Model airplane

Jan. 27, 1959

H. A. BERGSTRAND

MODEL AIRPLANE

2,870,567

Filed March 18, 1957

Sheets-Sheet 1

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Jan. 27, 1959

Filed March 18, 1957

H. A. BERGSTRAND

MODEL AIRPLANE

2,870,567

Sheets-Sheet 2

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FIG. 7

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INVENTOR.

H. A.BERGSTRAND

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ATTORNEY

United States Patent Office

2,870,567

Patented Jan. 27, 1959

2,870,567 MODEL AIRPLANE

Harold A. Bergstrand, East Moline, Ill., assignor io Strombeck-Becker Mfg. Co., Moline, Ill.

Application March 18,1957, Serial No. 646,811

Claims. (CI. 46—76)

This invention relates to a toy or model airplane structure and more particularly to structures of the type furnished as ah assembly kit.

The problems in this field are many and complex, primarily because the parts of the kit must not only be such as to be readily assembled by the age group for which intended but must also be capable of adequate functional and structural performance. Added to this is the requirement that the finished model possess a reasonable degree of authenticity. If the model is a flying model rather than merely a display piece, it must additionally possess the necessary strength for flying, landing and the inevitable' crashes. At the same time, the necessary strength must be obtained without adding unnecessary weight.

Accordingly, it is a. principal object of the invention to provide an improved structure of the character described, at the same time 'maintaining adequate flyability, reasonable authenticity and low cost. An important object is to improve the wing structure and the wing-tofuselage assembly, by incorporating therein rigid spar means for tying the wings together via the fuselage. In this respect it is an object to provide each wing as a hollow structure, preferably by affording in the wing a spar-receiving pocket having a cover added after the spar-to-wing assembly is effected. A still further object resides in the use of spacer means between a pair of spars in each wing and the exploitation of the spacer means for the attachment of the landing gear. An overall object of the invention is to provide improvements in the nature of carefully designed bracing components so arranged as not to detract from the appearance of the finished plane.

The foregoing and other important objects and desirable features inherent in and encompassed by the invention will become apparent as a preferred embodiment is disclosed in the ensuing’ specification and accompanying sheets of drawings, the several figures of which are described below.

Figure 1 is-a perspective of the assembled model.

Figure 2 is an exploded perspective showing the preassembled relationship among the components of the model.

Figure 3 is an enlarged section on the line 3—-3 of Figure 1.

Figure 4 is an exploded perspective of part of the landing gear.

Figure 5 is an enlarged fragmentary perspective of the inner edge structure of a wing-as seen when looking generally in the, direction'of’the arrow bearing the encircled numeral 5 in Figure 1.

Figure 6 is an exploded perspective of the components shown in Figure 5.

Figure 7 is an enlarged section on the line 7—7 of Figure 1.

Figure 8 is an enlarged section on the line 8—8 of Figure 1.

As shown in Figure 1, the completed model has the typical appearance of airplanes in general, possessing however the scaled-down characteristics of a particular make and design, the identity of which is not material here. The plane has the usual fuselage 10, right and 5 left hand wings .12, tail assembly 14, nose cowl 16, propeller 18 and landing gear including right and left hand struts 20, wheels 22 and wheel pants 24. Since the right and left hand elements are symmetrical and in some instances identical, only one side of the ship will 10 be described in detail, with reference to the other side where appropriate.

Figure 4 illustrates the pre-assembled components of one-half of the landing gear, this being an instance in which the halves may be identical. The strut 20 has at 15 its upper end a stub 26 provided by notching the strut at 28, 28. In the case shown, the strut is of light-weight relatively rigid material, such as balsa, and the wheel pants, like the wings, fuselage, etc. are of extremely thin material such as polystyrene plastic, here typically 20 vacuum formed to achieve the required configuration. Each wheel 22 is of two complementary halves which complete the wheel when assembled between the pants 24, which are secured to opposite sides of the strut by an appropriate adhesive or cement the nature of which 25 is well known. The specific nature of the wheels is not significant here. Hubs 30 and axle pins 32 complete the landing gear assembly.

The fuselage is here shown as including upper and lower complementary halves 34 and 36, appropriately Ό flanged lengthwise thereof at 38 to afford areas at which the halves are secured together, as by an appropriate cement, to provide a rigid unitary tubular assembly. The lower half 36 has transversely opposed generally upright side walls or portions 40, each having front and 35 rear slits or apertures 42 and 44 respectively. The paired apertures are of course respectively alined transversely to receive spar means, here comprising front and rear spars 46 and 48 which are inserted through the respective apertures to extend outwardly from opposite 40 sides of the fuselage. The opposite outer portions of the front spar are identified at 50 and those of the rear spar at 52. The spars, like the landing gear struts 20, are of balsa, or appropriate light-weight material having greater rigidity than the wing and fuselage material.

