US2440296A - Rotor equipped aerial device - Google Patents

Description

April 27, 1948 J. P. PERRY ROTOR EQUIPPED AERIAL DEVICE Filed May 5, 1944 BY Q7 ATTORNEY5 Patented Apr. 27, 1948 ROTOR EQUIPPED AERIAL DEVICE Julian P. Perry, Holicong,

giro Company of America, Philadelphia, Pa., a

corporation of Delaware Pa., assignor to Auto- Application May 5, 1944, Serial No. 534,249

2 Claims. I

This invention relates to an aerial device, and particularly to an aerial device provided with a bladed rotor arranged for self-rotation or for autorotation, so that the device may be released in the air, for instance, from an airplane and will descend to the ground at a retarded rate.

Various features of the invention are adaptable to aerial devices of the general nature described above, modified for many different specific uses. In a preferred form, the device is arranged as a flare, of the type adapted for use in warfare. In this form, the device is adapted to be carried by an airplane over territory which it is desired to illuminate, one object of the invention being to provide a flare of this general character which is reliable in operation and which has a low rate of descent, whereby to provide for illumination over a, relatively prolonged period of time.

Many features of the invention may also be utilized to advantage as a pyrotechnic display device. Still further it may be used for the safe dropping of various articles, for instance, at a point where a cargo aircraft does not or cannot land. Many other adaptations will occur to those skilled in the art.

In addition to objects and advantages already mentioned, the invention contemplates an aerial device of the character briefly described in which the body portion and rotor rotate together as a unit, thereby simplifying the construction, particularly by virtue of elimination of rotor bearings.

Another object of the invention is the provision of novel blade mounting means for the rotor blades including, in the preferred construction, a common pivot for a pair of opposite rotor blades, which pivot has its axis arranged oblique to the longitudinal axes of the blades in a sense such that when the blades swing upwardly the pitch angle thereof decreases. In this way, when the device is released in the air, the initial descent will cause the blades to swing upwardly and thereby reduce their pitch, preferably to an appreciable negative value. This in turn aids in initiating rotation of the device until the centrifugal force acting on the blades attains a value which will cause them to pivot downwardly and thereby increase their pitch. The oblique pivot axis. therefore, aids in initiating the self-rotation or autorotation of the unit, and after the autorotation is established, the device will descend at a low rate, as above mentioned.

A further object of the invention is the provision of pivot means arranged to provide for folding of the rotor blades, preferably to lie in positions close against the sides of the body of the device, and especially in the case of a device having a vertically elongated body the pivoting of the blades adjacent upper edges of said body in such manner that the folded blades hang downwardly in parallelism to the longitudinal axis of the device.

When an oblique pivot is employed, the invention contemplates conjointly using additional pivot means preferably comprising a pivot for each blade arranged outboard of the oblique pivot, with the axes thereof perpendicular to the blade axes and lying in horizontal planes providing for folding of the blades to positions in which they lie against the sides of the body, whereby to facilitate compact stowage of the device.

Beyond the foregoing it is contemplated that an enclosure or casing be provided for the entire device, of dimensions adapted to accommodate the device when the blades are in folded position. In this way the devices may readily be handled and stowed in an airplane without damage to the rotor blades. The casing desirably has an aperture through which the unit may readily be discharged just before or at the time it is launched.

How the foregoing objects and advantages are obtained, together with others which will occur to those skilled in the art will be apparent from the following description referring to the accompanying drawing in which- Figure 1 is a longitudinal sectional view through the enclosing casing for an aerial device constructed in accordance with this invention, the section through the casing being taken as indicated by the line ll on Figure 2 and the device itself being shown in elevation;

Figure 2 is a View taken as indicated by the line 2-2 on Figure 1, showing the casing in transverse section and illustrating the top end of the device in plan, this view still further illustrating, in dotted lines, the positions of the rotor blades in normal operation;

Figure 3 is an elevational view of the upper end of the body portion, with the rotor blades mounted thereon, this view illustrating the blades in position swung upwardly on a mounting pivot; and

Figure 4 is a view similar to Figure 3 but taken in a plane at right angles to the showing of Figure 3.

