US3568726A

US3568726A - Catapult tape

Info

Publication number: US3568726A
Application number: US795379A
Authority: US
Inventors: Charles S Thompson; Melvin I Weiss
Original assignee: Gulf & Western Ind Prod Co
Current assignee: Gulf & Western Ind Prod Co; Gulf & Western Industrial Products Co
Priority date: 1968-12-10
Filing date: 1968-12-10
Publication date: 1971-03-09
Anticipated expiration: 1988-03-09
Also published as: DE1941910A1; GB1253747A

Abstract

This disclosure pertains to a solid woven tape considerably wider than it is thick so as to permit coiling upon a rotatable reel of the type used in aircraft launching or recovery gear. The tape is constructed of a plurality of longitudinally extending load bearing strands which are bound together by transverse strands. The transverse strands are composed of a material having a higher initial modulus than the longitudinal strands so that lateral bulging of the tape is minimized when it is subjected to compressive forces in being wound upon a reel.

Description

United States Patent RE25,406 6/1963 Byrne etal Inventors Charles S. Thompson Vincentown, N..I.; Melvin I. Weiss, Delaware, Pa. Appl. No. 795,379 Filed Dec. 10, 1968 Patented Mar. 9, 1971 Assignee Gulf & Western Industrial Products Company Grand Rapids, Mich. Continuation-impart of application Ser. No. $75,113, Aug 25, 1966, abandoned.

CATAPULT TAPE 15 Claims, 11 Drawing Figs.

[1.8. CI. 139/415, 139/426, 244/63, 244/110 Int. Cl D03d ll/00 Field of Search l39l408- 415, 426, 420, 3831;244/63, 110; 139/408-415, 426, 420, 383; 244/63, 110

References Cited UNITED STATES PATENTS 3,148,710 9/1964 Rieger et al 139/415 3,205,119 9/1965 Paul I39/426X 3,220,216 11/1965 Byrne et al 244/63 3,296,062 1/1 967 Truslow 139/426X 3,350,037 10/1967 Thompson et al.. 244/63 3,392,938 7/1968 Cruger et al. 244/110 OTHER REFERENCES Webbing and Tapes. Man-Made Textile Encyclopedia 1959. Textile Book Publishers, Inc. New York Pages 324 to 327 Copy in Gr. 364

Primary Examiner-James Kee Chi Attorney-Meyer, Tilberry & Body m sun 3.568.726

' SHEETl0F4 INVENTORS CHARLES THOMPSON y MELVIN I. WEISS PATENTEDHAR 9m: 3.568.726

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2 or 4 lOh INVENTOR CH ES 8. THOMP BY MEL I.WEISS PATENTEUHAR 91911 $568,726

' sum 3 or a nvmvrons CHARLES S. THOMPSON y MELVIN I. WEISS PATENTED MR 9 I97! SHEET l 0F 4 PERCENT CHANGE IN WIDTH O o 2 ll III! ill] 25 IIII llll

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2o GINAL HEIGHT" PERCENT CHANGE FROM ORI INVENTORS CHARLES S.THOMPSON y MELVIN LWEISS W CATAJPULT TAPE This is a continuation-in-part of application Ser. No. 575,1 l3 filed Aug. 25, 1966, and now abandoned.

This invention pertains to the art of launching aircraft along a predetermined path by means of a catapult launching system.

The invention will be described herein with particular reference to a single tape catapult system for launching an aircraft from a stationary position poised on a runway ready for takeoff, although it will be appreciated that the invention may also be used for arresting an aircraft or in connection with other applications where a textile tape is used as the load transmitting or purchase member.

A single tape catapult system as referred to hereinabove is described and claimed in US. Pat. No. 3,228,630 issued Jan. 11, 1966, to the assignee of the present invention. In such a system the aircraft is accelerated along a catapult path from a stationary position until it reaches its required takeoff velocity. A flat, wide band, textile tape is connected to the aircraft at one end and to a catapult reel at the other end. The reel is constructed so that the tape is wound thereon in every increasing, single-stack concentric layers. As the tape is wound on the reel, by virtue of driving means connected to the reel, the aircraft is towed by the tape and accelerated for takeoff. A

The tape is preferably woven of high strength synthetic yarn such as nylon. A :major problem is encountered however where the tape tension during launch is so high as to cause portions of the tape to become crushed on the reel. That is, as the tape winds upon the reel hub, individual layers are compressed under extremely high unit pressures beneath the layers above, which layers are laid under high tension with each revolution of the reel. Experience has shown that with a tape made of synthetic materials, when the tension is great enough, the pressure on the lower tape layers is sufficient to cause localized width growth due to conditions similar to cold plastic flow occurring in the synthetic fibers. Under such conditions, the forces acting bilaterally in the tape are sufficient to cause it to bulge against the sides of the reel with enough pressure to cause it to bind in the reel but also, and more significant, to actually spread the reel sides which loss of support causes the tape to split longitudinally.

it is the main purpose of the present invention to overcome the problem referred to, namely tape split, which problem reveals itself in particular when winding a synthetic textile tape upon a reel under high tension in aircraft launching applications.

