US2432320A - Torque responsive variable pitch propeller - Google Patents

Description

Dec. 9, 1947.

D. G. LILLEY TORQUE RESPONSIVE VARIABLE PITCH PROPELLER Filed March 15, 1944 DA N/EL 2 Sheets-Sheet 1 INVHVTOR. G. LILLEY Afforney Dec. 9,1947. D. e. LlLLEY 3 .320

TORQUE RESPONSIVE VARIABLE PITCH PROPELLER Filed March 13, 1944 2 Sheets-Sheet 2 INVENTOR. DAN/EL G L/LLEY Patented Dec. 9, 1947 TORQUE RESPONSIVE VARIABLE PITCH PROPELLER Daniel G. Lilley, Denver, Colo.

Application March 13, 1944, Serial No. 526,273

Claims. 1

This invention relates to improvements in torque responsive, governor controlled, variable pitch propeller mechanisms, and is a continuation in part of copending application, Serial No. 352,352, filed August 13, 1940, Patent No. 2, 346,979.

Whether the device be a boat floating on the medium of Water, a kite, balloon or an aeroplane supported in the medium of air, if any of these devices are moved head-on against such me diums, or if they are merely held against movement with respect to a land station by any means whatsoever, said mediums when traveling with.

respect to the land station, will also be forced to travel with respect to such devices. This is the method used in flying a kite.

Therefore, so longas a plane travels into a head wind and makes progress, or merely maintains a definite position with respect to a land station by propeller effort, the wind will be forced to travel head-on relative to the plane, and since the propeller is carried by the plane, the wind must travel windmill fashion relative to the propeller at the same rate of speed as though the propeller were mounted for operation upon the land station.

, Careful consideration shouldbe given to the statements in the above two paragraphs, which form the basis for this invention. If a plane will normally travel in air that is still at the rate of 180 M. P. H. withrespect to aland station, andis caught in a 70 M. P. H. head wind, it will be slowed down to approximately 110 M. P. H. with respect to the land station, and the wind will be traveling in the opposite direction at the rate of 70 M. P. H. relative to the land station and towards the ono-omingplane. Therefore, we must come to the conclusion that the wind will blow head-on relative to the plane and propeller at the same rate of speed it blows relative to the land station.

If the above were not so, th plane would not be slowed down to 110 .M. P. H. with respect to the land station, nor could it have normal (180 M. P. H. air speed) when traveling only 110 relative to the land station unless the air did travel 70 M. P. H. head-on relative to the plane, and incidentally windmill fashion relative to the propeller.

If the headwind did nottravel windmill fashion relative tothe propeller, it could not travel relative to the ship to make up part of the ships air speed and act as a drag to slow down the progress ofthe ship to 110 M. P. H. relative to the land station. "This voluntary movement of air causes a lossin the rate of blade hitting speed relative to;

(Cl. fill-135.6)

the air, resulting in a loss of propeller thrust efll ciency, and which thrust efliciency can be rethe case of the head wind on the one hand, and

the displacement of airby the propeller on the other hand, are able to produce a thrust force, one upon the other only in the proportion of their respective speeds.

. Rule 2. Tail winds which are traveling against the tra-ctive effort side of the whirling propeller blades represent a case of two parallel mediums of force directed in opposite directions, which combine to producea thrust force and rate of plane travel equal in value to the combined rates of travel of said two parallel forces. When these two rules are applied to aeroplane propulsion, it will be found, when th propeller is restricted to operate at a constant number of R. P. M., that head winds will cause a drop in propeller torque value, and a tail Wind will cause a drop in ship drag value, either of which will cause a drop in torque value upon the engine, and result in a corresponding loss-in plane air speed. While suchtorque loss in a tail wind may be of a temporary nature, the torque loss caused by a head wind will obtain as long as the wind continues, unless the pitch-is'increased and for the number of propeller R. P. M. is increased surficiently to compensate for the head wind velocity. Head winds blowing windmill fashion into a propellerwill cause a loss in the propeller thrust and torque value upon the-engine of from one to as much as 20% or more, resulting in a similar loss in plane velocity and air speed unless the pitch is increased and/or' the number of engine R. P. M. is increased, as above mentioned. Said loss in thrustwill be set upinthe proportion of wind velocity to therotational speed of the propeller.,- H

.Where the medium of either water or air is stillrelative toa station: on the earths surface, and where a propelling mechanism is employed to move a boat orplane relative to said mediums,

mept orthemovement of the boat or plane rela- 3 tive to the medium, and relative to the land station, and so long as the air is still with respect to the land station, a propeller operated at constant speed will produce a uniform rate of movement of the plane or boat with respect to the land station, in which operation only the two relative movements are involved.

The instant these mediums of air or water begin moving relative to the land station, and parallel to the line of boat or plane movement, a third relative movement is set up with respect to the boat or plane and the propelling mechanism. While this third relative movement cooperates to maintain relative ship and air speed even though the ship loses speed relative to the land station, the effects of this same third relative movement upon the thrust efiiciency of the propeller, where the latter is operated at constant speed, has just the opposite eirect, and is diametrically opposed in its effect upon thrust efficiency under constant speed propeller operation. There is a point beyond which this condition cannot be allowed to exist depending upon the velocity of the wind, if safe relative ship and air speed is to li -maintained.

The fact that this third relative movement, set up by headwinds in the immediate vicinity of the flying plane, normally causes an increase in blade pitch due to the automatic action of the centrifugal governor proves that a change in the interaction between the propeller and the air medium takes place, causing an unloading of the engine, due to a drop in propeller torque value, otherwise the governor would not operate in a manner to cause an increase in blade pitch out of coordination with plane air speed and velocity.

The interaction between the blades and the air medium would indicate that the speed responsive governor is also a torque responsive device, which derives its initiative for operating the blade moving motor control means from variations in propeller torque value upon the R. P. M. of the engine, which fact will become clearly apparent when the operation of the following mechanism .is more fully explained and understood.

Provided the above-mentioned third relative movement comprised of wind velocity will cause variations in propeller torque value upon the engine, together with a resulting loss in plane veloc-. ity and air speed, then in the above-mentioned case with an air speed of 180 M. P. H., let us say the safe minimum air speed of a heavil loaded plane is 100 M. P. H. This would leave only the very slight margin of M. P. H. between minimum safe plane air speed and plane velocity of 110 M. P. H.

The above mentioned margin of safety'of 10 M. P. H. between minimum air speed an iane velocity would be the same if the wind and plane velocities were both reduced say by 40 M. P. H. and it will be seen that if plane velocity and air speed were at say 140 M. P. H. should the craft encounter a 70 M. P. H. head wind, plane velocity would be reduced to 70 M. P. H., or 30 M. P. H.

Y below safe minimum air speed, which would be a dangerous plane velocity in the event of a sudden shift in wind direction. Here it will be seen the real danger is in the ratio of wind velocity to plane velocity, and the number 1 of propeller .R..P. M. at the instant the wind is encountered,

also the factor of lapse of time before making an increase in Ditch and/or the number of engine and propeller R. P. M. under such circumstances.

Sucha condition might easily be set up, especially ity. Since it might not have much noticeable reaction upon the plane, it might go unobserved by the pilot, which conditio might be the begin nin of a serious loss in plane velocity and air speed.

