US 3881729 A
A flying toy of the boomerang type having either three or four equiangularly spaced arms extending radially from a central junction and disposed substantially in a common plane, the arms having alternate or consecutive tips turned upward and downward. The arms may be either planar or cambered and are preferably tapered from wider to narrower in the direction from the central junction toward the arm tips with the edges of the arms being beveled to a relatively thin leading edge. the central junction or hub is provided with an air permeable aerodynamic resistance element in the form of a cylindrical tube to which a stabilizing disc or cap may also be attached.
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United States Patent [1 1 Block et al.
 May 6,1975
[ FLYING TOY  Inventors: Milton L. Block, 68 N. Main St., Sellersville, Pa. 18950; David D. Goldberg, 1032 Bloomfield Ave., Philadelphia, Pa. 19115; Kenneth S. Douthit, 5130 Butler Pk., Plymouth Meeting, Pa. 19462 221 Filed: Jan. 9, 1974 21 Appl. No.: 431,681
 US. Cl 273/106 D; 46/82; 416/199  Int. Cl A6311 65/08; A63h 27/00  Field of Search 273/106 D; 46/82-85; 416/199, 228, 203, 175; 259/107, 108
 References Cited 7 UNITED STATES PATENTS 477,748 6/1892 Emerson 273/106 D 862,094 7/1907 Morton 46/82 906,206 12/1908 Dawes et a1. 273/106 D 1,040,702 10/1912 Lee 273/106 D 2,816,764 12/1957 Gleason 273/106 D 2,972,481 2/1961 Shapiro 273/106 D 3,403,909 10/1968 Cleveland et a1. 273/106 D 3,403,910 10/1968 Claycomb 273/106 D Primary Examinr-Paul E. Shapiro Attorney, Agent, or FirmEdelson and Udell  ABSTRACT A flying toy of the boomerang type having either three or four equiangularly spaced arms extending radially from a central junction and disposed substantially in a common plane, the arms having alternate or consecutive tips turned upward and downward. The arms may be either planar or cambered and are preferably tapered from wider to narrower in the direction from A the central junction toward the arm tips with the edges of the arms being beveled to a relatively thin leading edge. the central junction or hub is provided with an air permeable aerodynamic resistance element in the form of a cylindrical tube to which a stabilizing disc or cap may also be attached.
11 Claims, 16 Drawing Figures PHENTEUHAY ems saw 2 or 2 FIG. /2
FLYING TOY This invention relates generally to flying toys, and more particularly relates to flying toys of the type which are thrown outward and which after flying away from the thrower return to the position from which the device was thrown, such devices being generally known as boomerangs.
Boomerangs have of course been known for centuries and have been developed in many different forms. Some types are used for hunting of small animals and when thrown with skill can either stun or sometimes kill. These hunting devices have characteristics which can make them extremely dangerous if not properly used. Among such potentially dangerous characteristics are very rapid blade rotation, hard and sharp edges, and substantially straight line return flight which renders it difficult to instantaneously ascertain the position and speed of the returning object.
The foregoing characteristics of boomerang dev'ices render them generally unsuitable as a toy for children since unskilled use can result in serious injury. Accordingly, it is a primary object of this invention to provide a novel flying toy of the boomerang type which is safe for use by a child under substantially any circumstance, does not require an inordinate amount of skill to operate, and does not require long hours of practice to master.
Another object of this invention is to provide a novel flying toy as aforesaid incorporating features which cause the linear and rotational flight speed of the flying toy to be decreased to prevent impact injury to the thrower or anyone who might be in the path of the return flight.
Still another object of this invention is to provide a novel flying toy as' aforesaid incorporating features which provide a smooth non-fluttering flight and a sweeping return flight path of generally ovaloid shape which provides good depth perception for visual tracking of the instantaneous position of the flying toy.