In accordance with the invention a textile tape comprises a plurality of longitudinally extending load bearing strands bound together in a tape configuration by substantially parallel strands extending above and below the load bearing strands and transversely thereto, the transverse strands being composed of a material having a higher weight to strength modulus than the other strands.

Further in accordance with the invention, the tape has an increased number of transverse strands particularly for wider and thicker tapes and although having a greater number of transverse strands, the tape thickness is nevertheless kept to a minimum without affecting its longitudinal load bearing characteristics.

More specifically, the present invention relates to a woven tape for use in apparatus for launching or recovering aircraft. in such apparatus, an elongated flat tape is wound upon a reel in ever-increasing convolutions. The tape is subjected to a very high tension force which causes a tremendous compressive force on the innermost convolutions on the reel. The tremendous compressive force causes the innermost convolutions of the tape to bulge laterally. When the tape bulges laterally, the sides of the reel are subjected to a tremendous pushing force tending to break the reel sides from their mounting hub. When this happens, the reel is not only destroyed but the tape is no longer laterally restrained and tends to split.

it has been found that a flat woven tape behaves somewhat in the manner of an incompressible fluid when compressive loads are applied to the fiat surface of the tape. This is, compressive loads applied to the flat surface of the tape are transmitted laterally so that the tape tends to bulge and the filler or weft fibers are placed in tension. Placing the filler or weft fibers in tension causes them to elongate and this in turn allows the tape to widen or bulge laterally. In order to reduce this lateral bugling and elongation of the weft fibers, the tape of the present invention is woven with weft yarn which is stiffer or less stretchy than the warp yarn. That is, the initial modulus of the weft yarn is greater than the initial modulus of the warp yearn.

The initial modulus of textile fibers is similar to Young's modulus or the modulus of elasticity for other materials, and relates to the ratio of unit stress to unit deformation. if two textile fibers are taken, and one has an initial modulus which is two times the initial modulus of the other, the one having the higher initial modulus will theoretically elongate only one-half as much as the other when both are subjected to the same unit stress. By making a woven tape with weft fibers having a higher initial modulus, the lateral bulging of the tape is substantially reduced and this in turn reduces the force against the sides of a reel as well as reducing longitudinal splitting due to excessive bulging.

The initial modules for textile yarns is a ratio of stress to elongation or strain, with the stress being expressed in grams per denier and the strain being expressed in inches per inch. The initial modulus of a given textile yarn is the same regardless of its denier. The actual initial modulus of a given textile yarn depends upon both the physical and chemical structure of the yarn. For example, the initial modulus will reflect the characteristics of the fiber from which a yarn has been made and will also reflect methods used in construction of the yarn such as twist, weave, and physical and chemical finish.

In a preferred arrangement, the initial modulus of the weft yarn is increased when the width or thickness of the tape is increased. The total elongation of a member depends upon its length. For example, a 10 inch long yarn or rubber band is capable of elongating a substantial length greater than a 5 inch yarn or rubber band. Thus, when a tape is made wider the weft yarns are longer. This makes the wider tape capable of bulging laterally a greater amount than a tape which is not so wide. in order to hold the lateral bulge of a wider tape within a certain tolerance and prevent tearing the sides from a reel, it is necessary to make the weft fibers even stiffer in order to hold the lateral bulge to the same amount as in a tape which is not so wide. In addition, a thicker tape has a greater projected side area. With the tape acting like an incompressible fluid, the total force against the side area of a unit length of thicker tape is greater than the total force against a unit length of side area of thinner tape. This is because the projected side area of a thicker tape is greater than the side area of a thinner tape. Thus, the weft fibers of a thicker tape will be subjected to a greater elongating force. In order to hold down the lateral bulge, it is necessary to increase the initial modulus of the weft yarn so that they will be of sufficient stiffness to withstand the greater elongating force and hold the bulge or lateral deformation within a certain tolerance.

