US2337861A - Propeller - Google Patents

Description

m. 28, 1943. M. T. ADAMTCHIK 2,337,861

PROPELLER Filed April 25, 1942 5 Sheets-Sheet 1 INVENTOR yqlch qel Thuddws Adomrc hik A44 ATTORNEY DH; 28,, 1943. M, ADAMTCHIK 2337 861 PROPELLER Filed April 25, 1942 5 Sheets-Sheet 2 M. T. ADAMTCHIK 2,337,

PROPELLER Filed April 25, .1942 5 Sheets-Sheet 3 Michael Thadd'ws AdonrficHK M. T. ADAMTCHIK PROPELLER Filed April 25, 1.942 5 Sheets-Sheet 4 M {chad Thodehb 5 Admwckik \NVEN g @m. 28, 1943. M, T. ADAMTCHlK PROPELLER Filed April 25, 1942 5 Sheets-Sheet 5 \m m M LI mm M .T .N A L WW m m QM Q mama Dec. 1943 U'NirEo STATES PATENT orgies PROPELLER Michael Thaddius Adamtchik, Saltdean, England, assignor of one-half to James Russell Kennedy, Belsize Park, London, England Application April 25, 1942, Serial No. 440,498 In Great Britain February 4, 1941 6 Claims.

' used in conjunction with a screw propeller enables the latter .to'operate at its maximum emciency throughout its entire range of operation.

In order toachieve this result various arrangements have been used hitherto. One arrangement, generally known as a variable pitch propeller, is based on changing the ratio 'of the mean geometrical pitch of the propeller relatively to its diameter.- This arrangement, however, has the disadvantage that it is complicated, by reason of the necessity of I pivoting the blades under a load produced by the centrifugal force acting on the blades, an excessive effort is required to pivot the blades, and the efficiency. is low when the ratio of the geometrical pitch to the diameter of the blade is small.

Another known method is to provide the. screw propeller withflxed or adjustable vanes for imparting to the ingoing fluid a counterswirl substantially in excess to the circumferential drag of the impeller. Under these conditions the coefllcient of the load of a given propeller increases by reason of the increase of the rotational momentum. However the conditions only obtain at the commencement of the propeller operation and no provision is made for obtaining suitable conditions at cruising or maximum speeds.

In a thirdknown arrangement adjustable inlet guide vanes of symmetrical aerofoil section The real purpose of inlet guide vanes in an' aerodynamic sense is to produce an alteration in the circulation of the fluid around the pro-.

peller blades, the circulation" being the expression IV cos 0 ds, where V=the velocity around an aerofoil; 0=the angle between the path around the aerofoil and the path of movement of the air, andds=an element of the path.

It is known that the blades of a screw propeller may be designed either for aconstant circulation or for a variable "circulation."

Investigations have shown that adjustable or fixed inlet guide vanes at present in use are not capable of producing variations in the circulation" which are comparable with those produced by variable pitch propellers'as-only a small increase in the circulation is obtained by the use of negative angles of pivoting .of about 10 to 15, the "circulation decreasing'when the angle of pivoting is increased beyond these values. This is due to the use of symmetrical aerofoils which produce a variation of the circulation which is not directly proportional along the blade. g

It has now been foundthat in order to obtain the maximum efliciency at every position of the inlet guide vanes it is necessary to produce an increment in the circulationfi either negative or positive, which is proportional to the basic variations in the circulation along the blade. This implies the use of stationary inlet guide vanes having a variable pitch and a variable camber of aerofoil section. V

The present invention obviates the disadvantages of the known arrangements referred to above. 4

According to the present invention a number of flexible preferably hollow vanes or variable pitch and variable camber arearranged to be pivotally mounted in a stationary position, relatively to a screw propeller, so as to enable them to be set at a positive or negative angle.- The setting angle is preferably variable to a maximum amount of :20% from the neutral position for high efllciency. When efllciency is not of primary importance the angle of curvature may be greater. The vanes may be constructed of stainless sheet steel of high elasticity or of'other suitable material, for example canvas. The vanes are preferably constructed in sections arranged in close fitting overlapping relationship along the length of the vane so as to assume the various required positions. 1

Preferably the number of vanes is greater by one than the number of propeller blades so as to to the circulation avoid sound interference between the blades and vanes. The vanes are preferably mounted be-' tween a central hub and an outer casing member so as to form a self-contained unit applicable to any type or engine in a stationary manner. Means are also provided for varying the position of the vanes simultaneously.

