US2045355A - Pitch differential means for lifting propellers - Google Patents

Description

June 23, 1936. R. R. HAYS 2,045,355

' PITCH DIFFERENTIAL MEANS FOR LIFTING PROPELLERS Filed April 27 l935 2 Sheets-Sheet l INVENTOR Passe Hays June 23, 1955 R R. HAYS 2,045,555

PITCH DIFFERENTIAL MEANS FOR LIF'IING PROPELLERS FIG. 4

INVENTO/f /?usse R. Hays dam A TTORNE V Patented June 23, 19 36.

UNITED STATES PATENT OFFICE PITCH'DIFFERENTEAL MEANS FOR LIFTING PROPELLERS 7 Russell R. Hays, Encinitas, Calif.

Application April 27, 1935, Serial No. 18,648

20 Claims. (01.170-162) My invention, relates to means for varying the pitch of blades of lifting propellers at difierent moments of rotation, more particularly to'means of eifecting such variation by reason of the drag dissymmetry.

In testing articulative blades which are so mounted that variation in their lift and centrifu- First, to providea hinged mounting for the blades of a lifting propeller whereby they are free to oscillate within their plane'of rotation andin which said oscillation automatically produces a change in their pitch;

' Second, to provide a yieldable mounting for articulativeblades of a rotating blade structure whereby the drag of the opposed blades is momentarily balanced across the axis of rotation and movement'of this point of balance away from the axis of rotation produces a decrease in the pitch of one blade and an increase in the pitch" of the opposite blade;

Third, to provide a hinged mounting for blades of thisclass in which the drag dissymmetry produces a dissymmetry of the blades in plan form with a consequent movement of the blades in planes perpendicular tothe plane of rotation;

Fourth, to provide a hinged mounting for propeller blades which permits articulation of the blades within and at right angles to their plane of rotation, such articulation not being directly responsive to the driving torque;

Fifth, to, provide a hinged mounting for articulative blades of a rotating blade structure whereby the blades are free-to oscillate within their plane of rotation which results in a feathering action of the blades, such oscillation being inde; pendent mechanically of the oscillation perpendicularly to their, plane of rotation, which also produces a feathering reaction of the blades;

Sixth, to provide a means that is automatically operative in case of engine failure to convert a lifting propeller having the foregoing characteristics into an auto-rotative blade structure of the gyrcplane type;

, Seventh,- to provide a means of this class which will reduce to a minimum the usual extreme Fig. 3 is a diagrammatic plan view of a propeller pitch variation occurring by reason of the movewill reduce to a minimum the vibration in the operation of propeller blades of this class;

Eighth, to provide a means of this class which stresses in. connection with propeller blades of this class; and

Ninth, to provide a means of this class which is very simple and economical of construction, eificient in its action, durable, and which will not readily deteriorate or get out of order.

With these and other objects in view as will appear hereinafter, my invention consists of certain novel features of construction, combination and arrangement of parts and portions as will be hereinafter described in detail and particuflarly set forth in the appended claims, reference being had to the accompanying drawings and to the characters of reference thereon which form a part of this application, in which: t

Figure 1 is a side elevational view of my differential hinge structure shown in connection with afragmentary portion of the propeller blades and] showing the varying axial lines diagrammatically; Fig. 2 is a top or plan view of the same;

differentially mounted showing the varying positions of the blades resultant to drag dissym-' 'metry; Fig. 4 is a diagrammatic sectional view taken along the line 4-4 of Fig. 3 illustrating the ment of the axes of the differential, and Fig. 5

is a diagrammatic view. showing thelimitation of the coning angle resultant to engine failure whereby the propeller is converted into an autorotative blade system.

Similar characters of reference refer to similar .parts and portions and diagrammatic relation throughout the several views of the drawings.

Referring to Figs. 1 'and 2 of the drawings, there is provided a drive shaft I which is rigidly 40 secured to a head bracket member 2 by means of a reduced portion 20. extending through a, conforming hole in the member 2 and upon which is mounted a nut la. This bracket 2 is provided with upwardly extending journal portions 2b in which are mounted journal bolts 3 which may be tap bolts rigidly screwed into the differential bracket 4 which difierential bracket is free to rotate about a main horizontal axis 3-3 to the center of the journal bolts 3, said axis B-B being at right angles to and intersected by the axis AA of the drive shaft I. This differential bracket 4 is substantially a rectangular piece 'of metal, the shorter axis: of which coincides with the axis A-A pf rotation, and the longer axis. of