For engineering structural materials, the ratio of stress to strain is often referred to as the elastic modulus, the modulus of elasticity, or Youngs modulus. In determining this modulus, a load is applied to a structural material and the stress is determined by dividing the load by the cross-sectional area of the material to which the load is applied. Thus, stress is usually in pounds per square inch. Strain is determined by dividing the change in length under load by the original unloaded length. Thus, strain is usually in inches per inch. Dividing stress by strain usually gives a ratio of stress to strain in pounds per square inch.

For textile yarns, it is extremely difficult to accurately determine the cross-sectional area. Therefore, the initial modulus of textile yarn is determined by taking a predetermined length of yarn and placing it in tension under a predetermined load. The load is then divided by denier to obtain stress rather than dividing by a cross-sectional area of the yarn. Thus, stress for textile yarns is normally expressed in grams per denier. To determine strain, the elongation of the yarn under the load is divided by the original unloaded length. Thus, strain is in inches per inch. This gives an initial modulus in grams per demet.

The initial modulus of a given textile material is the same regardless of its denier. This may be shown by theoretical example. Taking a 20 inch length of 50 denier yarn and applying a tensile load of 20 grams, let it be assumed that the elongation will be 1 inch. The stress will then be 0.4 grams per denier and the strain will be 0.05 inches per inch. Dividing stress by strain gives na initial modules of 8 grams per denier. If we take two lengths of yarn of this same material and apply the same load so that the total load on each is only 10 grams, the elongation should be only half as great. Likewise, if we take a yarn of the same material but of twice the denier the elongation should be only half as much because the cross-sectional area of the yarn will be twice as great. Thus, taking yarn of the same material but of I deniers and applying a load of 20 grams should give an elongation of only 0.5 inch. The stress on this yarn will be only 0.2 grams per denier while the strain will be 0.025 inches per inch. Dividing the stress by the strain will still give an initial modulus of 8 for this yarn. For a given steel or any other structural material, the modulus of elasticity is the same regardless of the weight or cross-sectional area of the material. Likewise, the initial modulus of a given textile yarn is the same regardless of its denier.

The primary object of the present invention is to provide a textile tape especially constructed to prevent tape splitting under the conditions imposed'by aircraft launching applications.

Another object is to provide a textile tape as referred to above having dissimilar bidirectional load bearing properties.

Still another object is to provide such a tape of minimum thickness and without decreasing the longitudinal load bearing capacity.

It is also among the objects of the invention to provide a tape composed primarily of synthetic fibers which is economical to manufacture, durable in use and has greater loading capacities than such tapes heretofore known due to an increased resistance to tape split.

These and other objects and advantages of the invention will become apparent from the following description used to illustrate the preferred embodiment thereof as read in connection with the accompanying drawings in which:

FIG. 1 is a perspective layout of a single tape catapult system showing an aircraft being launched thereby;

FIG. 2 is a purely schematic view of a catapult reel showing the tape being wound thereon under tension;

FIG. 3 is a schematic cross-sectional view taken along line 3-3 of FIG. 2 showing localized tape width growth adjacent the reel hub;

FIG. 3A is a longitudinal portion of tape showing the destructive effect of tape width growth causing the tape to split;

FIG. 4 is a fragmentary longitudinal sectional view of tape constructed in accordance with the invention;

FIG. Sis an edge view ofthe tape shown in FIG. 4;

FIG. 6 is a fragmentary cross-sectional view of the tape;

FIG. 7 is a schematic representation of the weave pattern of the transverse strands in the tape;

FIG. 8 is a fragmentary top view of the tape showing the laminations thereof;

FIG. 9 is a plot of load versus percent change in width for a standard tape as compared to one constructed in accordance with the invention; and,

FIG. 10 is a plot for tapes corresponding to those in FIG. 9 showing the effects of greater compressive strength.

Referring now to the drawings which are intended to illustrate a preferred embodiment of the invention only and not for the purpose of limiting same, FIG. 1 is a layout of a single tape catapult launcher in which an aircraft A is accelerated down a runway R along a predetermined catapult path CP extending longitudinally of and parallel to the center line of the runway. Positioned on one side of the runway R is a catapult 9 including a tape reel 10. The tap reel 10 is connected to drive means 12L and 12R. An hydraulic brake 18 is carried on each side of the reel 10 for purposes of braking it to a stop when the aircraft A becomes airborne. A textile tape 20 is secured to the reel hub 10h and extends through a tape protector conduit 24 which guides the tape from below the surface of the runway to above the runway at a turn around assembly 26. The tape is attached to a shuttle 28 adapted to tow the aircraft A down the runway. A wire rope trailing cable 32 is connected to the other end of the shuttle 28 and thence to a shuttle arrest and retract engine 40 the purpose of which is to restore the system to the ready position in preparation of the next launch.

