US3398949A - Method of forming a rigid loop from a limp loop - Google Patents

Description

Aug. 8 N. o. YOUNG 3,398,949

METHOD OF FORMING A RIGID LOOP FROM A LIMP LOOP Original Filed Sept. 19, 1966 INVENTOR. NIELS O. YOUNG BY ATTORNEY United States Patent LooP Original application Sept. 19,1966, Ser. No. 595,283, now

Patent No. 3,330,557, dated-July 11, 1967. Divided'and this application June 8, 1967, Ser. No. 644,556 .2 Claims. (Cl. 2723) Y ABSTRACT on THE DISCLOSURE Method of erecting an ordinarily limp closed loop into a rigid structure :by driving the loop continuously at high speed-through a guide which serves as a constraint on only a portion ofthe loop.

This application is a division of copending application Ser.'No. 595,283, filed Sept. 19, 1966, now Patent No. 3,330,557. This invention relates to erecting systems and mor particularly to means for and method of erecting a flexible, closed loop into a substantially rigid structure.

Under ordinary circumstances, a flexible loop of material cannot assume a self-supporting configuration if it is completely compliant, i.e., lacks stiffness. The shape and size in which a flexible loop can be self-supporting depends largely upon the extent to which its degree of stiffness opposes loading, such as would bedue to gravity.

" It has now been found that a compliant flexible loop moved along itself provides an appearance of mechanical stiffness and can thus be erected to form a substantially element or line-mass formed into an endless or closed loop, a guide in which a portion of the loop is mounted so that the loop is freely movable substantially longitudinally along the guide, and means for moving the loop through the guide with speed suflicient to cause the portion of the loop not constrained by the guide to erect into a substantially rigid structure. In a preferred embodi ment the means for moving the loop is in the form of means for introducing a fluid flow into the guide with a suflicient mass velocity component directed along the longitudinal axis of the portion of the loop therein such that passage of fluid into the guide will propel the loop at the desired speed.

Other objects of the invention will in part be obvious and will in part appear hereinafter. The invention accordingly comprises the apparatus possessing the construction, combination of elements, and arrangement of parts and the method comprising the several steps and relation of one or more such steps with respect to each of the others,

all of which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims. 7

For a fuller understanding of the nature and objects of the present invention, reference should be had to the following detailed description taken in connection with the accompanying drawings wherein:

FIG. 1 is an elevational view in cross-section through a "ice simple embodiment of the principles of the present invention.

'FIG. 2 is an elevational view in cross-section through yet another-modification of a device embodying the principles of the present invention.

Referring now to FIG. 1, there is shown an embodiment of'the present inventioncomprising guide means in the form of U-bent, hollow tube 20. An ingress end 22'of tube 20 preferably is flared internally and has a'rounded lip such as is provided by ring flange 24'. The other or exit end 26 of the tube 20 need only be simply open. Flexible loop 28 is positioned so that a portion thereof extends through tube 20, loop 28 being dimensioned in cross-section so as to be freely movable through the tube. Loop 28, in the form shown in FIG. 1, is simply a beaded string or chain, the beads preferably being formed of some light-weight material such as synthetic polymers, light or hollow metals, e.g., aluminum, or the like.

The embodiment of FIG. 1 further includes means for introducing a fluid flow into tube 20 tangentially (i.e., so that a major component of its flow direction is directed substantially along the longitudinal axis of at least part of the loop in tube 20 and toward exit end 26). To this end, there is included hollow tube 30 mounted, for example, on a convex portion of tube 20 and communicating with the interior of tube 20 so that fluid introduced in open end 32 of tube 30 will flow into tube 20 substantially entirely toward exit end 26.

In operation, fluid under pressure, such as orally expelled air or water from a hose or the like, is applied to tube 30, entering therefore into tube 20 and discharging largely from exit end 26 of the latter' Because of the irregular surface of loop 28 provided by the beaded structure, the fluid flow through tube 20 drives loop 28 so that the latter moves continuously through tube 20. When the loop is driven at suflicient speed, the free portion of the loop (i.e. the loose part unconstrained by tube 20) will extend into an elongated, apparently rigid, selfsupporting configuration. The size of the loop, and therefore the extent to which it becomes self-supporting depends on a number of factors, e.g., the loop density, the cross-section diameter of the tube, the length of loop, the mass velocity of the fluid, the compliance of the loop, and others. These factors, however, are all quite variable within wide limits. Typically, the U-tube can have a bend radius of about 2 inches and an internal diameter of A". A beaded loop of polystyrene beads of diameter about 3. feet in circumference can be readily driven in such a tube by an impinging airjet, at a speed of about 60 ft./sec. The latter is more than suflicient to force the free portion of the loop into a self-supporting, elongated configuration that remains quite rigid regardless of the orientation of the axis of loop elongation with respect to gravity. The loop Will remain erected, i.e., selfsupporting, for a few seconds even after the driving fluid flow is cut off, demonstrating that its rigidity depends on its own motion and not on support provided by the driving fluid.

It is believed that the phenomenon observed occurs because the bead string or line-mass is under tension generated by its motion. For a string of density, P, moving at velocity, V, there is a tensile stress a, nearly independent of local curvature of the string, i.e.,

' Now for a loop standing up to a height h, the compressive stress ogenerated by the weight of the line mass would be g=P g where g is the acceleration due to gravity.