which is intersected by and makes an acute angle equal to the value of Y, as shown in Fig. 2, with the axis BB rearwardly to the propellers direction of rotation'R. Each of the corners of the rectangular bracket member 4 carries a journal bolt 5 alined with the diagonals of the rectangle and comprises axes CC and D--D for the hinge members 8 and 9 which are held by the hangers 1 and 6, respectively. The axes 0-0 and D.D make acute angles Y with the main horizontal axis BB rearwardly and downwardly. The outer ends of the hinge members 8 and 9 extend from the upper hangers and are secured to the propeller blades [0 and II in such a manner that the longitudinal axes E-Eof the blades form an acute angle X with the axes CC and DD downwardly and forwardly. Consequently the blades l0 and l I are free to rotate about the axes CC and D-D downwardly. until the hinge members contact the diiferential bracket 4, and upwardly until their movement is arrested at auto-rotative attack angles by reason of the projections I2 on the hinge members'a and 9 contacting the differential bracket 4, shown best in Fig. 1 of the drawings.

It will be here noted that all the parts and portions are symmetrically disposed and the posi-' tioning of the blades l0 and II issuch that they have an effective attack angle when in equilibwhere the inflow of air is uniform the equilibrium of the blades will remain constant and hence there will be no oscillation. However, with translation, the inflow ceases to be uniform and consequently the lift on the blade advancing in the direction of the air motion increases, whereas that on the retreating blade decreases. When this occurs the consequent movement of the blade is about the axis BB rather than either the axis CC or D-D since the lift L of the blades, shown best in Fig. 4, has a more nearly vertical component L' and hence'leverage effect to the axis BB, than the component L" to the axis CC. Therefore, since the longitudinal axis EE (see Fig. 3) of the blade has a sweepback angle Z to the axis BB in plan form, Fig. 3, a feathering action results as is well known in the art with a consequent tilting of the plane of rotation P-P, Fig. 4. Simultaneously with the creation of such feathering action the differential bracket 4 becomes efiective. The primary reaction is that due to feathering the drag on the blades at rearward moments of rotation becomes greater than the drag at forward moments, hence destroying the equilibrium relative to the center point of th differential bracket and consequently producin rotation of the bracket in the direction of. the rearwardly working blade.

With such rotation of the differential bracket, the axes CC and D-D describe a conical path about the axis BB in opposite directions relatively to the direction of rotation of the attached blades Ill and II. At the same time the longitudinal axes -EE of the blades having sweepback to the axes CC and D-"-D also describe conical paths relatively to the latter. Due to the fact that the blades are held in their plane of rotation by lift and centrifugal forces and since movement at right angles to the lift is confined to this plane, it will be seen that rearward movement of the blade, Fig. 3, produces rotation of the axis CC about axis BB along a path M Fig. 4 to a point C'C' and at the same time a counter rotation of the blade axis E-E about the axis CC along a path N which has moved back to the position N with a consequent decrease in pitch. At the same time the reverse rotation of axes takes place onthe opposed blade with resultant increase in pitch.

The secondary reaction of the differential bracket results from the fact that'by this arrangement of axes rearward movement of one blade produces a corresponding forward movement of the opposite blade, thus the angle Z, Fig. 3, increases to Z on the rearwardly working blade, whereas the angle Z decreases to Z" on the forwardly working blade. Consequently the lift L of the former blade has a greater leverage effect relatively to the axis BB than the lift on the latter, thereby producing rotation of k the propeller about the axis BB with a resultant decrease in the pitch of the rearward blade and an increase of the pitch in the forward blade.

Inasmuch as the greatest lift dissymmetry on a lifting propeller in translation occurs at lateral moments of rotation, whereas the greatest drag dissymmetry occurs at longitudinal moments of rotation, and since as a result of lag, means responsive to either dissymmetry persist over a quarter of a revolution, it is readily apparent that pitch variationwhich anticipates airflow variation will greatly reduce pitching and rolling moments of the propeller as well as increase its efficiency. In the case of engine failure and-with the use of an over-running clutch as is conventional in the art, the equilibrium of the blade changesthereby increasing its coning angle. Withthe use of small values of angles X, Figs. 1 and 2,.

such an increase in the propellers coning angle throws the pitch into extreme negative angles, :therefore theprojections l2 on the hinge members 8 and 9 are utilized to restrict this coning at A a point giving an eifective auto-rotative pitch setting of the blades. Thus as shown in Fig. 5, the normal coning pitch J-J of the blades would tend to increase to K--K but is restricted at the position H-H. This in efl fect locks the action of the differential bracket as responsive to the drag' dissymmetry and consequently the propeller is automatically converted to a rigid blade structure of the gyroplanetype as is well known to the art. From the foregoing description it will be seen that I have provided a selective differential for an articulative blade of'a rotating blade structure whereby variation of the airflow encountered by the blade at different moments of rotation produces rotation of the elements about three separate axes. It isobvious that sucha means is ,capable of broad modification, as for instance, a

. rearrangement of the three axes'to permit the use claim as new'and desire to secure by Letters Patent is:

1. In a pitch differential means for lifting propellers, a main bracket member provided with a main horizontal axis and axes at acuteangles thereto.