Referring now to FIGS. 2 and 3, the catapult reel 10 is shown in the process of winding the tape 20 which is under a steady tension imposed by the conditions of launching the aircraft A. At the start of the launch, the tape 20 is placed under maximum tension in overcoming the inertia of the aircraft A. As the reel 10 rotates, the tape 20 is wrapped onto the hub 10h in ever increasing layers 20L. Due to a cinching action within the tape stack caused by slipping of one tape layer 20L relative to the next, the layers near the bottom of the stack normally become tightened more severly than those on the top. The behavior of the synthetic fibers of the tape due to the tremendous compressive loads is the chief cause of the failure referred to as tape split (FIG. 3A). First, the textile tape layers, which naturally contain some voids, become compacted. Thereafter further free compression is impossible, and the tape layers closer to the reel hub 10h bulge or widen as shown in FIG. 3. This latter effect is the most damaging as it builds up pressure on the reel sides and forces them apart sufficiently to do permanent damage to the tape. When the support of the reel sides fails, or alternatively, sufficient clearance is given to avoid damage to the reel sides, the tape may develop a longitudinal split S as shown in FIG. 3A for example. Actual cause of the split S is the failure of the transverse strands as explained hereinafter. The problem of tape split places a very restrictive limit on the performance of the launching system. That is the tension in the tape must be kept below a certain value in order to avoid this destructive failure.

The invention has as its main purpose that of overcoming the problem of tape split and thereby enabling heavy aircraft to be launched from shorter runways. Referring now to FIGS. 4-8, the textile tape 20 constructed in accordance with the preferred embodiment of the invention comprises a plurality of longitudinally extending load bearing strands 50, called stuffer, largely held together in a tape configuration by transversely extending strands 52, called filler, and longitudinally extending sinuously interwoven strands 54, called binder. The stuffer 50 is grouped into bundles 55 between each binder 54 and are arranged in upper and lower

parallel rows

58, 59. The filler 52 is a continuous strand woven above, below and in between the

stuffer rows

58, 59 and advancing longitudinally of the tape as shown in FIG. 7. Tracing in FIG. 7, the filler 52 travels from between

stuffer rows

58, 59, to the edge of the tape. Then downwardly across the bottom surface to the opposite edge, then up to the top inclined in the direction of advance, then across the top to the opposite edge, then straight down to the center and back through the middle and so on throughout the tape length. The binders 54 extend longitudinally through the tape in a series of parallel rows lacing with the filler 52 in a sinuous manner as shown in FIG. 4. Closing the tape is a case warp 60 interwoven with the top and bottom filler strands 52.

In accordance with the invention, the tape 20 has bidirectional strength properties. That is, the longitudinally extending stuffer 50 have a lower grams/denier strength modulus than the transversely extending filler 52. Furthermore, the number of filler strand ends or picks per inch of tape length and the filler ply, both of which determine the amount of transverse yarn available, are increased for wider tapes.

In one example of the principles of the present invention, let it be assumed that an ordinary tape has an 8- /inch width and a 6 ply filler with 15 picks/inch of tape length. This provides 30 transverse yarns per inch of tape length. With such a tape made of DuPont type 714 nylon yarn, the yarn has a breaking strength of 17 pounds. However, the breaking strength for yarns is normally taken at 90 percent of its theoretical strength. Multiplying 30 transverse yarns per inch of tape times 17 pounds strength per yarn and times 90 percent gives the transverse strength per inch of tape. On this basis the filler members can handle a maximum loading of 1380 lbs/inch of tape length. Taking an effective flat area of tape under compression at 50 square inches, a 5.9 inch length of tape is the increment of length exposed to bilateral forces. This is obtained by dividing 50 square inches by the 8- /zinch width. lf compressed thickness is then around 0.230 in., the development of a compressive pressure of 11,000 p.s.i. due to tape tension of 550,000 lbs., would also mean 11,000 p.s.i. acting bilaterally when assuming a fluid behavior. Therefore, this would be a load of 5.9 inches X 0.230 inches X 11,000 p.s.i. 14,900 lbs. in the projected side. However, strength resistance would be only 1380 5.9= 8140 lbs.

in contrast, for a standard 7 inch tape having 5 ply filler of 18-:picks/inch of tape length for a strength of 1415 lbs/in., the approximate effective increment of length exposed is 7 inches. With as assumed compressed thickness of 0.15 inches, the load imposed on the projected side area is 0.15 X 7 X 11,000 11,550 lbs. while resistance would be 1415 X 7 9900 lbs. This indicates that the 8-%inch tape is basically weaker in this application than the 7 inch tape, i.e., 7 inches 9900/11,550 0.857; 8- /zinches 8l40/14,900 0.547 or 31 percent less effective. Thus, by an increase in the width and thickness of the tape, the ratio of filler to stuffer is lower requiring a greater difference between the modulus of the filler and stuffer to achieve the same loading capacity.