The invention will now be described by way of example to the accompanying drawings, wherein:

Figure 1 is a partial sectional elevation on the line I-I of Figure 2, I

Figure 2 is an end elevation of a screw propeller provided with a regulating device according to the invention,

Fig. 3 shows to a larger scale a sectional plan of a vane with its governor plate in the neutral position.

Figs. 4 and 5 show similar views to Fig. 3 with the governor plate in its rearward and forward positions respectively.

Fig. 6 shows a diagrammatic plan view to the same scale as Fig. 1 indicating the position of the upper end of the vane with the governor plate in the positions shown in Figs. 3 to 4,

Figure 7 is an end elevation of a screw imp ller or pump,

Figure 8 is a section on ure 7,

Figure 9 is a partial section on the line 9-9 of Figure 7,

Figures 10 and 11 show details.

Referring first to Figures 1 to 6 showing an example of construction as applied to an aircraft engine, the apparatus consists of a central streamlined boss I which is shaped to correspond with the adjacent aircraft or engin'e frame 2 to which it is to be attached. Arranged inspaced relation to the boss I is a circular outer casing member 3 of streamline shape which may extend over the propeller blades 4 with slight clearance 5. The outer casing member 3 is preferably of material sold under the registered trade-mark Duralumin and in cross section resembles a. hollow aerofoil of which the outer side 6 is formed of sheeting.

In the hub I and casing 3 there are mounted uniformly spaced shafts I on which sleeves 8 are rotatably mounted. On each of these sleeves 8 is mounted at about its leading edge III a hollow vane 9 of aerofoil cross section. These vanes are of stainless steel of high elasticity or other strong material. Preferably each vane 9 consists of a number of sections arranged side by side along the length of the vane and slightly overlapping one another.

Intermediate the leading and trailing edges III, II of each vane 9, preferably nearer to the trailing edge II, a second shaft I2 passes through the vane 9 parallel to the first shaft I. Around the shaft I2 is fitted a sleeve I8.

Around the boss I there is mounted concentrically a casing member I3 which is secured positively to the boss I. The shafts 'I, I2 and sleeves 8 and I8, pass through thi casing member I3 whilst the first shaft 1 is secured to the boss I. The shaft I2, with its sleeve I8, passes through a suitably shaped slot in the casing I3. To the lower end of the sleeve 8, inside the space between the casing member I3 and the boss I, there is secured a lever I4 having a short slot the line 88 of- Fig- I5 (Figs. 3, 4 and 5) for the reception of the lower end of the second shaft I2 and its sleeve I8. Between the two shafts I, I2, the lever I4 carries a guide pin I8, whilst a guide pin I1 is connected freely to the lower end of the sleeve I8 above the lever I4. To the lower end of the sleeve I8 is secured a guide pin I9. The guide pins I6, I9, I'I engage with slots 20, 2|, 22 in a governor plate 23 (Figs. 3, 4, 5) slidably mounted on the boss I. The guide pin I6 on the lever I4 engages with the slot 20, the guide pin I9 on the sleeve I8 with the slot 22 and the guide pin I9 with the slot 2I.

The slots 20, 2I, 22 in the governor plate 23 are so arranged that when the governor plate 23 is moved from the neutral position shown in Fig. 3 into the position shown in Fig. 4, the vane 9 is moved from the position shown in Fig. 3 to that shown in Fig. 4.

During this movement of the governor plate 23 the pin I6 moves along the slot 20 about the shaft 1 with the axis of this shaft as centre of rotation. This rotary movement of the pin I6 is followed by the lever I4. The slot 2I is made of such a'shape that the pin I9 at the end of the sleeve I8 is caused to lag relatively to the pin I8 so that the sleeve I8 and shaft I2 are tilted from the lower end thereof outwardly, that is to say towards the bottom of Fig. 4, the slot I5 being of sufiicient size to permit of this tilting.

The tilting movement of the shaft I2 and sleeve I8 is assisted by the action of the pin H, which turns on the sleeve I8, whilst moving along its slot 22 which latter is so arranged as to cause the pin II to move in advance of the pin I9.

By this arrangement of the pins I8, I9, I! and slots 28, 2I and 22 the pitch and camber of the vane 9 are varied in one direction.

By moving the governor plate 23 from the position shown in Fig. 3 into the position shown in Fig. 5 the pins IS, I9, I! and the slots 20, 2I and 22 serve to vary the pitch and camber of the vane 9 in the opposite direction to that described with reference to Figs. 3 and 4.