Since the element of time may be such an important factor in circumstances similar to the last two above mentioned cases, it appears imperative as a. safety factor, that. the number of engine and propeller R. P. M. provided for by the governor should be automatically increased the instant wind causes a predetermined drop in propeller torque value upon the engine, to avoid the possibility of plane velocity dropping to a point below minimum plane air speed.

In cOnnection with the foregoing, it is well to keep in mind that air density will always be an integral factor, that for a given power expenditure, plane velocity and air speed will automatically be at a rate corresponding to air density and ship drag resistance.

Obiects It is therefore an object of this invention to provide torque responsive, governor controlled propellers with means for automatically increasing the number of propeller R. P. M. whenever wind velocity causes propeller torque value upon the engine to drop below a given predetermined value.

It is an object of the invention to employ the blade pitch responsive element for the double purpose of limiting the blade pitch angle to a predeterminedvalue, and for operation as a propeller torque responsive element for automatically causing an increase in the number of propeller R. P. M. whenever the torque value of, the propeller upon the engine drops below a given value, whereby a substantially constant propeller torque load upon the engine will be automatically maintained, and result in a substantially constant predetermined rate of plane velocity irrespective of wind conditions.

A further object is to provide a pilot with means for determining plane air speed, ground speed, wind velocity and direction at any time, by the number of engine and propeller R. P. M. that is required to bring the propeller under full torque load upon the engine, as indicated by the position or action set up by the torque responsive element, and which can be employed as. a dependable air speed indicator either by itself or as a check against the orthodox air speed indicator.

It is an object of the invention to take advantage of changes in propeller torque value upon the engine for automatically increasing the number of engine and propeller R. P. M. the instant said propeller torque value drops below a predetermined value, and for maintaining said torque at a substantially constant value simultaneously as the blade pitch is limited to a value commensurate with plane velocity and air speed.

It is, an object of the invention to eliminate the dangerous-lapse of time during which conditions above mentioned will be allowed to become set up unless means are provided for an immediate increase in the number of propeller and engine R. P. M. for restoring the normal rateof blade hitting speed relative to the air, and to avoid the lapse of time during which plane velocity and air speed will otherwise be allowed to drop back out siveelement, as well as a'blasde pitch limiting element, and to employ said torque responsive element as an automatic means for indicating to the pilot when propeller torque drops below a given predetermined value, or for increasing the number of engine and propeller R. P. M. automatically whenever such drops in propeller torque value occurs.

A further object ofthe invention is to provide automatic means, for stabilizing the operative characteristics of the governor, for altering the blade pitch in conformance with any changes in number of engine R. P. M., and plane drag resistance, whereby said governor will operate to decrease the blade pitch, whenever propeller torque value upon the enginereaches a pointabove mean value, to avoid overloading the engine under any operating conditions, as during period of take-off and steep angles of climb.

It is a further object of the invention, to provide means for interconnecting the governor control means with the engine throttle mechanism for maintaining a substantially coordinated and stabilized relationship between thesetwo elecally by the blade pitch responsive pitch limiting control element; or by a manually operable means. 7 I

Still another object of the invention is to provide means for making quickchanges in the number of engine and propeller R. P. M. by either manual or automatic means, by providing means for interconnecting the engine throttle with the governor spring tensioning means for coordinating and maintaining the operative characteristics in proper relationship between these two elements.

A still further object of the invention isto provide a means by which a pilot may control the operation of the blade moving motor, by manual means for moving and holdin the'motor control means in adjusted position against the action of the governor.

I Another object of the invention is to enable the operator to move the throttle to increase the number of engine and propeller R. P. M., to meet any emergency or maneuver requiring a sudden burst of speed, without fear of increasing the blade pitch out of coordination with plane velocity and plane drag resistance. A still further object of the invention is to provide the pilot of a plane having a governor controlled propeller with a safety device, which when snapped into operative position will operateto automatically maintain a rate of plane velocity with respect to a given land reference point at a valueequal to the planes minimum rate of air speed.

Having thus explained the theory upon which this invention is based and set forth the objects thereof, the construction by means of which the objects are attained will now be described in detail, and for this purpose reference will be had to the accompanying drawings in which one embodiment of the invention has been illustrated, and in [iii - Figure-4 is a section taken on line 44, Figure 2; and v V Figure-5 is a view showing a hand and foot control for manual operation of the engine throttle.

Referring now to the drawing and more particularly to Figure 1, which shows the preferred form of the invention, reference numeral 5 shows a portion of the crank case wall from which a bottom wall 6 extends forwardly and terminates in an end wall i. Reference numeral 8 represents a part of the propeller drive shaft and this has a circular. flange 9 that is connected along its peripherial edge to the flange IU of the housing portion lea of the drive shaft. The part designated by reference-numeral Illa: is the rotor of the pitch adjusting motor which is shown in Figure 3. A tubular shaft ll extends through an axial opening in the drive shaft and terminates in'a .threaded end portion l2 to which a nut I 3 is connected. A spur gear i4 is nonrotatably connected with the tubular shaft. so as to be rotated therewith and this gear corresponds to the spur. gear designated by the same number in the extension of Figure 1. I

In the, embodiment illustrated in Figure}, a gear pump Ida is carried by the crank case a d a portion of Figure 1 has been broken away to show gear i5 that forms part of the gear pump which serves to maintain a constant flow of oil for use. in operating the motor that changes the pitch of theprope ller blades, the rotor of which has been designated by like. A ring gear [6 car ried by the drive shaft serves to operate the gear pump whenever the engine is running. The oil for use in operating the parts is contained in a sump ii from which a pipe I8 extends to the intake portlof the gear pump and a pipe l9 extends from the delivery port of the pump to a pressure chamber 26 in the body 2| of a slide valve which will be hereinafter more fully described. When the rotor I81; is turning. it'carries with it the tubular shaft I I because the two are held against relativerotation by means of splines. A ring gear 22 is splined to the tubular shaft and cooperates 2; witha spur gear 23 that is carried by the housing iealand which is nonrotatably' mounted on a shaft24 whose front end is threaded and engages in a threaded opening in the inner ball race .25 of a ball bearing whose outer ball race has been designated by. reference numeral 26. There are two gearsZS and two threaded shafts 24, which are operated in unison and therefore when shaft 2-! turns in one direction, itmOVes the ball bear ing towards the left and when it turns in the opposite direction it moves it towards the right; Two arms 2? arenonrotatably connected to a shaft 28 and extend downwardly on opposite sides of the ball race 26'and have their lower ends at tached to the pivots 29 and therefore whenever the ball race moves longitudinally, it will rock shaft ZBfaboutit-s axis. A lever 30 has on end nonrotatably secured to the shaft 28 and has a connecting rod 3i pivotally connected with its free end. The other endof this connectingrod is connected by means of apivot 32 with the free end-of a lever 33 that is pivoted at 34, It is now evident that whenever the ball race 25 moves to wards the right ortowards the left, the lever; 33, togetherwith the arm 35 which is integralthere: with will rock about pivot-34. The purpose of this lmovement will appear as the description proceeds. Y q

Re ferring now to shaft. 28, it will be seen that this is journaled in bearings in link 35 that is pivoted at 31. This link permitsltheshpfi to inqye Se astoprevent any binding action due to the change of angle when the ball race 26 moves.