Since -the string cannot endure compression without collapsing, being to some extent compliant, then for the string to be self-supporting, a, must be greater than a or In other words the kinetic energy of the line-mass must alway exceed its gravitational potential energy for the loop to be in erection. The simple analysis does not explain a number of curious properties that the standing loop exhibits, and which contribute toward the fascination that the device arouses in users. For example, an impulse applied transversely of the line mass adjacent exit end 26 appears to propagate at approximately the velocity of the string toward the ingress end 22 of the device. Thus, the string follows translations of the device as if it were a rigid structure.. Rotation of the device about .the axis of elongation of the standing string reveals effects which seem gyroscopic. Thus, if so rotated, the string forms a double helix having a plurality of turns, although the upper bight of the loop tends to maintain its original orientation. When the rotation of the U-bend is stopped, the upper bight appears to precess, slowly turning and unwinding the helix until the loop again lies substantially in a single plane.

The extent to which the structure of the present invention can be modified without essentially changing the basic elements is illustrated in the embodiment of FIG. 2 wherein the guide means comprises hollow tube 40 which has a bore which is substantially straight rather than curved as in the structure of FIG. 1. Extending through the bore of tube 40 from ingress end 42 of the latter to exit end 44, is a portion of flexible endless loop 46. The loop, in this embodiment, is shown simply as an endless length of fibrous material such as a cotton string, woolen yarn or the like, with a typical hairy or fibrous and therefore uneven surface. Loop 46 can bear slubs or the like in various colors if desired, provided however that the maximum diameter of the yarn is sufliciently less than the minimum internal diameter of tube 40, thereby allowing the yarn to pass freely through the tube.

If the slubs are fairly uniformly distributed along the yarn, the motion of the yarn can produce a siren effect. Ingress end 42 of the tube preferably is slightly flared and has rounded edges to prevent undue friction between the edges of the tube and the incoming motion of the loop.

As drive means for impelling loop 46 through the tube, there is provided second hollow tube 48 mounted, as a mouthpiece or the like, so that the interior of tube 48 communicates with the interior of tube 40. In the form shown, the longitudinal axis of tube 48 is positioned normally to the longitudinal axis of tube 40, and it is, therefore, desirable to provide means for redirecting a fluid flow entering tube 40 from tube 48 so that the flow direction is substantially toward exit end 44 andtherefore has a component of mass velocity substantially along the longitudinal axis of that portion of loop 46 positioned within tube 40. To this end, tube 40 preferably includes annular chamber 50 disposed around its interior bore intermediate the ends of tube 40 and providing opening 52 along a substantially annular path into the bore of tube 40. Tube 48 opens directly into chamber 50. The portion of the bore of tube 40 from the annular opening of chamber 50 to ingress end 42 has a slightly smaller diameter than the portion of the bore from the annular opening to exit end 44. Wall of chamber 50 surrounding the bore toward ingress end 42 is preferably conical so as to present a surface canted at an angle which, when struck by a fluid flow, will redirect the fluid flow through opening 52 into the bore of tube 40 and toward exit end 44. Tube 48 is disposed so that fluid flow there- .through will be thus redirected.

In operation, the device of FIG. 2 functions in much the same manner as the device of FIG. 1. It will be 1 appreciated, however, that because tube 40 .is straight it will not of itself provide any bend or bight in loop 46. Nevertheless, when the line mass of loop 46 is driven through the tube, the loop will form a long elongated, self-supporting structure with end bends. Because the loop in this embodimentis quite light in weight, a substantial length up to several feet can readily be driven into erection with lung-power and maintained in its rigid state for several seconds. If one desires to use compressed gas sources such as carbon dioxide or tetrafluorethylene bottled tinder high pressures, loops of twenty or more feet long can readily be maintained in erection for much longer periods.

It will be apparent that a number of other modifications can readily be made without altering the basic inventive concepts. For example, the flexibility of the loop does not preclude the quality of elasticity. Thus, the loop it formed, for example, of an elastically extensibly yarn, when placed in its free standing mode will tend to elongate considerably. Although as described, the force driving the loop is derived from a fluid flow, other driving forces can be employed, for example a friction drive from a Wheel rotated by spring forces. And while the device as hereinbefore described is particularly useful as a novel interesting toy, its principles are susceptible of many other applications.

Since certain changes may be made in the above apparatus without departing from the scope of the invention herein involved it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted in an illustrative and not in a limiting sense.

What is claimed is: 1. Method of erecting a flexible, closed loop into a substantially rigid structure, and comprising the steps of: constraining said loop so that only a minor portion thereof is movable substantially along its longitudinal axis through a substantially fixed path, the remainder of said loop being unconstrained as to path, and

propelling said looping at a speed along said fixed pat sufiicient to cause said unconstrained remainder to erect into said structure.

2. Method as defined in claim 1 wherein the speed, V, at which said loop is propelled is at least that necessary to establish the relationship.

V2 h 9 where h is a linear distance of about one-half but not more than the perimeter of the closed loop and g is the ambient acceleration.

References Cited UNITED STATES PATENTS 1,966,895 7/1934 Kuhns .'46- 51 2,039,731 5/1936 Martin 46-51 2,756,737 7/ 1956 Resch 46-44 X 3,180,043 4/ 1965 Larson 40-37 3,232,557 2/1966 Winn 226--97 X FOREIGN PATENTS 639,136 11/1936 Germany. 662,613 7/ 1938 Germany.

OTHER REFERENCES Advertisement circular entitled Phony Squirts" published in 1965 by H. Fishlove and Co., 712-.20 North Franklin St., Chicago, Ill. 60610. ANTON o. OECHSLE, Primary Examiner.

A. W. KRAMER, Assistant Examiner.

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