US3576086A - Toy glider and method for constructing same - Google Patents

Abstract

A toy glider constructed from expanded polystyrene with a wing having a V-shaped center section, a thickened leading edge having no dihedral at the leading edge and having a generally elliptical semispan trailing edge in planform with maximum chord outboard of half of the semispan. The maximum chamber of the wing occurs at the maximum chord with extreme ''''wash out'''' twist in the form of upward twist on the trailing edge of the wing from zero at the root to a maximum at the tip. The tip-leading edge of the wings has triangular projections on its underside for stability and minimization of tip vortex. The boom or body is constructed of expanded polystyrene formed into a V-shaped cross section and attached to the center section of the wing trailing edge. A balancing weight is located in the leading edge''s center, and a flat horizontal stabilizer is attached to the aft end of the body.

Description

United States Patent Richard S. Halsey 2593 Riggs Drive, East Point, Ga. 30344 [211 App]. No. 771,740

[22] Filed Oct. 30, 1968 [45 Patented Apr. 27, 1971 [72] Inventor [54] TOY GLIDER AND METHOD FOR Primary Examiner-Louis G. Mancene Assistant Examiner-A. J. Heinz Attorney-Newton, Hopkins & Ormsby ABSTRACT: Attoy glider constructed from expanded polystyrene with a wing having a V--shaped center section, a

thickened leading edge having no dihedral at the leading edge and having a generally elliptical semispan trailing edge in planform with maximum chord outboard of half of the semispan. The maximum chamber of the wing occurs at the maximum chord with extreme wash out" twist in the form of upward twist on the trailing edge of the wing from zero at the root to a maximum at the tip. The tipJeading edge of the wings has triangular projections on its underside for stability and minimization of tip vortex. The boom or body is constructed of expanded polystyrene formed into a V-shaped cross section and attached to the center section of the wing trailing edge. A balancing weight is located in the leading edges center, and a flat horizontal stabilizer is attached to the aft end of the body.

PATENTED APRZ'HSY! 357 30 SHEET 1 BF 2 INVENTOB RICHARD "7. HALSE PATENTEU APR27 19?:

SHEET 2 BF 2 TO! GLIIDER AND METHOD FOR CONSTRUCTING SAME BACKGROUND OF INVENTION 1. Field of the Invention This invention relates generally to toy airplanes and gliders. More particularly, the invention relates to a glider which is extremely light and slow moving which can be flown indoors without harming furniture and which can be constructed from sheet-expanded polystyrene material or the like.

2. Description of Prior Art Toy gliders have been constructed of expanded polystyrene arid balsa wood previously. These toys have generally been constructed in the configuration of operational aircraft having reasonably high aspect ratios AIR (span lwing area), high lift/drag ratios (L/D), a positive angle of incidence, and a conventional vertical stabilizer. These toys have generally consisted of four parts, e.g., a wing, a fuselage, a horizontal stabilizer and a vertical stabilizer. Single piece gliders have been designed, however, they have not been in the light, highly efficient class which show good slow-speed characteristics. Because of high aspect ratios high L/D, and positive incidence wings, the previous toy gliders had a high forward speed covering a prolonged glide path. These type toys are destructive to furniture and other household furnishings when launched indoors. These type gliders often, because of their high L/D ratios, escape the confined areas in which urban children are required to play.

SUMMARY OF THE INVENTION These and other problems and disadvantages associated with the prior art are overcome by the invention disclosed herein by providing a toy glider which is constructed from expanded polystyrene being very light and having a very low gliding speed. The toy glider has a wing with a negative angle of incidence, a low aspect ration, and which is highly cambered, and has washout twist which operates very stably just above stalling speed. As a result, use of the glider indoors is relatively safe since low gliding speed coupled with light weight yield an almost harmless amount of momentum. The aforementioned configuration having a low lift-drag ratio (L/D) has a relatively short gliding distance; therefore it is not as likely to collide with walls and is most appropriate for play in confined spaces in which children are required to playin many urban areas. The endurance of the glider is greater in these confined spaces since the configuration operates at just above stall speed; hence, the endurance of the flight within the confined space is longer than that of gliders with a higher L/D ratio.

Modern forming methods of expanded polystyrene using heat and pressure allow the following method of constructing a light toy glider with thin wall structure as follows.

The glider includes a wing formed from expanded polystyrene sheet or like material, a body attached to the trailing edge center section of the wing and a horizontal stabilizer attached to the aft end of the body. These parts may be formed and glued together or formed in part or in whole from a single sheet of the material.

The wing has approximately an aspect ratio (span larea) of 3. The center section forms a small V-section constituting about percent of the span. The leading edge outboard of the center section has little or no dihedral. The leading edge radius is about 1.50 percent MAC. The cambered upper surface proceeds smoothly back from its point of tangency with the leading edge radius and the lower surface of the leading edge extends tangentially from the leading edge radius diverging from the upper surface such that the thickness of the leading edge is a maximum of about 8.0 percent MAC at a point at l0-l5.0 percent chord. The thickness returns to about 1.5-2.0 percent MAC at that point with the lower surface having a step which is the aft end of the leading edge reinforcement.