Also in accordance with the invention, while textile material will naturally have some voids and will initially compress slightly, it is-desirable that the filler have a higher density than the stuffer, thus obtaining some improvement in the compressive strength.

In accordance with the preferred embodiment of the invention, the stuffer 50 may be of a material such as DuPont type 714 nylon having the following characteristics as shown in Table 1.

TABLE I.DUPONT TYPE 714 NYLON Yarn, den.-fils.-twist 840-140-1120 Nylon is chosen for the stuffer 50 because of the longitudinal stretch properties required in aircraft launching and arresting applications. That is, some stretchiness is desirable so as to minimize peak stresses in the tape as more fully described for example in US. Reissue Pat. No. 25,406 issued Jun. 25, 1963, to the assignee of the present invention. It has been discovered that the strength and stiffness requirements of a tape in a transverse direction are quite different from those required longitudinally. As noted above, it is not sufficient to merely increase the number of picks-per-inch since this necessarily decreases the number of load bearing strands or stuffer 50 which can be accommodated in a given thickness. Thus, in accordance with the invention, the fillerto-stuffer initial modulus ratio should be in the order of 1.5 to l or greater; that is, the filler 52 should have around 1.5 times greater strength modulus than the stuffer 50, and preferably, at least a ratio of 2 .to 1 is desirable. ln accordance with the preferred embodiment of the invention, Dacron type 68 polyester fiber has been found satisfactory, however, it will be appreciated that other types of high strength synthetic yarns, or such materials as fiberglass may also be used. In Table 11 properties of Dacron type 68 polyester fiber are listed corresponding to these for Nylon 714 listed in Table I.

TABLE II.PROPERTIES OF DACRON TYPE 68 Yarn, dcn.-fils.-twist 1100192R02 Specific gravity 1. 38 Braking strength, lbs 23. 0 Braking tenacity, gms./den 9. 5 Percent elongation at 5 lbs 2. 3 Percent elongation at 10 lbs 6. 6 Percent elongation at break 13. 7 Initial modulus, grns./den 115 From the comparison of Tables I and II it may be seen that DuPont Nylon 714 has an initial modulus of 50 grams per denier as compared to 1 15 grams per denier for Dacron Type 68 fiber. If the 714 Nylon is used for the stuffer 50 and the Dacron Type 68 for the filler 52, this indicates a theoretical increase in initial stiffness of about two to one in the transverse direction of the tape as compared to a tape which has nylon transverse yarns. As is well-known, Youngs modulus and the initial modulus is the tangent of the stress-strain curve at its initial stage. As is well-known, the stress-strain drops off quite rapidly after the ultimate strength of a material is reached. Therefore, the stiffness of the transverse yarns will not actually be doubled when under load as is indicated by the changing percent elongation of the two different yarns in Tables I and 11 under increasing load. For example, Nylon 714 elongates 6.9 percent under a five pound load while Dacron 68 elongates only 2.3 percent under the same load. Thus, the stiffness of Dacron 68 is more than double that of Nylon 714 under light loads. However, the elongation of Nylon 714 at its breakingpoint is 18.5 percent while the elongation of Dacron 68 is 13.7 percent. Thus, the stiffness of Dacron 68 is only around 5 percent greater than Nylon 714 at the breaking point. At any rate, the present invention contemplates operating loads well below the breaking point of the transverse yarns so that the stiffness of such yarns is substantially greater than the warp yarns.

Denier refers to a unit of fineness for yarn equivalent to yarn 9,000 meters of which would weigh one gram, i.e., 9,000 meters of 15 denier yarn would weigh 15 grams. The grams per denier basis at braking tenacity is 9.5 vs. 9.2 which gives a little better than 3 percent improvement in density and a corresponding improvement in resistance to compression.