Since the ball race 26 is operated directly from the tubular shaft II, and since the latter by its rotation controls the pitch of the blade, it is evident that the movement of lever 33 corresponds to the pitch adjustment of the propeller blade and arm 35 serves as a pitch indicator for a purposethat will hereinafter appear. The valve body 2| has a chamber 25 and has a central cylindrical opening 38' in which is positioned a slide valve 39. Chamber 2|? is connected with the opening 38 by means of ports 40 and M. The other'side of thevalve body is provided with a longitudinally extending opening Ma that is in communication with the cylindrical opening 33 through four ports which have been designated as a, b, c and d. The movable part of the slide valve which has been designated by reference numeral 39, is provided with annular recesses that have been designated by reference letters e, f, g, h and 2'. The wall of the valve body has two openings which have been designated by 425:: and 43$. These openings or ports are in communication with conduits 42y and 43y respectively. When the engine is operating with the parts in the position shown in Fig. 1, the pump will draw oil from the sump l1 and discharge it through pipe 19 into compartment 20 I from which it flows through the annular recess h and passes through the port into the longit'udinal opening Ma from whence it returns to the sump l'l. Extendin upwardly from the slide valve member 39 is a shaft 44, which is provided directly above the valve with a shoulder 45, on which is positioned a cup 46. A helical spring 41 has its lower end seated in the cup and its upper end in engagement with a disk 48 that is slidably mounted in the opening 49. This disk is provided with two or more splines that engage in the spline grooves 50 to hold it from turning. A hub t extends downwardly from the lower end of the disk and is slidably connected with the shaft 44. The upper surface of the disk has two aligned fulcrums 52 on which the upper arm 53 of a bell crank lever rests. The vertical arm of this bell crank lever has been designated by reference numeral 54. The bell crank lever is pivoted at 55 to the top of a spring bracket 564 This bracket is provided with a screw 51 by means of which its upper end can be moved to and from the body of the slide valve assembly so as to change the distance from the pivot 55 to the fulcrum 52 for a purpose which will hereinafter appear. Secured to the stationary part 58 of the engine frame is a centrifugal governor whose base has been designated by reference 59. R0- tatably mounted in the base is a sleeve 60 to which the upwardly extending brackets 6| are secured by suitable means such as the nut 62. The brackets are nonrotatably connected with the sleeve and are provided at their upper ends with pivots 63 by means of which the governor weights 64 are attached. Each weight is provided with an inwardly extending arm 55 that engages in a groove on the outer surface of the member 66. The lower end of sleeve 65 has a bevel gear 61 that is engaged by another bevel gear 68 secured to the end of a shaft 69 which extends to and is connected with a spur gear Ill that is C05 operatively engaged with ring gear [6 as shown in Figure 1. Since ring I6 is secured to the.propeller shaft, it is evident that the governor will be rotated at a speed corresponding to the propeller shaft speed.

Referringnowto Figure 2, itwill be seen that:

when the governor weights are thrown outwardly by centrifugal forces, they will moveshaft 44 and the slide valve 33 upwardly, thereby compressing spring 4-7, which, in this embodiment serves as i the governor control spring. Itis also evident that by changing the adjustment of the bell crank lever about its pivot 55, the operation of the governor can be adjusted.

A ringor nut TI is threadedly connected with the shaft 44 at a point above the arm 35, It will: be remembered that arm 35 can oscillate about the pivot or shaft 34 and that its position is controlled by a mechanism that moves in response to pitch adjustment. Carried by the inner part of arm 35 is a pivot 12 which secures the adjustable arm 13 thereto. The arm 13 is provided with a gear segment 14 that is engaged by a pinion 15 secured to the shaft 16-. A handle 17 is connected with shaft 16 and by means of this handle the pinion 15 can be-turned, thereby imparting a corresponding movement to the arm 13; A sprin detent 78 serves to hold the handle l1 and associatedparts in adjusted position.

Secured to the shaft 44 is a spool-like member 19 that is held from longitudinal movement, but permitted to rotate relative to the shaft by meansof the bearings 83. This spool-like member will move upwardly and downwardly in response to the action of the governor; A body 8| is secured to the machine in such a way as to be stationary with respect to the slide valve body. The upper surface of this body is provided with a cylindrical depression 82 for cooperative action with the adjustable member 83 that can be turned about the pivot 84. Member 83 has an upwardly extending cylindrical portion 85 on which a handle 86 is rotatably mounted. This handle is held in position by means of a bolt 81 and a nut 88. The body BI is provided with an opening extending from the lower surface thereof into the spherical depression and-positioned in this opening is a plug 89 that is urged upwardly against the outer surface of member 83 by means of a spring 90. The plug 89 serves as a brake to hold the member 83 from rotation and whenever the handle 86 is moved into the position shown in Figure 2, its front end 85a will engage in the groove of member 19 and hold the shaft 44 against the action of the centrifugal governor at the same time the operator or pilot can adjust the slide valve by turning handle 86 about the pivot 84. This means therefore serves to take automatic control away from the governor and to substitute manual control. It also serves as a means for holding the control valve in any desired adjusted position. Normally, lever 85 occupies one of the dotted line positions shown in Figure 4 and is therefore inoperative.

In Figure 2 which, it will be remembered, is a diagrammatic representation, the arm '13 has been. shown in two positions, the one to the right being a displacement intended to facilitate the description and the understanding of the invention with tively connected with worm gear 91 that is secured to the shaft 98. Shaft 98 extends through a housing 99 and is journaled in a bearing in the end closure I00. 'Shaft 98 is provided within the housing with a square thread which has been designated by reference numeral IIlI. Surrounding the threaded portion II is a sleeve I62 that is provided on its upper surface with spaced lugs I03 between which an arm I04 is mounted for pivotal movement. A spring I tends to hold the arm in the position shown. The end of arm IE4 at the right, when viewed as in Figure 2, is provided with a downwardly extending hook I95 that normally engages the threads in portion HM and therefore whenever shaft 98 turns, it moves sleeve I02 lengthwise in a direction to the left.

Extending downwardly from the under surface of sleeve I92 is a lug I01 that is perforated for the reception of a throttle control rod I08. This rod is provided with a stop I09 that is engaged by the lug-Iil1 when the lattermoves towards the left. The housing 99 is provided with longitudinally extending slots III] and III through which the lugs III'I andI93 respectively extend. The throttle control rod is connected to an arm IIZ to which the butterfly valve pivot H3 is attached. When rod I08 moves towards the left, the butterfly valve willopen. A spring I I4 serves to'hold the throttle valve in a predetermined position, which is controlled by adjusting screw II5 Rod Iil8 has a threaded section IIB, to which a nut H1 is connected. This nut engages the" downwardly extendingarm 54 ofthe bell crank lever and when rod I08 moves towards the left 'it turns the bell crank lever about its pivot and moves the upper abutment of spring 4? downwardly so as to increase the tension of this spring. Byincreasingthe spring tension the adjustment of the centrifugal governor is effected. Valve 9i is operated by means of a lever II8 that is nor mally held against the stop II9 by means of a spring I20. A screw I2 I is threadedly connected with the end of lever II8. Arm I3 is provided at its outer end with a plunger I22 that can be moved-by means of a knob I23. A spring detent I24 holds the plunger either in extended position, as shown, or in its innermost position. When the plunger is moved int-o the arm, the latter can swing past the lever III} without engaging the latter. The purpose of the screw I2I is to adjust the point at which the lever I3 opens the valve 9I. i I Extending from the rotatable portion of valve 9 I is another lever which has been designated by reference numeral I25 and which carries an electric contact I26 that is connected with one pole of the battery I2'I. A stationary switch contact I28 is positioned above the movable contact I26 andis connected to a lamp orother signal device I29 bysuitablewires.