The wings camber varies from 0 to approximately 6 percent of the mean aerodynamic chord at a point slightly outboard of one-half the semispan (distance from centerline to wing tip) and about 30 percent chord varying to 0 at the root and reducing substantially toward the tip.

The wings trailing edge is twisted upward with maximum twist occurring at the tip reducing to zero twist at the root accomplishing a washout effect.

Washout" normally refers to wing twist or airfoil variation between root and tip of the wing, giving the tip a lower angle of attack. The principal advantage of washout" twist as applied in this glider is lateral stability caused by prevention of tip stall, i.e., at high wing angles of attack the root will enter the stalled condition while the outboard sections are at a lower angle of attack, thereby giving stable lift while the aircraft is descending in the partially stalled condition.

The wing tip in the preferred configuration has a small protrusion at the leading edge reducing the tip vortex and further stabilizing the glider on the roll and yaw axis.

The body of the glider in the preferred configuration is simply a length of sheet-expanded polystyrene or the like which is formed into a V-shaped cross section which is attached to the trailing edge of the wings V-shaped center section. As the glider descends the shape of the body tends to further increase stability in roll since airloads increase on the side toward which the roll is made tending to oppose the roll. The V-cross section mounted in line with the wing V-section yields a low center of gravity further increasing stability.

The horizontal stabilizer is simply a flat sheet attached to the aft end of the body. The stabilizer is positioned with the trailing edge rotated upward about an axis through the leading edge, i.e., a negative angle of incidence, to hold the glider in a nose high attitude and a high angle of attack.

The combination of the stabilizing influences of the aforementioned design features obviate the necessity for a vertical stabilizer resulting in a lighter and simpler glider.

It is an object of this invention to provide a toy glider which is very light and flies very slowly.

It is still another object of this invention to provide a toy glider which is inexpensive to produce and has the characteristics of being very light and very slow flying.

It is still another object of this invention to provide a toy glider which flies as long as possible in a confined area.

It is another object of this invention to provide a toy glider which flies with minimum momentum and is not dangerous to household furnishings.

It is another object of this invention to provide a method of constructing a glider having all of the aforementioned characteristics.

These and other objects, features and advantages of the invention will be more clearly understood upon consideration of the following specification and accompanying drawings wherein like characters of reference designate corresponding parts throughout and in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of enlarged scale showing the glider from above and in front rotated 45 to the right.

FIG. 2 is a left side view showing the horizontal stabilizer position.

FIG. 3 is the front elevation view showing the V-center section, the minimum dihedral angle in the leading edges, the upward twist of the trailing edge and the stabilizing protrusions in the leading edge tips.

FIG. 4 is the aft elevation view showing the washout twist of the trailing edge.

FIG. 5 is the top plan view showing the wing planform and horizontal stabilizer planform.

FIG. 6 is the bottom plan view showing how the body is joined to the trailing edge of the wing's center section.

These FIGS. and the following detail description disclose specific embodiments of the invention. However, the

inventive concept is not limited thereto since it may be embodied in other forms.

DEFINITIONS Angle of attack: Angle between the chord and the relative wind Angle of Incidence: Angle between the chord and the longitudinal axis of the aircraft.

Aspect Ratio (A/R): The ratio of the square of the span of an airfoil to the total airfoil area, or the ratio of the span to its mean chord. An airfoil of high aspect ratio is of relatively long span and short chord; one of low aspect ratio is of relatively short span and long chord.

Camber: The rise of the mean line (midpoint between the upper and lower surface) from the chord line.

Chord: A straight line joining the leading and trailing edges of an airfoil.

Dihedral Angle: The acute angle between two intersecting planes or between lines representative of planes.

'Leading Edge Radius: The radius of a circle tangent to the upper and lower surfaces with its center located on a tangent to the mean camber line.

Lift Drag Ratio (L/D): The ratio of lift to drag obtained by dividing the lift by the drag or the lift coefficient by the drag coefficient.

Mean Aerodynamic Chord (MAC): The chord for an imaginary airfoil which would have force vectors throughout the flight regime identical with those of the actual wing. In actual practice it has been found almost identical in length to the mean geometric chord which is the wing area divided by the wing span.

Semispan: One-half of the span.

Span: The dimension of an airfoil from tip to tip measured in a straight line.

Vortex: Any flow with closed streamlines.

washout: Aerodynamic twist of the wing whereby the effective angle of attack of the tip sections is made less than that of the root sections.

Wing Root: The intersection of the lifting surface with its supporting body.