A further object of the invention is to provide a novel flying toy as aforesaid wherein the linear speed of the flying toy along its flight path reduces sharply toward the end of the flight so that the toy returns to ground softly. I
The foregoing and other objects of the invention will become clear from a reading of the following specification in conjunction with an examination of the appended drawings, wherein:
FIG. 1 is a perspective view from above of one form of the flying toy according to the invention;
FIG. 2 is a top plan view on a reduced scale of the toy shown in FIG. 1;
FIG. 3 is a longitudinal vertical sectional view through a pair of alined arms of the flying toy according to the invention as would be seen when viewed along the lines 33 of FIG. 2;
FIG. 4 is a cross-sectional view through one of the arms of the flying toy as would be seen when viewed along the line 4-4 of FIG. 2;
FIG. 5 is an enlarged fragmentary cross-sectional view through the center post structure of the flying toy as would be seen when viewed along the line 55 of FIG. 2;
FIG. 6 is an enlarged fragmentary top plan view of an alternate form of center post structure;
FIG. 7 is a vertical sectional view through the alternate center post structure shown in FIG. 6 as would be seen when viewed along the line 7- 7 thereof;
FIG. 8 is a view similar to that of FIG. 6 showing another form of center post structure;
FIG. 9 is a vertical jump section of the center post structure of FIG. 8 as would be seen when viewed along the line 9-9 thereof, some parts being shown in section and other parts in elevation;
FIGS. 10 and 11 are cross-sectional views through modified forms of the flying toy arm structure and would correspond to showings taken as for FIG. 4;
FIG. 12 is a top plan view of a modified form of the flying toy having a continuous edge bevel around all of the arms thereof;
FIG. 13 is an enlarged longitudinal vertical section through a pair of apposed arms of the flying toy as would be seen when viewed along the line l313 of FIG. 12;
FIG. 14 is an enlarged cross-sectional view through one of the arms of the flying toy as would be seen along the line 14-14 of FIG. 12;
FIG. 15 illustrates a typical flight-path for a flying toy of the type illustrated in FIG. 1; and
FIG. 16 illustrates a typical flight path for a flying toy of the type illustrated in FIG. 12.
In the several figures, like elements are denoted by like reference characters.
Turning now to the drawings, and considering first FIG. 1 to 5, there is seen a flying toy designated generally as 20 having four arms 21 through 24 arranged in the form of a cross so that the arms 21 and 23 are axially alined as are the arms 22 and 24, with each pair of axially alined arms being perpendicular to and in-plane with the other pair of axially alined arms. Each arm tapers from a maximum width at the hub to its minimum width at its free end and is provided along its leading edge with a bevel 25 of approximately 45 which extends the complete length of the leading edge and outward around the tip substantially to the trailing edge of each arm. The outer free ends 26 and 27 of arms 21 and 22 respectively are turned downward out of plane from their respective arms while the ends 28 and 29 of arms 23 and 24 respectively are turned upward out of plane from their arms, the degree of angularity between the arms and their respective tips being designated as the angle 6 (theta) illustrated in the showing of FIG. 3. Extending perpendicularly upward from the plane of the crossed arms at the intersection of the longitudinal axes of the arms in an air permeable aerodynamic resistance in the form of a circular tubular center post 30 having extending completely therethrough from one end to the other a central bore 31 through which air may pass in either direction through the central hub 32 of the toy.
In operation, one of the down-turned tips 26 and 27 is grasped between the thumb and forefinger of the right hand and is launched upward and outward at approximately 45 angle by means of an arm throwing movement including a snap of the wrist. Some slight amount of practice might be necessary, but within a very short time, such as 5 or 10 minutes, the thrower will normally be able to cause the toy to follow a flight path as typically shown in FIG. 15. The flight path of the toy is substantially in a plane for approximately three quarters of its flight and moves at a reasonably constant speed. About the last quarter of the flight path is characterized by a reduction in linear and rotational speed of the toy during which the toy is characterized by a floating type action followed by a terminal descent at a fairly steep angle and much reduced speed. Consequently, when the toy returns to the thrower, its movement is at a relatively low speed which cannot cause inury.