One pole of the battery is grounded at I30. When the valve opens, the switch that has just been describedcloses, thereby lighting a signal lamp which. apprises the operator that the automatic throttle control mechanism is operating. Although a hydraulic motor 93 has been shown for turning shaft 95, it is to be understood that any mechanical equivalent can be substituted, such as an electric motor whose operation can be controlled by the switch at the end of lever I25.

Theautomatic control that has been described can be made inoperative by a downward movement of lever I04 and this lever maybeprovided with means for latching it in inoperative position. 'With the automa'ticmea'ns inoperative, the

throttle can be controlled manually by the means shown in Figure 5, in which reference numeral I3I designates a base to which a lever assembly comprising an arcuate quadrant I32 is connected, by bolts I33. A lever I34 is pivoted at I35 which pivot is concentric with the arcuate surface I32. The throttle control rod I08 is pivotally connected with the lever at I36. Spring pressed friction member I3'I engages the surface I32 and is urged against the latter by means of a spring I38. The operator, by grasping the handle I39 can move lever I34 to any desired position and thelever-twill be held against accidental movement by means of the friction device. If desired, the adjustment can 'be efiected by means of a foot operated pedal I40 which is pivoted at I4I. A linkI lZ connects the pedal with the lever I34. When the foot pedal is rocked about its pivot, it will move lever I34 to any desired position, and it is therefore possible to effect adjustment either by the handlellever, or bythe' foot operated pedal, or by the automatic means that .has been described above. It may be said here thatthefriction device associated with the. adjusting lever shown in Figure5 is adjusted so that it can move in response to the automatic mechanism.

Ilet us now assume that we have a construction like that shown on the drawings and described herein and that the propeller shaft is rotated from an internal combustion engine,the fuel supply to which is controlled by the throttle valve H3. The pitch of the propeller is adjusted to that mostsuitable for a take-off and when the engineand propellershaft begin to rotate, the centrifugal governor'will be put into operation. Since it isfrequently'necessary to run the en gine at a high speed'during take-off, it is essentialthat the governor be kept from functioning until the plane is inthe air, and therefore, be-

fore starting, the operator movesthe handle 86 into the full line position shown inFigure 4, and then movesSB in a vertical plane whereupon the shaft 44 with its attached slide valve 39 are held from moving in response'to the forces exerted on shaft by the governor. After the plane has reached the desired elevation,handle 86 can be moved to either of the dotted line positions shown in Figure 4, whereupon shaft 44 will be free to respond to the action of the governor. If the plane should meet air currents they unload the propeller and reduce the resistance and the engine will naturally speed up, thereby increasing the speed of governor rotatlon','whereuponthe slide valve will move upwardly. When this upward movement becomes sufficient to 1111- cover the ports-42:x:,,and 43w, port 40 will be covered and the 'oil from the pressure pump will then flow downwardly through opening 20, and into the space I, thence through port 42a: and pipe 4211 to the intake ports 42 of the hydraulic motor shown in Figure, 3 and the rotor Illa; of the latter willthen begin to rotate in a clockwise direction so as to increase the pitch of the blades, the oil exhausting through ports 43, 43a, pipe 43y, opening a and M0. to sump II. When the hydraulic motor operates, it turns shaft II and rotates the shafts 24 in a direction to move the bearing pivots 29 forwardly when viewed as in Figure 1. This produces a rearward movement of the connecting rod 3| and a clockwise movement of arms 33 and 35. The position of arm-I3 is-so adjustedby means of the handle 11 that 11 if the pitch increase exceeds a predetermined value, arm i3 will engage the top of the spoollike member 19 and limit its further upward movement and also move it, together with shaft 44 and the slide valve 35, downwardly into neutral position.

Since the speed of the driving motor is not constant, but varies with the torque which it must exert on the propeller to obtain the desired speed of rotation, the rod 31 and the elements it drives become, when the craft is at a constant attitude or flying horizontally, an indicator of the resistance of the craft to flight. With the higher resistance of the aircraft, it is necessary to open the throttle valve sufficiently to provide the necessary extra amount of fuel. This opening of the throttle valve is effected automatically by means comprising the valve 91, the hydraulic motor 93 and the movable sleeve H32 in a manner which has been described. Therefore, when the pitch reaches a predetermined angle of increase, the automatic throttle control will function so as to increase the fuel supply, whereupon the engine will be put into position to deliver the additional power necessary for the desired speed, of the craft. In case of an emergency, or where the automatic control is not desired, plunger l22'can be retracted into a position where it will not engage the lever H8 and the throttle controlled either by hand or by the foot pedal I40 shown in Figure '5.

when this reaches a predetermined amount, the

slide valve-3'9 will move downwardly until port 43m is opened and port in closed, whereupon the oil will flow from chamber 20 through port 4 I, thence through port 43:1: and through pipe 43y to the intake ports 43 of the hydraulic motor. The motor will then rotate in a, counterclockwise direction, whereupon the pitch of the blades will decrease, the oil exhausting through ports 42, 42x, pipe 42y, openings B and Ma to sump 11. As the pitch decreases arms 33 and 35 will move counterclockwise and when the pitch .decrease has reached a predetermined limit, arm 35 will engage the adjustable stop ll, whereupon a force will be exerted which moves the shaft 44 and slide valve '39 upwardly so as to return them to neutral position. It will be seen that stop H can be adjusted downward along shaft 44 to serve as a low pitch. The neutral exhaust arrangement comprising port 40, port 0 and recess h, will tend to avoid unnecessary hunting by the governor controlled 'valve 39 during periods when the blades have the correct pitch, with the engine and propeller operating under "constant torque load.

' It will be observed that the automatic device for operating the throttle valve does not function except when the parts are moving in a direction to increase the propeller pitch that is when resistance to flight has been substantially increased. At other times, the throttle valve must be manually controlled by means of the mechanism shown in Figure 5 or some equivalent mechanism.

If, during flight the pilot finds it necessary to dispense with the automatic pitch regulation .he can do so by moving the handle 86 into the positionshown in full lines in Figure 4 and will then be in a position to change the pitch manually 12 by tilting the lever about pivot 84. It is thus possible to take control away from the governor.

The pitch angles to which the propeller blades shall be limited can be controlled, first by the adjustable stop 1 I, and then by the arm 73 which can be adjusted about its pivot 12. It will be apparent that by spreading arms 35 and 13 a smaller lost motion is had between the movable arms and the stops 1! and 19 and by decreasing the lost motion, the blade pitch angles can be adjusted with greater nicety.