The wing 12 is a one-piece sheet, here polystyrene plastic and vacuum formed to have what may be termed the airfoil section representing generally a true wing (Figure 7). However, the airfoil section is interrupted in a substantial portion of the wing by forming the sheet with a depression which appears in the finished wing as a pocket or channel 54 which opens upwardly and also opens inwardly at 56 at the inner edge part of the wing, here comprising a pair of coplanar flanges or webs 58 and 60 separated by the inner pocket opening 56 (Figures 5 and 6). The web structure 58—60 affords an area that abuts the fuselage side wall 40, in the zone of the apertures 42 and 44, and is connected thereto, the wall haying an arcuate guide ridge 62 for positioning the web area, which ridge receives and cooperates with fore-and-aft alined ribs 64 and 66 respectively on the webs or flanges 58 and 60 (Figures 5, 6 and 8). The lower edge has a lip 61 which furnishes additional cementing area. This lip is substantially coplanar with the surfaces or flanges 58 and 60 and at any rate is flexible enough to conform to the fuselage side wall (Figure 3).

The fore-and-aft dimension of the pocket is such that the pocket opening at 56 generally registers with the fuselage apertures 42 and 44 so as to receive the outer portions 50 and 56 of the spars 46 and 48, the length of the pocket—or its transverse dimension—being such as to receive or house the spar outer portions. The pocket has a floor 68, upright front and rear walls 70 and 72

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and an upright outer end wall 74, and the spars are cemented to the front and rear walls and to the proximate portions of the pocket floor. The outer portions of the spars are appropriately shaped to conform to the depth of the wing pocket 54 and are thus wholly received in the pocket, being concealed from below by the pocket floor 68 and from the outer end by the pocket outer end wall 74.

Concealment of the spars from above is achieved by a wing cover 76, three of the major marginal edges of which are received in and connected to a conforming recess or ledge 78 above the three major sides of the pocket. The fourth or inner edge of the cover is formed as a rib 80 which completes or complements the rib means 64—66 at the inner end of the wing (Figures 5 and 6). The rib 80 of course cooperates with the guide ridge 62 on the fuselage side wall 40 and additionally furnishes an area for cementing to the fuselage and thus increases the strength of the fuselage-to-wing joint. If desired, the underside of the cover may be cemented to the tops of the spar outer portions 50 and 52.

The wing cover serves a further and vital function other than concealing the spars from above: it completes the airfoil section of the wing (Figures 5, 6 and 7) and when properly assembled the wing has an overall appearance of being of one-piece construction. The hollow or tubular structure afforded by the pocket and cover materially strengthens a major part of the wing, particularly in its zone proximate to the fuselage and this plus the spars produces relatively extreme strength and rigidity in the midportion of the plane, all with a minimum of added weight.

Further rigidity in this area is achieved in each wing by the use of spacer means, here a fore-and-aft block 82, preferably balsa, which spaces the spars apart fore-andaft (Figures 2, 3 and 7) and also serves to mount the proximate landing gear strut 20 via it stub 26, which enters a slot 84 in the pocket floor 68 next to the block 82. In view of the wood-to-wood joint between the block 82 and strut stub 26, glue rather than cement is used, the stub lying alongside and abutting the block (Figure 3) and the strut notches 28 limiting penetration of the slot 84 by the stub 26 (Figure 7). The block is glued to the spars and is cemented to the pocket floor before the cover 76 is added, and the cover may be cemented to the top of the block for further strength.

As will be seen, the combinative tubular wing and spar structure has great strength against bending, twisting and warping, and the tie between the wings and across the fuselage insures against fracture of the cemented joints. The use of balsa as structural members facilitates the use of sheet structure for the fuselage and wings, which sheet material, here polystyrene as already referred to, is easy to handle, lends itself readily to mass production, is decorative and possesses an adequate strengthto-weight ratio for the purpose intended. Securing of the landing gear struts to the spacer blocks 82 affords strong joints capable particularly of resisting lateral displacement of the landing gear as well as forces incurred in landing, etc. Here, as in the case of the spar-to-wing connection, the joints are concealed and thus do not detract from the authentic appearance of the model.

Features other than those elaborated will readily occur to those versed in the art, as will many modifications and variations of the preferred inventive embodiment disclosed, all of which may be achieved without departure from the spirit and scope of the invention.