Fig. 6 shows the outer end of the vane in the full line position indicated at 9 when the root end of the vane is in the position shown in Fig. 3, in the chain dotted position 9' when the root end of the vane is in the position shown in Fig. 4, and in the chain dotted position 9" when the root end of the vane is in the position hown in Fig. 5.

By means of the arrangement described with reference to Figs. 4 to 6 the curvature and geometrical pitch of the vanes can be varied as may be devised so as to vary the circulation.

The governor plate 23 is guided during its movement by a block 23 which engages with a slot 23" in the forward end of the governor plate 23.

The governor plate 23 can be moved manually, hydraulically, mechanically, pneumatically, electrically or in any other suitable manner.

As will be appreciated a separate governor plate 23 is provided for each vane 9, the separate plates 23 being coupled together in any suitable manner so as to operate in synchronism.

The plate 23 is preferably brought into the neutral position (Fig. 3) for a cruising speed which determines the most suitable ratio of the geometrical pitch to the diameter of the propeller for the design of the latter.

For taking off there are used the negative angles of pivoting and for maximum speed the positive angles of pivoting.

When the governor plate 23 is in the neutral position the centres of the guide pins I6, I9, II are all in alignment with the central plane of the vane 9 as shown in Fig. 3.

By making the hub I hollow the apparatus can be arranged in front of a hollow propeller hub 24 without interfering with firing through the propeller hub 24. i

As the huh I is stationary the application of de-icing arrangements is facihtated.

Provision may also be made for circulating heated air through the shafts I, I2, which are hollow, and shroud I3 for preventing the formation of ice.

Referring now to Figures 7 to 9 which show the invention applied to an impeller fan or pump,

ing 43.

the mechanism for varying the pitch and camber of the vanes is mounted inside a casing 25 connected by radial webs 26 to an outer housing 21. As the housing 27 is not spaced a considerable distance from the casing 25 a shaft 28, to which a vane 29 is secured near its leading edge, passes at one end through the casing 25 and a frame member 30, secured to the casing 25, whilst its other end is free.

Near its trailing edge the vane 29 is secured to a shaft 3| provided at its inner end with a ball 32 engaging with a corresponding seating at the inner end of a suitably shaped slot, in the casing 25. From the bal132 there extends inwardly a spindle 33 which passes through an arcuate slot 34 in the frame member 30.

To the inner end of the shaft 28, inside the frame member 30, is secured a lever 35 which is provided with a slot 36 with which the inner end of the spindle 33 engages.

To the shaft 28 is also secured an arm 31, whilst an arm 38 is secured to the spindle 33. The arms 31, 38 are connected together by a link 39 which engages with the arms by ball joints.

The levers 35 for actuating the separate vanes 29 are each provided with a pin 40. These pins 40 engage with a floating ring 4| which can be actuated manually, hydraulically, mechanically,

pneumatically, electrically or in any other suit-- able manner. By the rotation of the ring M in a clockwise direction the pitch and camber of the vanes 29 are varied whilst the vane is also twisted into an aerofoil of different curvature.

Thus assuming that the parts are in the position shown in Figs. 8 and 9 and the ring 4i is turned in a clockwise direction the lever 35 and thus also the shaft 28 are rocked in an anticlockwise direction Fig. 9. The shaft 3| thus moves in a direction through the drawing, whilst the spindle 33 moves away from the drawing (Fig. 8) (upwardly Fig. 9) whilst moving along the slot 36 in the lever 35. As a result-of the connection of the arms 31, 38 by. the link 39 the vane is also twisted.

With the arrangement shown in Figs. 8 and 9 the pitch of the vane 29 can only be varied in the'direction as above described, the vane 29 assuming substantially the position of the vane 3 as above described with reference to Figs. and 6. a

The impeller is indicated at 42 whilst its driving motor is indicated at 43.

If desired -a further set of vanes may be arranged behind the impeller 42.

Brackets 44 serve to support the motor cas- As shown in Figure lfl a vane 45 is hollow whilst the portions of theshafts 46, 41- which pass therethrough are of oval or elliptical cross section.

