Propeller With After-collision Propulsion Capability

Abstract

A propeller with two complete sets of blades on the same hub. One set has ng blades, the other short, so that in the event of collision with an object the longer blades will be the first to suffer damage thereby leaving the shorter blades undamaged and able to propel the vehicle.

Description

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.

BACKGROUND OF THE INVENTION

Submersible vehicles are finding widespread use in research and reconnaissance work at extreme depths as well as shallow water work. The nature of this work does not require high speed and the combination of low speed and high maneuverability has led to the development of the Hazelton or tandem propulsion system. The tandem propulsion system's propellers have large hubs which are annular in configuration and substantially the same dimension and contour as the hull of the vehicle. The blades are variable pitch either collectively for forward or reverse or the pitch can be varied cyclically at selected positions on the circumference, relative to the hull, thereby providing perpendicular motion. Thus, the six degrees of freedom of motion are provided by the propellers alone. This is illustrated in U.S. Pat. Nos. 3,101,066 and 3,450,083 to Hazelton. The maneuverability of a vehicle equipped with a Hazelton propulsion system allows navigation into small and confined areas not heretofore open to a submersible when propelled with conventional screw propulsion.

The intended use, set forth above, of submersible vehicles with Hazelton tandem propellers requires protection for the blades of the system against impact with other vehicles or underwater terrain since impact is much more likely and impact could cause both loss of propulsion and maneuverability.

DESCRIPTION OF THE PRIOR ART

The relative newness of the Hazelton tandem propulsion system has generated no devices to protect such a system or to ensure after-collision capability. The only existing protection devices are those used with conventional screw propellers, and these would have to be modified or adopted for use with the tandem propulsion system. Currently, skegs, struts or cages are built onto a hull in conjunction with a rudder to protect a screw propeller. Such appendages would create excessive drag if mounted on a hull with tandem propulsion, thus requiring additional power, and would cause turbulent water in the critical area around the circumference of the hull in the path of the blades.

Thus, there has been found no effective prior art with respect to protection of the Hazelton tandem propulsion system or provision for after damage capability.

SUMMARY OF THE INVENTION

This invention is meant to provide after damage capability for propeller driven vehicles. The concept is especially useful and necessary for vehicles using the Hazelton tandem propulsion system wherein propulsion and maneuverability are both dependent upon the integrity of the propeller. The invention additionally lends itself to use with conventional screw propellers as damage or loss of propeller blades occurs in spite of protection techniques. The invention comprises two complete sets of propeller blades on a single hub with each set of blades of a different length. Also, each set of blades is dynamically balanced of itself and with respect to the other set of blades in that the blades of each set alternate with the other. Thus, if collision should damage the propeller, only the long set of blades will be damaged or broken off, leaving the shorter set of blades complete and capable of propulsion and maneuvering.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a side view of a submersible vehicle with the subject propellers thereon.

FIG. 2 is an end view of the vehicle of FIG. 1.

DESCRIPTION OF THE INVENTION

Referring now to the drawing, a submersible vehicle 10 is shown with a pair of Hazelton tandem propellers 12 installed thereon embodying the invention.

The vehicle 10 has the pair of counter-rotating Hazelton propeller assemblies 12 mounted fore and aft, as set forth in the above referred to Hazelton patents. The annular rings or hubs 14 on which the blades are mounted are at a relatively tapered section of the hull with the rings 14 conforming to the contour of the hull. The variable pitch blades 16 of the propellers 12 are mounted on the rings 14 in sets of six, as illustrated in the drawing, or in any number of four or more.

The set of six or eight blades, etc. in the Hazelton propellers lend themselves to the instant invention, since half of the total blades, i.e., three or four, lend themselves to balancing as a complete set.

Referring now to FIG. 2, the set of six blades 16 of a Hazelton propeller 12 are shown adapted to the instant invention. A primary or larger length, set of three blades 18 are spaced around the ring 14 for dynamic balance, e.g., 120.degree. apart.

The secondary, or smaller length, set of three blades 20 are also spaced for dynamic balance in between the primary blades 18. Thus, the two sets of blades 18 and 20 form a six bladed array on the ring 14, while each set is distinct.

While the drawing and above description have set forth two three-blade sets for a six blade array, it is obvious that the invention lends itself to any blade array of four or more, as long as the total number of blades are separated into two sets with each set being dynamically balanced.

The operation of a vehicle with the subject invention is not changed from a vehicle with a standard Hazelton propulsion system. However, when maneuvering in close quarters, as small, low-speed submersibles lend themselves to, if a vehicle with the instant invention installed thereon should be envolved in a collision then the primary set of blades 18 will impact on the obstruction. As these propeller systems operate in the approximate range of 30 to 90 RPM's, the impact will either force the vehicle away from the obstruction, or shear off a number of blades from the primary set and provide sufficient warning to stop the propellers. The secondary set of blades 20 will then remain untouched. Thus, after damage capability remains, whether some or all of the primary blades are lost. If some of the primary blades are not lost, a minor imbalance will remain, but the complete and balanced secondary set of blades will remain and keep the imbalance of the partial primary set of blades to a minimum. In the absence of the present invention, an impact or collision will damage or remove two or three blades or more in succession, thus removing an entire quadrant of a six or eight blade array. The resultant imbalance would render use of the propeller impossible. Also, it would be possible, due to momentum and reaction time, to shear off all the blades of a Hazelton array. In such case all control would be lost.

While the subject invention has been illustrated with respect to a relatively slow speed Hazelton propulsion system, it is obvious that it lends itself to conventional screw-type propellers whether high or low speed. In such applications the subject invention would be equally effective since the relatively high RPM's of a screw type propeller insures that the blades will impact on an object at collision for perhaps up to hundreds of RPM's before it can be stopped.

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.

Claims

What is claimed is:

1. A propeller mounted on a water submersible vehicle, comprising:

an annular hub conforming substantially to the contour of the vehicle;

an array of variable pitch blades mounted on the hub for providing a Haselton type propeller, including:

a primary set of relatively long blades for providing propulsion and manueverability of the vehicle; and

a secondary set of blades relatively shorter than the primary set for providing propulsion and manueverability with the primary set and capable of providing propulsion and manueverability after damage occurs to the primary set.

2. The propeller of claim 1, wherein:

the long blades are spaced around the hub for dynamic balance; and

the short blades are spaced around the hub between the long blades for dynamic balance.