In developing a test procedure for evaluating textile tape it should be understood that the following is merely exemplary of one procedure and others may be engineered producing comparable results. The test procedure suggested is to prepare samples of tape having a 50 square inch area, e.g., for an 8- /2 inch tape the length would be approximately 5.9 inches. Since it is assumed that the reel makes about revolutions during the launch, ideally the stack tested would be about 100 samples high; however, for practicality only about 50 samples are stacked up for a loose stack height of about 15 inches. The load is applied directly onto the 50 square inch area and readings are taken by calipers of the width and length growth and decrease in height. Destructive failure occurs at a machine load of about 810,000 pounds for an 8- /2 inch Dacron filled tape as compared to about 700,000 pounds for the all-nylon 8- /2inch tape. Failure is manifested by shearing of the stack diagonally due to a breaking of the filler strands in each sample tape within the stack which is accompanied by a sharp report as the stack splits.

Referring to FIGS. 9 and 10, plots are made of load versus percent change in width and percent change from original ght for both a Dacron filled tape and an all-nylon tape ed in accordance with the above procedures. Curve m,m n,n in E1689 and represent the Dacron filled and allm tapes respectively. Referring to H6. 9, for a 300,000 nd load approximately a 7 percent change in width occurs he Dacron filled tape (curve m) while ll percent change urs in the all-nylon tape (curve in). On the other hand, :rring to FIG. 10, for the same loading a Dacron filled tape ergoes 26 percent change from the original stack height rve m) while the all-nylon tape stack will undergo approxtely 30 percent change (curve n lith a tape having a weave such as a binder weave, the p yarns are somewhat restrained against lateral movement to their interlocking with the weft yarns. However, in a fer weave tape, which is the preferred type of tape for use ircraft launching devices, the warp yarns are simply piled 11 layers or bundles throughout the thickness of the tape. In '1 an arrangement, it is readily apparent that the stuffer is may readily slide laterally past one another and move rally outward. Therefore, the problem of lateral bulging is articularly difficult problem with stuffer weave types of is. In accordance with the present invention, the weft yarns uniformly distributed throughout the length of the tape have a stiffness such that the tape will not bulge laterally ater than 10 percent of its original width when a compresforce of around 10,000 p.s.i. is applied to the flat surface he tape. in addition, the weft yarn preferably has sufficient Tness and strength so that the tape will not split or rupture rally and will withstand a compressive force of at least und 15,000 p.s.i. Vhile it is possible to increase the transverse strength of the e by increasing the number of weft yarns, these solutions uire that the tape be made more bulky in order to retain same number of warp yarns. If the tape width and :kness are to be left the same with these solutions, it would necessary to eliminate some of the warp yarns to make ce for the additional weft yarns or the weft yarns of inased cross-sectional area. In accordance with the present ention, the tape is provided with a much greater transverse fness and strength without increasing the bulkiness of the e and without eliminating any warp yarns. This is accomhed by using weft yarns which have a higher initial moduthan the warp yarns, but which are of substantially the ie cross-sectional area as the warp yarns. This also makes aving of the tape much simpler as it is difficult to weave h two different sized yarns. \s previously mentioned, and as explained in Pat. Re No. 406, some longitudinal stretchiness is desirable in the tape. :refore, a high degree of stiffness in the longitudinal fibers iot highly desirable and a yarn stiffness as indicated by an ial modulus range of around 40-80 is preferred. In addin, a stuffer weave type of tape is preferable wherein the ionidinal load bearing yarns extend in straight parallel paths oughout the length of the tape. A binder weave, wherein longitudinal or warp yarns are curved in and out of weft n5, is not desirable because the tensile strength is reduced 1 too much elongation or stretchiness exists. This is because mechanical elongation. That is, elongation caused by tightening out of the curved warp yarns under tension. rom the foregoing detailed description it should be unstood that the principal object of the invention is to proe a launching or purchase tape relatively free from the efts of width growth, namely tape split. The specific applican and chief advantage is to greatly increase the permance of a single tape, reel-type catapult. Clearly however, invention has other applications too numerous to mention, :h as in vertical launch applications of a missile, rapid, high, Jacity elevators, or basically anywhere that the tension on a the tape is limited by the bilateral strength capacity of its nsverse fibers. While the present invention has been scribed in connection with reel-type aircraft launching apratus, and has proven satisfactory for use therein, it will be vious that those skilled in the art may make modifications and alterations upon reading and understanding this specification.

We claim:

1. An elongated fiat stuffer weave tape adapted to be wound upon a reel in ever-increasing convolutions, said tape having a length dimension, a width dimension and a thickness dimension defined between flat opposite faces, said tape having a plurality of layers of stuffer yarns stacked through the thickness of said tape, said stuffer yarns extending continuously through the length of said tape, said tape having weft yarns extending transversely of said stuffer yarns, said weft yarns being uniformly distributed throughout the length of said tape, said tape being placed under longitudinal tension when wound upon said reel and being subjected to a compressive force acting substantially perpendicular to said flat faces, said compressive force acting to compress said tape and decrease said thickness dimension and acting to bulge said tape laterally and increase said width dimension, said transverse yams having sufficient stiffness to limit increase in said width dimension under action of said compressive force to not greater than around 10 percent.