2. In a pitch differential means for lifting propellers, a main bracket member provided with a main horizontal axis and with axes at acute angles thereto, a journal bracket journaled on said main bracket member at the main horizontal axis thereof. I

3. In a pitch difierential means for lifting propellers, a main bracket member provided with a main horizontal axis and with axes at acute angles thereto, a journal bracket journaled on said main bracket member at the main horizontal axis thereof, and propeller blades mounted on said acute angle axes in opposed relation to each other.

4. In a pitch differential means for lifting propellers, a main bracket member provided with a.

main horizontal axis and with axes at acute an-y gles thereto, a journal bracket journaled on said main bracket member atthe main horizontal axis said main bracket member to limit the feathering action of said blades.

6. In a device of the class described, a main bracket member provided with a central normally horizontal axis and with a plurality of axes-intersecting said central axis at acute angles to each' other.

'7. In a device of the class described, a main bracket member provided with a central normally horizontal axis and with a plurality of axes intersecting said central axis at acute angles to each other, means for supporting said main bracket member on a normally horizontal axis.

8. In a device of the class described, amain bracket member provided with a central normally horizontal axis and with a. plurality of axes intersecting said central axis at acute angles to each other, means for supporting said main bracket member on a normally horizontal axis, propeller blades pivotally mounted on said second mentioned axes in opposed relation to each other.

9. In a rotative blade, structure for aircraft, means for universally mounting the blades comprising a plurality of axes, one of which "is fixed inits position relative to the axis of rotation of the structure, and a bar journaled for movement about the first axis carrying a. second axis on which is pivotally mounted the blade.

10. In a rotative blade structure for aircraft, means for universally mounting the individual blades comprising a plurality of axes forwardly disposed to the blade, one of which is fixed relative to the axis of rotation, a bar iournaled for movement about the first axis carrying a second axis to which is hinged the blade, this axis lying between the first axis and the longitudinal axis of the blade, and making an acute angle with the plane defined by the last two axes.

11. In a rotative blade structure for aircraft, means for differentially mounting the blades comprising a plurality of axes, a fixed axis forwardly disposed to the lift line ofthe blades providing a pivot for simultaneous movement of opposedv blades at right angles to their plane of rotation, a bar pivoted to the fixed axis and carrying symmetrically disposed axes to which are pivotally mounted opposite blades.

12. In a rotative blade structure for aircraft, means for differentially mounting the blades comprising a plurality of axes, a fixed axis forwardly disposed to the lift line of the blades providing a pivot for simultaneous movement of opposed blades at right angles to their plane of rotation, a bar pivoted to the fixed axis and carrying symmetrically disposed axes to which are pivotally mounted opposed blades, these latteraxes making acute angles with each other, with the fixed axis, and with the longitudinal axes of the attached blades.

13. In a rotating blade structure for aircraft, means comprising a plurality of oblique axes for universally mounting the individual blades for simultaneous movement in a plane at right angles to articulative movement of the blades.

14. In a rotative blade structure for aircraft, means for universally mounting articulative blades comprising a plurality of oblique axes vertical planes through which make acute angles.

15. Ina rotative bladestructure, for aircraft, means for differentially mounting articulative blades comprising a plurality of oblique axes vertical planes through which-make acute angles.

16. In a rotative blade structure for aircraft, means for universally mounting articulative blades comprising a plurality of oblique axes, and differential means responsive to the first means.

17. In a rotative blade structure for aircraft, means for universally mounting articulative blades comprising a plurality of oblique axes vertical planes through which make acute angles, differential means responsive to the first means.

18. In a rotative blade structure for aircraft,

means for universally mounting theindividual blades comprising a plurality of oblique axes forwardly disposed to the lift line of the blade relative to its direction of rotation.

19. In a rotative blade structure for aircraft, means for universally inounting the blades comprising aplurality of oblique axes forwardly disposed to the center of pressure of the blade, means arranged for relative movement of these axes coincident with fore and aft movement of the blade within its plane of rotation.

20. In a rotative blade structure for aircraft,

means for differentially mounting the blades comprising a plurality of oblique axes, and means operative to rotate the blades about their longitudinal axes with relative fore and aft movement within their plane of rotation.

RUSSELL R. HAYS.

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