In Figure 11 a vane 48 is formed of a single layer of material of which one end is looped 1. In apparatus for the purpose described, the combination with a screw propeller of a plurality of flexible vanes, each of said vanes having a leading edge and a trailing edge, a plurality of shafts mounted in a stationary position relatively to said propeller, one shaft being associated with each vane, each of said shafts extending parallel to the leading edge of its corresponding vane and being located towards said leading edge, a plurality of a second series of shafts'said second series of shafts being associated one with each of said vanes and being located parallel to and towards the trailing'edge of its associated vane, and mechanism operatively associated with said second series of shafts, said mechanism serving to rock the said second series of shafts relatively to the first series of shafts so as to vary the camber of said vanes at their trailing edge.

2. In apparatus for the purpose described, the combination with a screw propeller of a plurality of flexible vanes, each of said vanes having a leading edge and a trailing edge, a plurality of shafts mounted in a stationary position relatively to'said propeller, one shaft being associated with each vane, each of said shafts extending parallel to the leading edge of its corresponding vane and being located towards said leading edge, mechanism operatively associated with all of said vanes, said mechanism serving to vary simultaneously the pitch and camber of all the vanes at the same time at a positive or negative angle relatively to said propeller, said mechanism including means for twisting each of said vanes into an aerofoil of different curvature.

3. In apparatus for the purpose described, the combination with a screw propeller of a plurality of flexible vanes, each of said vanes having a leading edge and a trailing edge, a plurality of shafts mounted in a stationary position relatively to said propeller, one shaft being associated with each vane, each of said shafts extending parallel to the leading edge of its corresponding vane and being located towards said leading edge, a second series of shafts, said second series of shafts passing one through each of said vanes and being located parallel to and towards the trailing edge of its associated vanes a plurality of sliding plates corresponding with the number of vanes, a plurality of sleeves located one around each of said shafts, a plurality of pairs of guide pins secured one pair to each sleeve surrounding the second series of shafts, a plurality of levers mounted one on each sleeve surrounding the first series of shafts, a plurality of guide pins secured one to each of said levers, each of said sliding plates having three slots therein, the slot nearest the leading edge being engaged by the guide pin on said lever, whilst the other two slots are engaged by the pair of guide pins on the sleeve of the second series of shafts, each of said levers having a transverse slot near its free end, said transverse slot being engaged by the sleeves of the second series of shafts, the said sliding plates when moved from a neutral position, in which the vanes are also in a neutral position, rocking the second series of shafts, relatively to the first series of shafts so as to vary the pitch and camber simultaneously of all the vanes, whilst at the same time also twisting the separate vanes into an aerofoil of different curvature.

4. In apparatus for the purpose described, the

combination with a screw propeller of a plurality shafts mounted in a stationary position relative- 1y to said propeller, one shaft being associated with each vane, each of said shafts extending parallel to the leading edge of its corresponding vane and being located towards said leading edge, a second series of shafts, said second series of shafts passing one through each of said vanes and being located parallel to and towards the trailing edge of its associated vane, a plurality of levers mounted one on each of said first mentioned shafts each of said levers having a slot therein, a plurality of balls mounted one at the end of each of the shafts of the second series of shafts, seatings for said balls, a plurality of spindles secured one to each of said balls, said spindles engaging said slots, and mechanism operatively associated with said levers, the arrangement being such that when the levers are operated the pitch and camber of all the vanes is varied simultaneously.

5. In apparatus for the purpose described, the combination with a screw propeller of a plurality of flexible vanes, each of said vanes having a leading edge and a trailing edge, a plurality of shafts mounted in a stationary position relatively to said propeller, one shaft being associated with each vane, each of said shafts extending parallel to the leading edge of its corresponding vane and being located towards said leading edge, a plurality of a second series of shafts, said second series of shafts being associated one with each of said vanes and being located parallel to and towards the trailing edge of its associated vane, the portions of all of said shafts passing through said vanes being of elliptical cross section.

6. In apparatus for the purpose described, the combination with a screw propeller of a plurality of flexible vanes, each of said vanes having a leading edge and a trailing edge, a plurality of shafts mounted in a stationary position relatively to said propeller, one shaft being associated with each vane, each of said shafts extending parallel to the leading edge of its corresponding vane and being located towards said leading edge, a plurality of a second series of shafts, said second series of shafts being associated one with each of said vanes and being located parallel to and towards the trailing edge of its associated vane, the portions of said first mentioned shafts being of elliptical cross section, said vanes being of sheet material and havingtheir. leading edges looped around said elliptical portions, said second series of shafts being of as flat a section as possible and being secured to said vones towards their trailing edge.

MICHAEL THADDIU S ADAMTCHIK.

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