2. The tape of claim 1 wherein said transverse yarns have sufficient stiffness to limit increase in said width dimension to not greater than around 10 percent when said compressive force is at least around 10,000 p.s.i.

3. The tape of claim 2 wherein said transverse yarns have an initial modulus substantially greater than the initial modulus of said stuffer yarns.

4. The tape of claim 3 wherein said transverse yarns have substantially the same cross-sectional area as said stuffer yarns.

5. The tape of claim 2 wherein said transverse yarns have sufficient strength to prevent rupture of said tape when said compressive force is at least around 15,000 p.s.i.

6. The tape of claim 5 wherein said transverse yarns have an initial modulus substantially greater than the initial modulus of said stuffer yarns.

7. The tape of claim 6 wherein said transverse yarns have substantially the same cross-sectional area as said stuffer yarns.

8. The tape of claim 1 wherein said transverse yarns have an initial modulus substantially greater than the initial modulus of said stuffer yarns.

9. The tape of claim 8 wherein said transverse yarns have substantially the same cross-sectional area as said stuffer yarns.

10. An elongated flat tape adapted to be wound upon a reel in ever-increasing convolutions, said tape having longitudinal yarns extending continuously throughout the length of said tape, said tape having transverse yarns uniformly distributed throughout the length of said tape, said transverse yarns having an initial modulus substantially greater than the initial modulus of said stuffer yarn.

11. The tape of claim 10 wherein the ratio of the initial modulus of said transverse yams to the initial modulus of said stuffer yarns is at least around 1.5 to l.

12. The tape of claim 11 wherein the cross-sectional area of said transverse yarns is substantially the same as the cross-sectional area of said stuffer yarns is substantially the same as the cross-sectional area of said stuffer yarns.

13. The tape of claim 11 wherein said transverse yarns has sufiicient stiffness to limit lateral bulging of said tape to not greater than around 10 percent under a compressive load acting against the fiat of said tape ofat least around 10,000 p.s.i.

14. The tape of claim 11 wherein said transverse yarns have sufiicient strength to prevent rupture of said tape under a compressive load acting against the flat of said tape of least around 15,000 p.s.i.

15. In combination with an aircraft launching system for launching an aircraft from a stationary position including a rotatable reel and means for rotating said reel, a textile tape connected at one end of the reel and at the other end to an aircraft, said tape being coilable on said reel during launching of an aircraft, said tape having high strength synthetic stuffer and holding it in a tape configuration, said filler yarn being yarns extending continuously throughout the length of the uniformly distributed throughout the length of said tape and tape tensioned by the launching cycle, and a high strength having a higher initial modulus than said stuffer yarn such that synthetic filler yarn extending transversely of the stuffer yarn the initial modulus ration of filler to stutter is at least 1.5 to 1.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 Dated Mar 9 1971 Inventor) Charles S Thompson I It iscegrtified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 7 should read as shown below:

height for both a Dacron filled tape and an all-nylon tape tested in accordance with the above procedures. Curve m,m' and n ,n' in FIGS 9 and 10 represent the Dacron filled and nylon tapes respectively Referring to FIG 9', for 300,000 pound load approximately -a 7 percent change in width occurs in the Dacron filled tape (curve'mj while 11 percent change occurs in the all -nylon tape (curve n). 0n the other hand referring to FIG. 10 for the same loading a Dacron filled undergoes 26 percent change from the original stack height (curve m while the all-nylon tape stack will undergo apprl imately 30 percent change (curve n With a tape having a weave such as a binder weave, the warp yarns are somewhat restrained against lateral movement due to their interlocking with the .weft yarns However in stuffer weave tape, which is the preferred type of tape for in aircraft lauching devices the warp yarns are simply pile up in layers or bundles throughout the thickness of the tap! such an arrangement it is readily apparent that the Stuffe] yarns may readily slide laterally past one another and move laterally outward. Therefore the problem of lateral bulgir a particularly difficult problem with stuffer weave types 01 tape. In accordance with the present invention, the weft ye are uniformly distributed throughout the length of the tape and have a stiffness such that they tape will not bulge later greater than 10 percent of its original width when a compres sive force of around 10 ,000 p .s i is applied to the flat su of the tape In addition, the weft yarn preferably has suff cient stiffness and strength so that the tape will not split rupture laterally and will withstand a compressive force of least around 15,000 p.s.-i'.