The structural feature which causes the rotational and linear flight speed of the toy to be decreased so that the return speed is slower and softer is the upwardly and downwardly turned tips of the arms 21 through 24. Additionally, the turned tips 27 through 29 cause the flight path to follow an expanded curved are so that visual judgement of the return flight of the toy is greatly improved. With the tips 26 through 29 of the arms 21 through 24 not turned, but formed as straight continuations of the arms, the flying toy flies outward and returns on a substantially straight line thus making the return speed and instantaneous position somewhat indeterminate. This also renders such a device much more hazardous because the straight arm configuration without the turned tips results in a much more rapid rotational speed of the boomerang arms and renders such a device considerably more dangerous to a child.
It has been found by experiment that the optimum configuration for the tips is with two turned upward and two turned downward as illustrated in FIG. 1 of the drawings. It is also possible to turn alternate arm tips in the same direction so that for example the tips of arms 21 and 23 might both be turned downward while the tips of arms 22 and 24 might both be turned upward, in accordance with the phantom line showing superimposed on FIG. 1. This arrangement seems to reduce the rotational speed of the arms to a somewhat greater degree, and in general the preferred form is that illustrated in solid line. If the arm tips are all turned in one direction, either all upward or all downward, the toy flies outward and at its farthest point from the thrower descends slowly to the ground. This seems to occur irrespective of whether the tips are all turned upward or all turned downward with respect to the arm edge bevels. If the tips are all turned upward, the toy will first invert so that the tips point downward and will then descend to the ground. The optimum angle at which the tips are turned away from their respective arms has been found to be approximately 45 to 50 with increasing angles 0 causing progressively slower flight characteristics, and decreasing angles causing more rapid flight characteristics. At an angle 6 of approximately 70, the toy does not fully return to the thrower.
The bevelled edges 25 of the arms 21 through 24 provide a smoother non-fluttering flight with somewhat faster blade rotation, the bevel being necessary on the leading edge of the toy as thrown. A bevel of 45 to 55 appears to work well, although reasonable results are achievable with bevels generally less than 70. As shown in FIG. 10, an alternate form of arm crosssection 21a is illustrated having a pair of parallel oriented bevels 25a disposed at opposite edges of the arm. Similarly, FIG. 11 shows a modified type of arm crosssection 21b having bevels 25b inclined in opposite directions to provide a trapezoidal shape. With either of these double bevelled arms, the toy may be thrown either right handed or left handed, and in either event the leading edge will have the bevelled shape.
As best seen in FIG. 2, the arms of the flying toy are tapered, and a set of typical dimensions would be as follows:
A 6 inches B l inches C 1 inch D 1 inch E /s inch The arm taper rate provided by the aforegoing dimensions has been found to work very well with the turned tip configuration in that the toy can be made to return to the thrower. The effect of the taper appears to be to increase the rotational speed of the arms somewhat to partially offset the decrease in rotational speed caused by the turning of the arm tips. It has been found that increasing the taper rate, as for example by holding the tip dimension constant and increasing the root dimension causes the device to terminate its return flight at a distance from the thrower. A similar effect has been observed to occur if the toy is constructed so that the edges of the arms are parallel'to one another, that is, with a zero taper rate. The toy can be suitably cut and formed from mil polyethelyne sheet material.
The center post 30 with its through central bore 31 permits the movement of air through the toy, stabilizing the flight and aiding in return to the thrower. This appears to be achieved by the aerodynamics involved which provide lift forces under the arms while simultaneously urging the central hub 32 groundward by substantially reducing the lift under the central hub due to the ability of the air therebeneath to move quickly upward through the central bore 31 of the center post 30. The length of the post F together with the diameter H of the central bore 31 constitutes a controllable aerodynamic resistance, and for a toy of the dimensions previously given, a suitable center post 30 could have the following dimensions:
F /& inch G 5/16 inch H A; inch A central apertured cap in the form of a rubber disc 33 may also be provided for use with the toy as shown in the detail of FIG. 7. The rubber disc 33 may be merely pressed over the end of the center post 30 and retained thereon by friction. The addition of the disc seems to add stability to the flight of the toy in heavier winds, probably due to the addition of mass at the center of mass of the flying toy. Another form of center post cap attachment is shown in the detail of FIG. 9 in which a mushroom shaped cap 34 is fitted onto the center post 30. This mushroom cap 34 has a similar effect to the rubber disc 33, but in addition seems to reduce the speed of the toy, possibly due to the air catching umbrella effect, so that it flys more slowly and softly. The return flight of the toy with the mushroom cap attached is short of the thrower and seems to have a somewhat wider sweeping arc. The caps 33 and 34 are typically on the order of l A inches in diameter.