In considering the drawings, it is herein assumed that the embodiment shown comprises an aerial flare. The flare or flare material itself may suitably be contained in a body shell 5. A

ing the folding pivots for the blades which are arranged so that the blades may be brought to positions adjacent the sides ofthe body 5 (see Figure 1), thereby enabling enclosure of the entire device in a relatively small casing [2 which may conveniently comprise a cylindrical member open at one end, but provided with a releasepin 12a.

, The following features of structure and operation should be noted.

When the device is launched or released, for instance, from an airplane, all that is required is that the casing be held or mounted so that the unit may fall out through the open end of the casing upon release of pin I2a. In the initial portion of the descent, the air flow on the blades It will cause them to swing outwardly and upwardly from their folded position to positions such as indicated in Figures 3 and 4 in which, it

will be noted, the blade mounting forks 9 have swung upwardly about the axis of pivot 8. Attention is now called to the fact that pivot 8 is arranged with its axis oblique to the longitudinal axes of the blades in a direction such that the pivot axis makes an acute angle with the longitudinal'axis of each blade at the outboard side of the pivot axis and at the leading side of the blade axis. With respect to this obliquity note the showing in Figure 2 in which the direction of rotation is indicated by the arrow R.

In consequence of the obliquity of the pivot axis as just described, when the blades swing upwardly in the initial descent of the device, to the position shown in Figures 3 and 4, the pitch angle of the blades is considerably diminished, the setting of the blades preferably being such that in this position the pitch angle is appreciably negative. This reduced pitch angle aids in initiating rotation of the rotor (and of the body portion therewith), and as rotational speed increases, the centrifugal force causes the blades to swing downwardly on the oblique pivot to positions whichdefine a very shallow cone. The setting of the blades on their mounting forks, and the obliquity of the pivot axis 8, in the preferred construction, is arranged so that when the blades occupy positions close to the horizontal the aerodynamic angle of attack is in the range of autorotation, for instance, about 4 or 5 degrees above the no-lift setting calculated with reference to a plane p p ndicular to the axis of rotation, T

' timing device may be employed to pitch angle selected will depend somewhat on the use for which the device is arranged, since different rates of descent may be provided by adopting difierent pitch angles. When employing a positive autorotational pitch setting the rate of descent of the device may be made to be exceptionally low, which is of advantage for many purposes, as will be understood.

From the foregoing it will be seen that an .extremely simple device is provided which may 'readily be modified or used in conjunction with other features and thereby serve many different purposes. In the case of a flare an automatic 7 ignite the flare at the desired elevation.

In connection with the folding of the blades,

' note that'it is of advantage that the folding pivots II, are perpendicular to the blade axes, since if the folding pivots were oblique the blades, when folded, would not parallel the major axis of the body but would extend toward opposite sides thereof at corresponding oblique angles.

I claim:

1. An aerial device adapted to be launched from an aircraft comprising an elongated body portion and a bladed sustaining rotor adapted to rotate therewith, and pivot means connecting the rotor with the body portion, providing for upward blade swinging movement to a position approach ing parallelism with the rotational axis on a pivot axis obliquely inclined to the longitudinal blade axis in a sense to reduce the blade pitch in the upper range of swinging movement, and said pivot means further providing for downward blade folding movement to a position of substantial parallelism with the rotational axis, on a second pivot axis perpendicular to the longitudinal blade axis displaced from the rotational axis so as to fall beyond the edge of the body portion when the blades are perpendicular to the rotational axis.

2. A construction'in accordance with claim 1 in which the rotor incorporates a pair of blades and in which the pivot means includes an oblique pivot axis common to said pair of blades and a separate folding pivot axis for each blade.

JULIAN P. PEER REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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