Instead of employing lever 86 during take-01f, this can be moved into either dotted line positions. Then after first moving I22 also into dotted line position, and with the engine running arm 73 can be moved in a downward direction against spool 79 until valve 39 is forced into neutral position, after the blades have been reduced to the take-off pitch, thus leaving the governor free to reduce the blade pitch further in the event the propeller exerts enough torque load upon the engine during take-off, and in this way avoid stalling the motor during such periods.

Screw IN is of such length as to cause a given percentage of increase in engine R. P. M., above a basic low rate of constant speed cruising number of R. P. M., toward a higher crusing rate of engine R. P. M. to maintain safe air speed regardless of wind conditions. In the drawings the nut I09 carried by rod [68 is to occupy the approximate position shown with respect to lug H31 during the lower rate of constant speed propeller operation. It is apparent that if the pilot so desires nut I09 may be moved slightly to the left along rod I08, which will be equivalent to shortening screw illl. In this manner the percentage of increase in engine R. P. M. can be shortened to avoid increasing the engine R. P. M., unnecessarily. .Also, sufficient space should be provided at the right of screw IC-l, to enable the pilot to move lug It! to the right, whereby the latter will not interfere with reducing the engine throttle when desired. A careful study will disclose that a fault will be set up which will cause excessive engine R. P. M. if this screw lfil is too long, as hereinafter described.

In order to secure dependable operation, the cockpit of any given type plane should carry a guide chart for the pilot to assure correct presetting of member 73. Said chart to be based upon still air operation and horizontal flight, and to show what the blade pitch, plane velocity or air speed will normally be at any given altitude and plane load factor, at a given basic number of cruising engine R. P. M.

Thus, after the initial plane take-off and before the plane has reached the intended rate of cruising speed, the adjustabl arm 73 should be moved by easy stages in an upward direction as fast as the plane picks up velocity and until it reaches normal cruising air speed. Whatever the plane velocity, air speed and blade pitch may be, they should be at practically the same value time after time at a given altitude under similar still air flying conditions in horizontal flight, and

where arm 13 is preset one or more degrees ahead of this normal blade pitch position, arm 13 will not interfere with normal governor control of pilot valve 39, under substantially or nearly still air operating conditions.

Arm 13 should be reversed in a similar manner as engine R. P. M. is reduced with the plane approaching the vicinity of a landing field, to reduce the extent of lc-stmotion gap between arm 13 and spool 19, to enable the pilot to increas the number of engine R. P.M. should the occasion arise without causing any material increase "in blade pitch.

Since arm 13 is atorque responsive element as well as a blade pitch limiting element, it can be used to perform two different functions. Since this arm l3is moved in an upward direction with a decrease in blade pitch and downward with increase in blade pitch, it not only will move the control valve 39 into neutral position when the blades reach a predetermined pitch angle, stopping the blade moving rotor Him, but it will also at the same time actuate the control valve 9| to motor 93 simultaneously, when a drop in propeller torque causes the governor to increase the blade pitch to a predetermined angle limit.

Arm 13 thus being able to increase the number of engine and propeller R. P. M. commensurate with drop in propeller torque, together with the blades being allowed to advance one or more degrees above normal blade pitch, will so fully reload the propeller that the number of engine R. P. M. will be automatically reduced enough so that the governor will move the motor control valve 39 in a direction to reduce the blade pitch, which action in turn will move arm l3 away from lever .I 18, allowing spring I2l to cut the source of power to stop motor 93 as soon as propeller torque value is fully restored to normal.

When the correct presetting of arm '13 is once established for normal still air operation, and it is found that this setting does not cause operation of motor 93, then when it is found that wind of any appreciable velocity will cause operation of motor 93, and when it is found that the increase in engine throttle will be increased in proportion to Wind velocity, or until propeller torque value is fully restored before motor 93 will be automatically stopped, such a performance should be proof enough of the entire theory.

The above operation is based upon horizontal flight, as this appears necessary to establish a dependable working basis. However, angles of flight from horizontal will largely take care of themselves as, for instance, in climbingat any particular angle the governor is left free to reduce the blade pitch in accordance with ship drag and propeller torque action upon the engine, and if the plane is nosed downward into a more or less steep dive or glide, and the pilot does not care touse the propeller as a brake against plane velocity, he can move arm 13 upward toward full feathering pitch position, and maintain a blade pitch commensurate with plane velocity, by propeller torque and windmill action.

Rod H18 interconnecting lever H2 and lever 54 will be found especially advantageous for maintainingthe correct blade pitch, where the pilot finds it necessary to increase the number of engine and propeller R. P. M. suddenly for any reason.

Rod ms connects throttle lever H2 and governorxlever 55. While this arrangement will serve as an .aid to the pilot for quickly adjusting the number of engineR. P. M. with the manual means shown in Figure 5, it should be employed in conjunction with an adjustable blade pitch limiting means substantially as shown. If the latter is not employed in connection therewith, and the pilot fails to increase the number of engine R. P. M. promptly and commensurate with wind velocity when the latter causes a drop in propeller torque, the governor will operate to increase the blade pitch out ofcoordination with ship drag resistanca'and whereby the latter, together with 14 plane velocity, will drop below a value com mensurate with the maintenance of a safe, predetermined rate of plane air speed. Where a preadjusted pitch limiting means is provided, the lapse of time necessary for this condition to arise, can be entirely avoided,- at least within safe limits.

Where the cockpit chart shows, or the pilot knows, the extra number of engine and propeller R. P. M. that is required to compensate for, say a ten-mile per hour wind, then where the engine R. P. M. is automatically increased by any given amount by action of the torque responsive element increasing the engine throttle, a pilot can determine wind velocity, as well as plane velocity with respect to a land reference point merely by the extra number of engine R. P. M. required before the torque responsive element automatically moves away from the engine throttle speed increasing means H8.

To more fully explain the operation of the various parts, when a plane is flying at a rate above normal cruising speed, arm 13, throttle lever I34, valve H3, rod H38 and nut I09 will all have positions corresponding to the number of engine R. P. M. employed, which will leave nut I09 in a position to the left of lug' till, leaving a gap between the latter and nut I09. Therefore, if screw Ill-l is designed to cause an increase in engine R. P. M. from a given base value to the R. P. M.'employed at normal cruisingspeed, it

Will not be long enough to span this gap, andwill be unable to cause any increase in number of engine R. P. M., above that obtained by the first mentioned throttle setting.

It is-when flying at a low altitude, low crusiing speed and "a basic low number of engine R. P. M., that screw it and motor 93 are intended to operate as asafety factor, when the above mentioned parts will have positions corresponding to those shown in the drawings. Under which condition the pilot will snap plunger 122 into operative position, and move arm 13 downward to reduce the gap between these parts, and spool '19 and lever H8, and thus avoid having the blades being jumped out of coordination with plane velocity, and to insure an increase in the number of engine R. P. M., the instant it is required for maintaining a safe predetermined rate of plane velocity, to compensate for drops in propeller torque, due to any appreciable change in the rate and direction in movement of the air medium, and thereby insuring a rate of plane velocity, equal in value to the planes minimumrate of air speed. Nut H can be adjusted with respect to arm 35 and pilot valve 39 to alter the point of low,. or reverse blade pitch at which'arm 35 will move valve 39 into neutral position, and by means of lever 88 valve 39 can be moved into position for reversing the rotor was until the blades aremoved through neutral pitch and on into reverse pitch angle of attack for the purpose of using the engine and propeller as a brake in slowing down plane velocity during landings, using brake 89 to maintain said pitch position against the action of the governor regardless of the number ofpropeller R. P. M.