Considering now FIGS. 12, 13 and 14, there is shown a preferred embodiment of the invention which differs from the showing of FIG. 1 in that a camber 135 is provided to each of the arms 121 through 124 of the flying toy 120, and all of the arms are provided with a continuous edge bevel 125. The tips 126 through 129 and the center post 130 are as previously described in connection with their counterpart structures in the showing of FIG. 1. The camber provided for each of the arms improves the aerodynamics of the arms in the well known manner resulting in better lift and control of the toy, and further modification of the flight path to the more opened out path illustrated in the showing of FIG. 16. The center post 130 could of course be optionally fitted with a rubber disc such as that shown at 33 in FIG. 7 or a mushroom cap of the type shown at 34 in H6. 9, with similar consequent results.
A three armed toy made in accordance with the aforedescribed principles has been also successfully flown, the arms being of course equiangularly spaced at 120 intervals. If the arm tips are turned two up and one down, the toy will fly faster than a four armed type, while if the arm tips are turned two down and one up the flight is appreciably slowed and a lower flight path results.
Having now described our invention in connection with particularly illustrated embodiments thereof, various modifications of the invention will now be apparent to those normally skilled our the art without departing from the essential scope of oru invention, and accordingly is intended to claim the same broadly as well as specifically as indicated by the appended claims.
What is claimed is:
l. A flying toy comprising in combination,
a. a hub provided with an air permeable aerodynamic resistance comprising a cylindrical tube affixed to and extending orthogonally upward from the top surface of said hub, the tubular central bore being extended through the said hub from the top surface to the bottom surface thereof, whereby a controlled flow of air is passable therethrough when said toy is in flight,
b. at least three equiangularly spaced arms extending radially outward from said hub and each terminating in a tip at a free end,
c. at least one of said tips being turned upward at a first predetermined angle to the plane of its arm, and at least another of said tips being turned downward at a second predetermined angle to the plane of its arm.
2. A flying toy as described in claim 1 wherein the longitudinal center lines of said at least three equiangularly spaced arms are substantially co-planar.
3. A flying toy as described in claim 1 wherein said first and second predetermined angles are substantially equal and are in the range between twenty five degrees and seventy degrees.
4. A flying toy as described in claim 1 wherein the leading edge of each said arm is bevelled along 'its length to provide a relatively thin leading edge transitioning to the thickness of the material from which the arm is formed.
5. A flying toy as described in claim 1 wherein each said arm tapersfrom a maximum width at said hub to a minimum width at its free end.
6. A flying toy as described in claim 1 wherein said first and second predetermined angles are substantially equal and are in the range between twenty five degrees and seventy degrees, and wherein each said arm tapers from a maximum width at said hub to a minimum width at its free end and is cambered from one arm edge to the other so as to have a concave bottom surface and convex top surface.
7. A flying toy as described in claim 6 wherein the leading edge of each said arm is bevelled along its length to provide a relatively thin leading edge transitioning to the thickness of the material from which the arm is formed.
8. A flying toy as described in claim 1 wherein said at least three equiangularly spaced arms consist of four such arms with the tips of two of said arms being turned upward at the aforesaid first predetermined angle and the tips of the remaining two said arms being turned downward at the aforesaid second predetermined angle.
9. A flying toy as described in claim 8 wherein the edge of each said arm is bevelled along its length to provide a relatively thin edge transitioning to the thickness of the material from which the arm is formed.
10. A flying toy as described in claim 8 wherein the longitudinal center lines of said four equiangularly spaced arms are substantially co-planar.
11. A flying toy as described in claim 1 further including a cap shaped stabilizing member secured to and carried by said cylindrical tube aerodynamic resistance at the upper end thereof and extending generally radially therefrom, said stabilizing member being apertured so that the passage of air through said aerodynamic resistance is not prevented.
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