|Publication number||US2459357 A|
|Publication date||Jan 18, 1949|
|Filing date||Mar 30, 1944|
|Priority date||Mar 30, 1944|
|Publication number||US 2459357 A, US 2459357A, US-A-2459357, US2459357 A, US2459357A|
|Inventors||Bell Richard A|
|Original Assignee||Philco Corp|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (8), Referenced by (10), Classifications (8)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Jan. 18, 1949. R. A. BELL BOMB FIN STRUCTURE Filed March 30, 1944 Patented Jan. 18, 1949 ES ATENT FFiCE BORE FIN STRUGTURE Vania Application March 30, 1944, Serial No. 528,749
This invention relates to improvements in aerial bombs and the like, and more particularly in bombs of the type wherein the fin structure is required to function as an antenna for radio al paratus incorporated in the bomb.
The vibration of the fin structure of a bomb when in flight has an appreciable effect upon the aerodynamic characteristics of the bomb. This effect is not necessarily consistent and introduces a potential source of error affecting bombing accuracy. In bombs incorporating radio apparatus of which the fin structure constitutes an antenna, the said vibration may additionally seriously interfere with this special function of the fin.
A principal object of this invention is to provide a fin structure constructed in a manner to avoid or to materially reduce the aforesaid undesirable effects of fin vibration.
To this end the invention contemplates maximal reduction of vibration in the fin structure, and modification of the character of residual vibration, so as to substantially eliminate interference with the normal functioning of the fin structure in the respects noted.
The invention resides further in certain structural details of an improving nature hereinafter deescribed and illustrated in the attached drawings, wherein Fig. 1 is a View in perspective of a fin structure made in accordance with the invention;
Fig. 2 is a view of the fin structure in a bomb assembly, the said structure being shown in cross section on a line corresponding to the line 22, Fig. l, and
Fig. 3 is a sectional View on the line 33, Fig. 1.
With reference to the drawings, which illustrate a preferred embodiment of the invention, the fin structure basically is built on conventional lines. It comprises a main hub element i having a conical skirt 2 which, in assembly, fits the coned extremity 3 of the bomb casing as shown in Fig. 2. Th structure also includes a secondary hub element a, which in assembly, embraces a stud 5 at the outer end of a cylindrical extension 6 f the casing 3, said extension constituting, in the present instance, a housing for the radio apparatus. The collar is secured to the stud by means of the retaining nuts l'l. Extending radially from the collar 4 in uniformly spaced relation are four arms 8, the outer ends of the arms being attached to and supporting .a rectangular fin member 9. From each corner of the member 9 a flange l I projects outwardly and radially with respect to the common center line of the hub elements 1 and l. The flanges H, which form active elements of the fin structure, extend from the outer edge It of the fin member 9, i. e. that edge which, in assembly, is relatively remote to the bomb casing 3, to points beyond the roximate edge ill-a of said member, and the projecting' ends of the flanges H are united to the hub element l by means of struts it. In the present instance, the struts l2 extend radially with respect to the common center line of the collars and t. This structure is made entirely of metal, and while it is designed specifically for use with bombs incorporating radio apparatus, it corresponds basically with conventional bomb fin structure.
It has been proposed to reduce or to eliminate the objectionable vibration to which fin structures of this general type are subject, by reinforcing or strengthening the structure by additional metal to the end of obtaining greater inherent rigidity in the structure as a whole. Attempts to reduce vibration by this means have proven unsuccessful. In accordance with the present invention, each of the elements of the fin structure which is subject to vibration is provided superficially with one or more pads of a nonmetallic material such, for example, as wood, such pads preferably being attached at both faces of the element and being separated from the metallic surfaces by interposed pads of felt or like material. Thus, with reference to the drawings, each of the sides of the rectangular fin member 9 is provided in the present instance with two sets of such pads, each set including a pair of non-metallic elements l3i3, secured at the inner and outer faces respectively of the said sides, and two pads of felt l4 respectively interposed between the elements It and the metal faces of the fin. In the present instance the elements it and M are secured to the fin structure by means of bolts l 5 which pass through the elements l3l3 and Ml4 of the respective sets and through the metallic Wall of the member 9. The said bolts bind the elements it solidly against the felt pads l4 and compress the latter to a fraction of their normal thickness. In the present instance, the two sets of elements l3 and H3 which are applied, as described, to each of the sides of the fin member 9, are arranged to afford an intervening space, and within these spaces the struts 8 are secured to the inner faces of the side walls.