To avoid any misconception about the mechanism being fully operative within perfectly safe limits to the extent intended, it is believed a detailed description of the different methods of operationis advisable.

First, this mechanism is believed to beef special importance where employed in conjunction with an automatic pilot for holding a plane in substantial .level flight, and which condition is intended to prevail in the following explanations.

Second, it is intended to Operate to maintain a predetermined rate of plane velocity with respect to a, given land reference point, equal in value to the ,planes minimum rate of air speed. Unless means is provided to accomplish this purpose under the above mentioned level flight conditions, in the lower ranges of cruising speeds, the plane is quite apt to be inadvertently converted more or less into a glider by movement of the air medium, and its efiect upon plane velocity, which condition might not be easily discernible by the pilot, is a matter which should not be overlooked, since a glider with insuflicient or no engine power .is not believed adaptable for control by means of an automatic pilot for obvious reasons. ,Since head wind velocity will have a definite bearing upon the predetermined rate of plane velocity, the latter is believed to be -a safety factor of utmost importance, and an object of the invention, which has not heretofore been fully brought out, :nor given the attention it deserves.

A very important function resides in the mechanism comprising rod I08 and nut H! for operatively interconnecting bell crank arms 53 and 54 with lever H2 and throttle valve H3 for properly changing the compression on spring ll, whereby a properly balanced relationship can be maintained between the governor and any particular number of engine R. P. .M. resulting from movement of said rod I08, and whereby the number of engine R. P. M. can be changed from one rate of constant speed to another without disturbing the above mentioned balanced relationship. For the purpose of future reference this mechanism is identified by the letter W.

Propeller torque actionupon the above mechanism will cause the governor to operate motor Iflmin .either direction or to stop same as required to maintain the desired balance relationship and coordination between blade pitch and plane velocity and ship drag requirements, regardless of the number of engine R. P. M. employed, provided motor 93 is operated to actuate throttle H3 substantially fast enough to compensate for any quick drops in propeller torque as fast as they 'become set up. 'The importance of the latter will be observed in the following cases.

First assuming that the above-mentioned mechanism W is properly adjusted to produce satisfactory results in still air operation, then when planes are flying at comparatively low cruising speeds and altitudes, with the number of engine R. P. M. just sufficient to maintain a plane velocity at a rate safely above the planes mini-mum rate of air speed in still air operation, the advantages to be gained tending towards safety and economical operation will readily become .apparent.

To avoid unnecessary hunting by the governor, the :main automatic control resides in the bell crank arms '53 and 54 that are pivoted at 55. Provided these arms are of suitable lengths, their constant relat'ionshipfor coordinating the tension of spring 41 commensurate with any reciprocal movement of elements I08 and H2, will tend to constantly maintain a balanced relationship between the number of engine R. P. M. and the governor, which relationship is very important if the governor is to move valve 3.9 for operating motor l or to either decrease or increase-the blade pitch in accordance with any slight variations in torque value upon the engine, as .it should do under constant speed-control.

With careful adjustment of nut l I! along element I 08 for loading the governor and in turn the engine as desired, this mechanism will, undersubstantially still air flying conditions, with the craft at constant attitude, or in horizontal flight, cause the governor to operate motor [01: to alter the blade pitch back andfor-th in accordance with variations in torque, and will thus control the blade pitch within predetermined limits determined by the setting of adjustable arm 13, when the latter is preset fora given plan of flight. The movement of valve 39 into neutral position by means of rod 3|, and adjustable arm 13 to stop motor i002, thus limiting the blade pitch, simultaneously as arm 13 causes operation of motor 93 to increase the number of engine R. P. M., when arm l3 reaches a predetermined position, will bring both of these auxiliary automatic controls under the influence and direction of movement of rod 3| and arm 13, and since the movement of these twoelements are controlled by the governor, valve 39 and motor .93, will likewise be controlled by the governor.

Opening of the throttle valve increases the power (in order to overcome the greater drag on the craft due to a head wind, or the like, without :unduly lessening the air speed), which power must be absorbed by the propeller, and since the power is dependent on the product of the rotational speed of the propeller and the torque (or blade pitch) on the propeller, a sufiicient increase in the rotational speed is provided for by the automatic setting of the governor bell crank arms 53 and '54 to prevent excessive and mutual hunting of the governor and the two auxiliary controls.

Since the governor control-led arm 13, is adjustable during propeller operation, it will enable the pilot to obtain the optimum blade pitch in combination with a given increase in number of engine R. P. M., and thus prevent any unnecessary hunting by the govern-or, said arm 13 being gradually moved to a more advanced position as required to permit the governor to increase the blade pitch with any increase in the rate of plane velocity, and thus avoid unnecessary hunting.

Where a plane is traveling at a comparatively high rate of velocity, therewill be less chance of plane-air speed dropping below the planes minimum requirements, for such a high rate of plane velocity can absorb a certain amount of wind velocity without reducing plane velocity below the planes minimum rate of air speed.

If we figure :the lapse of time in which any given loss in plane velocity might become set up, and treat said lapse of timeas an unknown factor, then we must come to the conclusion that the extent of any resulting loss in plane velocityland air speed within a corresponding lapse of time will also become an unknown factor, and hazard, especially at low altitudes and reduced rates of engine R. P. .and plane air speed.

Radio reports, while important, cannot predict in :advancethe exact time, place .or lapse of time during which such a hazard will become set up. A propeller torque responsive mechanism mounted for :automaticallyractuating the engine throttle when these causes produce a drop in propeller torque action "will compensate for such hazards the very first instant they occur. Otherwise such hazards will remain a continual threat to safety and progress in heavier than air flight, and such threat will .stand as a challenge to the most experienced pilot to use commensurate corrective measures beforeit is too late. It will be 17 seen that even with an air speed as high as 140 R. P. M. planes may not be entirely safe from such hazards, depending a lot of course upon altitude,

to say nothing about shifting winds of higher velocity and the economical factors involved where high landing speeds are resorted to. Hence the need for some such automatic safety means as disclosed.

Any manual means such as shown in Figure 5 may, of course, be used for increasing the number of engine R. P. M. instead of the automatically actuated means. However, where a plane is flying at some predetermined low engine R. P. M. and rate of plane air speed, at a low altitude, where any material drop in plane air speed might result in mishap, it is believed that said automatic means will have the advantage of avoiding guess work, carelessness and lapse of time before increasing the number of engine R. P. M.the instant it is required, and which would be comparable to the timely operation of any automatic gear shift.

Duringhorizontal flight conditions it is well to keep in mind, that ship drag resistance at any given plane air speed will be of the same value flyinginto a head wind as when flying in still air operation. y

Even though a head wind willslow down'plane velocity, and will substitute its velocity to take the place of plane velocity, no change will take place in ship drag resistance as long as plane air speed is maintained. Since this isso, then provided a correct blade pitch angle of attach for a given ship drag resistance has any significance, it should be at the same pitch angle in either case, in order to maintain plane velocity to a valve substantially equal to the planes minimum rate of air speed against the head wind, otherwise a safe rate of plane velocity will not be maintained.