page 1 FORM PO-OSO (10-69) UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 32568726 Dated Mar. 9, 1971 Inventor(s) Charles 5 Thompson It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

While it is possible to increase the transverse strength 1 tape by increasing the number of weft yarns, these solutions require that the tape be made more bulky in order to retain the same number of warp yarns. If the tape width and .thickm are to be left the same with these solutions it would be ne sary to eliminate some of the warp yarns to make space for t] additional weft yarns or the weft yarns of increased crosssectional area In accordance with the present invention t1 tape is provided with a much greater transverse stiffness an strength without increasing the bulkiness of the tape and wit eliminating any warp yarns This is accomplished by using we yarns, but which are of substantially the same cross-section:

area as the warp yarns. This also makes weaving of the tape much simpler as it is difficult to weave with two different 5 yarns.

As previously mentioned and as explained in Pat. Re No 25,406, some longitudinal stretchiness is desirable in the t2 Therefore, a high degree of stiffness in the longitudinal fit is not highly desirable and a yarn stiffness as indicated by initial modulus range of around 40-80 is preferred. In addit a stuffer weave type of tape is preferable wherein the longit nal load bearing yarns extend in straight parallel paths thrc out the length of the tape. A binder weave, wherein the longitudinal or warp yarns are curved in and out of weft yarn is not desirable because the tensile strength is reduced and much elongation or stretchiness exists. This is because of mechanical elongation. That is, elongation caused by straigh ing out of the curved warp yarns under tension.

From the foregoing detailed description it should be under that the principal object of the invention is to provide a launching or purchase tape relatively free from the effects 0 page 2 FORM PC4050 (ID-69! UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 568 ,726 Dated 9 71 Inventor(s) Charles 5 ompson It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

width growth, namely tape split. The specific application a chief advantage is to greatly increase the performance of a single tape reel-type catapult Clearly however the inven has other applications too numerous to mention such as in vertical launch applications of a missile, rapid, high, capa elevators or basically anywhere that the tension on a texti tape is limited by the bilateral strength capacity of its tr verse fibers While the present invention has been describe connection with reel-type aircraft launching apparatus, and proven satisfactory for use therein it will be obvious that those skilled in the art may make modifications Signed and sealed this 23rd day of May 1972 (SEAL) Attest:

ROBERT GOTTSCHALK EDWARD M.FLETCHER,JR.

Comm1ss1oner of Pat Attesting Officer page 3 Fan. p. earn [In enl

Claims

1. An elongated flat stuffer weave tape adapted to be wound upon a reel in ever-increasing convolutions, said tape having a length dimension, a width dimension and a thickness dimension defined between flat opposite faces, said tape having a plurality of layers of stuffer yarns stacked through the thickness of said tape, said stuffer yarns extending continuously through the length of said tape, said tape having weft yarns extending transversely of said stuffer yarns, said weft yarns being uniformly distributed throughout the length of said tape, said tape being placed under longitudinal tension when wound upon said reel and being subjectEd to a compressive force acting substantially perpendicular to said flat faces, said compressive force acting to compress said tape and decrease said thickness dimension and acting to bulge said tape laterally and increase said width dimension, said transverse yarns having sufficient stiffness to limit increase in said width dimension under action of said compressive force to not greater than around 10 percent.

11. The tape of claim 10 wherein the ratio of the initial modulus of said transverse yarns to the initial modulus of said stuffer yarns is at least around 1.5 to 1.

13. The tape of claim 11 wherein said transverse yarns has sufficient stiffness to limit lateral bulging of said tape to not greater than around 10 percent under a compressive load acting against the flat of said tape of at least around 10,000 p.s.i.

14. The tape of claim 11 wherein said transverse yarns have sufficient strength to prevent rupture of said tape under a compressive load acting against the flat of said tape of at least around 15,000 p.s.i.

15. In combination with an aircraft launching system for launching an aircraft from a stationary position including a rotatable reel and means for rotating said reel, a textile tape connected at one end of the reel and at the other end to an aircraft, said tape being coilable on said reel during launching of an aircraft, said tape having high strength synthetic stuffer yarns extending continuously throughout the length of the tape tensioned by the launching cycle, and a high strength synthetic filler yarn extending transversely of the stuffer yarn and holding it in a tape configuration, said filler yarn being uniformly distributed throughout the length of said tape and having a higher initial modulus than said stuffer yarn such that the initial modulus ration of filler to stuffer is at least 1.5 to 1.