Each of the flanges H is also provided with a set of elements Ill-l6 and l'll1 corresponding respectively to the elements I3 and M of the sets previously described and similarly secured to the opposite sides of the fins H by means of bolts l8. Since the fin structure is to function as a radio antenna, it is desirable to electrically insulate the bolts 15 and 18 from the metallic fin structure, and to this end, and as shown in Fig, 3, the fins are provided with insulating washers l9 through which the said bolts extend.
A fin structure constituted as described above has been found relatively free from objectionable vibration. The reduction of vibration is due in part to the favorable stiffness-to-mass ratio ef fected by addition to the metal fin of the nonmetallic pad system which adds considerable stiffness With a disproportionately small increase in mass. Thus, applying the formula wherein 1 represents resonant frequency, 3
the stiffness factor, and 722 mass, it will be apparent that the frequency of vibration will be in-- creased. Reduction of vibrational amplitude also occurs by reason of vibration of the metal fin and of the attached pad system at different frequencies with resultant frictional cancellation. This damping action involves both sliding and impact friction between the surfaces of the metal fins and the opposed felt surfaces of the pads.
It is to be noted that the pad elements 53 are formed so as to provide a streamlined contour with respect to the normal direction of movement in flight, and this streamlining is also preferably extended to the struts 8 and I2. This is of advantage in reducing turbulence in the flow of air through and past the fin structure and is a further factor in eliminating variable conditions adversely affecting bombing accuracy.
As previously set forth, wood has been found suitable for use in the pad elements i3, and
Woods of relatively great density, such as oak and gum, are desirable. Materials other than wood but having similar properties may be substituted.
Commercial felts may be used in the pad elements M, and other padding materials such as resilient rubber may be used with success. There is considerable permissible latitude not only as to the compositions of the pad elements, but also in the form and relative disposition of the active elements of the fin structure.
In an aerial bomb of the type including radio apparatus, a fin structure constituting an antenna for said apparatus and comprising a plurality of active fin elements of thin metal, and vibration-inhibitin-l pads secured to the faces of said elements, said pads lending stiffness to the said elements and being composed of wood having a stifinessto-mass ratio substantially in excess of that of the metal of said fin so as to increase the stiffness-to-mass ratio of the composite fin element as a Whole.
RICHARD A. BELL.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 1,962,202 Meredith June 12, 1934 1,972,005 Berbecl: Aug, 28, 1934 2,18%,145 Lambert Dec. 19, 1939 2,340,133 Martin Jan. 25, 1944 2,393,604 Berger Jan. 29, 1946 FOREIGN PATENTS Number Country Date 91,592 Sweden Feb. 24, 1938 505,625 Great Britain May 11, 1939 502,711 France Feb. 27, 1920
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US1962202 *||Oct 30, 1929||Jun 12, 1934||Rca Corp||Antenna|
|US1972005 *||Jul 21, 1931||Aug 28, 1934||Trian Berbeck||Aircraft|
|US2184145 *||Jan 22, 1936||Dec 19, 1939||Clayton & Lambert Mfg Company||Bomb tail|
|US2340133 *||Dec 14, 1940||Jan 25, 1944||United Aircraft Corp||Propeller blade|
|US2393604 *||Feb 10, 1943||Jan 29, 1946||Berger William F||Bomb stabilizer|
|FR502711A *||Title not available|
|GB505625A *||Title not available|
|SE91592A *||Title not available|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US2786414 *||Feb 25, 1955||Mar 26, 1957||Wall Lester R||Mine fin|
|US2845026 *||Nov 17, 1953||Jul 29, 1958||Bernard Smith||Multiple box fin|
|US2851950 *||Jan 18, 1954||Sep 16, 1958||Aken Ray W Van||Rocket fin assembly|
|US5191351 *||Dec 29, 1989||Mar 2, 1993||Texas Instruments Incorporated||Folded broadband antenna with a symmetrical pattern|
|US6699091||Nov 4, 1999||Mar 2, 2004||Jon A. Warner||Hand-launchable underwater projectile toy|
|US7207518 *||Apr 8, 2002||Apr 24, 2007||Olympic Technologies Limited||Cartridge with fin deployment mechanism|
|US8033890||Oct 11, 2011||Warner Jon A||Self-propelled hydrodynamic underwater toy|
|US20040217227 *||Apr 8, 2002||Nov 4, 2004||Michael Alculumbre||Cartridge with fin deployment mechanism|
|US20040259463 *||Feb 26, 2004||Dec 23, 2004||Warner Jon A.||Hand-launchable underwater projectile toy|
|US20070123139 *||May 17, 2006||May 31, 2007||Warner Jon A||Self-propelled hydrodynamic underwater toy|
|U.S. Classification||102/385, 343/708, 244/3.3, 343/892|
|International Classification||F42B10/00, F42B10/06|