It is wrong to allow a drop in propeller torque due to wind, to cause the governor to increase the blade pitch as the wind automatically slows down plane velocity, unless such is done in moderation andto a limited extent only. In still air operation, the blade pitch will increase with increase in plane velocity, and the pitch will decrease with a decrease in plane velocity. It is important to compare the direction of blade movement in the latter case with the direction of blade movement under a head wind operation, in which case, unless the blade pitch is limited to a predetermined value,the pitch will increase as plane velocity is decreased by the force of the wind. It will be seen that the direction of blade movement will b just opposite to the direction of blade movement in the still air operation, and by such change in direction of blade movement it can be seen how a drop in propeller torque due to wind will set up a wide disparity in blade pitch with respect to plane velocity and ship drag.

Since the head wind will cause no decrease in ship drag resistance provided plane air speed is maintained, it will be seen how inconsistent it is to allow the governor to increase the blade pitch materially, or more than enough to perform the additional function of automatically increasing the number of engine R.P. M. to a higher constant speed rate, when the blades reach a predetermined pitch angle limit, thereby restoring pro-' peller thrust and torque to a value commensurate with ship drag resistance by increasing the rate of blade hitting speed relative to the moving air medium. Thus maintaining a safe rate of plane velocity with respect to a land reference point,

a safe width by means of lever 11, the pilot can control the functions mentionedin the correct proportions as desired, according to altitude, plane air speed, engine performance, etc., as flight conditions seem to dictate in the interests of safety.

The pilot should be cautioned to guard against an extreme width of gap between the above identified members as during horizontal flight, otherwise a condition will exist as with a nonadjustable maximum "pitch limiting means during flight,

in which a drop in propeller torque value upon the engine due to wind will cause the governor to increase or jump the blade pitch until torque is fully restored, or until the maximum pitchlimiting means becomes effective, which as explained may result in ablade pitch and thrust efficiency Way out of coordination with ship drag resistance, causing serious engine overload and automatic loss in plane velocity and air speed.

Even in a tail wind, where the lost motion gap is too wide, a drop in propeller torque may cause an increase or jump in blade pitch so wide as to absorb a large percentage of the engine power by torque resistance, when more of this power should be applied to propellerthrust action for maintaining plane velocity, which is synonymous with air speed and calls for first consideration. This order of operation is important, since the governor cannot move the blades to occupy two different thrust positions at the same instant.

In view of th foregoing, if ship dragresistance commensurate with maintaining a given rate of plane air speed calls for a given blade thrust position, and a drop in propellertorque upon the engine due to wind calls foran entirely different blade thrust position to furnish propeller torque upon the engine, it can be seen how the governor will be caught between two entirely different demands, only one of which can be taken care of at a time. Since plane air speed and ship drag resistance is of paramount importance, and in the interests of safety, demands that the blade pitch shallnot be materially'altered. Then where a drop in propeller torque due to wind demands an increase in blade pitch to restore propeller torque upon a the engine, we are confronted with a decision of whichdemand shall be taken care of. Both demands'cannot be taken care of simultaneously by merely altering the blade pitch. The drop in propeller torque must be taken care of in someother way.

Where it is found that Wind causes the governor to increase the blade pitch for restoring propeller torque, we must come to the conclusion that this drop in torque due to windmill action, is caused in the first place by a drop in the relative rate of blade hitting speed with respect to the moving air, and since the blade pitch should not be materially increased when there is no change in ship drag resistance as mentioned above, then we come to the final conclusion that an increase inthe number of engine R. P. M. suflicient to restore propeller torque and thrust value is the only safe solution. If this is not done promptly, propeller torque and thrust value will remain below normal value, causing plane velocity and airspeed to automatically -drop accordingly, and the various factors cannot be maintained in coordinated relationship with respect to each otherfonmaintaining a predetermined safe rate of plane velocity and air speed.

Windmill action due to a head wind W111 persist at a value commensurate with wind velocity portion of the plane velocity to windvelocity, and

,planeair speed will drop in the same proportion. Thus, with the safety mechanism disclosed, it

wi l be p ss ble t f y at fa s ds s ht y ov safe minimum air speedreguirements for still air on ra ionta s o a ma a in r a e tho i mba o en ne a d p o e ler R. P. omm

rate with the rate and direction of movement of the ai ed. um o ub tantially mai a n n normal propeller torque and plane velocity regardless of wind conditions, all or which appears to be in line with the laws ior generating forces :by respective rates of relative movements.

I-Iowevertheabove is provided, the engine has then'ecessary available number of B. ;P. M. above th t em o d fo main a n n minimum ai peed w t wh h t om ens t for wind and to ma n in a lane ve c t e ual to min um ai speed, otherwise, pilot control must be resumed in time to take advantage of the law of gravity to n iplane e o t and airspeed where -r.e-'

guired to avoid .a forced landing.

he foregoing appears especially significant, since all planes regardless of size and speed, must resort to areduced number of engineand propeller R, P. M. and rate of plane velocity during periods of approach, befor the final lap and glide to a landing field.

When pilots speak of their plane hittin an air p ck t and d ppi se a hu red fee t i pointedcut that similar drops in altitude may be due ,to conditions described herein. When ,such drops ,occur at low altitudes, occasional accidents are bound to result, unless wind velocity, and shifts in direction with respect to the plane are compensated for immediately and without delay, otherwise plane velocity will not be maintained at a ratein certain instances that is substantially equal .to minimum plane air speed.

Having described the invention what is claimed as n i? 1. In a device of the class described, in combination, a propeller having blades mounted for pitch adjustment, means comprising an engine for rotating the propeller, means for changing the speed and power of the engine, including :a throttle valve in the fuel supply of the engine, means comprising a motor for changing the blade pitch, control means for the motor, a governor mechanism for actuating the control means in accordance with propeller speed, means for automatically actuating the control means tostop the motor against the action of the governor when the pitch angle of :the blades has been increased to a predetermined limit, means for automatically moving'the engine throttle valve to increase'the number of engine R. P. M. when the blades reach said predetermined pitch angle, means responsive gtO- movement .of said governor to conform to the .change ,in number of engine R. P. M., and means operable by the operator for changing the effective position of said blade pitch angle limit =during propeller operation,

2. In a device of the class described, in .com- ,bination, a propeller having blades mounted for pitch adjustment, means comprising an engine for rotating the propeller, means for changing the speed and power of the engine, including a throttle valve in the fuel supply of the engine, means comprisinga motor for altering the blade pitch, control means for the motor, a governor mechanism for actuating the control means for the motor, a governor mechanism for actuating .the control means in accordance with propeller sp-eed, means for automatically actuating-the control means to stop the motor, against the action of the governor, when the pitch angle of the blades have been increased to a predetermined pitch ,;m 1s c mp s ng a se ond mot means for automatically operating said second motor to increase the engine throttle valve opening when a drop in' propeller torque value upon the engine causes the blades to reach said predetermined pitch angle, means responsive to and commensurate with throttle valve movement for automatically changing the operative characteristics of the speed responsive governor ,to conform to the change in number of engine R. P. and means operable by the operator {for changing the operative position of said predetermined vpitchangle during propeller operation.