Zero Lift Chord: A chord taken through the trailing edge of an airfoil in the direction of the relative wind when the airfoil is at a zero lift angle of attack.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENT The wing W is formed from a single piece of sheet-expanded polystyrene. The V-center section 1 (FIG. 3) is constructed by forming a V-shaped depression along the wings entire centerline 2 (FIG. fonning center section walls 3 and 4. The leading edges 5 and 6 are formed from about 6075 of a very small circular are 20 (FIG. 2) referred to as the leading edge circle with the top of the circle forming the forward portion of the wing upper surfaces 7 and 8 and the lower arc of the circle forming the forward edge of the leading reinforcements 9 and 10. Referring to FIG. 2, the leading edge reinforcements 9 and 10 begin at the leading edges 5 and 6. The leading edge is formed by a radius of about 1.5 percent MAC. The cambered upper surfaces 7 and 8 proceed smoothly back from their point of tangency with the leading edge radius and the lower surfaces of the leading edges extend tangentially from the leading edge radius diverging from the upper surfaces such that the thickness of the leading edges is a maximum of about 8 percent MAC at a chordwise point of about 10-15 percent. At that point the lower surfaces have steps 11 and 12 (see FIG. 4) which return the wing thickness to about l.5-2 percent MAC. These aft facing steps 11 and 12 are the aft end of the leading edge reinforcement. The leading edges 5 and 6 have no dihedral angle as viewed from the front (FIG. 3). The trailing edges 13 and 14 are convexly arcuate in planform yielding a maximum chord at or slightly outboard of onehalf the distance from the centerline to the win tips (15 and 16) (asemis ian).

e railing edges 1 and 4 as shown in FIG. 4 are twisted upward toward the tip to create washout" to maintain the tips at a low angle of attack. The wing surfaces 7 and 8 are cambered such that the maximum camber from a straight line through the leading and trailing edge occurs at about 30 percent of this chord. The camber varies spanwise from zero at the center section to a maximum at about one-half the semispan. The trailing edge are continues into the V-section 1 forming an elongated V-trailing edge 17 (FIG. 6) to which the body may be attached. The center of the wing leading edge receives a balancing weight 21.

The body B is constructed by forming a small length of sheet into a V-cross section having curved edges on the longest sides which are on each side of the fold line forming body sides 18 and 19. The forward end of the body is pointed and is shaped to fit into the trailing edge center section 17. The upper aft edges of 18 and 19 are straight rather than curved to receive the horizontal stabilizer S.

The horizontal stabilizer S is a flat sheet attached to the aft upper edges of the body sides 18 and 19. In FIG. 5, the planform of the stabilizer can be seen as generally rectangular disposed along a lateral axis with cambered comers and a cutout in the forward section. The cutout allows the curve on the upper edges of 18 and 19 to continue back to the center of the horizontal stabilizer to maximize bending strength of the body from the point of application of the stabilizer loads. The horizontal stabilizer is installed in the negative incidence position as shown in FIG. 2.

While a particular embodiment of the invention has been illustrated and described, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from the invention, and it is intended to cover in the appended claims all such modifications that fall within the true spirit and scope of this invention.

lclaim:

1. A toy glider for flying in confined space comprising:

a wing member having maximum chord and camber substantially outboard of its centerline and having its trailing edge curved increasing upward toward its tips to provide washout twist;

a body member attached to said wing; and

a horizontal stabilizer attached to said body member and spaced from said wing member;

said stabilizer having a negative incident angle;

the wing having a double thickness reinforced leadingedge and having a generally elliptical semispan trailing edge planform;

the maximum chord and maximum camber occurring no less than one-half the semispan from the centerline and the trailing edge being twisted upward amaximum at the tip, diminishing to zero twist at the root;

the leading edges of both sides of the wing being on the same straight line 2. A toy glider as in claim 1 wherein the wing has a V-center cross section and wherein the body has a V-cross section corresponding to that of the wing cross section.

3. A toy glider as in claim 2 wherein the reinforced leading edge has stabilizing protrusions at each tip end.

4. A toy glider as in claim 3 wherein the entire glider consists of expanded polystyrene.

Claims (4)

1. A toy glider for flying in confined space comprising: a wing member having maximum chord and camber substantially outboard of its centerline and having its trailing edge curved increasing upward toward its tips to provide washout twist; a body member attached to said wing; and a horizontal stabilizer attached to said body member and spaced from said wing member; said stabilizer having a negative incident angle; the wing having a double thickness reinforced leading edge and having a generally elliptical semispan trailing edge planform; the maximum chord and maximum camber occurring no less than onehalf the semispan from the centerline and the trailing edge being twisted upward a maximum at the tip, diminishing to zero twist at the root; the leading edges of both sides of the wing being on the same straight line

2. A toy glider as in claim 1 wherein the wing has a V-center cross section and wherein the body has a V-cross section corresponding to that of the wing cross section.

3. A toy glider as in claim 2 wherein the reinforced leading edge has stabilizing protrusions at each tip end.

4. A toy glider as in claim 3 wherein the entire glider consists of expanded polystyrene.

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