 with the rotatable members 19, 18, respectively. Any suitable roll sensing device, such as a restrained pendulum, may control actuator rod 44 to selectively engage one of the oppositely rotating brake shoes and thereby impart an opposing roll torque to the hull in either of opposite directions.

Referring now to FIGS. 4A, 4B and 4C, these embodiments of the invention are the same as that described for FIGS. 1 to 3 except that the propellers rotate about a fixed axis, as in conventional torpedoes, and small movable rudders are provided for azimuthal, elevational and roll control, these functioning in a manner similar to the conventional rudders provided on prior art torpedoes.

FIG. 4A illustrates the tail cone of a torpedo provided with pairs of rudders and FIGS. 4B and 4C illustrate two different locations of similar rudders disposed on nose sections of torpedoes. In any of these figures, as compared with the preferred embodiment of the invention, the rudders produce somewhat increased overall drag to the torpedo. The embodiment of FIG. 4A also tends to produce propeller cavitation due to its wake effects resulting from large deflections and the close forward proximity to the propellers. Nose rudders, as illustrated in FIG. 4B require larger deflection for turning, and may tend to eavitate. The drag of the torpedo is noticeably increased with the addition of any fins. From the considerations, aforesaid, it becomes apparent that where optimum torpedo performance is desired the control means of the preferred embodiment has certain advantages since it produces, in addition to the advantageous effects previously mentioned, the quickest turn rate for the least deflection (of the propeller shafts), the least drag, and minimized cavitation.

The propellers employed may follow known design criteria but differ in that they are of large diameter (approximately the maximum diameter of the torpedo). Their average cord length should be large as compared with the smaller conventional highly loaded propellers This will result in some decrease in propeller efiiciency since they will have surface areas larger than necessary for propulsion but they will be more eflicient than the combination of the conventional smaller propellers and the associated fixed fins required for stabilization. It can be shown that the conventional combination just referred to has approximately 15% greater drag than the hull of this invention used without the stabilizing fins. As to the average pitch of the blades, it will be apparent that if the pitch angle is 0, that is, the plane of the blades is perpendicular to the axis of rotation, the blades produce no propulsion, and also have no stabilizing effect. If this pitch angle is now increased to the extreme of so that the blades now become flat paddles in planes passing through the axis of rotation they again produce no propulsive effect but produce maximum stabilization since they now act as fins disposed in the direction of torpedo movement, like fixed fins, differing in that they rotate. Since the blades obviously must produce both propulsion and stabilization their average pitch must therefore be between these two extremes so that the optimum combination of propulsive force (forward component of force on the blades) and stabilizing force (lateral stabilizing component of force on the blades) is chosen to produce the desired combination of these forces. This will vary for the particular application of the invention and the proper design may be chosen by application of propeller design techniques known in the art. Since the rear propeller operates in the wake of the front propeller and hence in a less favorable hydrodynamic stream than the front propeller, it may be desirable, where cavitation must be minimized, to rotate the rear propeller at a lower speed than the front propeller. Cavitation may also be minimized in some instances by employing propellers of unequal diameters. Similarly, the propellers may be of unequal diameters and of unequal areas and rotatable at ditferent speeds.

As referred to in the penultimate object, it is well known that misaligned or damaged stabilizing fins of conventional torpedoes produce a tendency to turn. In the present invention, while the propellers serve the function of fixed stabilizing fins, a misaligned or damaged propeller blade does not affect the turning because any tendency to produce a side force at a particular point of rotation is balanced by an equal and opposite restoring force when the blade is disposed at a point opposite to the particular point referred. As will be apparent, the same effect obtains regardless of the number of damaged or misaligned propeller blades.

It can be shown that the requisite side or lateral controlling forces created by orienting the axis of the propellers away from the axis of the torpedo can be attained with small angles of orientation. In an exemplary torpedo having a finless hull, but otherwise comparable to a prior art hull with stabilizing fins, a 1 deflection produces an 18 per second turn rate, adequate for most homing torpedoes.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A torpedo having an elongated hull devoid of fixed yaw and pitch stabilizing fins, tandem contra-rotating torque balanced propellers disposed at its rear end, rotatable about its longitudinal axis, said propellers having a diameter at least substantially the maximum diameter of the hull and of suflicient area to solely effect stabilization of the torpedo in yaw and pitch, means for rotating the propellers, and means for steering the torpedo to move it in desired directions.

2. A torpedo in accordance with claim 1 wherein said means for steering comprises means for selectively moving the axis of rotation of the propellers angularly away from said longitudinal axis in any direction.

3. A torpedo in accordance with claim 1 including means for opposing roll moments which tend to roll the torpedo about said longitudinal axis.

4. A torpedo in accordance with claim 3 wherein the means for opposing roll moments comprises means within the torpedo for applying torque to the hull in either of opposite directions about its longitudinal axis by power delivered from the means for rotating the propellers.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Marine Engineers Handbook, 1945, McGraw-Hill, New York, 1408-1423.

Claims (1)

1. A TORPEDO HAVING AN ELONGATED HULL DEVOID OF FIXED YAW AND PITCH STABILIZING FINS, TANDEM CONTRA-ROTATING TORQUE BALANCED PROPELLERS DISPOSED AT ITS REAR END, ROTATABLE ABOUT ITS LONGITUDINAL AXIS, SAID PROPELLERS HAVING A DIAMETER AT LEAST SUBSTANTIALLY THE MAXIMUM DIAMETER OF THE HULL AND OF SUFFICIENT AREA TO SOLELY EFFECT STABILIZATION OF THE TORPEDO IN YAW AND PITCH, MEANS FOR ROTATING THE PROPELLERS, AND MEANS FOR STEERING THE TORPEDO TO MOVE IT IN DESIRED DIRECTIONS.

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