3. In a device of the class described, in combination, a propeller having blades mounted for pitch adjustment, means comprising an engine for rotating th propeller, .a throttle valve in the fuel supply of the engine for changing its speed and power, means comprising a speed responsive, governor controlled motor for automatically changing the pitch of the blades in response :to propeller torque "resistance, automatic means for stopping theblade moving motor against the action of the governor, when the blades reach a predetermined pitch angle, means operable by the operator for changing said predetermined pitch angle during propeller operation, means for moving the throttle valve, and means responsive to throttle valve movement interposed between the speed responsive mechanism and the throtfile valve for stabilizing the operative characteristics of the speed responsive mechanism :to conform to the various positions of the throttle valve and changes in number vof engine R. P. M.

4. In a ,device of .theflclassdescribed, in combination, a propeller having :blades mounted for pitch adjustment, means comprising. an engine for rotating the propeller, means for changing the speed and power of the engine, including a throttle valve in the fuel supply of the engine, means comprising a speed responsive, governor controlled motor forlautom-atically' changing the pitch of rhea-blades in responseto. propeller torque resistance, means for operating the throttle valve, automatic means for. limiting the blade pitch to a predetermined anglev against the action of the governor, when the blades reach said predetermined pitch angle sald governor being provided with vcentrifugalweights, means for loading said weights, and means movable commensurate with throttle valve. movement :Ior changing the load value upon said weights toconform to change in the-number of engine R; P. M. for -maintaining 217 a substantially constant balanced relationship between said governor and number of engine R. P. in coordination with throttle valve movement, and means operable by the operator for changing said efiective predetermined blade pitch angle during propeller operation.

5. In a device of the class described, in combination, a propeller having blades mounted for pitch adjustment, means comprising an engine for rotating the propeller, means for changing the speed and power of the engine, including a throttle, valve in the fuel supply of the engine, means comprising a blade moving motor and a throttlemoving motor, control means for each motor, a speed responsive governor for controlling the operation of said motors in accordance with propeller speed and torque value upon the engine, automatic means for actuating the control means of said blade moving motor to stop the latter against the action of the governor, and for starting said throttle moving motor when th blades reach a predetermined pitch angle, means responsive to said throttle valve movement for automatically changing the operative characteristics of the speed responsive governor to conform with the change in number of engine R. P. M. in accordance with throttle valve movement, and means operable by the operator for changing said operative predetermined blade pitch angle during propeller operation.

6. In a device of the class described, in combination, a propeller having blades mounted for pitch adjustment, an engine connected with the propeller for rotating it, means for controlling the speed and the power of the engine, including a throttle valve, a motor for changing the blade pitch, control means for the motor, a governor for actuating the control means in accordance with propeller speed, means comprising a blade pitch responsive member for stopping the motor against the action of the governor, when a drop in propeller torque value upon the engine causes the governor to increase the blade pitch to a predetermined pitch angle limit, means for moving the engine throttle valve, means comprising an element responsive to and commensurate with throttle valve movement for automatically changing the operative characteristics of the speed responsive governor to conform with the change in numb-er of engine R. P. M., whereby the governor will operate to decrease the blade pitch, when propeller torque action upon the en gine reaches a point above mean value, and means operable by the operator for changing the predetermined pitch angle limit during propeller operation.

7. In a device of the class described, in combination, a propeller having blades mounted for pitch adjustment, an engine operatively connected with the propeller for rotating it, means for controlling the speed and power of the engine to include a throttle valve, a motor for altering the blade pitch, a source of power for the motor, control means for the latter, a speed responsive governor operatively associated therewith for normally altering the blade pitch in response to variations in propeller speed, said control means including means comprising a power cutout element mounted for automatic actuation, when the blades reach a predetermined pitch angle, means comprising a blade pitch responsive element for actuating said cutout element to render the motor and governor ineffective to move the blades beyond said predetermined pitch angle, means operable by the operator as the propeller operates for changing the blade pitch angle at which said cutout element will be actuated, means for moving the engine throttle valve, and means responsive to said throttle valve movement for automatically changing the operative characteristics of the governor to conform to the change in number of engine and propeller R. P. M.

8. In a device of the class described, in combination, a propeller having blades mounted for pitch adjustment, an engine operatively connected with the propeller for rotating it, means comprising a motor for altering the blade pitch, means for controllingthe operation of the motor, a governor, responsive to the speedof the engine and operatively associated with the motor control means, for changing the blade pitch in accordance with engine speed, automatic means for stopping the motor against the action of the governor, when the blades reach a predetermined pitch angle, said governor being provided with centrifugal weights, means comprising a spring for loading said weights against the action of centrifugal force acting upon them, a throttle valve in the engine fuel supply, means for automatically moving the throttle to change the engine power when the blades reach said predetermined pitch angle, means comprising a throttle valve responsive element interposed between said governor sprin and throttle valve for altering the compression upon said spring commensurate with throttle valve movement, for changing the load value of said spring upon said weights to provide for a change in number of engine R. P. M., substantially in accordance with throttle valve movement, and means operable by the operator for changing the effective predetermined blade pitch angle during propeller operation.

9. In a propeller mechanism adapted to automatically maintain a predetermined rate of plane velocity, substantially equal to the planes minimum rate of air speed, comprising, in combination, a propeller having blades mounted for pitch adjustment, means comprising anengine for rotating the propeller, means for changing the speed and power of the engine, including a throttle valve in the fuel supply of the engine, means comprising a motor for changing the blade pitch, control means for the motor, a governor mechanism for actuating the control means in accordance with propeller speed, means for automatically actuating the control means to stop the motor against the action of the governor when the pitch angle of the blades has increased to a predetermined pitch angle, means for automatically moving the engine throttle valve to increase the number of engine R. P. M. whenthe blades reach said predetermined pitch angle, means responsive to movement of said throttle valve for automatically changing the operative characteristics of the speed responsive governor to conform to the change in number of engine R. P. M., and means operable by the operator for changing the effective position of said predetermined blade pitch angle during propeller operation.

10. In a propeller mechanism adapted to automatically maintain a predetermined rate of craft velocity, substantially equal to the crafts minimum rate of air speed, comprising in combination, a propeller having blades mounted for pitch adjustment, means comprising an engine for rotating the propeller, means for changing the speed and power of the engine, including a throttle valve in the fuel supply of the engine, means comprising a motor for changing the 'blade pitch, control means for the motor, a governor mechanisrrr foractuating. the .contrormeans in accordance withzpropeller speed, means comprising an indicator mounted for movement in response to craft resistancezto flight for automatically actuating the motor control means to stop the motor against the action of thetgovernor, and foriauomatically moving the throttle valvecontrol means to increase the enginepower, when said indicator reaches a.predetermined position with respect to saidcontrol means,means responsive to throttle valve movement for automatically changing the operative characteristics of the speed responsive governor to provide for a change in the number of engine R, P. M., and, means operable by the operator during propeller operation for changing the ,efiectivepredetermined position of saidindicator with respect to said control means.

. DANIEL G. LIILE-Y.

REFERENCES CITED The following references are of record in the file-of this patent:

UNITED STATES PATENTS

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